Basic Assumptions:
     This paper was written using the following assumptions as a baseline.
     1. Physical laws:
     The laws of physics as we know them still apply. This means that spacecraft move in a Newtonian (or Einsteinian, though this realm is outside the scope of the paper) manner, using reaction drives or other physically-plausible systems (such as solar sails) for propulsion. Thermodynamics dictate that all spacecraft must radiate waste heat, and lasers obey diffraction. The only exception is FTL, which will be included in some scenarios.
     2. Technology:
     The technological background is less constrained. If a system is physically plausible, the engineering details can be ignored, or at most subject to only minor scrutiny. The paper will examine a spectrum of technology backgrounds, but will focus on near to mid-future scenarios, where the general performance and operation of the technology can be predicted with at least a little accuracy. A common term used to describe this era is PMF, which stands for Plausible Mid-Future. This term (coined by Rick Robinson) is difficult to define, but it assumes significant improvements in technologies we have today, such as nuclear-electric drives, fading into those we don’t, such as fusion torches.
     3. Environment:
     This paper will attempt to examine a wide variety of environments in which space combat might occur. However, it will make no attempt to examine all of them, and the scenarios described will conform to several principles.
     First, this is a general theory. Any scenario that is dependent on a one-shot tactic or highly specific circumstance will likely not be included, except during the discussion of the beginnings of space warfare, or to demonstrate why it is impractical in the long run. The recommendations made are not optimal for all circumstances, nor is such a thing possible. They are instead what the author believes would be best for a realistic military based on the likely missions and constraints. Picking highly unlikely and specific sets of circumstances under which they are not optimal is best answered with a quote from the author about one such scenario, posting on the Rocketpunk Manifesto topic Space Warfare XIII: “You need a blockade, a hijacking (innocents aboard a vessel trying to break the blockade), and a high-thrust booster on the hijacked ship. Two stretch the limits of plausibility. The third is ridiculous. Claiming that this justifies humans [onboard warships, see Section 2] is like claiming that because warships sometimes run aground, we should install huge external tires on all of them to help get them off.”
     Second, no attempt will be made to include the effects of aliens or alien technology, because to do so would be sheer uninformed speculation.
     Third, the default scenario, unless otherwise noted, is deep-space combat between two fleets. Other scenarios will be addressed, but will be clearly noted as such.

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The biggest question, of course, is what a realistic space force would look like.  This is perhaps more sensitive than anything else to the beginning tech assumptions, as it is the product of all the tech assumptions made and their interactions, but a large part of the purpose of this paper is as a reference for fiction writers, so as much will be covered as possible.

First and foremost, space forces are not navies, even if they copy the rank structure and traditions of one.  While the vessel type names might be the same, the vessels themselves are not.  They would not be some form of navy, be it that of Trafalgar, Jutland, Midway, or today, IN SPACE!!!  While a number of parallels can be drawn between space warfare and other forms of warfare, the environmental differences mean that all must be closely examined.  On a broad strategic level, naval (or more accurately maritime) strategy is a good fit, but on an operational and tactical level, what parallels exist come from all forms of warfare.

The first question that must be asked is the technology available, and most specifically drives and weapons.  These two, more than anything else, drive the types of ships available.  The most conservative (PMF) scenario is what will be discussed in depth.  The main weapons are lasers and various forms of kinetics, while drives are limited to chemfuel, nuclear-thermal, and nuclear-electric.  This means that vessels in general have very limited tactical delta-V, either due to low acceleration, or due to the limited delta-V of their drives.  In particular, the velocities built up by nuclear-electric craft during cruise, and the ranges involve, render any form of tactical maneuver somewhat pointless.

While the exact systems chosen will vary based on the fine details of technology, history, and politics, it is possible to draw conclusions about the systems that might be used.  Vessels can be broadly divided into laser platforms, kinetic platforms, and control ships.  As mentioned in Section 2, there is no reason to place humans in battle aboard either of the first two types of craft.  A command ship is likely built on the same drive section as some class of warcraft, the exact one depending on the command requirements, with moderate defenses, and crew and maintenance facilities aboard.  It hangs back a few light-seconds from the battle, which is generally fought at a range measured in tenths of a light-second.  

It has been suggested that the command ship could be a parasite attached to one of the larger combat ships, but this has a significant impact on fleet performance in most cases.  It is virtually certain that a command ship will be of non-negligible mass compared to the combat vessels, and the vessel it is attached to will suffer from significant reductions in both delta-V and acceleration.  The rest of the fleet must then match this, significantly reducing strategic mobility.  The alternative is to make a special class of command-carriers, but this would probably require the development of a new drive system, and leave the vessels in question with excess performance during combat.  Another problem is that this arrangement automatically limits the ability of the command ship to operate independently.  As discussed in Section 2, the command ship will be on a significantly different vector from the rest of the fleet.  If it is a parasite, it either must be placed on such a trajectory by its carrier, which must then return to the fleet, or it must be capable of putting itself on said trajectory, undermining any savings accrued by use of this method.  Also, it would probably be unable to escape if the battle goes poorly.  Dealing with these problems raises the question of why it needs to be a parasite at all.

Laser platforms are not the popularly-imagined space battleships, bristling with laser turrets on all sides.  Instead, they are likely to be laserstars, a ship built around a single large keel-mounted laser.  Because of the nature of lasers, it is significantly more efficient to make use of a single large laser mirror then to use two mirrors of the same total area.  One key point that must be understood is that lasers are not of unlimited range.  They suffer from diffraction, which sets a minimum size on the spot that the laser can place its beam in.  The spot size scales inversely with the diameter of the mirror.  Thus, it makes sense to use the largest possible mirror, which can be limited by one of three factors.  First, the size of the ship carrying the mirror.  Second, the ability to make large mirrors.  Third, jitter.  Jitter, which is the term for small vibrations in the mirror and aiming system, will also serve to limit the spot size, and can make it inefficient to enlarge a mirror past a certain point.  If the first situation is the limiting factor, then the classical laserstar will be used.  The second will tend to result in lasernoughts, vessels with two to four large mirrors.  The third could go either way, as the amount of laser power puts a lower limit on the size of the mirror.  It is possible that a vessel might use a larger-than-optimal mirror to allow a more powerful laser to be used.  (For more details, see Section 7).  Laserstar is an overused term, which has been used to describe either a very large laser-armed vessel that is the political and operational equivalent of a modern CVN, or simply a vessel that has as its primary offensive armament a single large laser.  The second sense is what is intended throughout the paper, unless otherwise noted.

The laserstar would not be armed solely with the large laser of course.  It would also carry some form of point-defense weaponry, probably smaller lasers, and possibly some form of offensive kinetics.

The form of the kinetic platforms or kinetistars will vary based on the type of kinetics it fires.  For those kinetistars that use rail/coilguns as their main armament, the purpose and general design of the vessel will be the same as that of a laserstar, with obvious changes due to the nature of the main armament.  Vessels of this type might well be significantly longer than laserstars, depending on the specifics of the weapon, which would have detrimental effects on maneuverability.  Those that carry missiles are generally going to be a simple rack and a drive system.  It’s entirely possible that they will be considered at least semi-expendable, though recovery should not be too much of an issue under most circumstances.

The above are the main combat units of the battle fleet, or constellation.  They will vary in size and design based on the operational environment, but the outline is clear.  The constellation will also include various remote sensor platforms, defense parasites, and other auxiliaries.  To quote Rick Robinson:

“Taken as a whole you might call it a fleet. But it more nearly resembles a mobile, distributed, and networked fortification, deploying in action into a three-dimensional array of weapon emplacements, observation posts, and patrol details, all backed up by a command and logistics center. (Armies in SPAAACE !!!) Very little of it fits our template of 'space warships,' because it is designed for space, not simply borrowed from the sea.”

Of course, the battle constellation is not the entire Space Force.  Patrol craft have their own role (though the actual mechanics of patrols will be covered separately.)  A patrol craft is likely to resemble a naval warship far more than those previously described.  A patrol mission implies that the craft will have a crew, and probably some sort of boarding team.  The boarding team is generally referred to as Espatiers, derived from French in the same way as the term Marine.  The patrol craft will likely also carry various sensor drones, and possibly remote weapons drones as well.

The degree of modularity in a space force is open to debate.  In space, there are no aerodynamic or hydrodynamic issues to prevent one from hooking an engine up to a modular payload and taking off.  At the same time, major weapons are unlikely to be modular, as large optical trains and precision equipment are hardly plug-and-play.  On the other hand, systems like point-defense lasers, missile racks, and secondary fuel tanks are very likely to be modular, and swapped out depending on the mission.  These have the advantage of being generic enough to be in high demand, which avoids the problem of having to have lots of extra modules sitting around or not having enough modules for a mission.  On the other hand, it’s entirely possible that ‘modular systems’ will end up becoming permanent parts of the vessel, as has happened to similar systems on modern warships.

Of course, it would be possible to construct a ship out of three types of elements: a drive, a main mission module, and some number of secondary modules.  The main laser, coilgun, or command module would be the main mission module, with the secondary elements as described above.  The biggest potential challenge with this is arrangement is that all elements of a fleet will either waste part of their performance, or have to be of the same mass.

Another key question in the design of a space force is the size and number of ships.  A number of factors play into that decision.  The most important are, of course, the amount of money available and the role the force must play.  Technical considerations, such as those that drive laserstars, are also vital.  The lethality of weapons must be factored in as well.  Particularly if nuclear weapons are in common use, ships will look for survivability in numbers.  This obviously must be balanced against the fact that smaller vessels are less effective than larger ones, as outlined in the section on fighters.  Even small Space Forces will probably field a dozen or more ‘battleships’ while larger ones might number into the hundreds.

Depending on the political situation, command ships might be far larger than then battle vessels.  If both sides use drone forces, the command ships might be viewed quite like the king in chess.  If its force loses or its defenses fail, the command ship in question surrenders.  Both sides honor such surrenders, making warfare very bloodless.

All of the above assumes a deep-space engagement.  While that is the easiest environment to analyze, it is hardly the only, or even the dominant, environment where space combat is likely to take place.  The various environments for space warfare can be classified as follows:

1. INTRAPLANETARY WARFARE: Intraplanetary warfare is between two or more powers on the same planet. In any setting of this kind, space warfare will be a sideshow to the rest of the war.
   
   
   1. SATELLITE WARFARE: This is the current situation. Space war will be mostly about shooting down the other guy's satellites, and it will be done from the ground (in the broadest sense). Humans in space will almost certainly be uninvolved directly in the war. There are no spacecraft shooting at each other, unless one chooses to count co-orbital ASATs.
      
      
   2. STATION WARFARE: Activity in space has picked up significantly. Militarily significant human concentrations are in orbit. Warfare is still mostly ground-to-orbit, but there is likely to be some orbit-to-orbit warfare as well.
      
      
   3. CLOISTERED ORBITAL WARFARE: For whatever reason the earth-based powers aren't using surface-to-orbit weapons. Fighting is likely mostly done by short-range ‘fighters’, which leave stations, attack, and return to their bases. Delta-V requirements are minimal.  This is unlikely to occur in reality, but has interesting story potential.
      
      
   4. ORBITAL PATROL: This is a non-combat situation. It favors ‘fighters’ (more accurately small parasites/gunboats) even more than IC. Inspections and boarding actions are far more common than battles. Delta-V is low, as are weapon powers. All-out warfare will probably result in IB, though IC is possible.
      
      
2. INTRAORBITAL WARFARE: Intraorbital warfare covers battles between powers in orbit around the same body when at least one power isn't on the body.
   
   
   1. SURFACE TO STATION WARFARE, TOTAL: An orbital population is fighting with a surface population. This is most likely to involve the surface power shooting at the orbital power from the surface.
      
      
   2. SURFACE TO STATION WARFARE, LIMITED: This is similar to IIA, but it is far more likely to be space-to-space. If the surface power has limited goals, such as capturing the orbital population, kinetics alone are unlikely to work. It overlaps with IC and ID.
      
      
   3. STATION TO STATION WARFARE: This is a battle between two space-based powers. It will likely resemble IIB, though unlimited kinetic warfare is a possibility.
      
      
   4. ORBITAL PATROL: See ID.
      
      
3. INTERBODY WARFARE: This is warfare between two or more powers on different celestial bodies. This includes situations where one power is in an orbit around a separate body.  There are a broad variety of factors at work here, so this list is somewhat less organized then the other two.
   
   
   1. INTRASYSTEM: The powers are based on celestial bodies within the same planetary system, either with one on the planet and another on the moon, or with both on separate moons. Delta-V for spacecraft will likely be low, and transit times will be on the order of days. Fighters are on the edges of possibility, though the gunboats described in Section 1 are more likely.  Battles in this scenario will variously resemble Types II, and IIIB.
      
      
   2. INTERSYSTEM: The powers are in different planetary systems. Transit times will be on the order of months, and delta-V requirements will be high. There are several specific environments within this.
      
      
      1. INTERPLANETARY TRANSFER: This applies to any ships in an interplanetary transfer orbit. High delta-Vs are required, as is long endurance. Closing velocities during battles will be high, and classical “fleet battles” are unlikely. The attacking constellation will be opposed mostly by KKVs.
         
         
      2. OUTER ORBITS: The outer orbits are orbits that are at the edge of the Hill sphere of a body. They are likely to be mostly empty except for the Lagrange points, and can be seen as relatively flat. An attacking fleet will likely move into the outer orbits first, and probably be opposed by the defender's fleet there. For the attackers, the constellation will likely be their interplanetary vessels. The defender might have specialized vessels for this region, which will generally have lower delta-V then interplanetary vessels, but be largely the same otherwise. Encounter speeds will be low. The reason for engaging this far out is to minimize debris problems and collateral damage, which is in the interests of both sides, so long as they are relatively evenly matched.
         
         
      3. MIDDLE ORBITS: Middle orbits are the orbits where a significant orbital curvature appears, and strategically significant objects begin to be seen, but where spacecraft are out of range of most ground-based defenses. Ships built to fight here will probably be low delta-V (nuclear-thermal class). The defender will be at a disadvantage, as the attacker can shoot into these orbits with his outer orbit warships.  It is entirely possible that a typical invasion will see little combat here.  There is no reason for the defender to avoid sending all combat-capable vessels to fight in the outer orbits, leaving them nothing to engage with in this band if defeated.  The attacker might move into this band later to attempt to dominate low orbits with his interplanetary craft.
         
         
      4. LOW ORBITS: These orbits are going to be the most cluttered, as well as being in range of ground-based defenses. Fighters and gunboats will most likely be the primary warcraft here, supported by either ground defenses or by interplanetary ships. Delta-Vs will be low, with high accelerations.  Orbital curvature is highly significant, as is the presence of the body itself.  Engagements will generally be short, though the chance of serious kinetic use is somewhat low, given the amount of stuff in low orbit.  For more details on this, see Section 6.
         
         

One point that has become obvious during the construction of this taxonomy is how likely space warfare is to be asymmetrical in the broadest sense. Except for Type I warfare, just about every scenario described does not occur between equal powers. For example, take a IIC. Station A is trying to take over Station B. Station B doesn't want Station A, they just want to be left alone. They can use improvised kinetics against A's assault shuttles. A can't use kinetics because that would ruin what they are trying to attack.

Any form of interplanetary warfare must be asymmetric. It is impossible to project enough force between planets to overwhelm a defender who is within an order of magnitude economically, and the imbalance required is likely to be significantly larger, depending on the objective.

The exception to this is a variant on Type III when both sides are deploying forces to the objective.  If the US and China decide to fight around Mars, but avoid conflict on Earth, a largely symmetrical war is possible.  This assumes that the Martian colonies themselves are evenly matched or minor compared to the forces deployed.

It is impossible to wage symmetrical warfare with an equal opponent if the objective is anything but destruction. Total destruction of a roughly equal opponent is possible, but only at the gravest risk to yourself. If the objective is anything else, then a large advantage is required.

One point that is commonly brought up in the discussion of space warfare is the three-dimensional nature of space, and the need to think in three dimensions.  While this is technically true, it is probably not as big of a factor as it is often portrayed to be.  First, efficient transfers will be in the ecliptic plane, which means that most of the deployments will be made in that plane, in two dimensions.  Even if one side chooses an inefficient transfer to avoid this, they would have to split up their force on the way to achieve meaningful separation between its elements, throwing away any advantage of surprise it might give them.  Second, ships will be generally unable to maneuver in combat (as described above), limiting the impact of any brilliant 3-D tactics, as the opponent will have plenty of time to respond.  Third, humans have been fighting in a 3-D environment for almost a century, and with a little bit of training, most people do not seem to have a problem thinking in 3-D.  All but the most inexperienced officers will be familiar with the fact that space is not 2-D, and react accordingly.

Many of the fleets found in modern Sci-Fi broadly follow the pattern seen in fleets since the start of the 20^th Century, with the big ships of the fleet surrounded by escorts of various types.  The existence of fleet escorts is a recent development, and they are not likely to move into space.  Up through the Age of Sail, fleet actions were fought by the major warships alone.  Smaller craft that travelled with the fleet were for scouting, a function that will not exist in space.  The first fleet escort was the Torpedo Boat Destroyer, introduced to counter the threat of the torpedo boat.  The TBD evolved into the destroyer, which during the first half of the 20^th century became a vital part of the fleet.  It was tasked with protecting the fleet from submarines, aircraft, and surface torpedo attacks, along with conducting torpedo attacks on the enemy fleet.  However, none of these functions has an analogue in space.  Submarines and naval aircraft rely on the fact that there are three fundamentally different environments in close proximity, a feature that does not apply to space.  Likewise, there is no reason to suppose a ‘torpedo’ would exist that is best deployed by a small escort instead of being fired from the main fleet units.  This is not to say that no smaller vessels would exist.  During the Age of Sail, ships below the line played an important role.  Besides scouting, they protected convoys, hunted commerce, patrolled, and showed the flag.  While scouting and patrolling are not likely to have spaceborne analogues, commerce warfare and general station duties will, and smaller warships will exist to fill those roles.

• 

      One of the problems with figuring out how ships are going to fight in space (assuming that we have ships in space, which isn’t as likely as I wish; and, that we’re still fighting when we get there, which is unfortunately more probable) is that there are a lot of maritime models to choose from.

     It’s also true that some of the maritime models came from very specialized sets of circumstances; and a few of them weren’t particularly good ideas even in their own time.

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     And it’s also true that some of the writers applying the models have a better grasp of the essentials than others. That isn’t limited to writers of fiction. For example, I recall two essays which were originally published about fifty years ago in Astounding.

     In the first of the essays ("Space War", Astounding Science-Fiction, Aug 1939), Willy Ley, a very knowledgeable man who had been involved with the German rocket program, proved to my satisfaction that warships in space would carry guns, not missiles, because, over a certain small number of rounds, the weight of a gun and its ammunition was less than the weight of the same number of complete missiles. The essay was illustrated with graphs of pressure curves, and was based on the actual performance of nineteenth-century British rocket artillery (“the rockets’ red glare” of Francis Scott Key).

     As I say, the essay was perfectly convincing … until I read the paired piece by Malcolm Jameson ("Space War Tactics", Astounding Science-Fiction, Nov 1939).

     Jameson’s qualifications were relatively meager. Before throat cancer forced him to retire, he’d been a United States naval officer—but he was a mustang, risen from the ranks, rather than an officer with the benefit of an Annapolis education. For that matter, Jameson had been a submariner rather than a surface-ship sailor during much of his career. That was a dangerous specialty—certainly as dangerous a career track as any in the peacetime navy—but it had limited obvious bearing on war in vacuum.

     Jameson’s advantage was common sense. He pointed out (very gently) that at interplanetary velocities, a target would move something on the order of three miles between the time a gun was fired and the time the projectile reached the end of the barrel.

     The rest of Jameson’s essay discussed tactics for missile-launching spaceships—which were possible, as the laws of physics proved gun-laying spaceships were not. Ley could have done that math just as easily. It simply hadn’t occurred to him to ask the necessary questions.

     Light-swift beam weapons were a fictional staple in Jameson’s day (he used them in his stories about Bullard of the Space Patrol) and a realistic possibility in ours. And the advent of the electrically-driven railgun has brought even projectile artillery back into the realm of space warfare.

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     Present realities don’t prevent a writer from building any number of self-consistent constructs of how space war will work, however.

     At one time, boarding and hand-to-hand combat were common notions in military science fiction (which, in the 1920s and 30s, was rather a lot of science fiction). Boarding has a long naval tradition as, at times, the heaviest available weapons were not by themselves sufficient to sink major warships. When oared warships grew sturdy enough to be equipped with rams, however, ramming replaced boarding as the tactic of choice …

     Until sailing ships replaced oared warships. Sailing ships can’t mount effective rams because their masts and rigging would come down with the shock. The guns available during the next five centuries weren’t effective ship-killers, and boarding returned.

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     As guns became more powerful and ships were designed to mount large numbers of them along the sides, the sort of melees that characterized the Armada battles and the meeting engagements of the Anglo-Dutch Wars of the seventeenth century gave way to formal line-of-battle tactics. Opposing fleets were expected to sail along in parallel lines, firing all their guns at one another, until something happened.

     Mostly, nothing much happened. A typical example is the action between the fleets of DeGrasse and Graves in 1781 in Chesapeake Bay. This was the crucial battle that decided the fate of the British army at Yorktown—and, thus, the Revolutionary War. It was a draw, with no ships lost on either side (which turned out to be good enough for the American rebels, of course).

     Nelson changed matters by what amounted to assertiveness training for the British navy. His captains were expected to close with the enemy and board if necessary, instead of staying at a reasonable range and letting noise and smoke stand in the place of doing real damage. Nelson’s opponents never beat him. In the end, they were able to kill him; but even dead he led his forces to victory.

     The appearance of steam and armored warships in the nineteenth century gave rise to an amazing number of theories and some of the most outlandish warships ever built. What didn’t emerge were major battles between the new vessels.

     At Lissa in 1866, an Austrian fleet humiliated an Italian fleet of more modem and powerful ships, proving that competence and leadership had more to do with victory than equipment alone. (Nelson must have smiled from his grave.) Lissa proved little or nothing about the new hardware (theorists of the time thought otherwise; they were wrong). but it was as good a test as the century provided.

     Ships generally mounted mixed armaments of large and mid-sized weapons. though there was a brief fad of equipping battleships with small numbers of very heavy guns. This was partly in the hope that a single huge shell could smash opposing armor (in the unlikely instance that such a shell hit its target); and partly because the planners wanted an easily quantifiable marker for their arms race. (The dangerous buffoons in the Pentagon and Kremlin with their “My throw weight is bigger than your throw weight” arguments had nineteenth century predecessors.)

     Incidentally. as soon as steam removed the necessity for masts and rigging, rams returned as well. There were few successful examples of ramming in war. but in peacetime, rams sank almost as many friendly naval units as decomposing smokeless powder did.

     The only real test of nineteenth century warships came in the twentieth century—1905—at the Strait of Tsu Shima, where a Russian fleet that did nothing whatsoever right met a Japanese fleet that did nothing important wrong. The Russians were massacred, and it was heavy gunfire alone that did the butchers' work.

     An idiosyncratic genius named Jackie Cooper was running the British admiralty at the time. He came up with the first good idea in warship construction since Ericsson put a turret and screw propeller on the Monitor: Cooper built the Dreadnought.

     The Dreadnought was big and fast and carried ten of the most powerful naval guns available, with none of the mid-sized weapons that had proved almost useless at Tsu Shima. Every battleship built after the Dreadnought is more similar to her than the Dreadnought was similar to anything that came before her.

     Having had a brilliant idea. Cooper went on to have a lethally bad one: the battle cruiser. The battle cruiser was a dreadnought (the name became generic for all-big-gun warships) which had lighter armor and more powerful engines than a battleship. and was therefore faster. The theory was that “speed is armor.” The reality was quite different, and thousands of sailors (mostly British) died in the two World Wars (the Hood was a battle cruiser) because a clever slogan can’t repeal the laws of physics.

     The dreadnought brought back the concept of the line of battle. It didn’t work any better in the twentieth century than it had in the eighteenth, because both sides had to agree to play the game and the weaker side—the Germans, in this case—would inevitably lose. The German admirals of the World Wars were less than brilliant, but they weren’t stupid.

     Besides, the fleets of World War II were dominated by aircraft. The one major battleship-to-battleship fleet action of the war occurred at night in the Surigao Strait. It was a close copy of Tsu Shima, with the Japanese playing the part the Russians had forty years earlier.

     There is enough in actual maritime history to provide models for almost any form of space warfare a writer wants to postulate. Because there are so many possibilities, writers can find a solidly-grounded situation that suits their story, rather than forcing the story into a narrow matrix.

     And that, I think, makes for some very good stories.

Weapons like particle beams and lasers may have "unlimited ammo" if a space warship's electrical power generation and storage system is powered by nuclear reactors, with gigawatts or more of firepower.

Future ultracapacitors could have an energy density higher than 60 Wh/kg along with a power density greater than 100 kW/kg. Such is from a MIT study on ultracapacitors for future cars, implied here. That would be up to 0.2+ TJ of electrical energy stored per 1000 metric-tons of ultracapacitors, able to be discharged at a rate of 0.1+ TW. For example, a 100,000-ton warship with just 5% of its mass as ultracapacitor banks could store a terajoule, then discharge it at a rate of half a terawatt. Technology of the distant future may be superior, but the preceding is a reasonable lower limit. Energy storage is not the only limiting factor, though.

(ed note: Anthony Jackson thinks that 60 Wh/kg should be considered a high end estimate, not a low end. He further notes that 100x is approximately the theoretical limit for energy storage with chemical bonds, and as noted, 5 kilotons of capacitors hold 1 TJ.)

What is the recharge rate from warship power generation? The energy content of fission, fusion, or antimatter fuel can matter less for the attainable electricity generation than engineering limits. Even before melting, metals weaken if temperatures rise from more heat transfer into them than coolant systems take away; parts deform if subject to excessive mechanical stress; etc. For example, plutonium "fuel" in a bomb allows a power-to-mass ratio of billions of gigawatts of heat and radiation per kilogram during the fraction of a microsecond of detonation, but that of a plutonium-fueled power plant must be orders of magnitude less. A nuclear-electric concept with a MHD generator was estimated to obtain 0.37 kg/kWe, which would be 2.7 MW/metric-ton. For perspective, car engines of today are sometimes hundreds of kW of mechanical power per ton (i.e. 200 hp engine = 150 kW), with aircraft engines up to much higher power density. Even with need for electricity rather than mechanical power alone, the many thousands of tons involved in a space warship would allow it to have nuclear power generation at least in the gigawatt range or higher, likely terawatts for large ships. There would also be inefficiencies.

What about waste heat? Deploying large radiator panels while firing weapons wouldn't be desirable. Internal phase-change-material (PCM) heat sinks like ice/water might temporarily absorb heat. Actually, if the space warship has structure, armor, and individual weapons massing thousands of tons, such could absorb some gigajoules to terajoules. But such could not sustain a high rate of fire for long without needing a "cooling off" period, so a different system would be needed, at least as a supplement. The preferred radiator design for an armored warship is a droplet radiator, a charged (solid) particle radiator, or another alternative to large, vulnerable panels.

Radiator mass for the weapons is going to depend much upon acceptable operating temperature. If most parts of the weapons can operate at moderately high temperature, the waste heat from high power consumption can be transferred away fast enough without excessive radiator size. One study of what is obtainable for heat rejection in space with merely today's technology indicates that 30 MW of heat could be dealt with by a 45 metric-ton Curie point radiator ( CPR) or by a 29 metric-ton liquid droplet radiator, for an average temperature of 380 degrees Celsius or 650 K. The space warship would operate at least in the gigawatt range, with orders of magnitude greater heat rejection from its weapons, but it could afford to have orders of magnitude greater radiator system mass. And it would be more advanced, higher-performance technology.

The 0.37 kg/kWe reactor described has a heat dump at 150K. That's not practical for a spaceship; you're not going to run your radiators at 150K, nor are you going to use liquid nitrogen as a heat sink. It also has an efficiency of 22%. Using a higher temperature heat dump will reduce efficiency or power density (or both); in practice the heat dump has to operate at the same temperature as the radiator. Assuming a 10 GW reactor, it's likely going to have a heat output of 20-40 GW.

Let's assume that we can get a reactor with a 1000K heat output and an efficiency of 20%, with a power density of 1 kg/kWe. A 10 GW reactor produces 40 GW of heat. A perfect blackbody at 1000K has a heat output of 56.7 kW/m², so we need about 18 square meters per MW, or 1.4 million square meters. A perfect blackbody could radiate from both sides, but if we're using a non-solid radiator of real materials it's not a perfect blackbody, so we'll just have a wing with an area of 1 million square meters. Assuming our ship is 200M long, that means the radiator wing is 5 kilometers long.

I think not. So much for heat radiators. Let's shift over to heat sinks. We'll use water, since it's easy to work with. This gives us a heat sink at around 400K, so we'll double our efficiency; a 10 GW reactor now produces only 15 GW of heat. Without vaporization, cold water can hold about half a gigajoule per ton; 10,000 tons could hold 5 TJ (if we store a slurry of ice, increase by 50%). If we allow the steam to vent (which more or less requires dumping it to space; you need a phase change, which means you can't keep the water compressed) we get another 20 TJ.

Now, a laser system that would make the military jump for joy would have a peak output of 1 kW/kg, an efficiency of 20%, and a duty cycle of 20%, for a mean power output of 1 kW/kg. It will produce low temperature heat, well suited to our water sinks (and nearly impossible to radiate away with our high temperature radiators). A 10,000 ton weapon system requires a power input averaging 10 GW, and a peak power input of 50 GW. If we can fire for 15 seconds before triggering a cool down cycle, we need capacitors good for 40 GW * 15 seconds or 0.6 TJ, so 3,000 tons is all we really need.

During 1 duty cycle we produce 800 GJ of waste heat from the weapon. Generating 1 TJ produces another 1.5 TJ of waste heat, for a total of 2.3 TJ. We'll round up, and discover that we can run through 2 15-second duty cycles without venting coolant, and another 8 by venting coolant. Our combined system mass is 33,000 tons.

Now, if we have some down time, we probably want to bring the coolant temperature down to near freezing, or if possible turn it into an ice slurry. Unfortunately, that means a radiator operating at an average of about 300K, with a heat output of 0.46 kW/m2. If we figure extended radiators are 1 km long and 200m wide, they can dump heat at a rate of 180 MW, or approximately 8 hours to cool to near freezing. Generating the ice slurry would take another 6 hours or so. Also, unlike high temperature radiators, sunlight heating the radiators will interfere substantially with cooling, so we need to remain edge-on towards the sun.

Let's add an intuitive illustration of the overall picture. Consider 10% of the mass of a 100,000-ton warship being a beam weapon, with the maximum energy it could fire per shot or in a second being somewhere between 0.01 TJ and 1 TJ. That proportionally corresponds to as much firepower per unit mass as a half-kilogram energy pistol firing shots between 500 J and 50 kJ of energy. Such is equivalent to the energy pistol being able to vaporize a volume of ice between 0.7-cm and 3.3-cm in diameter per shot, like vaporizing a ball of ice between the size of a pea and a golf ball. While the whole range is conservative by sci-fi standards, one could take the low end of the range if concerned about the reliability of it being plausible. The comparison is proportional since the sample space warship's weapon masses 20,000,000 times more than the energy pistol.

Big Proviso: (Sikon) is talking in terms of big ships; the example they give is a ship with mass of 100,000 tons, presumably "Washington Treaty" mass, not including remass (propellant/reaction mass). This is roughly the size of the largest ships I think are provided for in Attack Vector: Tactical. It is about 10x the mass, from my impression, of the largest type (DiGleria?) in regular service in the AV:T Ten Worlds setting.

By my general rule such a ship would cost (the societal equivalent of) some $100 billion. (YMMV!) Mid-future colony worlds of the Ten Worlds or Human Sphere type, with populations no more than ~100 million, would be hard put to have more than a showboat or two of this class. (Sikon) speaks of fleets with thousands of such ships - so they're implicitly dealing with vast galactical-imperial scale polities.

I've gone into this a bit because it makes an interesting point: scale matters. I didn't carefully examine (Sikon's) analysis, but it gave the impression of being well thought out, and I can imagine that you could indeed get Incredible Firepower ... if you can afford an Incredibly Huge And Costly Ship.

Yet the warship's shots each correspond to the equivalent of approximately between a 2500-kg high-explosive bomb and a 0.25-kiloton tactical nuke in the energy delivered. Beam weapons of such energy can have "unlimited ammunition," powered by the discharge of the capacitors, which are recharged by the warship's nuclear reactors to fire thousands of shots in a period of a few hours. Or smaller shots could be used for an even higher firing rate. For example, if a warship can fire a single concentrated 0.01 TJ to 1 TJ laser shot in a second, it might alternatively have weapons capable of sending out equal energy in the form of 100,000 to 10,000,000 one-hundred-kJ pulses per second over a huge shotgun-like pattern to hit a target at much greater range than would be likely otherwise. What was optimal could depend upon factors including the type of target, but the attainable firepower is vast.

For perspective, a 100-kJ vehicle-mounted laser concept is considered by the Department of Defense to be lethal against common rockets, aircraft, and light ground vehicles with little armor. Yet, at the technological level implied by sci-fi interplanetary or interstellar space war, average firepower of a far larger space warship could be astronomically higher, either in the energy per shot, the number of shots fired per minute, or a combination of both. Every 0.01-TW of average weapons power corresponds to 400 million times the energy per hour.

Propulsion system power could be much greater than electrical power and beam weapons power. For example, the MS Word document from researchers here describes a magnetic compression pulsed fission concept with a magnetic nozzle, in which a vehicle of 1310 metric tons initial mass and 100 tons final mass could have 263 GW jet power. That is between 0.2 GW/ton and 2.6 GW/ton, with relatively straightforward technology. For this distant-future scenario, such is just a probable lower limit. A much larger 100,000-ton space warship could be more than 1 GW/ton, corresponding to an exhaust jet power above 100 TW.

As an initial beam weapons illustration, consider a space warship firing a lethal radiation beam against planetary targets including aircraft. Against humans, on the order of 10 kJ per square meter of some types of radiation would be enough to cause enough exposure for relatively quick mortality, much above the level for slow death. The end result is a little like the effect of the radiation of a neutron bomb, for which 8000 rads or 0.08 kJ/kg-tissue (80 Grays) are enough to immediately incapacitate enemy soldiers like tank crewmen according to an U.S. military estimate, a couple orders of magnitude above the dosage usually lethal over a longer period of time (1% as many neutrons = 80 rads = 800-1600 rem in long-term). But the radiation wouldn't be neutrons.

This is not an ordinary particle-beam weapon concept, being instead a wide beam with particle composition and energies chosen to equal or exceed the atmospheric propagation of penetrating natural cosmic radiation. As GeV energies are obtained in contemporary research accelerators, the preceding would be attainable by an accelerator within a large space warship. Natural cosmic rays are 16 rem/yr in interplanetary space, dropping to 0.027 rem/yr at sea level. Since natural cosmic radiation experiences such an attenuation factor of 600 going through earth's atmosphere from space to ground at sea level, assume the wide-beam radiation should have an intensity on the order of 6 MJ/m² before entering the atmosphere.

The result is that each shot of 0.01 TJ to 1 TJ energy can deliver a pulse of quickly lethal radiation to an area around 46 meters to 460 meters in diameter. If a given intensity level is insufficient, such as firing on a relatively hardened unmanned target, making the beam more narrow by a factor of 10 would increase the intensity by a factor of 100, and so on. But wide beams can kill ordinary tanks, aircraft, infantry, etc. The beam is unaffected by weather and sufficiently penetrates the mass shielding of the atmosphere, despite it being 10 metric tons per square meter. Unlike even neutron bombs, the beam would have no blast and just a few degrees heating effect when fired in wide beams, leaving structures unharmed aside from disruption to electronics, yet killing the occupants.

Now, when talking about targeting the ground with a particle beam, it's worth noting that cosmic rays not only attenuate on hitting atmosphere, they scatter. You can't really target a region smaller than about 100 meters radius (31,000 m²). The attenuation length of cosmic rays at ground level is a bit over 100g/cm², so 1 kJ/m² produces a dose of about 1 gray; however, the radiation involved has a RBE of around 2, so it's about 2 Sv. Prompt incapacitation requires about 50 Sv (more vs rad-hard electronics, way way more vs bunkers), so we need at least 25 kJ/m², or 800 MJ at ground-level, or 500 GJ at top of atmosphere. One duty cycle from our gun above is 150 GJ (15 Sv at ground level), and we probably don't want to dump coolant on secondary targets, so we likely only fire once or twice. In practice, the lethality difference between 15 Sv and 30 Sv is negligible (in either case, nausea after 5-30 minutes, a couple days of normal activity, then delirium and death), so one shot is fine.

It is also the type of thing that gets called a war crime.

Lethal radiation beams may also be used against other spaceships, with effectiveness determined in part by their shielding (armor) thickness. The extreme case is firing against a thin-hulled ship, in which case the attenuation factor of 600 for the previous scenario of firing through the 10,000 kg/m² mass shielding of the planetary atmosphere doesn't apply. In that case, a quickly-lethal 0.01 TJ to 1 TJ shot can be up to about 1.1-km to 11-km in diameter. Actually, since enemy vessels can be detected at great range, the warship might not wait but rather open fire on lightly-armored targets at such extreme range that beams hit only by being hundreds of kilometers in diameter or more. The cumulative radiation dose delivered over many shots every minute would add up to enough in time. One potential countermeasure is mass-shielding or thick armor around vulnerable areas of a ship, like the battle stations for the crew and vulnerable electronics, such as with enough meters of metal to stop practically all of the radiation.

Another weapon can be microwaves. Against non-hardened civilian targets, as little as a few joules per square meter or less can be enough if delivered in the right time frame, concentrated into microseconds or less. Gigantic "EMP" pulsed microwave beams can fry ordinary electronics over up to many square kilometers per shot. EMP beams could be about the opposite of lethal radiation beams, devastating planetary infrastructure without killing any people aside from a few indirect deaths like crashing aircraft. Against more hardened targets, more focused microwaves in the form of narrow-beam MASERs might physically overheat and destroy. The potential firepower of such a concentrated MASER beam is implied by the many-gigawatt or terawatt-level power generation of a large space warship being equivalent to a number of tons of high-explosive per second.

As implied by what happens to sunlight, light from space doesn't always reach the ground well on cloudy days. Thus, lasers might be an unreliable weapon against planetary targets, unless the basic principle of this could be applied with ultra-intense pulses. However, the situation is different in space against enemy warships. The shorter wavelength of lasers compared to microwaves allows a more narrow focus at long range.

During planetary attack, yet another potential weapons system for space warships is firing non-nuclear mass driver projectiles and missiles to hit air, sea, and ground targets on the planet below, impacting at hypersonic velocities. A 1977 NASA Ames study referenced here determined that an earth-launched mass driver projectile going up vertically could pass through earth's atmosphere from ground level to space with a few percent of its mass being an ablative carbon shield, losing only 3% of its total mass in the transit. Such is for a telephone-pole-shaped projectile of a metric ton mass. That means the reverse is also possible for projectiles with the right mass, dimensions, ablative shield, and trajectory. For example, consider a similar projectile fired from space, reaching the upper atmosphere at 12 km/s velocity and going nearly straight down. It could hit a ground target at about 11 km/s, a kinetic energy equivalent to about 15 tons of TNT explosive.

Projectiles and missiles fancier than the cheapest unguided shells could use small thrusters to adjust trajectory to home in on a target. Although sci-fi sensors or even remote-control communications systems might be able to operate through the plasma sheath from atmospheric passage (i.e. using high-frequency pulses of directed radiation or particles rather than ordinary radios), the simplest solution is if it instead slows down to a lesser Mach number first. Advanced robotic missiles tracking by the right combination of infrared, visible, radar, and/or other sensors could be hard for planetary targets to evade ... although space warships could alternatively just use their beam weapons against those targets.

Large numbers of nukes may be used in planetary assault. For example, one cheap "brute force" method of dealing with atmospheric fighters trying to avoid shells or missiles might be to have them explode with sub-kiloton to single-kiloton yield. The equivalent isn't done by terrestrial militaries for reasons like political issues, but those do not necessarily apply so much in a sci-fi planetary assault scenario. Even in the real-world today, nukes do not have to cost more than merely hundreds of thousands of dollars each or less in mass-production, compared to fighters costing orders of magnitude more: tens to hundreds of millions of dollars each.

Fallout from such nukes would tend to be harmful to the planetary defenders and localized regions without making the planet unusable by the invaders. Localized radiation levels shortly after a detonation can be lethal, but such decrease over time. The radioisotopes emitting the most initial radiation are those with the largest fraction of their atoms decaying per unit time. (The rate of radiation emission per unit time from a radioisotope is inversely proportional to half-life, to a degree such that stable elements can be thought of simply as those with infinitely long half- lives). Compared to residual radiation one hour after the detonation, radiation levels are 1% as much after 2 days and 0.1% as much after 2 weeks. The fallout of a nuclear weapon detonation of low or moderate yield can much elevate radiation levels over a limited number of square kilometers, but it can do very little overall over the half-billion square kilometer total area of a planet like earth.

Historical above-ground nuclear weapon tests in the 20th century amounted to 440 megatons cumulatively, with 189 megatons fission yield ... 189000 kilotons (UNSCEAR 2000 Report Vol. I, Annex C). Total collective dosage to the world's population from such past tests corresponds to 7E6 man-Sv, for the UNSCEAR estimate for total exposure in the past plus the result of currently remaining radioisotopes projected up through the year 2200. The preceding total over the decades and centuries is less than what is received every year from natural sources of radiation, which is in turn orders of magnitude less than what would make an eventual death from cancer probable. Of course, from a real-world civilian perspective, any potential increased risk of cancer is undesirable, but, from the perspective of the hypothetical space invaders, the bulk of the planetary surface is not harmed enough for them to necessarily be concerned.

For example, even with fission devices, if the orbiting warships are firing quarter-kiloton-yield nuclear shells or missiles against targets like enemy aircraft, it would take on the order of 800,000 warheads even just to exceed the limited radiological contamination from the 189-MT fission component of the preceding nuclear tests. If available, pure-fusion devices would be cleaner. Sci-fi technology allows other possible ordnance, such as biological weapons genetically engineered to have a non-lethal temporary incapacitating effect or infectious nanobots. Different attackers might use different techniques depending upon their psychology, ethics, objectives, etc.

In combat between space warships, the vast firepower attainable from nuclear projectiles or missiles, combined with no particular limit on range, might make them dominate the battlefield. Or they might not, depending upon the effectiveness of missiles versus point defenses, their relative cost, and other factors in a given sci-fi scenario. With lasers destroying artillery shells becoming possible even now, the point defenses of distant-future space warships are not to be underestimated.

As little as a 100-kJ projectile can destroy an ordinary missile. (For perspective, 100-kJ is like the kinetic energy of a 200-gram projectile going 1 km/s, although the analogy should not be taken too far since the momentum is different for a much higher velocity but far smaller projectile). For example, if warship firepower of 0.01 TJ to 1 TJ per second is attainable as previously suggested, such could allow a mass driver or mass driver array firing a 0.01-GJ to 1-GJ shot per millisecond. If firing pellets like a shotgun, such could deliver on average a 100-kJ pellet per square meter within a 11-meter to 110-meter diameter pattern per millisecond, a thousand times as much per second, potentially destroying many different incoming missiles. Or, to maximize engagement range, firing a whole second at one target could amount to a shotgun pattern 0.36-km to 3.6-km in diameter. Alternatively, comparable firepower to the preceding might also be obtained with another weapons system like a laser array instead.

Against such point defense firepower, ordinary missiles are at a disadvantage against warships. Still, if the missiles aren't so ordinary, there may be countermeasures to point defenses, such as faster, more armored, and/or more numerous missile swarms. One possibility could be a space missile swarm not carrying sizable nuclear warheads but rather dispersing clouds of kinetic-kill masses, such as billions of grains of sand or the equivalent, too numerous for point defense weapons to hit and vaporize them all. Point defenses might try to destroy such missiles far enough away for clouds deployed before missile destruction to subsequently miss due to the warship's changing course.

Imagine two modern-day soldiers. One is armed with a sniper rifle, while the other is armed with a pistol. If they face each other in a jungle or in dense fog with visibility not beyond several meters, either one may have a good chance of being the winner. But now imagine them starting a kilometer apart on a featureless flat plane of solid rock with perfect visibility. Then the guy with the sniper rifle wins, as the man with the pistol can not approach close enough to hit before being shot by the sniper. Since there is typically no effective stealth in space, the situation for warship combat can be like perfect visibility, no horizon, and usually no cover. That makes effective weapons range particularly important.

Fire control computers try to predict a target's position based on its velocity and current acceleration, but, at ranges with significant light speed lag, mobility matters much against beam weapons (and possibly the missile-deployed kinetic-kill clouds described earlier). For example, a ship doing 5g of unpredictable acceleration deviates 25-m in 1 sec, 2.5-km in 10 sec, 88-km in 1 minute, and so on. One countermeasure may be to fire many shots, but the earlier illustration of a warship firing a huge pattern of 100,000 to 10,000,000 100-kJ shots per second doesn't work well if the target has armor making 100-kJ too little. Armor could make the enemy fire a low rate of concentrated high-energy shots, reducing the chance of any hitting at long range. Of course, good enough point defenses are also needed, or else the armor would just be penetrated by a missile with a nuclear warhead.

What about space warships fighting planetary anti-space weapons? Typically the planet would be better off having space warships than planet-based weapons. Launch a missile from a planet with a regular rocket, and more than 90% of its mass is involved just getting off the planet. Even if an advanced propulsion concept like nuke-pulse or nuke-saltwater rockets is used instead, having such launched from a planet during a battle would make them relatively easy targets during boost phase.

Craft launched from a planet may tend to be smaller and more limited than space warships. For example, a mass driver sending even just ten tons per hour to orbit could over a decade put almost a million tons up, enough to be potentially the seed of a society processing eventually billions of tons of extraterrestrial material into habitats and ships. But, in that scenario, billions of tons of spaceships might exist without the planet necessarily being able to launch more than a proportionally minuscule amount in a day. There is likely shipment off-planet of some valuable goods and also passenger traffic, but X million people per decade going off-planet only corresponds to just 20 * X * Y tons per day needed, where Y is the ratio of total launch mass to body mass.

A planet could have gigawatt to terawatt range beam weapons, but the effective range of such against space warships would tend to be less than vice versa: In a duel at up to light-minutes or greater range with light speed weapons, a space warship fleet will tend to win against a planet, as the immobile planet with zero unpredictable acceleration can be engaged at extreme range.

For example, if technology allows a variant of the lethal radiation beam weapon described earlier to have 0.1 to 10 microradians divergence, the beam would diverge 0.01-m to 1-m per 100,000-km distance, hitting a spot 100-m wide at 10 million kilometers to 1 billion kilometers range. With thousands of 0.01-TJ to 1-TJ shots fired per hour with electricity from the nuclear reactors, enough hitting a planetary target sooner or later, warships could devastate appropriate parts of the planetary surface from up to light-minutes to light-hours of range. That gives the mobile warships plenty of time to evade any light speed weapons fire from the planet. Such would arrive long after each warship has moved to another location in the vastness of space, perhaps millions of kilometers away from its previous position.

If even more firepower is needed, kinetic-kill clouds might be used, i.e. billions of particles of debris that defenses could not stop. For example, ships with nuke-pulse engines able to carry and send "cargo" on the right trajectory at 100 km/s to 1000+ km/s velocity could indirectly deliver 1,200 to 120,000+ megatons of destruction per million metric tons of material carried. Optionally, the columns of fire in the atmosphere created by the preceding might "blind" remaining defenses for critical seconds while missiles with nuclear warheads arrived right behind them. Before inefficiencies and aside from the other mass in nuclear weapons, fissioning plutonium and fusioning lithium-6 deuteride are 17 million megatons and 64 million megatons respectively per million metric tons mass. Of course, if the goal is to capture the planet with it still inhabitable, the level of firepower used in destroying anti-space weapons from extreme range would need to be limited. Warships could afterwards move closer, into orbit, providing final fire support for an invasion.

I was struck by how it assumed the space ship had amazing beam weapons capable of penetrating the atmosphere, but for some unknown reason ground defenders using that same beam weapon technology simply lose.

On rec.arts.sf.science, the contest between beam weapons on mobile warships vs beam weapons on planets is completely lopsided in favor of the planetary defenders. They have a stupendous advantage in heat rejection, shielding, and mobility. Sikon ... ignores the heat rejection advantage and ... assumes the planetary systems can't use any shielding other than the atmosphere. He seems to assume planetary defenses must be fixed, despite the explicit example of aircraft which can literally jink all week (which, of course, spacecraft can't). Never mind about submarines, ships, or underground weaponry.

And the most important one of all, IMHO (though you may be subsuming it under mobility): stealth/concealment. A habitable-planet surface is about as cluttered an environment as you can find. Other parts of the post also seemed to blow off the problem of detecting targets on a planetary surface.

As an aside, at least "guns" reveal themselves when they fire. Assuming you have a suitable tech for lobbing missiles out of a gravity well, a missile engagement is even more in favor of the surface, because once a missile is fired all it leaves behind is its launcher, probably of insignificant value as a target.

Returning to beams, the whole sensor-blinding issue also heavily favors the planet, because finding a passive sensor on a planet surface approaches the level of trying to find a guy with binoculars somewhere on the nearside of the planet.

With good enough targeting information transmitted from recon drones through a computerized system, space warships could help kill even individual vehicles or even individual enemy soldiers from orbit when possible. Such would not be their primary mission, and initially the warships would attack more valuable targets. But afterwards, a warship would still have practically unlimited ammo for its electrically-powered beam weapons running off nuclear reactors. Using a hundred-thousand-ton warship to kill a couple enemy soldiers riding around in a truck might superficially seem wasteful, but there is next to no marginal cost in the preceding scenario.

Consider a warship orbiting at 200-km low-orbit altitude for final fire support. A little like a terrestrial sniper can shoot an enemy from 0.5-km away, some beam weapons on the warship could be designed to hit precise locations on the ground below, with potential accuracy of within a meter. If there was a single person or handful of people on the warship manually trying to search for targets, aim, and fire the weapons, it would be a slow process. Yet, if there are a large number of robotic recon drones searching for enemy vehicles and soldiers, transmitting their precise coordinates, a computerized fire control system on the warship could shoot thousands of designated targets per hour, continuing for hours or days if necessary. Given the firepower and capabilities possible with one space warship, imagine what a fleet of thousands of such warships (or more) could do against a planet.

Space warships would initially destroy all targets they could see from space, but, for foreseeable technology, orbital surveillance might not find every last target. Deploying air and ground versions of robotic recon drones could help give further targeting information. For example, if a golf ball-sized robotic drone with a miniature jet engine flies up to the window of a building and sees enemy soldiers inside, it can transmit a signal causing the warship's computers to fry the area within a 50-meter radius with a lethal radiation beam a fraction of a second later ... potentially very effective yet still with less collateral damage than just nuking the whole city.

The preceding could be done before sending in regular armies or occupation forces in order to drastically reduce ground combat casualties, although use of expendable robots and/or telepresence whenever possible might make human or sapient casualties beyond non-sapient robots be low anyway.

Even in a hard sci-fi scenario, predicting the capabilities of technology that may be centuries or millennia beyond the 21st-century is highly uncertain. For example, perhaps technology would allow a million tons of raw materials to be quickly and cheaply converted to its mass-equivalence: a billion one-kilogram missiles to be dispersed at low altitude. Or there could be other weird military technologies. A little like a person from centuries ago couldn't very well predict the capabilities of modern combat, the preceding is mainly just a lower limit on what could be accomplished at the technological level commonly implied by interplanetary and interstellar wars in science fiction.

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I don't think there would be a huge variation in the types of warships seen. You'd have the big battleship which would dominate everything it fights, and then maybe smaller ships that could cover more area at once and engage in light combat, but wouldn't stand up to the battleships. Red called these 'frigates' in his Humanist Inheritance fiction, probably because their role is similar to the ship of the same name from the age of sail, and it is a term I like, so I will use it here. However, note 'cruiser' may also be an applicable moniker for these ships, probably depending on its specific mission rather than its design goal.

I feel these would exist due to economic efficiency rather than speed or range difference like those seen in the real sailing frigates. Let me explain.

Many of the arguments against space fighters can actually be used when talking about other capital ship classes as well. Let's look at what the roles of various naval ship classes basically were, and see if they could have an analog in space.

You had corvettes, which were small, maneuverable ships used close to shore. This role doesn't really apply in space. You might argue low orbit around a planet could be seen as a shore, but the problem is combat ranges would be rather large. If you have a stationary asset in LEO that you want to attack, you could put your battleship arbitrarily far away and attack it at will. If you have a mobile asset in LEO you want to attack, you can still attack it from some distance away, probably around one light second, to avoid too much light speed lag targeting issues and diffraction of your laser beams over the distance.

For comparison, the moon is about one and a half light seconds away from Earth. So, the battleship could be sitting out two thirds the distance to the moon and easily engaging the LEO target with precision and power. Corvettes being there wouldn't be of any help on defense, and the battleship can do their job on offense just as well, and at longer range.

A corvette type ship might be useful to the Coast Guard for police and search and rescue work, but that is an entirely different realm than a warship.

How about cruisers / frigates? The historical usage of the term referred to a small but fast warship, capable of operating on their own, and often assigned to light targets or escort duty. I do see an analog to this role in space.

A frigate would be no match for a battleship, however they would be useful in force projection, due to presumably being cheaper to produce and operate, thus more numerous. I'll be back to this in a moment.

And of course, battleships would be the backbone of the war fleet, able to swat down anything that comes at them except other battleships. If it were economically feasible to build a huge fleet of battleships, I see no reason not to. Let's investigate some of their traditional disadvantages and see if they apply in space.

The big one is speed: the huge battleship can take just about anything dished out to it and dish out enough to destroy nearly any other class of ship, but its huge size makes it slow. This isn't so much of a concern in space. Allow me to elaborate.

There are two things in space that are relevant when talking about "speed": delta-v and acceleration.

Delta-v is determined by the specific impulse (fuel efficiency) of the ship's engines and the percentage of the ship's mass that is fuel. Tonnage of the ship doesn't really matter here: it is a ratio thing. If the specific impulse is the same and the fuel percentage to total mass the same, any size ship will eventually reach the same final speed. Thus, here, if fuel costs are ignored, small ships have no advantage over large ships. (And indeed, if you are going on a long trip, the large ship offers other advantages in how many supplies or for war, how many weapons it can carry at no cost to delta-v, again, if the ratio remains constant) So the question is how fast can they reach it, which brings me to acceleration.

Acceleration is determined by total engine thrust and the total mass of the ship. At first glance, it seems that the smaller ship would obviously have the advantage here, but there are other factors that need be observed.

One is the structural strength of the materials of which the ship is constructed. This becomes a big problem on insanely huge ships with larger accelerations, since the 'weight' the spaceframe must support goes up faster (it cubes) than the amount of weight it can handle (it squares). Mike talks about this on the main site when he debunks the silliness of giant insects. However, steel is strong enough that with realistic sizes and accelerations, this should not be an issue before one of the other ones are.

One that is a much bigger problem is how much the human crew can handle. In the space / atmospheric fighter thread we had the week before last, Broomstick discussed the limits of the human body to great accelerations. Well trained people in g-suits can handle 9 g's for a short time, but much more than this is a bad thing to just about everyone - their aorta can't handle it. In fact 5 positive g's are enough to cause most people to pass out, as she explains. If the crew is passing out, the ship is in trouble. This problem can be lessened by the use of acceleration couches: someone laying down flat can handle it much better for longer, but even 5 g's laying down is going to be very uncomfortable, and the crew will have a hard time moving their arms. Extended trips would probably be best done at 1 g so the rocket's acceleration simulates Earth normal gravity, with peak acceleration being no more than 3-5 g's for humans in the afore mentioned couches if possible.

That is probably the most significant limit on acceleration, since it is an upper limit of humans. No matter what technology exists, this cannot be avoided.

The third limitation will be based on the technical problem of generating this much thrust for the mass. This, too, can provide an upper limit, since adding more engines on to a ship will eventually give diminishing returns. The reason for that is the available surface area on the back of the ship where the engine must go increases more slowly than the mass of the ship as it grows. But, for a reasonably sized ship, this should not be a tremendous problem, especially when nuclear propulsion techniques are used, many of which have already been designed and proven feasible in the real world. Fission nuke pulse propulsion can provide 400 mega-newtons of thrust according to the table on Nyrath's Atomic Rockets website (see the row for Project Orion).

Three gees is about 30 metres per second squared acceleration. F = ma, so let's see what mass is possible. 4e8 / 3e1 = 1e7 kg, or about 10000 metric tonnes. Incidentally, this is the number Sikon used for his demonstrations in the October thread about brick vs needle. I think it a reasonable number for a battleship, so rather than repeat the benefits of this, I refer you back to that thread and the posts of GrandMasterTerwynn and Sikon on the first page, who discussed it in more depth than I am capable of. I agree with most of the views Sikon expressed in that thread.

So, for these sizes, the speed argument against battleships is very much sidelined.

You also pointed this out later in your post that these advanced propulsion techniques do not necessarily scale down very well, which may also serve as a lower limit on ship size, which is probably more relevant than the upper limit it causes.

You might ask if pushing for a greater peak acceleration would be worth it, and it is not, in my opinion. The reason again goes to the human limitations. Even if your warship is pulling 10 gees, it most likely won't help against a missile, which can still outperform you.

An acceleration of even 1 g should be enough to throw off enemy targeting at ranges of about one light second. By the time the enemy sees what you are doing, you have already applied 10 m/s change to your velocity. Then, if he fires back with a laser, you have another second to apply more change. This would be enough to help prevent direct, concentrated hits. Having even five times more acceleration will offer little advantage over this in throwing off targeting or wide spread impact of lasers of particle beams, due to the ranges and the size of your warship, which is certain to measure longer than 50 metres. For missiles and coilgun projectiles, it matters even less, simply due to the time the enemy fire arrives, you have plenty of time - minutes - to have moved. 1g is plenty for that, attainable by a nuke pulse engine for sizes around 30,000 metric tonnes.

Long range acceleration would again be limited to around 1 g or less due to the humans, mentioned above. However, even at 1g constant acceleration (which would probably not be used due to fuel concerns anyway), an Earth to Mars trip could be measured in mere days. More offers little advantage there either.

Lastly, there may be a question of rotation. A more massive and longer ship would have a greater moment of angular inertia than a smaller ship, thus requiring more torque to change its rate of rotation. Again, I don't feel this will be a major concern. At the ranges involved, you again have some time to change direction. However, this does pose the problem in quick, random accelerations to throw off enemy targeting.

Going with the 10,000 metric ton ship, let's assume it has an average density equal to that of water: one tonne per cubic meter. For the shape, I am going to assume a cylinder, about 10 meters in diameter (about the same as the Saturn V), with all the mass gathered at points at the end. The reason of this is to demonstrate a possible upper number for difficulty of rotation (moment of inertia), not to actually propose this is what it would look like. Actually determining an optimal realistic shape for such a ship would take much more thought.

With this, we can determine the length of the cylinder to be 10000 / (π r²) = about 130 metres long. Now, we can estimate the moment of inertia, for which, we will assume there are two point masses of 5000 tons, each 65 meters away from the center. So moment of inertia for the turning axis (as opposed to rotating), is 2*5000 * 65^2 = about 4e10 kilogram meters squared.

Now, let's assume there are maneuvering jets on each end that would fire on opposite sides to rotate the ship. Let's further assume these have thrust about equal to that found on the space shuttle, simply because it is a realistic number that I can find: about 30 kilo-newtons. Let's determine torque, which is radius times force, so 3e4 * 65 * 2 (two thrusters) = about 4e6 newton meters. Outstanding, now we can determine angular acceleration possible.

Angular acceleration = It, where I is moment of inertia and t is torque. So, we have 4e6 / 4e10 = 1e-4 radians per second squared. This is about a meager 10th of a degree per square second. Remember this is acceleration - change in rotation rate. Once spinning, it would tend to continue spinning. This is also a lower limit: most likely, the thrusters would be more numerous than I assumed, and probably more powerful as well, and the mass probably would be more evenly distributed. But anyway, let's see if it might be good enough.

As I said when discussing linear acceleration, you would want some quick randomness to help prevent a concentrated laser beam from focusing on you, and you would want the ability to change your path within a scale of minutes to prevent long range coilgun shells from impacting. There isn't much you can do about missiles except point defense: a ship cannot hope to outmaneuver them due to limitations of the crew, if nothing else.

Some unpredictable linear acceleration should be enough to do these tasks, unless the enemy can get lined up with you, in which case, you will want to change direction to prevent him from using your own acceleration against you, and blasting you head on. So the concern is can you rotate fast enough to prevent the enemy from lining up with you. So, let's assume the enemy can change direction infinitely fast, and can thrust at 3 g's. The range will still be one light-second.

We can calculate how much of an angle he can cut into the circle per second if he attempted to circle around you. His thrust must provide the centripetal acceleration, so we can use that as our starting point. Centripetal acceleration is equal to radius times angular velocity squared, thus, sqrt(30 / 3e8) = 3e-4 radians per second.

So, its angular velocity is three times that of the acceleration of the battleship. Thus, it would take the battleship three seconds to match that rotation rate. It would also want to spin faster to make up for lost time, thus lining up on your terms again. I feel this is negligible because of two factors: if the enemy actually was orbiting like this, its position at any time would be predicable, thus vulnerable, and the battleship can probably see this coming: the enemy's tangential velocity must also be correct to do such a burn - he can not randomly change the orientation of his orbit due to his limitations on linear acceleration. This means you can see what he is doing and prepare for it with a small amount of time of him setting the terms. In this small time, he would not even move a degree on you: still easily within your armor and firing arc. (Also, weapons turrets on the battleship would surely be able to rotate at a much, much faster rate, so outrunning them is impossible anyway).

Thus, I feel neither linear acceleration nor angular acceleration are significant limiting factors as size increases within this order of magnitude.

Long story short: unlike marine navies, speed is not a significant factor in space warship design, unless you are getting into obscene sizes.

And, since I find it interesting, I want to finish talking about possible ship classes, so back to the comparison list.

Submarines depend on stealth, and since there is no stealth in space (barring pure magic like the Romulan cloaking device), there are no submarines in space.

Destroyers operated to protect larger ships against submarines and small, fast ships, like torpedo boats. Since speed is not a significant factor and stealth impossible, there are no fast ships nor subs, meaning the destroyer has nothing to do, thus would not exist. (Though, you might chose to call what I call frigates destroyers if you prefer the name, but IMO the role is different enough that is isn't really accurate. But the US Navy somewhat does this, so it is up to you as the author.)

A cruiser is simply a ship that can operate on its own. Frigates, destroyers, and battleships can all also be called cruisers depending on their mission.

A battlecruiser is a ship meant to be able to outrun anything it can't outgun - it had the speed of a lighter cruiser with the guns of a battleship. In real navies, this was usually achieved by taking armor off a battleship. However, since speed is not limited by mass in the given order of magnitude, a battleship and battlecruiser would have the same speed: the battleship would be a clearly superior vessel. Thus, no battlecruisers. (Now, if you have FTL, then that might create a battlecruiser class, but I am trying to avoid talking about magic in this discussion, since as the author, it is entirely up to you what the magic can and cannot do.)

A destroyer escort is a small, relatively slow ship used to escort merchant ships and protect them against submarines and aircraft. But, in the real world, aircraft can threaten a ship due to its superior speed and submarines due to stealth. So neither of them are there, making the destroyer escort worthless. Frigates or battleships would have to be doing the escorting, since they are the only things that can stand up to what they will be fighting: other frigates or battleships.

Now, a little more on what I mean by frigate. It is basically a smaller battleship, built simply because I am presuming they will be cheaper to produce and maintain, thus allowing more of them to exist. With more of them, they can be in more places doing more things. Cost is the only real benefit I can think of: if for some reason you could crank out and operate / maintain battleships for the same cost, I see no reason why you would not.

The 10,000 ton proposal might actually be the frigate, with the battleship being larger than that, or it might be the battleship with the frigate being smaller than that. The relationship would remain the same, however.

But what of vehicles intended to fight in space? As colonies and mining outposts spread throughout our solar system, there may be military value in capturing or destroying far-flung settlements -- which means there'll be military value in intercepting such missions. The popular notion of space war today seems to follow the Dykstra images of movies and TV, where great whopping trillion-ton battleships direct fleets of parasite fighters (ed. note: Battlestar Galactica and Star Wars). The mother ship with its own little fleet makes lots of sense, but in sheer mass the parasites may account for much of the system, and battle craft in space may have meter-thick carapaces to withstand laser fire and nuke near-misses.

Let's consider a battle craft of reasonable size and a human crew, intended to absorb laser and projectile weapons as well as some hard radiation. We'll give it reactor-powered rockets, fed with pellets of solid fuel which is exhausted as vapor.

To begin with, the best shape for the battle craft might be an elongated torus; a tall, stretched-out doughnut. In the long hole down the middle we install a crew of two -- if that many -- weapons, communication gear, life support equipment, and all the other stuff that's most vulnerable to enemy weapons. This central cavity is then domed over at both ends, with airlocks at one end and weapon pods at the other. The crew stays in the very center where protection is maximized. The fuel pellets, comprising most of the craft's mass, occupy the main cavity of the torus, surrounding the vulnerable crew like so many tons of gravel. Why solid pellets? Because they'd be easier than fluids to recover in space after battle damage to the fuel tanks. The rocket engines are gimbaled on short arms around the waist of the torus, where they can impart spin, forward, or angular momentum, or thrust reversal. The whole craft would look like a squat cylinder twenty meters long by fifteen wide, with circular indentations at each end where the inner cavity closures meat the torus curvatures.

The battle craft doesn't seem very large but it could easily gross over 5,000 tons, fully fueled. If combat accelerations are to reach 5 g's with full tanks, the engines must produce far more thrust than anything available today. Do we go ahead and design engines producing 25,000 tons of thrust, or do we accept far less acceleration in hopes the enemy can't do any better? Or do we redesign the cylindrical crew section so that it can eject itself from the fuel torus for combat maneuvers? This trick -- separating the crew and weapons pod as a fighting unit while the fuel supply loiters off at a distance -- greatly improves the battle craft's performance. But it also mans the crew pod must link up again very soon with the torus to replenish its on-board fuel supply. And if the enemy zaps the fuel torus hard enough while the crew is absent, it may be a long trajectory home in cryogenic sleep.

(ed note: the detachable fuel torus concept is vaguely similar to Traveller's Battle Rider concept.)

Presuming that a fleet of the toroidal battle craft sets out on an interplanetary mission, the fleet might start out as a group of parasite ships attached to a mother ship. It's anybody's guess how the mother ship will be laid out, so let's make a guess for the critics to lambaste.

Our mother ship would be a pair of fat discs, each duplicating the other's repair functions in case one is damaged. The discs would be separated by three compression girders and kept in tension by a long central cable. To get a mental picture of the layout, take two biscuits and run a yard long thread through the center of each. Then make three columns from soda straws, each a yard long, and poke the straw ends into the biscuits near their edges. Now the biscuits are facing each other, a yard apart, pulled toward each other by the central thread and held apart by the straw columns. If you think of the biscuits as being a hundred meters in diameter with rocket engines poking away from the ends, you have a rough idea of the mother ship.

Clearly, the mother ship is two modules, upwards of a mile apart but linked by structural tension and compression members. The small battle craft might be attached to the compression girders for their long ride to battle, but if the mother ship must maneuver, their masses might pose unacceptable loads on the girders. Better by far if the parasites nestle in between the girders to grapple onto the tension cable. In this way, a fleet could embark from planetary orbit as a single system, separating into sortie elements near the end of the trip.

Since the total mass of all the battle craft is about equal to that of the unencumbered mother ship, the big ship can maneuver itself much more easily when the kids get off mama's back. The tactical advantages are that the system is redundant with fuel and repair elements; a nuke strike in space might destroy one end of the system without affecting the rest; and all elements become more flexible in their operational modes just when they need to be. Even if mother ships someday become as massive as moons, my guess is that they'll be made up of redundant elements and separated by lots of open space. Any hopelessly damaged elements can be discarded, or maybe kept and munched up for fuel mass.

• 

(ed note: Please note that this article was written in 1979. It was very good for the time, but parts of it may be a bit dated now.)

      Awareness of the military advantage offered by space has been prominent, in science fiction and during the age of actual exploration. Of course, the Outer Space Treaty of 1967—the “Mother Treaty”—prohibited military activity in space. Although the Soviet Union signed it, its space activities have remained basically military in nature from the first. Russian space launches are conducted by the Rocket Forces, and major Soviet efforts in the 1960s were aimed at development of an orbiting bomb-carrying satellite—FOBS, fractional orbiting bombardment system—followed by a “killer satellite” program. At the same time, the United States tried to keep space exploration a civilian affair, allowing the world press and the public to attend U.S. space shots; and while the creation of NASA was a step away from armed service control, military involvement was unavoidable due to shared technology and personnel needs. (The preponderance of military pilots in astronaut roles has been the focus of recent debate.) In that respect, it is interesting to note that much space aboard the Space Shuttle has been allocated to the U.S. Air Force.

     In any event, those roseate visions of a conflict-free cosmos are gone. War in space is now being planned openly; and if a broad definition is applied, inner space—the zone between the Earth and Moon—is already a theater of operations and has been since the early 1960s, with a myriad of spy satellites scattered among 4,000 pieces of orbiting hardware, freely carrying out strategic missions. If this is the first step, what will be the second?

The Evolving Context

     At the time of this writing, in late 1978, the stationing of a bombardment platform in inner space, carrying nuclear missiles, lasers, or charged-particle weapons, is openly discussed, and is not beyond the scope of contemporary technology or strategic thinking. Yet such a system, manned or automated, is really only a slight extension of contemporary military systems and policy, and does not truly represent war in space. This will also be the case in related military space operations in the next decade or so, with space serving not so much as an independent zone of conflict, but as a component in an Earth-based strategic equation. Presuming the millennium is not at hand, and total peace does not arrive, space conflict of the kind envisioned in such works’ as Haldeman’s The Forever War will not be seen until man moves well out into the solar system, establishing mining and industrial colonies, and when distance and time, combined with technology, create conditions for independent action, unrelated to the security or perhaps even the perceived interest of terrestrial states.

The Immediate Future

     Initial combat in space would at this point be analogous to WWI air operations with fragile, primitive craft operating over limited areas, with the exception that many first generation space fighters might well be unmanned drones. Space weaponry in the immediate future will draw heavily on current or designed aircraft and antiaircraft systems. At the present time, the shift from passive to active forms of strategic space hardware is led by direct-energy weapons, in the form of the laser, whose main application so far has been range-finding, but which has also been examined as an instrument for ballistic missile defense. Since 1968, U.S. high-energy laser research has been classified, with occasional reports of experimental weapons under development emerging from time to time. The canceled B-1 bomber was reported to have carried a laser gun as defensive armament. Among types of lasers now in the forefront of military discussion, according to the 1978 edition of Jane’s Weapons Systems, are carbon-dioxide gas dynamic and carbon-dioxide electric. Development of beam weapons is also underway, as are refinements in propulsion, guidance, reconnaissance techniques, and attendant technical systems.

     The complex of change has already eroded the nearly pristine view of the solar system and space as a kind of simplistic mechanical model. More and more subtleties and nuances, such as the Van Allen Belts and LaGrange libration points, are filling in the “map” of space and reducing the ability to extrapolate and anticipate with any sense of surety. Innovation in technology produces pressure to adapt in the realm of policy and doctrine. Controllers tend, as they have in terrestrial warfare during the Industrial Age, to lag behind in their visualizing the future and altering systems to maximize potential. The interaction between the forces of inertia and change in modern organization is laden with high drama, sometimes farce, and occasionally tragedy. As cyberneticians are aware, an increase in numbers and sophistication in a system increases the range of possibilities rather more geometrically than arithmetically.

The Dilemma of Perception

     The difficultues of conceptualizing such changes in any kind of perspective are evident in the vagueness of description of battles between spacecraft in militarily oriented science fiction. While undoubtedly a testament to the Duke of Wellington’s observation that he would as soon describe a battle as a ball, many of the actions in science fiction are treated broadly, metamorphically, or take place in a two-dimensional matrix on the surface of planets, rather than in the fluid and shifting context of space. The fixation, in recent space-opera, on fighter aircraft and tactics, slightly extrapolated from the models of World War II is one example of that problem.

     The craft in Star Trek, Star Wars, and Battlestar Galactica are designed to fight in a two-dimensional plane, have individual pilots, no evident problem from solar glare, or from the incredibly high gravitational stresses depicted. They fly in formations oriented to a gravitational plane even in deep space, and yet somehow seem able to monitor the 360-degree environment in which they operate, without great concern for jamming, spoofing, or jinking, all in the spirit of Wings, Hell’s Angels, Dawn Patrol, Fighter Squadron, and Baa, Baa, Black Sheep.

The Tactical Spectrum

     Given the scarcity of resources and repair facilities in space, one might well expect to see tactics conform to some variant of the pattern seen in desert warfare in the twentieth century, in which scavenging and refitting enemy equipment for one’s own use became a major dimension, and in which tactical brilliance was offset by communication and supply factors. Similarly, targeting could be expected to minimize damage, to compartmentalize it, leaving the targeted system with capacity to barely function, perhaps only with the assistance of the attacker, thus assuring the support of the conquered in a unique way. The design of operations to maximize apparent threat rather than inflict damage would conform to the pattern of increasing precision and diminishing collateral damage seen in conventional wars since 1970. In this respect, the use of insidious radiological or chemical warfare, vibration, electromagnetic waves, or poison might well become the focus of development.

The Implicit Redefinition of Leadership

     Given these implicit complexities, an arms-control analyst might well ask, “Is it worth it?” and beyond that, “Is it possible?” A number of quandaries could arise as the military considerations begin to influence living patterns. Perhaps rigid selection or genetic alteration would produce a warrior subrace with the demands of conflict handled by direct human-battle computer links. A critical question that emerges from this is: how much of the control as well as the fighting might be handled by artificial intelligence? It is difficult—if not impossible—to imagine weapons systems free of the contest of command-and-control acting with total independence, but this will be a main question imposed by the arrival of superintelligent machines. In some tactical systems, machines already have been delegated the option of opening fire. A fear of artificial intelligence seizing the upper hand and overdependency of humans on mechanisms is laced through the corpus of science fiction, e.g., E.M. Forster’s The Machine Stops, Harlan Ellison’s “I Have No Mouth and I Must Scream,” and Fred Saberhagen’s Berserker.

     Whatever type of weapon is used—solid or explosive missile, using magnetic, electromagnetic, chemical, or kinetic propulsion, beam weapons, mines, or abalative clouds—its deployment or use in space poses problems of perception and control which, as with the leap from two- to three-dimensional arrays of force, transcend in complexity most Earthly conflict situations. This effect will be compounded by several factors. Velocities and stresses of directional change will be much greater, placing tremendous demands on reflexes, the human body and spacecraft structure.

     To add to the complexity, the operational matrix of space is a sphere. The traditional two-dimensional planar orientation to the Earth’s surface will be gone. Although pilots now operate in three-dimensional situations, land reference and the role of gravity as orienting factors are close at hand. In seeking adaptation to this new milieu, crew selection and development techniques may move toward genetic screening, and perhaps engineering, as well as to more sophisticated selection, as demands on crews increase with the scope and range of action. Optimizing duty-tour periods and crew rotation would obviously be critical. Levels of rest-and-recuperation could be programmed, varying in degree, to gradually reduce physiological tensions and then reintroduce them. It is fairly obvious that new drugs and meditative techniques would merit exploration, to enhance crew power and reduce fatigue generated by the tension and physical demands of space combat.

     Further along, while human capabilities may initially dictate the design of spacecraft and systems, more and more of the actual fighting may be done by drones, controlled from and housed in the parent craft, or prepositioned and actuated from a distance. In the way of yet further complications, a weapon of any type fired in space will go on until deflected by magnetic fields, radiation, or gravity emanating from planets or stars, or until it collides with gas clouds, dust, or meteors. The visions, so common in science fiction from Buck Rogers to Lupoff’s Space War Blues, of ships and fleets blasting away wildly at each other in virtual art deco Trafalgars, will give way to more restrained vectors of fire. Ships, unless well out into deep space, will be constrained by the background of satellites, colonies, drones, other ships, and base planets. Maneuvering for maximum restricted background and hiding in the sun’s glare will be at a premium. The danger of their weapons’ destructive effects continuing on beyond targets may see them reduced to but one (and not necessarily the most desirable) weapon in a diverse arsenal. Self-destruction or braking to zero-velocity of missiles will have to be considered, and the control of arrays of remotely actuated firing drones and stations may well emerge as alternatives. In this regard, it is interesting to note how combat information display systems and weapons portrayed in science-fiction films and television programs remain two-dimensional in presentation format.

The Naval Analogy

     Another problem related to all this is that noted by F. W. Lanchester in 1914 in War in the Air, his well-known theoretical analysis of the implications of air war, in which he suggested that success in war went to the side that massed its units and went for the enemy’s center. He hypothesized further that, all other things being equal, the relationship between opposing forces’ firepower was a relationship of the square of the units of fire. A debate currently rages in respect to this problem over naval force mix; the problem is that many small units provide more targets, but are also more likely to be eliminated by first-round kills than are armored ships. This debate may well be expected to continue in regard to extraterrestrial force balance, which underlies the structural similarity between space war and naval war. Sailors in action must stay in one place physically and fight their part of the ship, analogous to cogs in a machine. Commanders share danger with their subordinates and in the way of a further parallel the crew live as shipmates the rest of the time. Science-fiction writers from Doc Smith on through Larry Niven and Jerry Pournelle have noted this, and have used naval forms of rank, usage, and organization in describing space forces-fleets-armadas-navies. (Perhaps the fact that Robert Heinlein went to the U.S. Naval Academy is worth mentioning at this point.)

     As true spaceships develop, and form follows function, battle craft built in orbital construction yards will not resemble the cylindrical (some might suggest phallic) and unnecessarily aerodynamic configurations of science-fiction vessels. Yet, as science-fiction writers have noted, as these ships move out into space, the organizational model of the space forces will more resemble naval rather than an air-force analogy, or at least be a fusion of the two, whether operational conditions dictate large cruisers, a destroyer flotilla approach, or a spectrum analogous to the fleets of the world wars. Most combat will occur in space, and planetary actions will be limited and precise, akin to marine-commando operations and, at this point, it is hard to better the perspective of Heinlein in Starship Trooper.

The Weapons Possibility

     What weapons will fleets of the more distant future carry into battle? The range of weaponry will be varied and complex, as will their methods of defense and protection. There will be limited application of weapons derived from existing concepts. Rotary cannon such as the U.S. Vulcan type and other aerial guns could have applications, but they would be limited by the consumable nature of their ammunition and resupply difficulties. This is also true for missiles of various sizes and types, be they explosive or solid. The role of missile weapons—versus—beam weapons tends to be minimized in visions of future space combat, perhaps because of the limited range of such weapons on earth.

Propellant Possibilities

     Weapons design will be influenced by technologies tangential to that area of research; e.g., metallurgy, hydraulics, ballistics, physics, and so forth. An overview of such currently evolving fields as explosive optics suggests the complexities that will be encountered in the long run, while reducing a sense of certainty in forecasting. Similarly, parallel developments in micropowder metallurgy and related work on enhanced chemical explosives is now producing a “new ball game” in an area that sat on the back shelf from World War II until the 1970s. There are many possible configurations for firing missile weapons beyond the use of rockets, whose propellants and explosives would constitute a high battle-damage risk. That suggests that a premium would be placed on developing instantaneous mixing systems, in which the relatively inert ingredients would be separate until actual deployment, already seen as a working principle in chemical-warfare systems. The development of ethnic-specific enzyme destruction agents (chemical warfare agents that attack enemy soldiers but have no effect on friendly soldiers) may be of more significance to terrestrial than space conflict in the near future, but should not be ignored in terms of their implications. Since rockets also present problems of weight and bulk, perhaps research may move toward centrifugally impelled solenoids, or even torsion- or spring-powered propellant systems; perhaps firing ice, or very small particles of solids which offer low radar profile. Similarly, there are more than a few ways to skin the cat of beam-weapon generation. Even at the present time, work is underway on a variety of counterinductance generator systems, capacitor technologies, jet-driven generators, and a number of other approaches.

Missile Weapons

     Variants of missile weapons offer some possibilities in terms of reaching very high velocities, unaffected by air drag or gravity. One example is the “HARP” satellite launching system developed in the early 1960s by the Canadians, employing large-caliber American naval guns firing shells boosted by rocket motors, a technique which has continued to be the focus of research. By the mid-1960s, such a system applied to a smaller gun was reportedly able to fire 175mm shells a distance equaling that from Philadelphia to New York, albeit with crude accuracy. The “light gas” gun suggests another possibility; a system in which a volatile gas is detonated in a chamber closed by a thin metal shield, which, when the pressure mounts to a high enough level, ruptures and frees the gas to work against a piston, firing a projectile at speeds above 8,000 feet second—almost three times the speed of a hunting rifle, and higher than contemporary tank guns. Such a system, hybridized with a HARP technique, could produce hypervelocity missiles with microminiaturized homing systems.

The Nuclear Dimension

     The use of nuclear weapons in space has already been closely examined within the framework of antiballistic missile systems, with particular interest shown in their ability to generate X rays and thereby damage ICBMs in high trajectory. Nuclear testing in its final phases included high-altitude detonations which showed spectacular auroras and ionization. In deep space, then, radiation, electromagnetic pulse, and immediate damage within a fireball would be the principal means of wreaking havoc, since heat and blast damage would not play destructive roles at the distances which they do on Earth against unhardened targets. In a related vein, a concept under evaluation currently for possible use as an anti-ICBM and satellite weapon in the near future is “junk,” or chaff—small pieces of metal, plastics or other solids. To protect a spacecraft moving at sixty miles a second into a floating cloud of such material would require an armoring system or sophisticated warning and maneuvering apparatus.

Replenishments

     More emphasis will be placed on renewable weapons, whose exhaustion of “propellant” or “change” will not easily deplete a ship’s ammunition store. Such systems might include beam weapons whose forces can be derived from ship-board power generating systems and collected from external sources. In some cases, energy of nearby sun-stars could be applied by means of collection, reflection and focusing mechanisms.

Configurations of Fragmentation

     Calling to mind again the great volume of territory that will be the maneuver ground of space fleets, it would be impossible to operate without supplementary equipment. Minefields could be sown for both offensive and defensive roles. These mines might take the form of giant hand grenades, since blast effect is greatly reduced in space by a lack of atmosphere. Damage is best assured by particles, across a range of sizes. Nuclear weapons could be jacketed in cases containing a myriad of shrapnel, actuated by either command or by remote sensing of targets that conform to a preprogrammed profile. While blast effect would be minimal unless it activated directly in contact with a target, particles and radiation would be the instrument of damage. Multistage aerosol might provide a tamping medium for concentrating blast.

Shielding

     While development of wide-spectrum defenses would be imperative due to the great value of both ships and their highly trained crews, defensive design considerations would be more easily expressed than in any previous form of fighting vehicle. Free of gravity and tension stresses, vessels could be constructed in linked modules, or shielded with multihulls, or surrounded by aerosol or microsolid “clouds.” Stable man-made, superheavy elements, now only projected as to “exist” by physicists, could provide defense against various forms of weapons radiation and missile damage, as well as from natural sources—e.g., solar flares and meteors. Further shielding could be obtained through plasma and aerosol technology, which would abrade or diffuse the effects of such obstacles, mines, “junk” or chaff clouds, and beam weapons, as well as pre-detonating contact and proximity-fused missiles. By cloaking a vessel in a cloud of suitable material, it would be possible to monitor, deflect, and reflect light stimulation and particle weapons. In a related vein, electronic countermeasures (ECM), which have developed along with military dependency on electronics, will be a key factor in both offensive and defensive space operations. Whether generated from manned ship or stationary mobile drones, the technique of providing false and confusing information will increase with the volume and complexity of space operations.

Space, Lag, and Command-and-Control

     Beyond projections of existing or immediately anticipated technology lies a broad landscape of theoretical possibility. The hypothesis that a weapon is anything which can be used to defeat an enemy implies that skills in management, intelligence and deception cannot be ignored as elements of a weapons system. Not immediately obvious is the fact that as military forces extend themselves into space, strategic planning will undergo a virtual reversal in thinking, since due to the factors of volume and time, commanders will have an autonomy of command not seen since the age of fighting sail. The theory of relativity will become the fact of relativity, as command-and-control links begin to move out of phase with the pattern of the electronic age on Earth, where, while weapons systems move with relative degrees of sluggishness, electric and electronic communications are virtually instantaneous.

     In space, distance will see speed-of-light communications and weapons facing increasing lag, which will produce command and targeting problems. Consider, for example, the simple case of a duel between two ships each traveling at 25,000 miles per hour at a range of 25,000 miles. First, each ship would not be able to sense the enemy ship’s firing of speed-of-light weapons in time to adjust or change course. Next there would be limits on a ship’s “jinking” ability, due to strains on structure, human crews, and the drain on fuel supplies. Moreover, such an encounter would require randomization of course and speed to confound an enemy’s firing pattern, which would, in turn, try to maximize chances of a hit within a cone of probability. Such uncertainties would virtually randomize tactics in a manner reminiscent of the Battle of the Atlantic in World War II, where mutual code-breaking merely produced mutual uncertainty and groping.

     To pursue the scenario a bit further, a laser would take about 0.13 seconds to transit. Radar pulses going and returning would take twice as long, leaving the actual location of a target problematical, since the target could vary course slightly and at a randomly oscillating speed. To complicate the problem, it should be noted that braking a spacecraft is not as simple a problem as it might seem, and it does consume energy. In any case, even with no computers or mechanical tracking time in the firing sequence, at least half a second would elapse between a ship’s sensing enemy radar tracking and receiving a hit.

     The development of hyperlight weapons and communication systems, while apparently impossible, may attract attention from research and development experts, at least as something more than a topic of parlor discussion. In the meantime, the limitations of radar for conning and combat, analyzed at some length by James Oberg in Space Wars, will place a premium on optical systems which, in addition to passivity, offer a chance to halve the response time of radar’s to-and-from mode of operation. It will be possible to construct optical systems in space with resolution capacity well beyond that of Earth-bound telescopes. Stereoptical-parallax sensitive systems would obviously be invaluable. Computer enhancement and response would be preferable to human-operated systems, which would have lag and error built into them. Problems of identification, countersystems employing dazzle, overload, camouflage, and cloaking would all devolve from the use of such systems, as would the equipping of spacecraft, manned and unmanned, with low visibility to optical or radar scan and, conversely, low-signature sensors.

Command-and-Control

     There are also problems related to command-and-control. It is sometimes hard to keep in mind that the headquarters is part of a general “weapons system.” The hampering of subordinates, the ignoring of warnings, the problems of authority and coordination are all part of the implicit paradox of hierarchical organization, as is the development of the “headquarters syndrome,” in which mission becomes subordinated to ego, whim, and the dynamic of the organization as a social system rather than as delivery system. In the wars of the twentieth century, progress in radiocommunications moved senior commanders farther and farther to the rear until, in the air war over Vietnam and in the Mayaguez affair, immediate battlefield decisions were made in the Office of the President, cases in which apparent political advantage outweighed conventional wisdom, or some might suggest, common sense. Such centralizing of command at a distance will tend to fade as elements are dispersed farther from Earth, and subsequently from nonterrestrial subordinate headquarters. If the lag is not fully appreciated, and subordinate commanders are not allowed discretion and comprehensive intelligence capability, the forces that result will be unable to make plans or decisions in far-flung tactical crises.

Intelligence, Propaganda, and Systems Vulnerability

     Intelligence gathering and analysis, always vital, will be no less essential in space military operations. Distance and the dispersion of force will put a special premium on optimum application of available forces; for no matter how many units a power may possess, they will become dramatically finite in an expanding infinity. Because deceptions are not truly weapons does not necessarily mean they are ineffective in that role. Black or gray propaganda would fall into this area, as would alterations in space ecology such as fusion-triggered solar flares or redirection of meteorites and comets. Even in the first phase of the militarization of space, the danger of attack from an unidentified source emerges as a new and somewhat unique problem. The identification of friend and foe was already a thorny matter in World War II. It has become more serious in the nuclear age, and presents a new order of complexity in space. Militarization of space requires rethinking the problem of protecting the infrastructure of societies against the impact of accurate and powerful weapons of uncertain origin and location. The “signature” of nuclear weapons can be “read” quickly to identify components and probably source. Conventional explosives and beam weapons would not be so easily traced.

     The vulnerability of the sinews and arteries of industrial societies was revealed in World War II, when raids by Allied bombers in the last few months of the European war against German synthetic-oil plants and transportation caused a plunge in German productive capacity, as well as a blunting of its air defense systems. In the Eisenhower era, stockpiling of crucial raw materials, an expanded civil-defense program and plans for dispersing the construction of new industry as well as moving strategic facilities out of major cities became policy for a time, reflecting an anxiety about their vulnerability. After the Cuban missile crisis and the shift to a “counterforce” strategy and the preoccupation with Vietnam, such programs faded from sight. The concern for vital modes of communication and the need for dispersion and shielding remained alive in the airborne command-post system and the MX missile complex. It is still hard for many to understand that the loss of a few key technical or communication elements may be more serious than the destruction of much larger combatant units. In “The Perfect Weapon,” Poul Anderson suggested another dimension of the querschnitt (vulnerable subcomponent) effect in suggesting that the dissolving of paper would render a modern military bureaucracy harmless. Today, neutralizing their computer terminals or photocopy machines might do just as well. Apocryphal stories abounded of computer cards swelling in the heat of Vietnam.

Quasi-War

     Conflict in space may eventually evolve to forms which are not easily discerned as warfare. Perhaps technological and cultural advances will heighten understanding of the fact that destruction is not victory, and the ultimate weapon may therefore not be one of violence, but rather a complex of alteration and conversion; e.g. synchronous satellite television and radio broadcasts of propaganda, as well as subliminal transmissions and scientific rumor generation. This effect was referred to in the eighteenth century by Marshal Saxe when he observed that the “object of war is not a pyramid of skulls.” More recently, Robert Asprey, in War in the Shadows, suggested a transition from “battle-and-victory” to “pressure-and-gain.”

     Another exotic “weapons system” examined from a variety of perspectives by science fiction writers is the alteration of time and space, to allow a close approach to an enemy permitting tactical surprise, such as concealing vulnerable targets in other epochs, etc., a theme treated lightly in Reg Bretnor’s “The Gnurrs Come from the Voodvork Out.” (also in Clarke's Superiority)

The Organizational Constants

     In essence, policymakers and fabricators and controllers of weapons in space will face many problems hitherto encountered in essence in military history. The politics of weapons choice will certainly be. evident, interacting with the bureaucratic politics of the armed services and related organizations. Unless human beings are somehow magically transformed, one can expect to see tension between rational choice and maintenance of the social systems, the interests of elites, factions, cliques, advocates, Young Turks versus Old Guard, corruption, and service rivalry, even within the framework of a National Space Command. The problems of overspecialization of force, of balance, of overruns, and of faddism are not likely to disappear.

The Challenge of Systems Balance

     Science-fiction writers since the Second World War have described systems in which research-and-development interacts with the traditional warrior ethos, variations on a theme of futuristic bushido, such as Gordon Dickson’s Dorsai in Soldier, Ask Not and The Genetic General. Dickson’s descriptions of battles, usually focused on ground action (an exception being The Battle of Newton in, the latter work) touch on basic principles. His mercenaries carry less than the last word in weapons, trading off destructive power against designs that offer the least possibility of being jammed or blocked; e.g., spring-loaded rifles firing nonmetallic slivers, requiring no maintenance and free from fouling. Such danger implicit in overcommitting to high technology is often referred to as the “KISS principle” in the American military; KISS is the acronym for “Keep it simple, stupid.” There are also references to a need for having systems designed by geniuses to be used by idiots. In 1950 Arthur C. Clarke examined this effect at some length in “Superiority,” a short story in The Magazine of Fantasy and Science Fiction, in which the narrator tells of a war between interplanetary powers. The side that uses lots of good solid, simple technology in ever-larger numbers overwhelms opponents who keep leaping from what seems to be one high-tech panacea project to another. Each leap presents a variety of bugs and unanticipated side-effects which fall short of the expected goal, generating hysterical frenzies, and further pratfalls. Looking at the story in the aftermath of Vietnam may create a sense of poignance in some readers and irony in others. Yet Clarke merely transposed Lanchester’s “laws” into a futuristic context.

The Arms Control Factor

     Beyond the questions of weapons system and hardware choice, in the immediate future one may expect to see a continuation of the disarmament dialogue evolving since the coming of “high technology” war in the middle of the nineteenth century. Much of what has gone on in that area seems to the cynical to be wheel-spinning and a mask for deception, intelligence gathering, and weapons development. The generation of World War II spoke of the Washington Naval Conference through clenched teeth, and some contemporary analysts have seen the SALT talks as a sop to public wishful thinking, as camouflage for espionage, or as empty gestures toward a shaky détente. Yet others have seen them as the hope of the future and evidence of a growing if grudging realization of the futility of major war in the nuclear age.

     With the expansion into space, this pattern is likely to continue. Politicians on both sides will maintain a rhetoric of peace and that ethic will impact from time to time on weapons choice, as well as supporting a consciousness of the danger of war in nations which allow open discussion of such matters; an effect which critics suggest makes disarmament conferences merely a weapon in the arsenal of psychological warfare of totalitarian states. The militarization of space has not yet become an agenda item in SALT, which may be a by-product of lag in perception due to the special complexity of the problem. In that sense, time will tell.

     The quickly changing perspectives regarding military developments in space are beginning to cause public discussion and may well intrude themselves into any future SALT-type conferences. Yet whatever controls are developed, they may be less like dams holding back military technological innovation, and rather more like rocks over which rapids ultimately break.

Epilogue

     This review of possibilities is necessarily based on extrapolations from existing knowledge, just as in the early days of the genre, science fiction focused on rather close projections of existing military technology, and a fairly heavy fixation on threats from obvious terrestrial enemies, as noted by I. F. Clarke in Voices Prophesying War. Erskine Childer’s The Riddle of the Sands and Hector Bywater’s The Great Pacific War were rather more like proto-RAND scenarios than science fiction in the projective sense, written without access to classified information, and without awareness of the full range of existing technology, as would be any essay on the subject. The breakneck developments in crystallography alone promise a complex of variants well beyond “reasonable” speculation. Science fiction has played the role of vanguard in tracing out possibilities and trends; a fact now recognized in the employment by futurologists of science-fiction plots in a kind of modified Delphi technique. The result of such prognostications, however, often seems to underline the truism that one must kill to dissect. Ultimately, there will be developments, like hypnosis, electromagnetism, nuclear fission, and the transistor, which will appear and recast frameworks and paradigms. As Arthur Clarke noted at the dawn of the true Space Age, the high technology of one culture may appear as magic to a less developed culture; e.g., the cargo cults born of the Second World War among Pacific islanders who saw ships and planes as the vehicles of gods. This problem has been nibbled at by Charles Fort, and by Bergier and Pauwels in The Morning of The Magicians. A mixture of anxiety and wonder has served as the yin-yang of science fiction, a distinction notable in, for example, the titles of such studies as Sam Moskowitz’s A Sense of Wonder versus Kingsley Amis’s New Maps of Hell.

     As Robert Ardrey argued in African Genesis, the development of weapons may be as valid a means of tracing man’s technological development as his use of tools, insomuch as many of the latter have been designed to build the former, a theme carried on in different forms by A. E. Van Vogt in The Weapon Makers and Arthur Clarke in several of his works. If humans are not by nature predators, they do show at least a love-hate relationship with weapons and violence, marked enough to make such peaceful tribes as the Arapesh and the Eskimos a small exception to a broad rule. Indeed, the least-expected possibility in both science fiction and public policy related to space is that Tennyson’s visions of a parliament of man will be made flesh. Whatever the successive realities, we can expect science fiction to continue to play and to grapple with possibilities, and steer into the fact of Wittgenstein’s caution: “Whereof we cannot know, thereof we should not speak.”

     Yet at this point, it is easy to conclude in surveying all these possibilities that the sheer scope of space and the complexity of waging war in it truly dwarfs mankind’s pretensions. One finds, however, that a similar sense of gigantism stimulating visions of peaceful idylls and utopias was born of the discovery of the Americas. In spite of our current apprehension and the intimidating sense of scale, human enterprise will then probably rise to the occasion, in the curious synthesis of pride, inventivity, assertiveness and bloody-mindedness that has characterized man’s evolution on the planet which seems now more and more to be only an incubator for his ultimate destiny.

In this post, we'll use the numbers we've put together so far, and the baseline spaceship from the last post, to create three 'complete' space warship designs. Each warship will have a datasheet and a commentary on design decisions and tactical considerations.

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MARTIAN INTERCEPTOR

Description: A high thrust, high performance warship that uses drop tanks to achieve enough deltaV to intercept interplanetary fleets. A solid-core nuclear thermal drive minimizes the need for radiators, but requires an on-board electric powerplant to power the lasers. Expendable mirror-drones are used to out-range potential targets.

Datasheet:

Name: Martian Interceptor

Role: Intercepting interplanetary Terran fleets

Dry mass: 1986.3 tons
Mass percentages: 68% Armor, 32% Components
Component masses:
50 ton solid-core nuclear thermal engine
100 ton nuclear-electric generator
100 ton armored radiators
38 ton Gyrotron-VECSEL laser generator
85 ton heat pumps
1 ton optics
112.5 ton mirror drones
11.4 ton life support
46 ton sensors
8.8 ton avionics
45.1 ton structure
33.6 ton tank mass
Propellant mass: 3359 ton internal, 34201.4 ton inner, 253035.6 tons outer

DeltaV: 5km/s internal, 15km/s inner, 25km/s outer.

Acceleration averages: 1.28G, 0.39G, 0.05G
Propulsion output: 100GW
Electrical output: 500MW
Ammunition: 8x Long Range mirror drones, 50x Short Range mirror drones

Standard laser performance factor: 5.7

Laser armor depth: 163mm, rotated, sloped.
Kinetic armor depth: 400mm, 600mm

Diagram: 
Shape is a narrow cone on top of a water cylinder.

Design comments:

100GW 50 ton nuclear thermal solid-core engine. Propulsion waste heat is absorbed by 8000kg/sec mass flow. Thrust is 36MN (90% efficiency).

100 ton nuclear electric power generators produce 500MW. At 33% efficiency, they put out 1000MW waste heat at 1500K.

Power generator waste heat removed by 2000m2 of double sided radiators. Mass is 100 tons with 50kg/m2 (armored). 1000 tons of water can be boiled off in 37 minutes if radiators are damaged.

Defensive gyrotron produces 333MW beam, 83MW waste heat, pushed from 500K to 1500K by 83MW heat pumps.

Offensive Gyrotron-VECSEL produces 158MW beam. Heat pumps move 170MW waste heat up to 1500K, consuming 170MW. Gyrotron masses 34 tons. VECSEL masses 4 tons. Heat pumps mass 85 tons. Aiming is through a 1ton side beam window.

6m radius mirrors composed of 113 hexagonal 1.12m diameter segments of 1m2 each, massing 4.9 tons for the mirror, 100kg for communications, resistojet RCS and electronics. 15.8kW is absorbed from the laser. It is removed by 35g/sec of liquid hydrogen boiloff. The heat exchanger masses 13.5kg/m2, based on a microtube design. 1.53 ton exchanger. 100kg liquid hydrogen provides operation for a maximum of 1 hour of continuous shooting. Power for pumps and the rest is provided by a 1kW 200kg electrostatic-thermoionic RTG generator. It is equipped with 12x2kg thrusters at 5 radial directions. 700kg of LOX/LH2 propellant in 10kg tank provides 500m/s deltaV.

Total mass is 7.4tons. Eight mirror drones add up to 59 tons, with 0.5 ton onboard LH/OX cracker and cryo-cooler tanks. Volume is 20m3 per drone.

Closer combat mirrors of 2m radius are composed of 12x1m2 segments, massing 528kg. 100kg for control, 162kg for heat exchanger, 100kg for LH2, 60kg 300W RTG, 24kg for thrusters, 2kg tanks, 98kg propellant for 500m/s deltaV. Total is 1.07tons. 50 of them mass 53.5 tons. Volume is 5.5m3 per drone.

Comments: Long range mirrors are nine times as effective compared to a 2m radius integrated mirror, and has the flexibility of one-ship flanking of multiple opponents, along all three axis. Close combat mirrors have swarm behavior.

Life support for a crew of three, with 1 month endurance. Pilot/programmer, comms/commander, engineer/teleoperator. Separated into two control centers and an inflatable rotating habitation ring. Consumables: open-ended 180kg of oxygen (72kg) and food (108kg). Water is drawn from the propellant tanks. Water recycling and CO2 scrubbing are handled by 150kg of equipment.

Control center resembles fighter jet cockpit and masses 1050kg. Inflated habitat masses 60kg/m3 and has a radius of 6m, and is a tube ring 2m wide. Mass 7.9 tons.

Total crew mass 11.38 tons.

Forward sensors are 10 degrees arc wide-angle x36 to cover the entire front arc, plus one forward facing wide-angle, plus three redundant 1 degree narrow-angle. Sides and rear are covered by three wide-angle sensors in scanning mode. Total mass 46 tons.

Comments: this is a very aggressive sensor layout. It relies on a planetary network to detect flanking threats. Multiple redundancy helps mitigate damage and blinding. Fixed positions allow for better detection of incoming stealth projectiles (zero scan delay).

Avionics represent 2% of dry mass, excluding armor. Mass 8.84tons.

Comments: an arbitrarily worse figure than the Terran's 1%.

Internal structure adds 10% to dry mass. Mass 45.1 tons.

Total internal mass is 597.8 tons. Volume is approximately 1800m^3, based on a 0.33ton/m^3 figure, derived from modern jet fighters. This is a cone 8.4m wide and 100m long.

External mass contains armor and point defenses. The Martian Interceptor is in some ways a battering ram: no stealth, high closing velocity, no regard for force disparity. It breaks through enemy defenses and creates an opening for missiles launched by a stealthy arsenal ship. The protection of an armored nose cone is a vital element, one of the reasons it does not have a keel-firing laser. It does not use laser point defenses, relying on kinetic PD instead to survive the one and only pass.

The rotating laser armor must survive the onslaught of three standard 250MW/2m/400nm lasers from maximum to 100km range. It uses a monolithic cone of DLC.

A standard laser penetrates 1mm/s of carbon armor starting from 2750km. This can be considered maximal effective range. At 100km, it penetrates 20.9m/s.

At a closing velocity of 10km/s, the MI spends 275 seconds under laser fire. If the closest approach is 500km, it accumulates 4133mm of carbon removed. If it closes to 100km, it takes 115532mm.

Failing to take out any targets leads to a 24803mm penetration flyby. Taking out one target at the closest intercept reduces this to 20699mm. An interceptor should take out at least one target before the closest intercept, and another after intercept, so 20699mm is the worst design case, and 24803 is the catastrophic failure case. We design to survive catastrophic failure.

The internal volume allows for a 2.41 degree cone. This sloping increases armor thickness by a factor 23.78, reducing requirements to 1043mm.

The cone has an average circumference of 13.2m. The standard laser's spot size averages 0.347m in diameter. An armor shell rotating twice a second can spread laser damage by a factor 76, reducing armor requirements to 13.72mm.

Actual armor requirements lie between 13.72 and 1043mm. In the best case scenario, the interceptor faces a tightly clustered opponent. At worst, the opponent has set up an un-escapable flanking shot. A compromise is necessary. If the interceptor can keep opponents within a 60 degree frontal arc, then it needs 163mm of armor.

The laser armor masses 655.5kg/m^2, for a total 438 tons.

Kinetic armor consists of two armor belts and two internal bulkheads. The front bulkhead is a 40cm hemisphere 4m wide. The main belt is 40cm thick, 20m long, moving up from the base of the armor cone (437 tons). An inner cylinder with 60cm armor protects the crew (5x4m cylinder, 86.7 tons). The rear belt is 40cm thick, 8.4 m wide, 9.08m tall cone, sloped at 65 degrees.

Front bulkhead is 8.18m^3 and masses 18.8 tons. Main belt is 437 tons. Crew tube is 86.7 tons. Rear belt masses 202 tons. The reactor cap 172.4 tons.

Total kinetic armor mass is 916.9 tons.

Total armor mass is 1354.9 tons.

Total dry mass is 1952.7 tons.

Internal water tank mass is 1% of water mass.

To achieve 5km/s deltaV, we need a mass ratio of 2.72. This can be achieved with 3359 tons of water propellant, requiring a tank mass of 33.6 tons and 8.4m wide, 60.6m long. Total mass is 5345.3 tons.

Inner drop tanks provide 10km/s. This requires 34201.4 tons of water. The water is held in balloons 60m long, 28.2m wide. Total mass is 39546.7 tons.

Outer drop tanks provide 10km/s with 253035.6 tons of water. It is held in a balloon 42m tall and 78.5m wide. Total mass is 292582.3 tons.

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MARTIAN ARSENAL SHIP

Description: An unmanned missile carrier that relies on liquid hydrogen boiloff and directional stealth to stay undetected. Cold missiles are delivered by a coilgun. An efficient nuclear-electric propulsion system allows it to catch up with Interceptors and build up an intercept velocity to compensate for the missiles' low deltaV capability. 
Datasheet:

Name: Martian Arsenal Ship

Role: Delivering missiles undetected. Dry mass: 1176.3 tons Component masses: 15 ton Pulsed Inductive Thruster engines 100 ton nuclear-electric generator 1.8 ton droplet radiators 122 ton coilgun 82.5 ton energy storage 173 ton heat pumps 354 ton missiles 9 ton sensors 6.5 ton avionics 171 ton stealth shroud 68 ton structure 73.4 ton hydrogen tank Propellant mass: 734 tons DeltaV: 24.6km/s

Acceleration average: 2.1 milliG Propulsion output: 1.5GW Electrical output: 1.5MW Ammunition: 10000 stealth missiles Standard laser performance factor: 0

Laser armor depth: 1mm. Kinetic armor depth: 1mm.
Diagram: 
Shape is a cylinder inside a cylinder, behind a hydrogen cylinder. 

Design comments:

Low exhaust temperature nuclear electric propulsion. 100 ton 1.5GW nuclear reactor, 15 ton PIT engines, 5000s Isp (49km/s) exhaust velocity, 30kN thrust (98% efficiency).

3030MW of waste heat is removed by four 1x5m liquid droplet radiators, using carbon-darkened tin at 1200K (emissivity 0.8, 1mm droplets). 146kg of fluid are used in operation. Radiator mass 0.8 tons, fluid mass 1 ton.
Missiles have 1km/s deltaV. They are launched by coilgun to 5km/s.

Missiles are all equipped with stealth capability. The penetrator and armor is a Diamond-Like Carbon cone 40cm long, 6.6cm wide, massing 10kg. It mounts a 1kg sensor and communications package. An 8kg, 10MPa (1450psi), 80K tank made of kevlar contains hydrogen gas for use as a propellant in a cold gas thruster, achieving an exhaust velocity of 2700m/s. Propellant density is 33kg/m^3. Thruster mass is 3kg. 9.86kg of hydrogen are required to provide 1000m/s deltaV.

Launch mass is 32kg. Total length is 1.22m, width 0.82m.

Missiles are delivered in 10-missile clusters massing 330kg, including a 10kg 'sabot'.
Coilgun efficiency is 90%. It requires 4.125 GJ to launch a cluster to 5km/s. The projectiles are accelerated at 2000g, reaching the muzzle velocity in 122m of acceleration. Coilgun mass is 122 tons.
Energy is stored in by SMES. Several superconducting loops with carbon bracing hold 4.125GJ in 82.5 tons.
A coilgun generates waste heat too quickly to be removed directly by a radiator. It must be transferred to a heat sink first. 413MJ is released per shot. Non-corrosive liquid helium at 20K is used as the coolant fluid. If it operates at 300K, it requires 278kg of helium gas to be flash-heated. 10 shots (one missile wave) require 2.8 tons. 

The waste heat from the coilgun has to be pumped from 300K to 1200K. This can be handled by 173 tons of heat pumps. They consume 346MW. The power draw of the heat pumps reduces firing rate to one shot per 3.6 seconds.    
Stealth firing and moving can be performed. Waste heat is removed by boiling off liquid hydrogen propellant. The reactor operates on a temperature difference of 3000 to 20K instead of 3000 to 1200K, reducing waste heat by 40% (from 3000MW to 1812MW.  Heat exchangers increase the propellant's temperature to 100K before ejecting it, thereby removing 1575kJ/kg of hydrogen. Stealth firing consumes 1222kg/s. At the cost of 33.6 tons of liquid hydrogen, the Martian Arsenal ship can drift into position and fire a full missile wave without breaking stealth. 

A standard enemy fleet formation can output 750MW of laser power, and take down between 75 and 150 missiles in the terminal 100km stage. Stealth projectiles evade detection long enough for long-range laser defensive fire to not matter. A wave of stealth missiles detected at 100km range must therefore number at least 150 to get through the target's defenses. 
To defeat an enemy that has survived the first wave, the missiles must deplete kinetic defenses, and attack frequently enough to force lasers into operating at high temperatures. 10 waves against 3 targets requires 4500 missiles. An ammunitions load of 10000 missiles will therefore be sufficient to take out dozens of unaware targets, three aware targets, or one target in a massive simultaneous attack. This will mass 322 tons and require an ammunitions bay 30m long and 4m wide. 10% is added for storage and handling, totaling 354 tons.

No crew.
9 wide-angle sensors: 3 front, 3 rear. Mass 9 tons.
Avionics add 2% to the dry mass, minus ammunition. Masses 6.5 tons.
The 4m wide internal cylinder is enclosed in a 30m wide, 170m long insulated tube. The far end is a radiator emitting at 1200K. The opposite end is open and limits emissions to 10 degrees of the sky. This is Mars's diameter at 38400km. Heat removed is 74.5MW. It allows 25MW of electricity to be generated, allowing one shot per 165 seconds, or 2.5kN thrust at 10km/s exhaust velocity. Mass is 171 tons. 
Structural mass adds 10%. Dry mass of the warship, minus ammunition, is 748.9 tons. With ammunition, it is 1102.9 tons.

The arsenal ship is not expected to come under laser fire. The insulated cylinder is no armor, but acts as a whipple shield. 
734 tons of liquid hydrogen are kept in the nose of the ship. It is contained in a cylinder 10m long and 30m wide, massing 73.4 tons. 

At worst, the Arsenal ship can absorb up to 3.2MW of sunlight side-on. This requires up to 7kg of liquid hydrogen to be boiled off per second to keep the ship thermally invisible. Front-on, this is reduced to 417kW, requiring only 0.9kg/sec.

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TERRAN ADVANCED BATTLESHIP WITH INTERPLANETARY STAGE

Description: An advanced two-stage warship that travels across the Earth-Mars distance on a large interplanetary stage, then detaches to use its high thrust open-cycle gas core engines to dodge incoming missile waves while a massive laser allows for re-usable offensive firepower. Missile complement its offensive role.
Datasheet:
Name: Advanced Terran Warship
Role: Destroying enemy battleships at 1000km distance. Dry mass: 4729.4 tons Mass percentages: 32% Armor, 68% Components Component masses: 200 ton open-cycle gas-core nuclear rocket with reverse thrust 750 ton 3.3GW MHD generator 354.6 ton tungsten wire radiator 330 ton 600MW free electron laser 450 ton heat pumps 33.7 ton optics 115.2 ton PD lasers 10 ton PD casaba howitzers 630 Silver Bullet missiles 33 ton crew and life support 168 ton sensors 30.8 ton avionics 310.7 ton structure 80 ton tank mass Propellant mass: 7997 tons
DeltaV: 20km/s

Acceleration average: 0.1G Propulsion output: 100GW Electrical output: 3.3GW Ammunition: 10 Silver Bullet Casaba-Howitzer missiles
Standard laser performance factor: 3.2
Laser armor depth: 291mm, triple rotated, sloped. Kinetic armor depth: 300mm, internal. 
Name: Interplanetary stage
Role: Transporting four Terran battleships to Mars. Dry mass: 15262.8 tons Propellant mass: 409879 tons Component masses: 10000 ton nuclear reactor 437.7 ton liquid droplet radiators 1500 ton PIT rockets 119.4 ton avionics 1205.7 ton structure 2000 ton tank mass DeltaV: 116km/s Acceleration average: 0.1G Propulsion output: 150GW
Design comments:
100GW 200 ton open-cycle gas-core nuclear rocket delivering 8.7MN of thrust at 2039 Isp exhaust velocity. It is 85% efficient, and produces 5GW of waste heat.
66% efficient MHD generators produce 3300MW of electricity and mass 750 tons, producing 1.65GW of waste heat.
A 30% efficient free electron laser produces a 600MW beam at 300nm wavelength, massing 330 tons. It operates at 600K temperature and is mostly immune to reduction in beam quality due to thermal effects. 
1800MW waste heat is moved to 1200K by 450 tons of heat pumps consuming 900MW. It requires 248kg/s of hydrogen coolant operating between 100 and 600K. 

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The laser is focused by a 4m wide adaptive dielectric mirror, shooting through a fused quartz conical window with 96% transparency to 250nm light at when shooting off-center by 5 degrees, up to 99% transparency at further diagonal angles and through the flat truncated section straight ahead. It achieves nearly 90% absorption of visible light wavelengths. It can survive a 900K temperature increase. It is 32mm thick, 4m wide and truncated at 12.5m length, sloped at a 4.5 degree angle to achieve 400mm relative thickness. The truncated window is 2m wide. 
The mirror masses 0.5 tons. The cone masses 8.3 tons. The warship is equipped with 3 onboard replacement cones and mirrors.    

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Comments: This cone serves to protect the main mirror. Acting as a blacklight, it prevents the Martians' lasers from attacking the mirror directly, while letting shorter UV wavelengths through. The 400mm straight-head thickness prevents penetrations from regular-sized kinetic impactors. Firing diagonally is preferred, as it decreases the laser power being absorbed. The truncated window is a 3.14m^2 weakpoint.
The cone can absorb up to 24MW during operation. This would bring the cone to dangerous temperatures within four minutes, with localized failure along the beam path. A liquid hydrogen cooling system is required to absorb this heat, with a throughput peak of 8kg/s, operating between 200K and 300K. 
3.45GW of waste heat is removed by tungsten tensile wire radiators operating at 1200K. The wires are 1mm thick and 10221km long, massing 154.6 tons (15.1g/m). They are extended into 100m wide loops in space. At 70m/s, they maintain a 10G centripetal force and will cool down to approximately 360K in 1.3 seconds. At 0.057m separation, they only block 0.6% of each other's radiating area. At 3mm separation, it is 10%, but they risk touching each other. 
The radiator loops can be stacked 50m long, in four sets, extending 100m into space. They are mostly resistant to laser fire and kinetic damage due to their small cross-section. 200 ton replacement wire increases survivability.

Anti-missile protection relies on point-defense lasers. 6x6 turrets with 60 degree traverse, massing 3.2 tons each, putting out 100MW maximum each and can take down 384 missiles. 10 Casaba-Howitzer wide-angle nuclear charges, massing a ton each, can be used to clear out a 30 degree cone of missiles at 100km range. However, this destroys the radiators. 
The Advanced battleship is equipped with another 10 'Silver bullet' missiles with 1200kg Casaba Howitzer 10000km range warheads, 4439kg of carbon armor (400mm thickness, angled at 30 degrees) and 10km/s deltaV with hydrolox propellant. Each missile masses 57.3 tons, for a total of 630 tons. 
The crew count is 9 individuals: 1 commander, 3 tacticians, 2 mechanics and 3 programmers. They inhabit two 10-ton habitation rings rotating to provide 0.3G. Life support is fully closed-cycle, with 3 tons of equipment. Control is through two CIC units massing 6.5 tons. Included is radiation shielding and a 20mm armored shell.
The Advanced battleship has a heavy sensor suite. It has three rings of 36 narrow-angle sensors, and six lines of 10 wide-angle sensors along the flanks. Total mass is 168 tons.

Comments: Terrans fear the roving stealth missiles deployed by the Martians. They believe Martian space to be infested by thousands of smart groups of such missile. A 360 degree view sensor suite is necessary to prevent a surprise attack by cold projectiles.

Avionics are 1% to the dry mass, adding 30.8 tons.
Structural mass is 310.7 tons, increasing total internal dry mass to 3417.5 tons.
This fits inside a cone 200m long and 14m wide. It is sloped at 2 degrees.
Comments: Battleships match orbit with their target and burn it down with their lasers. Zipping past would expose them to a cheap kinetic attack. Attack runs include closing the distance for a targeted laser strike, then pulling back on reverse thrust (to keep the armor cone pointed at the enemy). Armor requirements are calculated based on how long the armor must survive laser fire.
A standard fleet equipped with three standard lasers can remove 3mm/s of laser armor at 2750km, increasing to 60mm/s at 1000km.
Based on the setting's objectives, we can set the 'time to kill' duration as 1 hour at 1000km. This leads to an armor thickness of 216000mm. 

The armor cone's 2 degree slope can reduce the armor required by a factor of 28.6. However, battleships with low acceleration and locked down trying to stay out of one target's weapons' effective range can easily be flanked by another target. This means that the slope cannot be relied upon. 
In a typical 3 vs 1 scenario, two laser ships bracket the defender while a third rises above the plane and attacks from an angle. The Advanced battleship's cone would reduce one laser's penetration rate by 28.6, the second by 15.5 (the first two targets are 100km apart for mutual anti-missile defense) and the third by 1.006 (90 degree flanking). The sum of their penetration rates is 21.48, leading to a thickness requirement of 78748mm.
The Advanced battleship uses a nestled rotating armor scheme. Average diameter is 7m. Rotation is once per second, leading to the laser being dragged along at 22m/s. With a second shell under the first, the laser can be spread out over 44 meters of armor per second. With a third shell, it is 66m/s. 
At 1000km, spot size is 0.244m in diameter. The armor rotation reduces laser effectiveness by a factor 270. The armor thickness required is 291mm.  

Each shell is 97mm thick. Laser armor mass is 981.9 tons.

Kinetic armor is internal. A 4m wide, 60m long 'citadel' tube protects the crew during combat, life support equipment, backup power generation and redundant avionics, as well as the vulnerable the free electron laser. It is 300mm thick and masses 520 tons.

Internal dry mass is 3147.5 tons.
Armor mass is 1501.9 tons. Total dry mass is 4649.4 tons.
A deltaV of 20km/s requires a mass ratio of 2.72. This requires 7997 tons of water, contained in a cylinder 14m wide and 52m long. It masses 80 tons. Actual deltaV is 19661m/s. Launch mass is 12727 tons.

The interplanetary stage permits rapid movement from Earth to Mars. It moves 4 battleships as a payload of 50908 tons.
A 10000 ton 150GW nuclear electric reactor produces 300GW of waste heat. It is removed by two 60x60m droplet radiators operating at 1200K, massing 285.7 tons. They contain 52 tons of liquid tin, and 100 tons of replacement fluid are kept onboard.
For propulsion, 58km/s exhaust velocity PIT engines massing 1500 tons produce  5.17MN of thrust. 
The interplanetary stage's dry mass is 13151.7 tons, including avionics and structural components. It departs at 64059.7 tons.

Liquid hydrogen is the propellant. 409879 tons are required, to be contained in four spheres of 132m diameter. They mass 2000 tons.
DeltaV is 116km/s. It would take it 87 days to cross the average 225 million km distance between Earth and Mars.   

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Just how big can you feasibly make a spacecraft? The size of an aircraft carrier? The size of an asteroid? How about the size of a small moon? Today we will look at scalability of spacecrafts and the systems within.

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When designing a spacecraft, certain questions inevitably arise concerning how it should be sized. Crewed spacecrafts very obviously have a lower size bound, since you can’t really miniaturize people like you can lasers or rocket engines. At the very least, your spacecraft needs to be able to fit people. However, there is no clear upper size bound. With missiles and drones, there is no obvious lower size bound either.

Let’s take a look at size limits of subsystems.

Power usage is more or less the primary way to increase effectiveness of systems, and size is generally the way to reduce thermal and mechanical stresses caused by this power use. But these laws are almost never linear, and often hit ultimate limits.

Take lasers, for instance. As outlined in The Photon Lance, scaling a laser up or down in size produces very little difference in power output. However, scaling it up in size reduces the power per volume and power per area so it won’t melt when activated.

This means you often want to keep your weapons and subsystems as small as possible, but it’s physical limits that force them to grow larger.

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A trend with sizing of subsystems is that systems tend to work more efficiently when larger. A single 200 kN rocket thruster, for example, will perform more efficiently and be less massive than ten 20 kN thrusters. Larger singular systems distribute mass better and require fewer complex parts than many smaller systems.

On the other hand, those ten lower efficiency thrusters would probably be preferred in combat to the single high efficiency thruster because of redundancy. Compare a stray shot taking out all of your thrust versus taking out only one-tenth of your thrust. Clearly, there is a balance to be struck, between redundancy and efficiency.

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Similarly, crew modules come with significant overhead, such as the plumbing for the sewage and air recirculators. As a crew module expands in size, this overhead reduces proportionally to the number of people within. However, bunching all of your crew together in a single module is a major liability in combat.

Alternatively, rather than making a single large spacecraft with highly redundant systems, some playtesters went the route of smaller spacecraft with no redundant systems. In that case, the redundancy is with the spacecrafts themselves, rather than with the subsystems.

Another consideration is that smaller subsystems can be manufactured more cheaply on assembly lines compared to single large subsystems. In the era of widespread, highly advanced Additive Manufacturing, these benefits are less pronounced, however.

There are certain minimum size limits that show up with drones and missiles, too. For instance, nuclear warheads have a minimum size. The smallest nuclear device ever made was the W54 at about 20 kg and the size of a large suitcase. This lower limit is due to Critical Mass needed for fission. Thus, for missiles, their warhead tends to determine just how small you can make the missile. If your missile has no warhead, their lower size limit is based on the rocket motor generally.

For drones, it is similarly the mass and volume of the weapons on that drone which limit the size of them.

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But these are all lower limits. What about upper limits?

Generally, lower limits are all the rage because you want to make everything small, compact, and low mass. The smaller (volumetrically) you can make everything, the less armor you’ll need. The less massive you make everything, the greater the delta-v and thrust you’ll have.

There is actually very little stopping you from making enormous lasers or railguns, but simply making them bigger doesn’t actually improve their effectiveness or power, it only makes them deal with thermal and mechanical stress better. Essentially, you make things big because you have to, not because you want to.

But suppose you don’t care about making the most effective spacecraft, you just want to go big.

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At this point the Square-Cube Law begins to rear its head, and that is that volume scales cubically, while surface area scales quadratically. This is why large animals are built very differently than small ones. Without gravity, these issues are not quite as severe, but they still appear.

For instance, on the positive side, larger spacecraft are more efficient about their armor-to-everything-else ratio, because armor scales by surface area, and everything else scales by volume. Large capital ships tend to be armored like tanks while smaller ships run much lighter.

But on the negative side, acceleration suffers badly. Attaching thrusters to a spacecraft scales by surface area, and the mass of spacecraft scales by volume. Thus, the larger a spacecraft becomes, the lower and lower its acceleration inevitably becomes. As found in Burn Rockets Burn, thrust is hugely important, which is why only Nuclear Thermal Rockets and Combustion Rockets see major use in combat.

A ship that can’t dodge is a sitting duck to all manner of weapons. Most capital ships in Children of a Dead Earth range from hundreds of milli-g’s to full g’s of acceleration, and even that affords only partial dodging usually. Dropping that acceleration further is often fatal in combat.

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Another negative aspect of growing in size is that the the cross sectional area of the spacecraft grows accordingly. And having a fat targetable cross section vastly increases enemy projectile ranges against you.

For combat spacecrafts, then, miniaturizing your spacecrafts is often the most ideal choice. But what about civilian crafts? Civilian crafts make a lot more sense to balloon up in size, especially for the sanity of the passengers.

The acceleration is still a problem, as if it’s too low, the spacecraft will have difficulty getting anywhere taking enormous amounts of time. But the other issues are gone. If travel time is not an issue, such as with a multi-generational colony ship, then you could try scaling up to truly enormous sizes.

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When you start hitting small moon or asteroid sizes, though, then you begin to have to worry about gravitational stresses collapsing your ship into itself! But that’s far beyond the scope of what you’ll find in Children of a Dead Earth.

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• 

      Galactic empires in media have undergone a steady progress of increasing the size of their starships. It's almost as if, in addition to the technological problems or space space travel, the ships have to look good on film as well. Regardless of this, huge government ships are here to stay. But, there are a few problems for would be dictators who want to build mobile moons.

     Take the polities of Alpha and Beta, unoriginal but advanced worlds of equal engineering skill and resources. They both eye each other warily and then begin building ships for their defense a/o offense. Assume a flat cost per ton for military ships. Alpha decides on building a fleet of fast attack ships 100 meters long. Beta wants good photo ops for their glorious navy and builds their attack craft 200 meters long.

     That's where the cube law steps in and starts to ruin things. A ship with double the dimensions of yours will be eight times the mass and eight times the cost. For the moment the Betans go with the larger ships.

     Out of their available resources the Alphans build a navy of  72 ships. The Betans construct nine. Now a Beta cruiser is more than a match for an Alpha gunboat, correct? It depends. In terms of surface area the Betan ship has four times that of an Alphan ship and can mount four times the weapons.

     Or can it? The Beta ship needs larger engines, it's pushing eight times the mass and those glowing panels movie ships use to move take up surface area too. On a Beta ship they will have to be eight times the surface area of an Alpha style engine. That means they are 2.8 times the length and width of the engine panels/thrusters/whatever of the Alpha ships.

     So instead of four times the area, say a Betan ship has three times the area to mount weapons. That means for every eight weapons the Alpha fleet brings to the party, the Betans will bring three. Assuming there's an equal amount of tonnage.

     What about flexibility? Say both empires have 18 worlds to protect a/o invade. The Betans will have to shuffle their nine ships around to prevent rebellion, deal with pirates, and show the flag to keep the Alphans honest. The Alphans could keep four ships at each of their worlds, maybe get away with two ships and have a mobile reserve or attack force to keep those ships from Beta honest,

     In contrast, in the event of hostilities the Alphans could match the Betans in weapons using 24 ships of their fleet, and use the other 48 to attack and out gun the big ships. Moreover those 12 of the Betans worlds without protection are going to get awfully angry and might rebel or secede.

     So it looks like the guys with the bigger ships are going to lose. What are some reasons for building those lovely, gargantuan ships we all love?

     First of all, resources, technology, and missions might not be equal. The first example that springs to mind is the Trillion Credit Squadron GDW loved to organize. Your humble author had the distinction of playing in the first tournament GDW held at GenCon. Never mind how long I lasted! In TCS you had a fixed number of pilots which put a cap on the number and size of ships you could build. personnel are a very valuable resource, you can't train them overnight, and they might have other plans (like joining the Resistance!) Don't forget some of those pilots or whoever are needed to provide civilian shipping.

     Star Trek:TOS had dilithium crystals. they always seemed to be in short supply. Even the Enterprise never had any spares on board! This being the case yes, you bet you'd build big ships and get the most of a scarce resource.

     If your empire uses star gates of some sort then the 'resource' is how much mass a gate can move. Again you might want to consider that a limit on ship size.

     A navy designed to protect against pirates and other naughty types might run toward small ships, even smaller than the average pirate in order to be more places and swarm the odd corsair they find. A culture with little or no piracy might run toward large ships to do tasks the smaller locally built vessels couldn't. When war threatens you go ahead with the forces you have.

     Say the Betan Republic was a stable, secure and friendly power for years. With little or no piracy, their 200 meter ships were more a deterrent than anything else (but very good at that). The Betans have a revolution and become the Evil Empire of Beta. The overlords begin a crash ship building program (no pun intended) but for now their evil schemes are limited by their monstrously huge ships. The Alphans seeing the handwriting on the hulls decide to declare war.

     Scale efficiencies are another, important factor. In my simple and naive example, we were talking a fixed cost per unit of ship. What if say, larger engines were more efficient, cheaper per ton or more powerful? It might be cheaper to build bigger engines for bigger ships, it might be impossible to build them small. In Traveller you have the minimum size of 100 tons for an ftl capable ship. It could be a lot more than that in some settings.

     What about endurance? People do not often consider the cargo capacity or a warship. A ship's cargo hold contains the things it needs t complete a mission, whether that is hauling freight to remaining on station for weeks and months. If the Alphans have eight times the number of Betan ships but they have only half the supplies, then you'd have less of your fleet on station while the rest is heading back to starport, getting resupplied or heading back to station. Or we have to pay extra for supply ships that can be attacked and will require defense ships.

     For our example, I've kept weapons simple and ignored defense. In reality a bigger ship will probably want to mount a few bigger guns that smaller ships couldn't spare the space for. To continue our example, the Betan ships would have armor twice as thick as the Alphans. A Betan ship could defeat several enemy ships at once meaning attack forces would need to be built around several Alphan ships and cutting down on the flexibility of the Alpha fleet. A single Betan commerce raider that got past the defenses would raise a huge ruckus and draw many ships from their missions to track down and eliminate it. Moreover some weapons might be more dependent on volume than the size of their launcher. A really big laser could be mounted in the hull with a mirror in a comparatively small turret to direct it. Missile launchers need cargo for their ammunition and of course the spinal weapons beloved of Classic Traveller and anime take up a huge amount of internal space.

     As a final note: larger ships have more room for force multipliers. Classic Traveller excelled at this with the concept of battle riders. Basically ships carry smaller ships, fighters, missile buses and whatever to increase their firepower. If instead of building eight 200 meter cruisers the Betan build four and each of them carry four 100 meter ships well hey! -You have the same surface area as the Alpha fleet for mounting weapons and you have several ships with larger weapons and thicker armor to base your task forces around.

• 

• 

      It's a fact that you go to war with the space fleet you have. As I said in the previous post building big ships is uneconomical. Smaller ships can cover more bases and provide more surface area for mounting weapon systems.

     The Republic of Alpha and their neighbors, the Evil Empire of Beta are beginning hostilities. More than likely the first blow in any war will be crucial. Going off unprepared will be worse than doing nothing at all as it will waste ships and leave one open to attack.

     The Empire started out as a trade-friendly province in the mod rim. They were a local cluster capital and they produced mid-range (200 meter) ships for the Old Empire Navy. Since the Old Empire fell and a plethora of new empires (note the capitalization conventions) Beta decided to follow suit. After all, the new golden age has to start somewhere.

     They could build the biggest ships, but most of their worlds are agrarian with bucolic and stupid locals who do not build let alone comprehend the problems of building and crewing starships. Pilots, engineers and trained crew are crucial. The shipyards were optimized for such ships. It was their role in the galactic economy (RIP) and were less than efficient at building smaller ships. Furthermore, the firms producing larger ship systems were all tight with the Evil Parliament and you didn't want to mess with them.

     The Alpha Polity was a frontier province. It had shipyard facilities to service the smaller navy vessels and with some corner cutting can now produce smaller (100 meter) ships. Being spread out with defense and research outposts they have a larger pool of crew than the Betans but can't produce such big beautiful ships. The square cube law says the Betans are doomed. What can reverse this? Evil empires are a necessary component of the dramatic tension constant! Without the DTC the universe just ... winds ... down ... Everyone stays home and shops for shoes or hats.

     First, realize that people in power want to remain in power. Good guys and bad guys have that in common. Betans have a number of strategies to boost their firepower:

     1) Alliance with a power that will enhance their strengths and minimize their weaknesses. In this case someone with smaller vessels. this might be hard due to the 'Evil' in their title but it's too late to change the letterheads!

     2) A comprehensive education program for the bucolic population. That will take years and who wants to SF RPGs about comprehensive education reform? Monte Cook couldn't sell that idea.

     3) Go with the ship numbers and crew numbers they have. Once the Alpha Polity is conquered we will use their shipyards and non-bucolic population to increase our forces!!!

     Going with the plans for a brief successful campaign against the Alphans means maximizing the effectiveness of the Betan warships.

     The first design proposal was to simply stack eight 100 meter hulls lengthwise. This would have very nearly the surface area to equal eight Alphan ships in surface area. that was shot down (pun intended) quickly. A ship that long and skinny would have insufficient area to mount enough thrusters aft. The length made maneuvering harder and the shape was comparatively fragile.

     The next design proposal was to make most of the weapon systems internal. There were several ways to do this. The first was the spinal mount, building the ship around a horrifically huge weapon. This worked quite well if your target wasn't moving. Otherwise you had to steer the whole bloody ship.

     Then next three proposals were simple: missiles, missiles, MISSILES!

     While missile launchers took up space on a hull, they required ammunition which required volume. This was the main reason energy weapons were often favored over missiles. You could fire those till your power plant gave out. Larger ships could carry more missiles and afford to fire more missiles at longer ranges. More missiles co uld overwhelm defenses. Thus if you were lucky you could cripple or destroy several smaller ships.

     This had application for commerce raiding. Instead of say, five  defending gunboats of 100 meters to tackle a raider, you'd need six or seven since several would be disabled by long range fire before coming to grips. These extra ships added up fast when you were dispatching several task forces to find such a raider.

     As the Alphans soon learned such larger ships could also lay eight times more mines, creating a hazard for civilian shipping that required military ships to clear.

     The Evil Empire of Beta was also open to commerce raiding of course. However, the Alphan ships also had less fuel and supplies and thus a shorter range. The Evil Overlords gladly allowed several worlds of their frontier to be cut off. Remember the part about the high technology assets being concentrated on their capital?

     In any case when the raiding and feinting was over a task force of 20 Alphan ships faced an incursion of four Betan cruisers. Only the invaders were content to lob a whole bunch of missiles at long range, watch a few score telling blows and leave. They would repeat the process in a war of attrition. Appear, fire off long ranged missiles and leave.

     While this went on the Betans and Alphans were desperately trying to build more ships to tip the balance of power. Ironically the fleet with the larger ships continued hit and run and raiding tactics. The fleet of smaller gunboats would try to maneuver their enemy into a telling battle because losing even one such cruiser would be a huge loss.

"Which of you morons tried explaining the mathematics of spacecraft design to Brockhurst B. Borsten III?"

"Uhmmm he wanted us to replace two 100 meter Shiva Class gunships with a 200 meter Camazotz class. I explained we did not have the budget for this. Since the Camazotz is twice as long it ..."

"I know exponents, you moron. Twice the length is eight times the mass and eight times the cost!"

"Is he mad? Listen we can still cancel eight Shivas and build the Camazotz."

"Angry? No. Mad ... I'm sure there were some cousins in the Borsten line did more than hold hands. No. B-cubed decided he liked the idea of a lot of ships. He's scrapping the Shivas for eight times as many 50 meter Imps!"

" ... that actually makes sense. We don't need the big guns and our defense force will have more flexibility."

"Yeah? And where the flick are we getting the crews for this flotilla of tail biters? Each one needs a pilot. That's eight times as many pilots. Where are we suddenly getting eight times the number of berths for servicing them? And maintenance personnel? You've ruined us!"

(-with a nod of thanks to Sevoris Doe)

The classic historical example is the Battle of Jutland.

The (British) Royal Navy designed their ships for long cruises and extended habitability. The result of this was that their ships could stay on station and cruise for longer periods of time. A lot of resources were put into habitability, and when you're out in the South Seas and something breaks, you pretty much have to fix it from parts at hand.

The (German) North Seas Fleet was built with more powerful boilers. It had more armor; its guns were built with a fairly precise targeting systems. It could remain at sea for 2-3 weeks, tops. If something broke, it was meant to go back to port to be fixed.

I've given the impression that a "balanced ship" should have 20% maneuver, 20% offense, 20% defence, 20% command & control and 20% strategic endurance, I apologize for the confusion.

I typically see it as 27.5% maneuver, 27.5% defense, 27.5% offense, 15% strategic endurance and 2.5% command & control.

Some ships will trade offense or defense for greater cruise endurance (RN model) and others will trade cruise endurance for maneuver and offense (High Seas Fleet).

It's harder to find examples of ships that trade C&C capabilities for any of the other four categories; you can find science fiction examples (and limited real world examples) of ships that trade off offensive capabilities for better C&C. (This is, as far as I know, one of the things that distinguishes a CG {guided missile cruiser} from a DDG {guided missile destroyer} - they're built on nearly identical hulls, but the CG has less firepower and more "keep track of what's going on" gear.)

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In depicting combat in space, science fiction (movies in particular) long have conveyed rather simplistic models of WWI and WWII fighting. Tiny craft, for instance, are normally depicted as faster than large ("lumbering" is frequently the adjective) ships; this is indeed true, or can be true, on Earth, where conditions force trade-offs between mass/heavy weapons and speed/maneuverability. But conditions in space are not egalitarian.

For general expectations, sub-light ship speed would be limited by the size of the engine, if the types involved are equal, and by the mechanics of relativity which demand (at near-light speeds) great increments of mass/energy for tiny increments of speed. (There is also the problem of interstellar particles at high speeds turning the noses of ships into little atomic battlefields, to the misfortune of hull and crew.)

In space, ranges are unlimited by terrain or earth curvature, visibility is absolute, and surprise probably only strategically. In such conditions, the faster ship will be the one also with bigger and better weapons; engine performance will tie directly to range and breath of energy and field weapons. Evasive maneuvers carried out by necessarily shallow curves at even 0.1c speeds will hardly challenge sophisticated fire control and titanic-aperture lasers (free of planetary weight deformations, lasers theoretically can be of any size). The next time you watch Battlestar Galactica, ask yourself how well an F-16 would fare against an energy beam with a diameter of 2000 kilometers: in space, given quality, bigger is better.

GROUND SUPPORT TEAM (tan eche, world blanket) Variable force, but averaged 55 ships with about 40,000 cortex-suspended political defenestrators, police, and communication experts. Most effective against system defenses, but average small mass of a ship, about 30,000 tons, prevented mounting weaponry strong enough to stand up long in deep space combat.

MISSILE PACK Consisted of a manned command ship accompanied by 40 to 50 multi-tubed drones which packed the missiles. About 1000 crew, 2 million tons for complete group; main ship 1.5 kilometers, drone 0.2 kilometers. Fragile, but impressive in impact if the opposition lacked counter-fire. Very skinny command ship gave drone profile from front and back.

RANGER (vam, bully) A compromise between fully useful size and the need to defend more than one or two points. Non-situational weaponry, about as good in one sort of fight as another. Complement 2300 to 2600; mass 4.1 million tons; length 6 kilometers.

STARCRUISER (tal des, star noble; literally master of light) The balance point between armament and mobility, a craft sized by information theory comparing system size and significant dysfunction. Completely weaponed, including exotic items like condensor clouds and linkages for demi-lunar manipulation. Three in a team were a match for a solar system. Complement 4500; mass 10 million tons; length 9 kilometers.

STARGUARD (brev'tal bir, against the cold) The opposite of a Starcruiser, since the diffusion of thousands of discrete members initially lacks any significant target. A Starcruiser might cut for hours through this jungle of tiny ships, mines, etc., until suddenly there were more targets than fire control could handle. Once such a ship began to take damage, the Starguard units quickly stung it to death. Total spherical complement about 4 million; mass 40 million tons; length about 100 km.

• 

As long as there have been serious shoot-em-ups in science fiction there have been space navies. The analogy is traditional and 'natural,' and even in the rocketpunk era it easily turned back occasional efforts to model the Space Force after the Air Force. Unlike aircraft missions, space missions take days or weeks, often months, not infrequently years. Crews live aboard their vehicles, unlike aircrews or tank crews.

The naval analogy also invites some ways of thinking about force deployments and space operations. In spite of Star Wars and Battlestar Galactica, there is some preference for drawing inspiration from the big-gun era, especially — and a bit steampunkishly — the Mahanian golden age a century ago, before the World Wars and the complications introduced by submarines and aircraft. In this schema there are broadly three warship types, with familiar and evocative names: battleships, cruisers, and corvettes.

Battleships fight other battleships, especially in fleet actions. They carry the heaviest practical armament and protection, sacrificing some speed and range in order to do so. Cruisers patrol the seaways/spaceways, often operating independently. Though no match for battleships they are formidable against anything else, and are tailored for speed and range: In the classic formulation the ideal cruiser can outrun anything it can't defeat. Corvettes, though to 'Murricans their name connotes a classic car, are lighter patrol craft and workhorses of the fleet, with the virtue of being cheap and therefore plentiful. In the late 19th century these were called gunboats, hence 'gunboat diplomacy.'

Turn the time-regress dial back from 1890 to 1790 and the first two classes become ships of the line and frigates. Corvettes are still corvettes, unless they are sloops of war, gun-brigs, or whatever have you. (Gunboats were then small vessels, often oared, with one or two heavy guns, used mainly for inshore defense.) Ships of the line are rarely seen in space, but the name 'frigate' has captured the popular imagination, and indeed is used by present-day navies.

Take another ride on the wayback machine, to around 1400 — or 400 BC — and the battleships and cruisers blur together. Galleys could be assigned more rowers for cruiser missions, or more fighting men on deck for battlefleet service. (Lesser patrol craft went by a wide variety of names, of which one, fregata, turned out to have a big future ahead of it.) The mission configurability of galleys by loadout is a hint that the three main types are not a universal law, but science fiction has drawn few analogies from the mere 2000+ years of galley warfare.

In SF some hybrid models are also popular — notoriously battlecruisers, cruiser types scaled up to battleship dimensions: dashing, powerful, and with a nasty reputation for blowing up. In space wargames there's also some popularity to using 'dreadnought' for a super battleship, rather than what dreadnoughts were historically, battleships of a later type; and perhaps even bigger classes with colorful names like Annihilator. Destroyers are also rather popular, including as major combatants, though they originated as a specialized type, 'torpedo-boat destroyers.'

Such is the quasi-standard typology. I've used it myself, which didn't keep me from making snide comments about most of these classes here. A number of people have noted that some of these assumptions, such as cruisers being 'faster' than battleships, don't translate very well into space. As practically always, your go-to source is the Atomic Rockets site, specifically here.

But. Space is not really an ocean, and space war forces aren't navies. A few things to think about:

Even without demimagical high level AI, robotics and remote systems will surely be pervasive in space, as they already are. Robotic systems are cheap compared to the cost of spacecraft, they don't require heavy and expensive life support, and no letters saying 'We deeply regret' need to be sent to their families. Human presence, by and large, will be reserved for functions that cannot readily be automated, such as high level decisions — especially Open Fire! and Cease Firing!

Even within the traditional schema, this suggests odd consequences. A corvette has more need of a human crew than a battleship does. A squadron of battleships blazing away at their enemy counterparts in open space does not really call for a lot of high-level decision making, just intensive number crunching. Exercising gunboat diplomacy, on the other hand, or ordering a suspicious spacecraft to stand by for boarding and inspection, calls for policy judgment.

And suppose for a moment that kinetic weapons are dominant. This evokes an image of 'missile ships,' but is that really how it plays out? Say that an enemy war force (of whatever composition) is on orbit from Mars to Ceres, and Earth wants to send a force to intercept it. This does not call for missile ships, it calls for missiles. By definition you don't expect to recover kinetic weapons; their whole purpose is to smash into their target. Expendable buses can use all their propellant for a fast intercept, and use their own mass for whacking the enemy. If you need some battle managers closer than light minutes away, send a control craft along behind them, perhaps fitted with defensive — but not offensive — armament.

If beam weapons are dominant the picture is slightly more classical, but only slightly. Laser platforms don't cannonball themselves into the enemy, and since they are expensive and (unless wrecked) reusable, you would like to recover them if you can. But there is still no inherent reason to put a crew aboard one. It zaps, and is zapped back. The prospects of repairing it in the heat of battle are iffy, or more than iffy, and the repair crew with its life support is an additional expense and vulnerability.

Repairs after battle are more plausible, and for extended missions you might well want maintenance techs as well as a command staff, plus supplies, workshops, and other logistic facilities. But the spacecraft needed to carry all this are more like transport auxiliaries than men-of-war. They might also be largely modular, more like trains than ships. For that matter, fit a military space station with drive engine and tankage and you have a mobile support base. If you win, it becomes an orbital base supporting your forces around the objective. What it never becomes is a 'battleship,' or anything that fits the familiar warship typology.

It isn't even a Death Star, because while it may carry defensive armament there is no particular reason to mount a huge weapon laser aboard it, and good reason not to. If you scale the whole thing down for long range patrol you might call it a cruiser, but really it resembles a cruiser not much more than raiding cavalry does.

Thus, in broad (and sketchy) outline we have a picture of space forces that has little in common with traditional naval fleets. The largest spacecraft, perhaps, are mobile military stations with command and logistic facilities and personnel, not intended for direct fighting. They control and support weapon platforms, some of which might be quite big, whether these are laser platform or kinetic killer buses. You probably also have remote sensor platforms. And you no doubt have patrol/inspection craft, manned and fairly small, to put boots in the airlock when called for.

Taken as a whole you might call it a fleet. But it more nearly resembles a mobile, distributed, and networked fortification, deploying in action into a three-dimensional array of weapon emplacements, observation posts, and patrol details, all backed up by a command and logistics center. (Armies in SPAAACE !!!) Very little of it fits our template of 'space warships,' because it is designed for space, not simply borrowed from the sea.

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Ferrell:

What you've described is a kind of 'Space Control Ship', a type of mobile logistics and command vessel for battle platforms, as well as a base for a host of smaller vessels (both manned and unmanned), used for various secondary missions. They would be organized more like a Carrier Battle Group, or an Assault Ship Battle Group, than a Battleship Squadron. The central ship, or ships, carry maintainance & operations crews for the unmmaned weapons platforms, an enormous C4I electronics suite (communications/command/control/computers/intelligence), and a relitively small number of specialized troops for the secondary missions. Of course, this would be used as a major force; not as a routine patrol ship.

That isn't to say that patrol ships wouldn't be assigned to the Space Control Ship flotilla; it may well be, although independent patrol ship squadrons could also be used. These patrol ships would be smaller, faster-accelerating ships that more resembles a small escort or auxiliry carrier (or assault ship), than a traditional navy crusier. The patrol ship would incorporate into its design not just some defensive systems, but also some offensive systems; it would also carry several weapons-and-sensor drones, as well as a few small manned daughter ships they could use for secondary missions that need people on-scene. You could very well call these ships 'Drone Carriers'. A heavier variant would also carry a few smaller-scale weapons platforms simular to the ones operated by the larger Space Control Ships.

Aother type of combat spacecraft may well be an Assault Ship; an armmed troop transport that might have some sort of bombardment weapons system.

You could use patrol ships for a variety of missions; deep space patrol, convoy escort, intruder intercept, blockade, commerice raider, and others we haven't figured out yet.

I guess you'd have 'Space Control Ships' as capital ships, 'Drone Carriers' as your major combatents, and with various daughter ships and small specialized ships as minor combatents, just to keep with the naval theme.

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Charles Gannon:

While I had some reservations (strong) re: your conclusions vis a vis spaceside attacks upon planets, I am in 100 % agreement with your conclusions here. And would go further.

Those backup control ships? Indispensable in every regard. Firstly, given hacking and the rest, you will want LOS/Lascom to guide missiles, drones, USVs (unmanned surface vehicle) that are the actual "fighters" of the fleet—since the gees pulled are, in a survivable craft, going to be WELL beyond human toleration. Also, if you've spent an hour at max gee accel, you're going to have to counterboost at least as long (n.b.: important variable; if engagement is near planet, grav-assisted slingshots into near/reciprocal vectors). If that turns into days of accel,...well: you get the picture. The longer the duration required of a manned craft, the greater the amount of parasitic mass required for control interface with meatware and lifesupport (as well as crew escape subvehicles, etc.). In short, the advance control craft is going to be key—and therefore a key target. Speed, agility, countermeasures and defensive weapons out the yimyam.

Primary shipkiller = nuke? I don't think so. You still have to get pretty close. Weapon of choice? If Teller's numbers hold up and the folks at Livermore (including my friends Marty Pilch and Larry Warner) are right, then the x-ray laser is the way to go. But how to build an x-ray laser on a ship? answer: you don't. Drone vehicle carries nuke-pumped x-ray warhead emitter. One shot, but can lie doggo, hang back, disperse, re-group, etc. Why put all your offensive eggs in one, big, slow basket—and thereby give the enemy every good reason to take out your personnel, because with a "dreadnought" as the locus of all your offensive power and extended range ops, the war in space turns into a game of "kill the big ship and all problems are solved." Dispersal—of computing, personnel, offensive systems, commo nodes, sensors—is going to play a much larger role than anything for which we have a maritime analog.

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Marktheother:

I like to think of a group of spacecraft as a "constellation" to distance it from naval terminology. (at a distance it looks like a grouping of bright spots in the sky, so it seems appropriate, and it's already used for satellites)

With patrol ships and mobile orbital defenses (for lack of a specific term for what Rick described) being so different, and having such different missions, they could end up being run by different people, like separate branches of the military.

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Kedamono:

As for patrolling the system, you either have ships following a Hohmann orbit between ships travelling to the same destination, or just coasting in an orbit waiting to intercept someone.

The Hohmann patrol has a problem in that if a problem occurs in front of the ship, they really can't do much but chase after offending ship. Behind the patrol boat, it can try to intercept, but I wouldn't want to be the person working out that orbit on my slipstick.

A coasting patrol can't do anything about an incident behind it, it can only deal with what's in front of it orbitally. So you patrols coasting in counter orbits. Depending on traffic, you could make do with 8 patrols, four orbital and four retro-orbital.

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Ian_M:

This leads to some interesting points about the tender ships. Most of the craft will probably be automated and carry reaction mass, fuel, and whatever other volatiles the fleet needs. The tender ships carrying conventional weapons will probably also be automated. Transporting unconventional weapons will be subject to strategic/political pressures as to whether it's done by drone or crewed ship. The tender drone craft might also have robot arms and a tool kit for minor exterior repairs.

At the next step up in size and complexity we could see supply ships that also carry repair facilities and crew. A machine shop/fablab, workbay, parts, and small workcrew. This would still be mainly a supplies craft, but the crew would perform routine maintenance while the robotic systems swapped supplies.

The next step up is a large dedicated repairs craft. One with several workbays, a massive machine shop/fablab, and possibly a large hangar for auxiliary craft and cargo but certainly lots of exterior clamps for small work-drones. And facilities for whatever personnel, however minimal, need to be transferred off the damaged craft.

There's no point in trying to build a repair craft big enough to handle rebuilding a badly damaged major war craft. It's easier to build barges and drag the wreck home. And besides, a repair craft on that scale is a major logistics bottleneck and expensive target.

As in a modern fleet, the tender craft will outnumber the battle craft. For the most part they're not heavily armed (Probably just point-defence weapons), and never leave the bulk of the fleet unless under escort. They probably have minimal crews who are more technician and labourer than soldier, and are commanded either by a junior officer or a senior NCO (Actually, this is starting to remind me of Canada's corvette fleet in the Second World War). And when they get to wherever they're going, there's probably no-one to talk to. Just some broken machinery and the possibility that whatever broke the machinery is still around.

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Marktheother:

I was thinking that the human intensive jobs (Gunboat diplomacy, boarding etc.) would require a less specialized vessel, but in retrospect I realize it would be easy to put an engine on a command pod, and if more then the defensive armament is needed for a mission put engines on the necessary number of weapons platforms.

Taken to an extreme, modularity could mean that a spacecraft would last only as long as it's mission, when the missions over the modules are taken apart and used elsewhere. it would also be a good way to keep the other sides intel types guessing about ship capabilities and such. probably the only part of the space craft that would have a name would be the habitat, and if you broke the habitable parts of a ship into modules, maybe not even that.

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Rick Robinson:

Names of modular spacecraft might be analogous to the names of trains. The Santa Fe Chief did not refer to specific equipment, but to timetable and reputation. Military units don't operate by timetable, but there'd be some institutional continuity.

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Kedamono:

The only the worry I have about modular spaceships is that the connections between the modules may not be as strong as a purpose built ship. But then considering how such a ship would be built, it may not be that much different from a modular design.

As for the name given to such a ship would be based on it's primary bus module: The engine/fuel tankage/radiator module. There may be a dedicated control room on this bus for independent movement of the bus module and doubles as a backup bridge.

From this bus you'd hang extra fuel tankage, defensive, offensive, sensor, hab modules, and other specialty modules. depending on the mission plan.

So each bus module would carry the ship name, modified by the mission it was to carry out. So the FESS* Ty Cobb would be called the FESS Ty Cobb XP for a exploration mission and FESS Ty Cobb FP for a patrol boat mission.

*Federated Earth Space Ship

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Rick Robinson:

Modular design is always a tradeoff. You get more operational flexibility, at cost of more complicated/heavier/weaker connections. Integral designs will be favored when the components will consistently be used together.

Much will depend on tech. Torch type drives and even 'conventional' nuke electric drives pretty much have to be mounted on a pylon, which sort of invites the option of unbolting it from the rest. OTOH, as you note, the drive section may well have its own control center. And since the rest of the ship sits on top of the pylon, it's a fine line between 'pylon' and 'chassis.'

On naming, I could also make a case that the crew hab compartment is the main component, and so would be named. Especially if it is a spin gravity structure. And 'spaceships' may end up having more than one name, just as a named train might included Pullman cars with names of their own.

And if ships are highly modular, some terms might be borrowed from railroading. For example, 'consist' as a noun (pronounced CON-sist) for the whole assemblage. Thus, 'The Ty Cobb departed Mars with a consist of [such and such modules].'

Amusing side note: modular spacecraft reverse the order of trains: the 'locomotive' or drive engine is at the back (more precisely the base), while the 'caboose' or control cabin might well be at the front/top.

My bias about space warcraft evolution is that the progenitors could likely be exploratory craft. These naturally have lots of sensors, 'mission control,' and facilities for handling drone probes. In fact in my Human Sphere setting (now sort of in abeyance) I used 'survey ship' with more or less the connotation of 'cruiser.'

Note that the Trek Enterprise implicitly fits this template rather well.

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Ian_M:

Regarding the danger of prolonged wars of attrition — This is the standard way wars are fought and won. The Second World War is remembered today as ending in D-Day and Hiroshima-Nagasaki, but it lasted for seven years and the major battles were fought over strategic resources and supply routes.

If you can't deal a decisive blow to your opponent's supply chain, a conflict can last decades. This poses some interesting tactical problems for civilizations with asteroid bases, fablabs, and portable fusion plants. And it gets worse if you bring in Drexler's fairy dust (AKA nanotech). If you can't kill all of your enemy, you have to either pacify them or break them up to the point where the parts regenerate into something not interested in fighting you.

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Rick Robinson:

The difficulty of replacing costly equipment should tend to make leaderships risk averse — think of the High Seas Fleet in WW I. And it should also push them toward use of simple, cheap systems that can be quickly replaced.

This is something left out of the familiar (on SFConsim-l, at least) purple/green debate, missiles v beams. Both costly laser platforms and relatively costly torch missiles could end up being used sparingly in favor of unsophisticated but cheap chemfuel kinetics.

And in general one more thing pushing toward long but indecisive wars, with a great deal of sitzkrieg.

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Anonymous :

Now that I thought about it, the only two types of space craft in any future Orbital Defense Force that could require an onboard crew would be the command craft and the tender/repair craft.

The needs of a human mind to command the front have already been addressed, however ingenuity of the technicians and engineers would have to be noted. A computer, AI or not, would only know how to repair and with what depending upon what is part of its programming and in some cases where byte budgeting is an issue, the computer will only be able to repair simple, routine tasks that would have been regulated to interns and green enlisted personnel once upon a time. Human crew members, meanwhile, are tasked with the repair of complex, difficult repair tasks that would otherwise be impossible for the computer to think "outside the box" due to software and hardware limitations.

Resupplying a combat craft within a Task Constellation would predominately be within the realm of the computer and its more sophisticated AI kin and overseen by humans if only because the humans can use their brains to solve or counter any problems that could arise such as blockage in the refuel and re-remass lines. An engineer designing the ship class could create a fully automated system to correct blockages, however a problem could be better corrected with onboard crew with (arguably) the same amount of mass and without that many joints and other machinery that must be maintained as well.

One would argue that the boarding craft is also another spacecraft that could potentially require an on board crew, but from what I've been reading, that would only be possible for patrol and law enforcement craft. If a missile or any other drone is unable to get close enough to the hull of an enemy combat spacecraft with adequate defenses, how would a boarding craft?

Oh, and for those who think that nanomachines and nanotechnology is an end-all answer to warfare and manufacturing, let me direct you to this article: http://www.stardestroyer.net/Empire/Tech/Myths/Nanotech.html.

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Rick Robinson:

Pretty much agree that the main human functions are command and repair. (Though the chances of repair in battle, as opposed to afterwards, are probably not worth risking a crew.)

Boarding, as you say, is a patrol activity, not a battle activity. Though for battle in orbital space, where civilian craft may be in the clutter, there's a case for positive human control of weapons — the crew needn't be aboard the weapon platform, but close enough that light lag is substantially less than human reaction time.

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Люси Сорью

Oh, and on the subject of warship designation that's been raised here somewhere: why not look into Soviet warship designations for inspiration? They still called their cruisers cruisers(and aircraft carriers aircraft cruisers, as part of a loophole — however they did(and do) pack some serious firepower besides their air wing), but they had no destroyers or frigates or even corvettes. Instead, corvettes and smaller frigates were designated as Guard Ships(storogevoy korabl', or SKR in Russian), ASW frigates and destroyers as Anti-Submarine Ships(protivolodochnyi korabl'; a frigate was a MPK — malyi protivolodochnyi korabl', literally 'small ASW ship', and a destroyer was a BPK — bolshoi protivolodochnyi korabl', 'large ASW ship'). Yes, there ain't no submarines in space, but call them anti-shipping ships and it would work, or something along these lines. Not too original(except for the West, maybe), but it would look interesting, in my opinion at least.

And that's not getting into Soviet submarine designation, which groups subs according to size, role, armament and propulsion, and what you get in the end is something like a 'nuclear ballistic missile strategic underwater cruiser' or a 'non-nuclear cruise missile multipurpose cruiser'. Kind of like that.

• 

A century, a year, and a day ago, giants clashed across the North Sea. It was the single grand set-piece engagement of the big gun battleship era. Nothing like it was ever seen again, or probably ever will be.

Battleships and their dreadnought cousins, battlecruisers, loom large in our collective imagination. They were and are inherently operatic. Space opera, in particular, emerged as a genre during the dreadnought era. And while it may often favor swords or space fighters, on some level space opera is really all about Dreadnoughts in SPAAACE !!!

If you doubt this, take a look once again at the opening scene of the original Star Wars movie. No lightsabers are to be seen, nor even a space fighter. What we see is a spaceship - no small one - in desperate flight ... to be overtaken by a truly looming, immense, unmistakable battlecruiser.

We know it is a battlecruiser, rather than a battleship, because of its hunting-down role, something that Jackie Fisher would have identified without hesitation as a battlecruiser mission.

And yes, franchise canon describes this majestic ship as a 'star destroyer' but we are not fooled. Perhaps George Lucas was hazy on his 20th century naval terminology, or perhaps he felt that, in those days, battlecruiser belonged to the rival Star Trek franchise.

No longer. While battlecruisers continue to have a somewhat sketchy reputation among seagoing dreadnoughts (see below), they have clearly overcome their slower if more heavily armored cousins in the battle for the stars.

Google battleship, click Images, and you get pictures of historical seagoing battleships. Google battlecruiser and you mostly get renditions of operatic spaceships, with a mere scattering of seagoing vessels. (Battle cruiser as two words brings up a slightly different sequence of images, but equally space dominated.)

It is not quite clear why, of the two dreadnought* types, battlecruisers have become so predominant in space. Perhaps, for Americans at least, Pearl Harbor looms larger than Jutland. If battleships only ever existed in order to be obsolescent sitting ducks for Japanese carrier planes, their potential as terrors of the spaceways is diminished.

* Dreadnought is used inclusively here, applied to all big-gun capital ships, though the term was not often applied to new battleships once pre-dreadnoughts had faded from the scene.

On the other hand, the US Navy never had any battlecruisers, or at least never admitted to having any. Six were under construction during World War I, but under terms of the Washington Treaty two were finished as aircraft carriers while the others were scrapped before completion. The Alaska class of World War II was described officially as mere 'large cruisers', and their wartime service was brief, uneventful, and overshadowed by the much larger Iowa class 'fast battleships'. 

Independent of their role in science fiction, dreadnoughts have their own mythology. As recently as 1991, a book with the evocative title Sacred Vessels repeated the popular (pseudo-) contrarian argument that dreadnoughts were an inherently bad idea, impressive and expensive but with little actual fighting value.

The fact that there was only ever one grand clash of dreadnoughts - Jutland - and that it was not a classically decisive battle, is often implicitly offered as evidence of this proposition. In fact, battleships and battlecruisers mixed it up on multiple occasions in World War II, though in much smaller numbers than at Jutland. Running fights with one to three capital ships ships on a side was the usual pattern.

This makes Fisher's original conception of the battlecruiser somewhat prescient. In the early 1900s he argued that the time for stately formal engagements was passing, and that future war at sea would be, in modern terms, 'kinetic' - reliant more on speed and shock than pure mass. The experience of the 1940s generally bore him out.

And - again, quite apart from science fiction - battlecruisers have their own mythology, a myth that has undergone considerable evolution.

Three British battlecruisers exploded at Jutland, and went down with nearly their entire crews. These disasters were long attributed mainly to insufficient armor protection, and the whole battlecruiser concept was often denounced on this grounds.

In recent times, however, much more of the blame for the battlecruisers' losses has been placed on operational and doctrinal errors. The British battlecruiser force put great emphasis on rapid fire of their main guns - which doctrine, like the ships' speed, was part of the emerging kinetic vision of war at sea.

But the emphasis on rapid fire led gunners to ignore safety precautions such as properly closing anti-flash doors, so that when turrets were hit the resulting internal fires spread down to the magazines - with predictably catastrophic results.

The modern source linked above perhaps overstates the conspiratorial element in the traditional story about armor. I have 'always' known that flash protection was also lacking, so the shift is less a matter of new revelations and more a re-evaluation of what was already known. (Though perhaps it wasn't clear that flash doors were already in place, but not correctly used.)

This is often how scholarship proceeds, a cycle not unlike the fashion cycle. Perhaps by the 2060s a re-re-evaluation will again say that battlecruisers blew up because they were eggshells armed with hammers.

In the meanwhile, battlecruisers may well continue to rule the spaceways - as they deserve to. And readers of this blog may continue to suspect that laserstars, for all my disclaimers to the contrary, and details of armament and configuration, are still essentially Dreadnoughts in Space.

Play the Jupiter theme from Holst's The Planets, and decide for yourself.

Let's talk about rocketpunk space warfare. Instead of jumping right into weapons and the primitive-tech version of purple/green, let's first enumerate the basic types of available spaceships, and then consider not how they would shoot at each other, but what underlying military missions they would perform. I don't know how to fight you till I know what you intend to do.

SHIP TYPES:

Ramjet shuttles. Chemfuel, standard orbital shuttles. If refueled might reach geosynch, but not designed or suited for operation beyond LEO.

Tail-lift shuttles. Chemfuel, heavy freight shuttles. Mainly for orbit lift, but if suitably equipped and fully refueled in orbit (which takes a LOT of fuel), they can go to the Moon, land, and return, or go to Mars, land, and lift to Mars orbit. Expensive to operate, but possible military utility.

Orbital ships. Chemfuel, used for movement in local orbital space. Generally small. Limited delta v.

Moon/Mars surface shuttles. Chemfuel, designed for surface-orbit operation on those planets, usable in orbital space but not suited to deep space missions.

Deep-space ships, chemfuel. Available in all sizes. Many are streamlined for aerobraking at Earth and/or Mars. Interplanetary ships differ from cislunar ships in having long-duration life support, making them somewhat more expensive. Specific impulse 320-450 seconds, suited to Hohmann orbits only. Acceleration up to several g.

Deep-space ships, nuclear-thermal. Available in larger sizes. May be streamlined for aerobraking, with retractable engine pylons. Cislunar and interplanetary ships differ in life support as above. Specific impulse ~1000 seconds; normally use Hohmann orbits, but can use some faster ones in emergency. Acceleration around 0.1 g. Might carry chemfuel engines for a brief fast burn or two.

Deep-space ships, nuclear-electric. Available in larger sizes. Never streamlined; rely entirely on low-thrust engines with very high specific impulse, ~3000 seconds plus. Still often use Hohmann orbits for fuel economy, but capable of faster orbits. Climb-out orbits are slow spirals, inefficient; combined with lack of aerobraking and heavy drive engines the delta v advantage of these ships is not as great as it looks. Acceleration around 1 milligee. Have ample onboard electric power, the only ships that do.

MISSION TYPES:

Orbital command. Complete control of a planet's orbital space. No one leaves the surface, or at least the atmosphere, without risk of attack. Allows you to to do close-up recon, bomb the surface, or (if you have shuttles) land on the surface. Subject to attack only from deep space or by exoatmospheric fighters (Earth) or armed shuttle types (Moon/Mars). You must have orbital command to safely perform routine space operations.

Orbital interdiction. Denial of orbital command (possibly as a prelude to asserting it yourself). The target of successful orbital interdiction cannot safely carry out routine space operations. A condition of mutual interdiction might occur in which orbital space is a no man's land, and the planet may be subjected to sporadic bombing.

Deep space interdiction. "Space blockade," exercised from very high orbit or even a nearby solar orbit. You are too far from the planet to directly attack the surface or ships in low orbit, or for them to attack you, but you can shift orbit to intercept ships departing for or arriving from deep space. Logistic requirement is demanding unless you have a nearby friendly base (e.g., the Moon, for interdiction of Earth).

Deep space raid. Transient orbital interdiction — a drive-by attack executed at transfer-orbit speed, the attackers taking one passing shot before receding back into the Depths of Space. Requires less delta v than an orbital attack from deep space, but with no option to stick around even if you decisively defeat local forces. Deep-space raiders can bomb surface targets, though aiming is difficult. Given rocketpunk sensor limitations, early warning may be limited.

Deep space reconnaissance. A non-shooting drive-by in order to get a closer look at a planet's orbital space than you can get from interplanetary distances.

Flat-space warfare. This has the same basic mission types as above, but directed toward objectives with little or no local gravity gradient - bases, habitats, whatever, located at the L5 positions, or in the asteroid belt. (Ceres escape is 0.5 km/s.) Solar-orbit transfer velocities, however, are still multiple km/s, so the basic distinction remains between local operations and deep space drive-by operations.

ORBITAL COMBAT:

A basic tactical consequence of the above missions is that most combat is orbital. If ships are in different orbits they have substantial crossing velocities — thus considerable kinetic punch — but must expend a lot of delta v to change or match orbits. Kinetics and debris do not usually hurtle off into the void, but remain in orbit, potentially dangerous as kinetic mines. (And the hazard is more or less permanent.)

Orbits can be characterized by their velocities, and the constraints thus imposed on changing orbit. I suggest as a handy measure ~40 percent of circular velocity [sqrt(2) - 1]: the amount of delta v needed to go from circular velocity to escape velocity, or to change circular-orbit inclination by about 23 degrees. Let's call this "tactical velocity" — the delta v you need for a major tactical maneuver.

Some characteristic tactical velocities are:

• LEO: 3.1 km/s
• Mars low orbit: 1.5 km/s
• Geosynch: 1.3 km/s
• Lunar low orbit: 0.7 km/s
• L5 orbit: 0.3 km/s
• Ceres low orbit: 0.1 km/s

A ship with a 50 percent combat fuel fraction (which is a lot!) has available combat delta v ranging from 2.2 to 3.1 km/s for chemfuel (multi-g), or about 6.9 km/s for nuke-thermal (~0.1 g). Nuclear-electric ships would have 21 km/s of combat delta v, but at ~1 milligee these ships have no tactical mobility to speak of; a 1 km/s burn takes a day or more.

Sustained "dogfighting" or AV:T style shoot-pivot-scoot engagements seems more or less ruled out in orbital combat, except perhaps in distant orbits, or orbiting the Moon. In most low orbits, or even Earth geosynch, an orbit change or two will use up most of your combat delta v, leaving very little for gyrating combat maneuvers. Only in nearly flat space are ships likely to drift toward fighting range at low enough relative speed for them to maneuver around each other.

Orbital combat thus looks like a matter of successive firing passes, usually an hour or more apart. I'm not sure that individual firing passes hold much tactical interest — in a game they might be, basically, a die roll and table lookup. The tactical interest is more likely in the overall orbital maneuvering involved, with the logical turn length perhaps being expressed in fractions of an orbit rather than a fixed time period. The low-orbit period around rocky planets is always about 1.5-2 hours, but geosynch is of course a day.

Probably the most strategically important space in the rocketpunk-verse is LEO, but it is particularly difficult to fight in, with ship maneuvers highly constrained relative to the circular velocity of ~8 km/s. Kinetic impact speeds are likewise typically high, making kinetic hits more destructive.

DEEP SPACE OPERATIONS:

Given rocketpunk ship performance and likely weapon ranges, Earth-Moon space as a whole should be regarded as a deep space operational or even strategic theater, not a tactical theater. Leaving LEO to attack the Moon or L5 (or vice versa) has much in common with an interplanetary expedition, except that delta v required is somewhat less, and travel times are days instead of months.

Interplanetary operations are totally ruled by the solar gravity well. No torchship point-and-scoot orbits! Raiders and recon ships may take relatively fast drive-by orbits, but any force intending to spend time at its objective and then return home if necessary will have a demanding delta v requirement even using Hohmann orbits — especially if it must have combat delta v available when it reaches its objective. So, interplanetary warfare will in general follow the leisurely Hohmann timetable, with everything this implies about departure windows, threat windows, and logistics and duration of operations.

WEAPONS:

Kinetics. Ship velocities and missile performance make conventional explosive warheads generally unnecessary except as bursting charges; kinetic hits will carry, typically, 1-10 ricks of impact energy. Effective range of kinetics is largely limited by problems of tracking and guidance.

Lasers. Most ships have limited electrical power, precluding electrically-fired lasers, though they can carry chemical lasers, with limits on ammo. Nuke-electric ships, however, have up to hundreds of megawatts of available onboard power, so they can carry powerful lasers with unlimited zaps. (They might also carry coilguns, if these are useful.) Laser mirrors will be 5-meter absolute max (i.e., like Palomar), but 1-2 meters is much more likely, with 3-meter a very big gun. No adaptive optics. Laser range is largely limited by problems of precision aiming and holding a spot on target.

Nukes. Like other missiles, effective range of nukes is limited by tracking and guidance, though of course nukes don't need to score a direct hit. Kill radius is fairly limited for physical damage, but very large against insufficiently shielded personnel.

Armor. The large fuel fractions (requiring large tanks, as well as limiting all other mass) make armor protection very hard to combine with significant mobility, tactical or strategic. Armor protection is thus very limited, except for the radiation storm cellar that all deep-space ships must carry.

In general, rocketpunk space warfare is at once far more Realistic [TM] in most respects than torchship warfare, and perhaps quite difficult to either gameplay or carry out in real life. Which may be why the original rocketpunk classics had surprisingly few space battles!

The necessary large size, low tactical maneuverability, and high delta-V of the nuke-electric craft seems to make them serve a role similar to deep space fortresses or aircraft carriers. They can carry unlimited zap lasers, which depending on the wavelength might give good "reach out and touch-em" range, and can provide area defense of friendly forces by shooting down incoming missiles. Likewise, they can afford to carry smaller "fighter" craft - chemfuel craft with low endurance but high acceleration for tactical maneuverability.

A nuke-electric fortress could park in a higher orbit and send in its fighters for orbital interdiction. The main issue here is the endurance of the fighters. Perhaps it carries a few "patrol craft," larger chemfuel craft with more life support and room for crew quarters that can be launched from the fortress's parking orbit into lower orbit. One tactic that may be used is for the patrol craft to expend all their delta-V in the fight, trusting that (if they win) the fortress can spiral in and pick them up later. With this, and the use of aerobraking, the patrol craft could keep most of their delta-V for combat maneuvers.

For orbital command, it eats up the long spiral time to dominate the lower orbits with its laser firepower and long endurance. The lasers also allow orbit to surface bombardment, weather permitting, without using ammo. One of these craft can also carry sufficient nukes (excuse me - atom bombs) for reducing an enemy's planetary assets from orbit. In this situation, its low acceleration makes it vulnerable, so it relies on fighters and lasers for defense.

For deep space raids, interdiction, and reconnaissance, these would seem to be the craft of choice. With a known target and lots of time to build up speed, this allows intercept and flyby courses with little use of resources. With the delta-V advantage always with the nuke-electric craft, it can pretty much dictate the closing conditions with any chemfuel or nuke-thermal craft in deep space. The only craft that could evade one of these fortresses in deep space would be another nuke-electric craft, if it knew the attack was coming. For a single high speed pass, tactical maneuverability is not such an issue. Of course, it uses high acceleration chemfuel missiles to counter high acceleration evasive maneuvers of the target. It can also economically perform rendezvous maneuvers with chemfuel or nuke-thermal craft that it does not want to destroy, using lasers or fighters to disable the target if necessary. In fact, loitering on the edge of effective laser range is a good tactic, allowing the fortress to fire freely on the target without being in as much danger from kinetics (which will be closing at low speeds). If the other craft tries to use its superior acceleration to run, the fortress leisurely catches up to it again, and again, until the target is out of delta-V. This, of course, bleeds over to the realm of flat space warfare, with a fortress parked just in laser range and sending fighters for close-in high-G attacks.

It would make sense for fortresses to operate in "battle groups" of two or three, so they could cover each other with their lasers and deny the enemy the opportunity of presenting only the least vulnerable aspect.

It may work out to be more economical to separate the nuke-electrics into "carriers" and "laser fortresses," one focusing on providing boost and transport for fighters, patrol craft, and missiles; the other focusing on high power, long range lasers. Or it may be best to combine the two roles into a single, more versatile craft.

So, that's some thoughts from an armchair general. Actual wargame scenarios could expose limits of this thinking.

Now, just because I have to ask, what are the specs on the lasers? Are the chem lasers mid IR (~ 3 microns, likely DF) or near IR (~ 1 micron, possibly COIL)? Are the electric lasers solid state devices, gas lasers (ick, far IR!), or are they "optical klystrons" (FELs)? If solid state, what is the wavelength it lases at? Is frequency doubling or tripling available? I assume the lower wavelength limit for all lasers is given by the reflectivity of the mirrors, with nothing lower than around 0.2 microns. Do they use dielectric mirrors, or is aluminum (or silver, or gold, depending on wavelength) the only way to go?

Personally, for a rocket-punky feel, I'd use COIL lasers (err, heat rays) for the chemical stuff, optical klystrons for the electrics, and only metal coatings on the mirrors. Since optical klystrons are a development from radar technology, you could also use them for sensing, detection, and ranging ("optical radar." Would that be vidar? Odar? Or we could re-use lidar for a different acronym - LIght Detection And Ranging).

One of the problems with figuring out how ships are going to fight in space (assuming that we have ships in space, which isn't as likely as I wish; and, that we’re still fighting when we get there, which is unfortunately more probable) is that there are a lot of maritime models to choose from.

It’s also true that some of the maritime models came from very specialized sets of circumstances; and a few of them weren’t particularly good ideas even in their own time.

And it’s also true that some of the writers applying the models have a better grasp of the essentials than others. That isn’t limited to writers of fiction. For example, I recall two essays which were originally published about fifty years ago in Astounding.

In the first of the essays ("Space War", Astounding Science-Fiction, Aug 1939), Willy Ley, a very knowledgeable man who had been involved with the German rocket program, proved to my satisfaction that warships in space would carry guns, not missiles, because, over a certain small number of rounds, the weight of a gun and its ammunition was less than the weight of the same number of complete missiles. The essay was illustrated with graphs of pressure curves, and was based on the actual performance of nineteenth-century British rocket artillery (“the rockets’ red glare” of Francis Scott Key).

As I say, the essay was perfectly convincing … until I read the paired piece by Malcolm Jameson ("Space War Tactics", Astounding Science-Fiction, Nov 1939).

Jameson’s qualifications were relatively meager. Before throat cancer forced him to retire, he’d been a United States naval officer—but he was a mustang, risen from the ranks, rather than an officer with the benefit of an Annapolis education. For that matter, Jameson had been a submariner rather than a surface-ship sailor during much of his career. That was a dangerous specialty—certainly as dangerous a career track as any in the peacetime navy—but it had limited obvious bearing on war in vacuum.

Jameson’s advantage was common sense. He pointed out (very gently) that at interplanetary velocities, a target would move something on the order of three miles between the time a gun was fired and the time the projectile reached the end of the barrel.

The rest of Jameson’s essay discussed tactics for missile-launching spaceships—which were possible, as the laws of physics proved gun-laying spaceships were not. Ley could have done that math just as easily. It simply hadn’t occurred to him to ask the necessary questions.

Light-swift beam weapons were a fictional staple in Jameson’s day (he used them in his stories about Bullard of the Space Patrol) and a realistic possibility in ours. And the advent of the electrically-driven railgun has brought even projectile artillery back into the realm of space warfare. Present realities don’t prevent a writer from building any number of self-consistent constructs of how space war will work, however.

• 

• 

At one time, boarding and hand-to-hand combat were common notions in military science fiction (which, in the 1920s and 30s, was rather a lot of science fiction). Boarding has a long naval tradition as, at times, the heaviest available weapons were not by themselves sufficient to sink major warships. When oared warships grew sturdy enough to be equipped with rams, however, ramming replaced boarding as the tactic of choice… (This was featured in Isaac Asimov's Black Friar of the Flame)

Until sailing ships replaced oared warships. Sailing ships can’t mount effective rams because their masts and rigging would come down with the shock. The guns available during the next five centuries weren’t effective ship-killers, and boarding returned.

As guns became more powerful and ships were designed to mount large numbers of them along the sides, the sort of melees that characterized the Armada battles and the meeting engagements of the Anglo-Dutch Wars of the seventeenth century gave way to formal line-of-battle tactics (This can be seen in the Honor Harrington books, where the handwaving propulsion systems force them to use "wall-of-battle" tactics). Opposing fleets were expected to sail along in parallel lines, firing all their guns at one another, until something happened.

Mostly, nothing much happened. A typical example is the action between the fleets of DeGrasse and Graves in 1781 in Chesapeake Bay. This was the crucial battle that decided the fate of the British army at Yorktown—and, thus, the Revolutionary War. It was a draw, with no ships lost on either side (which tumed out to be good enough for the American rebels, of course).

Nelson changed matters by what amounted to assertiveness training for the British navy. His captains were expected to close with the enemy and board if necessary, instead of staying at a reasonable range and letting noise and smoke stand in the place of doing real damage. Nelson’s opponents never beat him. In the end, they were able to kill him; but even dead he led his forces to victory.

The appearance of steam and armored warships in the nineteenth century gave rise to an amazing number of theories and some of the most outlandish warships ever built. What didn’t emerge were major battles between the new vessels.

At Lissa in 1866, an Austrian fleet humiliated an Italian fleet of more modem and powerful ships, proving that competence and leadership had more to do with victory than equipment alone. (Nelson must have smiled from his grave.) Lissa proved little or nothing about the new hardware (theorists of the time thought otherwise; they were wrong). but it was as good a test as the century provided.

Ships generally mounted mixed armaments of large and mid-sized weapons. though there was a brief fad of equipping battleships with small numbers of very heavy guns. This was partly in the hope that a single huge shell could smash opposing armor (in the unlikely instance that such a shell hit its target); and partly because the planners wanted an easily quantifiable marker for their arms race. (The dangerous buffoons in the Pentagon and Kremlin with their “My throw weight is bigger than your throw weight” arguments had nineteenth century predecessors.)

Incidentally. as soon as steam removed the necessity for masts and rigging, rams retumed as well. There were few successful examples of ramming in war. but in peacetime, rams sank almost as many friendly naval units as decomposing smokeless powder did.

The only real test of nineteenth century warships came in the twentieth century—1905—at the Strait of Tsu Shima, where a Russian fleet that did nothing whatsoever right met a Japanese fleet that did nothing important wrong. The Russians were massacred. and it was heavy gunfire alone that did the butchers‘ work.

An idiosyncratic genius named Jackie Cooper was running the British admiralty at the time. He came up with the first good idea in warship construction since Ericsson put a turret and screw propeller on the Monitor: Cooper built the Dreadnought.

The Dreadnought was big and fast and carried ten of the most powerful naval guns available, with none of the mid-sized weapons that had proved almost useless at Tsu Shima. Every battleship built after the Dreadnought is more similar to her than the Dreadnought was similar to anything that came before her.

Having had a brilliant idea. Cooper went on to have a lethally bad one: the battle cruiser. The battle cruiser was a dreadnought (the name became generic for all-big-gun warships) which had lighter armor and more powerful engines than a battleship. and was therefore faster. The theory was that “speed is armor.” The reality was quite different, and thousands of sailors (mostly British) died in the two World Wars (the Hood was a battle cruiser) because a clever slogan can’t repeal the laws of physics.

The dreadnought brought back the concept of the line of battle. It didn’t work any better in the twentieth century than it had in the eighteenth, because both sides had to agree to play the game and the weaker side—the Germans, in this case—would inevitably lose. The German admirals of the World Wars were less than brilliant, but they weren’t stupid.

Besides, the fleets of World War II were dominated by aircraft. The one major battleship-to-battleship fleet action of the war occurred at night in the Surigao Strait. It was a close copy of Tsu Shima, with the Japanese playing the part the Russians had forty years earlier.

There is enough in actual maritime history to provide models for almost any form of space warfare a writer wants to postulate. Because there are so many possibilities, writers can find a solidly-grounded situation that suits their story, rather than forcing the story into a narrow matrix.

And that, I think, makes for some very good stories.

• 

With each trailer for Star Wars: The Force Awakens, we’ve been exposed to the new Starfighter being fielded by the Rebel Alliance – now rebranded as the Resistance (go figure). The Incom T-70 is carrying the legacy of the X-Wing into a new generation, combating a likewise new model of the TIE Fighter.

But each new trailer however has suggested something is lacking in the Resistance fleet – that is, a variety of other Starfighter types. It would appear that, in the 30 years since the Rebel Alliance deployed an array of X-, Y-, A- and B-Wings to the Battle of Endor, they have settled on a single multi-role type across the entire fleet.

---

With that assumption on board, it’s worthwhile considering what steps were taken over 30 years to go from a four-type Rebel Alliance fleet, to a single-type Resistance.

It’s a journey to consolidation that draws some parallels to the United States Navy’s own carrier-based combat aircraft fleet.

Both organisations were operating with different strategic priorities 30 years ago compared to what they are today. When Return of the Jedi hit cinemas in 1983, the Nimitz-class carriers were sailing with no less than four fixed-wing fighter/strike aircraft – the F-14 Tomcat for air superiority, the A-6 Intruder and A-7 Corsair in the strike role, and the S-3 Viking as an anti-submarine/surface warfare platform. Also operating was the EA-6B Prowler, a variation of the A-6, which was optimised for electronic attack.

Likewise, the Rebel Alliance went into the Battle for Endor with its own four dedicated strike/fighter platforms, albeit with no electronic attack variant (it seemed the Empire had the upper hand in the electronic warfare spectrum that day) [Editor’s note: or that electronic warfare just isn’t a big part of Star Wars]. Leading this charge were the T-65 X-Wing in the space superiority role, joined by fellow Yavin-veteran, the Y-Wing bomber. Also deployed were two newcomers – the high-speed A-Wing, and the B-Wing bomber, whose primary role was to attack capital ships.

It’s a safe assumption that the role of a Carrier Air Wing is much like that of the Rebel Alliance’s Starfighter squadrons fighting ‘A Long Time Ago in a Galaxy Far, Far Away’. Fundamentally, they both need to defend a home base, and are important tools for force projection in pursuit of wider campaign objectives.

Fielding a variety of types that each have a dedicated role carries with it benefits. A security or technical grounding for one type will (nominally) not affect the others. Dedicated types are optimized for function, rather than compromising performance to be truly multi-role. A Carrier Air Wing’s F-14 Tomcats can defend against high-speed bombers and provide a combat air patrol against MiGs and Sukhois. A-6 Intruders and A-7 Corsairs are optimized for striking surface combatants and hitting targets on land. The S-3 Viking – working in concert with other aircraft and vessels – can detect and defeat submarines. For the most part, the Soviet Union spent much of the Cold War trying to defeat the force projection abilities of carriers, and at the same time protect its home shores. Whilst the Soviet Union was spending the time, resources and money on countering Carrier Battle Groups, it was not delivering comparable force projection capabilities of its own.

While the Rebel Alliance faced a different strategic environment from the United States Navy, it too found itself benefiting from fielding a multi-type Starfighter fleet. It allowed them to pitch an asymmetric threat against the Empire, dictating the terms of engagements with dedicated platforms and avoid one-to-one engagements that it could not match with people, ships, or resources. The B-Wing Starfighter was primarily for attacking capital ships. Notwithstanding its kamikaze attack on the Super Star Destroyer Executor, the A-Wing was a hit-and-run Starfighter built to raid Imperial convoys and destroy remote satellite relays, degrading logistical and communications networks, and crippling the Empire’s ability to wage its campaign. Throughout it all, the X-Wing was intended to defeat the TIE Fighter; while the Y-Wing, a relic of the Cold War Clone War, was kept in service probably because it was bloody impossible to get rid of.

Striking from hidden fortresses and deployed capital ships, the Rebel Alliance’s force projection with these Starfighters would have forced the Empire to build defenses capable of defeating all forms of attack. Imperial Commanders were therefore kept guessing as to the composition of Rebel threats, and how they could attack them.

Having so many different types of Starfighters and aircraft however places a significant logistical burden, whether you’re a Rebel capital ship or United States Navy aircraft carrier. Each time a Carrier Strike Group goes to sea, it attempts to bring sufficient spares and workforce for the term of its voyage, but is otherwise reliant on C-2 Greyhound carrier on-board delivery aircraft; or port visits, which themselves are connected to a logistical pipeline supported by shore-based aircraft. Every different aircraft type in the Carrier Air Wing needs its own specially-trained workforce to operate and support, and must retain a spare parts stock for repairs. Different aircraft have different maintenance overheads, depending on their age and performance, which ultimately affects sortie generation. All of these factors determine the overall effectiveness of a Carrier Strike Wing whilst it’s at sea.

When Starfighters are embarked on a Capital Ships, we can assume their supporting constraints are almost identical to their United States Navy counterparts. There’s only so much space on the ship for hangars, spare parts storage, and workforce accommodation. Terrestrial bases for Rebel Alliance Starfighters would provide greater room, but still present similar logistical challenges in how they are sustained with spare parts and key equipment. The one advantages the Rebel Alliance has are astromechs. An R2 or R5 unit, for example, can maintain and conduct repairs on a Starfighter without sleep, and can work across multiple types on the hangar floor without limitations. They can diagnose directly using a ship’s computer, provide accurate stocktake assessments, and receive updated technical publications instantly. Admittedly, they do need their own spares pipeline and sustainment maintenance – but the efficiencies they deliver are worth it.

The United States Navy does have the advantage of protected warehouses and factories for all its supply needs. The Rebel Alliance likely has to disperse its equivalent facilities across the galaxy, keeping them underground to avoid the prying eyes of the Empire. Despite the range advantages of hyperspace travel, resupplying ships and bases with spare parts and personnel is a dangerous affair. Let’s take X-Wing powerplants as an example. Building them requires de-centralised workshops to avoid detection, but also skilled workforces due to the precision construction. Once built, these components are likely kept in hidden warehouse storage until they are smuggled through the galaxy to their end user. Replicating this logistics effort across all the systems of an X-Wing gives a good impression of how hard it is to keep a Starfighter ‘spaceworthy’, especially considering how complex they are compared to their Imperial foes, which lack shields and hyperdrives. We can assume there is little-to-no commonality in major components across Rebel Starfighters (even the Empire consolidated its TIE eye-ball across the Fighter and Interceptor variants). All of this puts Rebel Alliance at a significant logistical disadvantage during the Galactic Civil War.

Which brings me to a cynical explanation for why else the Rebellion had so many different Starfighters – in all likelihood, there was more gerrymandering required from the Rebellion than the Empire, when negotiating the support of planetary systems. How many times did Mon Mothma win the support of a local star system, but only because she promised to employ local workshops and factories to build X-Wing laser canons? Or gain safe harbor in space ports for Rebel vessels, but only because she was buying squadrons of unwanted Y-Wings from the port’s governor? Tyrannical governments like the Empire are built on decrees and corruption, leaving little question that the Rebellion had to resort to financial and employment incentives to guarantee support for its cause.

Over the past 30 years, there’s been significant changes to the strategic operating environment for both the United States Navy and the Rebel Alliance (now the Resistance). These changes undoubtedly influenced their respective moves towards a consolidated fleet of strike/fighter platforms. While aircraft carriers remain an important strategic tool, the years since the end of the Cold War have largely seen their warfighting efforts concentrated on sustained force projection for overland operations in the Middle East and former Yugoslavia. The dedicated platforms operated in 1983 were retired, their roles taken on by a shrinking variety of aircraft types (or, in the case of anti-submarine warfare, shifted to shore-based and rotary-wing aircraft). Today, most Carrier Air Wings limit their fighter/strike capability to the F/A-18 Classic Hornet and Super Hornet, and the E/A-18G Growler. Carrier Air Wing Five, based in Japan, has done away with the Classic Hornet altogether, and operates the Super Hornet and the Growler from the USS Ronald Reagan.

That consolidation was not a pre-ordained path, with failed programs (the A-12 Avenger, F-14 life extensions), receding budgets, and an operating environment that emphasized reliability and multi-role performance. The move to consolidation has robbed the United States Navy of, say, an F-14’s high-speed and long-range intercept talents. The upshot is that replacement types (in the form of the Super Hornet) are largely more reliable and efficient, and fewer types has allowed a more streamlined training and logistics pipeline. In an ideal world, this reduces operating costs and improves sortie generation rates with the same number of aircraft and personnel.

The experience of the United States Navy with the Super Hornet is therefore a good clue to how the Resistance came to operate the T-70 X-Wing as its sole type (if I can indulge my imagination, I’d like to think older T-65s are still in limited frontline service as well as operated by Reserve units). Much like the Super Hornet, the T-70 is based on a widely-used predecessor, and likely performs the roles of other types that have been since retired. Anti-capital ship functions, like anti-submarine warfare, have been transferred to the Resistance’s own capital ship fleet. While the Resistance cannot provide a dedicated type for specific roles, it can compensate through improved sortie generation rates thanks to a streamlined logistics pipeline and training model. These two factors are important when you’re fighting a sustained, 30-year conflict, as the case is suggested with The Force Awakens.

All evidence in the trailers suggest that the Galactic Civil War is still happening. The Resistance is now facing off against the First Order, an Imperial remnant which is a shadow of what we saw 30 years ago. The loss of a pair of trillion-credit Death Stars, coupled with the assassination of its senior leadership, is hard to come back from.

Faced with a degraded enemy, the Resistance had the freedom to reassess how it sustained its warfighting capability, and felt it was able to pair back the number of different Starfighter variants it operated. As these ships came to the end of their life-of-type, they were progressively replaced by squadrons of T-70 X-Wings. This in turn realized significant savings that could be reinvested in a larger fleet of Starfighters, and allowed them to face the First Order on more even terms (rather than conducting a ‘counter-insurgency campaign with Starfighters’). I’d love to speculate other reasons for how the Resistance came to operate a single Starfighter type. Were there Tomcat-style Service Live Extension Programs for the B-Wings? Was a wildly ambitious replacement for the Y-Wing proposed, only to be cancelled and lead to a decades-long lawsuit? These are the Marvel Star Wars comics that I want to read.

Now, I accept the United States Navy’s wider operating environment is different in many respects from the Rebel Alliance/the Resistance. It has the wider United States Air Force, Marine Corps, and Army to jointly operate with. And the United States Navy hasn’t entirely reverted to a single combat type, either. The Northrop Grumman X-47B is plotting the Navy’s path to an Unmanned Carrier-launched Airborne Surveillance and Strike’ platform. And very soon, the F-35C Lightning II will enter service with frontline units as a replacement for the remaining F/A-18 Classic Hornets. In keeping with the other F-35 variants, the C-model emphasizes a combination of sensor-fusion, stealth, and networked connectivity, and is intended to perform multi-role missions.

The F-35C however might still have a kin-type in the Star Wars Universe. Unless JJ Abrams takes us to the planet where the Resistance has its Pax River-equivalent facility, it’s unlikely we’ll see a brand new Starfighter in The Force Awakens. But I can predict when we will see it – in 2017, with the release of Star Wars: Episode VIII.

There’s a couple of reasons to speculate this case. Without having seen The Force Awakens yet, we can expect to see a major shakeup of the power balance in the Galactic Civil War after a sustained 30-year conflict (which will take at least two more films to resolve). The T-70 will have to soldier on, but I predict the Resistance will come into Episodes VIII and IX with a brand new Starfighter type to face this re-surging conflict.

The other reason to be confident of a new Resistance type (let’s call it the T-XX) in 2017 comes down, once again, to merchandising.Disney can only sell so many models before they have to come up with something new. This year, there’s going to be a lot of T-70s underneath Christmas Trees, making it unlikely that kids will want a repackaging of ‘old’ T-70s when Episode VIII comes around.

The new Resistance T-XX, much like the F-35C, is going to have big shoes to fill, and both types will affect how the Resistance and United States Navy emerge from their respective consolidated combat aircraft structure. There’s no guarantees for what conflicts the F-35C might be called upon in the future, and as for what pressures will drive the design of the T-XX? We wont know the answer to that question until December 18.

• 

The Last Jedi promises something not seen before – a Star Wars equivalent of a strategic heavy bomber.

To date, the Star Wars Universe has provided a science fiction examples to many real-life military roles (with varying degrees of artistic licence). Imperial Star Destroyers have largely stood in for the Navy, whilst the Army and Marines forces have been shown on all sides of the Galactic Civil War with armoured units, littoral forces, and even mounted elements.

The Air Force can take its pick – X-Wing fighters, Shuttle pilots, and even an Air & Space Operations Centre on Yavin. There’s one American air power staple however that’s been surprisingly missing from the eight live-action Star Wars films run (not including the two Ewok ventures) – a hulking, vulnerable, heavy-with-ordnance strategic bomber.

The Last Jedi will change this in December. Both trailers for the film have shown the ‘Resistance Bomber’, a ship which appears significantly larger than your 12.48-metre-long T-70 X-Wing; but probably a touch smaller than the 126-metre-long Corellian Corvette. That size means it doesn’t just carry a lot of bombs; it can carry all of the bombs. If the X-Wing is an F-15 or F-16 with a dozen or less hardpoints, then a Resistance Bomber is our B-52 with the capacity to carry every bomb that you own.

The Resistance Bomber isn’t just unique in the Star Wars cinematic pantheon – it stands out within the 40-years of storytelling canon. Whilst real strategic bombers have featured heavily in film (not to mention memoirs and other mediums), the Star Wars Universe doesn’t have a ship which matches something like a B-17, B-29, B-36 or B-52. That goes for the Expanded Universe, covering computer games, novels, comics, and roleplaying guide books. We’ve seen hundreds of different models of starfighters, but anything much larger is typically a freighter or capital ship. In the Star Wars canon, bombers have traditionally been more-or-less the same size as their starfighter escorts, and when they grew larger, they were seldom much bigger than the Millennium Falcon.

We only have modest information about the Resistance Bomber, but it’s not unreasonable to suggest it is derived from Second World War heavy bombers. It carries a crew of at least one pilot and one bombardier, and likely several gunners to operate laser turrets around the ship. Wookiepedia lists it as the B/SF-17 heavy bomber, a naming convention which means it’s probably a distant relative of the A/SF-01 B-Wing that appeared in Return of the Jedi. The B-Wing’s background was a poor dogfighter, but equipped with a heavy weapons load intended to take down larger capital ships. The Resistance Bomber follows this tradition, according to StarWars.com:

Now reinforced with new combat craft, the Resistance fleet dispatches hardy bombers into battle with the First Order fleet. Escorted by swift starfighters, these munitions-laden carrier ships drop powerful proto bombers onto their Star Destroyer targets.

Director Rian Johnson said The Last Jedi will use Twelve O’Clock High as a ‘touchstone’ for its combat scenes, and the B/SF-17 name is a nice callback to the B-17 Flying Fortresses that featured in the 1949 film. We wont know much more until The Last Jedi appears in cinemas in mid-December, coinciding with the release of the book The Last Jedi: Cobalt Squadron, which is expected to explore the backstory of Resistance Bomber crews in the movie. Accompanying this will be a source book The Last Jedi: Bomber Command, which promises detailed schematics and liftouts the likes of which would make an Artoo unit spin its dome.

The ‘Bomber Command’ title makes for as good a segue as any to discuss what place bombers – and munitions – have in the Star Wars films.

There’s two good reasons for why the Star Wars films have gone out of their way to not include any strategic bomber analogue until now – one to do with story-telling, the other to do with the real world. A good illustration of this appears in A New Hope, whose Death Star Battle is almost a word-for-word, shot-for-shot recreations of 1955’s The Dam Busters, itself based on  the May 1943 raid by Royal Air Force Avro Lancasters on the Ruhr Valley dams in Germany. As with the X-wing’s run in the Death Star Trench, the Dam Busters had to skim along the surface to drop a ‘bouncing bomb’ with pinpoint precision to guarantee destruction of the target. A big difference difference lies is in the delivery platform. In The Dam Busters, the weapon is delivered by a Lancaster flown by a six-man crew. In Star Wars, it’s just Luke and a busted-arse R2-D2 running along in their lone X-Wing.

The story-telling reason for why we’ve seen no heavy bomber is simple – small ships in Star Wars can take the story where it needs to go. A strategic bomber requires multiple crew to operate, and the plot has characters engaging with one another on multi-crew ships like the Millennium Falcon. When it comes time to attack a Death Star, crews fly one or two-person ships because the ‘hero’s journey’ of the Star Wars plot can more easily narrow its focus on the individual. This leaves other characters to be killed off in a dramatic and explode-y fashion. What’s more, nothing sells the ‘David and Goliath’ stakes between the Rebellion and the Empire better than a handful of starfighters firing their guided munitions at a colossal deus ex machina, all backed by a spectacular John Williams score.

The real-world explanation for why we’ve yet to see a heavy bomber is the same as the story-telling reason – small ships in Star Wars can take the guided munitions where they need to go. In real life, strategic bombers have a flying range that smaller aircraft lack, by virtue of their need to carry massive bombloads (or even nuclear weapons) over oceans and continents. X-Wings on the other hand have strategic reach throughout the galaxy through the use of hyperspace, and can achieve destruction on a strategically significant scale with a limited bombload because the bad guys keep building a deus ex machina that’s vulnerable to precision attack (and, you know, the Force).

Even the Empire, who you might expect to engage in a spot of terror bombing of their own, doesn’t need such a platform. Star Destroyers carry out orbital bombardment from space, delivering destruction akin to mass area bombing raids. TIE Bombers meanwhile deliver precision bombloads where bigger ships can’t reach.

If the Star Wars universe has gone 40 years with its own version of a ‘bomber gap’, why might we be seeing one in The Last Jedi? Again, there’s two likely reasons – one for story-telling, one for strategy.

Firstly, the story-telling – with so many other war films having covered strategic bombers on screen, it makes sense that Star Wars would finally adapt it for a Galaxy Far, Far Away. Starfighter combat will always feature in Star Wars films, but there’s only so many times we can see that same David and Goliath narrative play out. Bombers allow for multiple characters to crew the same ship and be forced to work together, with the dramatic tension further raised by their ship’s lack of speed or manoeuvrability as it bears down on the target. The trailers for The Last Jedi make it pretty clear that a number of Resistance Bombers are destroyed before reaching their First Order targets.

Secondly, there might be a strategy reason for why we’re seeing a Resistance Bomber. In Rogue One, a formation of Y-Wing light bombers brought down a Star Destroyer with some assistance from much larger vessels. It stands to reason that a formation of heavy bombers carrying racks and racks of guided munitions might be a valid threat to a Star Destroyer – so long as a bomber gets through.

After the events of The Force Awakens, the Resistance conceivably embarked on a massive rearmament program (resourced by what was left of the New Republic), and formed squadrons of B/SF-17 Bombers to provide an immediate anti-shipping capability. That’s a bold move to construct ship of such singular purpose – the Star Wars films reward ships that have multi-role applications throughout the saga. Whether or not the B/SF-17 will join those esteemed ranks will be seen in December 2017.

I had a discussion recently with friends about the various depictions of space combat in science fiction movies, TV shows, and books. We have the fighter-plane engagements of Star Wars, the subdued, two-dimensional naval combat in Star Trek, the Newtonian planes of Battlestar Galactica, the staggeringly furious energy exchanges of the combat wasps in Peter Hamilton’s books, and the use of antimatter rocket engines themselves as weapons in other sci-fi. But suppose we get out there, go terraform Mars, and the Martian colonists actually revolt. Or suppose we encounter hostile aliens. How would space combat actually go?

First, let me point out something that Ender’s Game got right and something it got wrong. What it got right is the essentially three-dimensional nature of space combat, and how that would be fundamentally different from land, sea, and air combat. In principle, yes, your enemy could come at you from any direction at all. In practice, though, the Buggers are going to do no such thing. At least, not until someone invents an FTL drive, and we can actually pop our battle fleets into existence anywhere near our enemies. The marauding space fleets are going to be governed by orbit dynamics – not just of their own ships in orbit around planets and suns, but those planets’ orbits. For the same reason that we have Space Shuttle launch delays, we’ll be able to tell exactly what trajectories our enemies could take between planets: the launch window. At any given point in time, there are only so many routes from here to Mars that will leave our imperialist forces enough fuel and energy to put down the colonists’ revolt. So, it would actually make sense to build space defense platforms in certain orbits, to point high-power radar-reflection surveillance satellites at certain empty reaches of space, or even to mine parts of the void. It also means that strategy is not as hopeless when we finally get to the Bugger homeworld: the enemy ships will be concentrated into certain orbits, leaving some avenues of attack guarded and some open. (Of course, once our ships maneuver towards those unguarded orbits, they will be easily observed – and potentially countered.)

Now, let’s talk technology.

First, pending a major development in propulsion technology, combat spacecraft would likely get around the same way the Apollo spacecraft went to the Moon and back: with orbit changes effected by discrete main-engine burns. The only other major option is a propulsion system like ion engines or solar sails, which produce a very low amount of thrust over a very long time. However, the greater speed from burning a chemical, nuclear, or antimatter rocket in a single maneuver is likely a better tactical option. One implication of rocket propulsion is that there will be relatively long periods during which Newtonian physics govern the motions of dogfighting spacecraft, punctuated by relatively short periods of maneuvering. Another is that combat in orbit would be very different from combat in “deep space,” which is what you probably think of as how space combat should be – where a spacecraft thrusts one way, and then keeps going that way forever. No, around a planet, the tactical advantage in a battle would be determined by orbit dynamics: which ship is in a lower (and faster) orbit than which; who has a circular orbit and who has gone for an ellipse; relative rendezvous trajectories that look like winding spirals rather than straight lines.

Second, there are only a few ways to maneuver the attitude of a spacecraft around – to point it in a new direction. The fast ways to do that are to fire an off-center thruster or to tilt a gyroscope around to generate a torque. Attitude maneuvers would be critical to point the main engine of a space fighter to set up for a burn, or to point the weapons systems at an enemy. Either way, concealing the attitude maneuvers of the space fighter would be important to gain a tactical advantage. So I think gyroscopes (“CMGs,” in the spacecraft lingo) would be a better way to go – they could invisibly live entirely within the space fighter hull, and wouldn’t need to be mounted on any long booms (which would increase the radar, visible, and physical cross-section of the fighter) to get the most torque on the craft. With some big CMGs, a spacecraft could flip end-for-end in a matter of seconds or less. If you come upon a starfighter with some big, spherical bulbs near the midsection, they are probably whopping big CMGs and the thing will be able to point its guns at you wherever you go. To mitigate some of the directionality of things like weapons fire and thruster burns, space fighters would probably have weapons and engines mounted at various points around their hull; but a culture interested in efficiently mass-producing space warships would probably be concerned about manufacturing so many precision parts for a relatively fragile vessel, and the craft would likely only have one main engine rather than, say, four equal tetrahedral engines.

How about weapons? Well, we have to consider just how you might damage a spacecraft to put it out of action.

Explosions are basically a waste of energy in space. On the ground, these are devastating because of the shock wave that goes along with them. But in the vacuum of space, an explosion just creates some tenuous, expanding gases that would be easily dissipated by a hull. No, to damage spacecraft systems, you can’t hit them with gas unless it’s really, really concentrated and energetic. So unless you want to just wait till your enemy is close enough that you can point your engines at him, the best bets for ranged weapons are kinetic impactors and radiation.

A kinetic impactor is basically just a slug that goes really fast and hits the enemy fighter, tearing through the hull, damaging delicate systems with vibrations, throwing gyroscopes out of alignment so that they spin into their enclosures and explode into shards, puncturing tanks of fuel and other consumables, or directly killing the pilot and crew. You know…bullets. But it sounds much more technical and science-fictiony to say “mass driver” or “kinetic lance” or something of the sort. Of course, the simplest way to implement this sort of weapon in space is just as some kind of machine gun or cannon. Those will work in space (ask the Soviets, they tested a cannon on their first Salyut space station), and the shells will do plenty of damage if they hit anything. However, space is filled mostly with empty space, and hitting the enemy ships might be a challenge. Furthermore, if the impactors are too large, the enemy could counter them by firing their own point-defense slugs and knocking the shells out of line. Therefore, I contend that the most effective kinetic space weapons would be either flak shells or actively thrusting, guided missiles. The flak shells would explode into a hail of fragmented shards, able to tear through un-armored systems of many craft at once without the shell directly hitting its target, or able to strike a target even after it tries to evade with a last-minute engine burn. The missiles would be a bit different from the missiles we are used to on Earth, which must continuously thrust to sustain flight. In space, such a weapon would rapidly exhaust its fuel and simply become a dummy shell. No, a space missile would either be fired as an unguided projectile and power up its engine after drifting most of the way to its target, or it would fire its engine in sporadic, short bursts. A definite downside to kinetic weapons on a starfighter is that they would impart momentum to the fighter or change its mass properties. Very large cannons or missiles might therefore be impractical, unless the fighter can quickly compensate for what is essentially a large rocket firing. Even that compensation might give the enemy just the window he needs…

Radiation-based weapons that burn out the electronics of a spacecraft sound exotic, but are still potentially achievable. This would be the attraction of nuclear weapons in space: not the explosion, which would affect just about nothing, but the burst of energetic particles and the ensuing electromagnetic storm. Still, such a burst would have to be either pretty close to the target vessel to scramble its systems, or it would have to be made directional in some way, to focus the gamma-ray and zinging-proton blast. But while we’re talking about focused energy weapons, lets just go with a tool that we already use to cut sheet metal on Earth: lasers. In space, laser light will travel almost forever without dissipating from diffraction. Given a large enough power supply, lasers could be used at range to slice up enemy warships. The key phrase there, though, is “given a large enough power supply.” Power is hard to come by in the space business. So, expect space laser weapons to take one of three forms: small lasers designed not to destroy, but to blind and confuse enemy sensors; medium-sized lasers that would be fired infrequently and aimed to melt specific vulnerable points on enemy space fighters, like antennae, gimbals, and maneuvering thrusters; and large lasers pumped by the discharge from a large capacitor or similar energy storage device to cut a physical slice into the enemy craft wherever they hit. Such a large weapon would likely only be fired at the very beginning of a battle, because the commander of a ship with such a weapon would not want to keep his capacitor charged when it might unexpectedly blow its energy all at once once he’s in the thick of things.

Deflector shields like those in fiction are not possible at present, but it would still make sense to armor combat spacecraft to a limited extent. The spaceframes of the fighters would likely be designed solely for the space environment; the actual ships would be launched within the payload fairings of a rocket or assembled in space. If launched from the ground, armor must be minimized to reduce the launch weight of the spacecraft. But if built and launched in space, it would make sense to plate over vital systems of the vehicle. Thick armor would prevent flak or small lasers from piercing delicate components, and might mitigate a direct strike from a kinetic impactor or heavy cutting laser. However, the more heavily armored and massive a space fighter is, the more thrust it will take to maneuver in orbit and the more energy it will take to spin in place. (Here’s where computer games get space combat all wrong: the mass of a huge space cruiser would not place an upper limit on the speed of a vehicle, but it would reduce the acceleration a given engine could produce compared to the same engine on a less massive vehicle.)

I’m assuming that we’d have some intrepid members of the United Earth Space Force crewing these combat vessels. Or, at least, crewing some of them – robotic drone fighters would be a tremendous boon to space soldiers, but the communication lag between planets and vessels in orbit would make the split-second judgments of humans necessary at times. (Until we perfect AIs… but if we’re giving them the space fighters from the beginning, we deserve the robot uprising we’ll get.) The crews will hardly be sitting around nice conference-room command bridges with no seat belts; nor will they be standing upright in slate-gray console pits with glowing glass displays all over. It’s not even a good idea for them to have windows, which would be vulnerable to flak and could give the crew an intense sense of disorientation as the spacecraft maneuvers, and could give them tremendous trouble adapting to rapid changes in light levels as the ship rotates near a planet or star. No, they should be strapped into secure couches and centrally located in the most protected part of the spacecraft. They should also be in full pressure suits, and the interior cabin of the spacecraft should already be evacuated – to prevent fires, or any secondary damage if all the atmosphere rushes out a hull breach. This also reduces the need for escape pods. Camera views from the exterior of the ship and graphical representations of the tactical situation would then be projected directly onto helmet faceplates.

Now, for the final word, let’s say the United Earth Space Force defeats the Martian rebels in orbit. What do we do to hit them on the ground? Well, strategic weapons from space are easy: kinetic impactors again. You chuck big ol’ spears, aerodynamically shaped so they stay on target and don’t burn up in the atmosphere, onto ground targets and watch gravitational potential energy turn into kinetic energy and excavate you a brand-new crater. At some point, though, the imperialist Earthlings probably want to take over the existing infrastructure on Mars. Time to get out the Space Marines!

It’s not terribly expensive or difficult, comparatively speaking, to get people from orbit down to a planet surface. You fall. This is the purpose of a space capsule. What’s really, really, prohibitively difficult is getting them back up again. So, the victorious orbital forces would have to bring in a transport ship chock full of Space Marines and drop them all at once in little capsules (little because they can only be so big for the atmosphere to effectively brake them, and because you don’t want all your Marines perishing in some unfortunate incident). Some orbital forces would remain in place to threaten the ground with bombardment and give the Marines a bit more muscle, but really, the ground-pounders are going to have to be pretty self-sufficient. If they ever want to come back up, they would have to build and/or fuel their own ascent vehicle. (This is the problem facing any NASA Mars efforts, too: getting back up through the Martian atmosphere is much harder than any of the lunar ascents were.)

[ADDENDUM, 14 Dec 09: What would combat spacecraft end up looking like?

Well, there are good arguments to have both large and small spacecraft in the Earth forces. A big spacecraft could have a lot more armor to keep its systems and crew safe, more room for large fuel tanks and electrical power supplies, and larger mass to resist impulses from cannon recoil. However, a smaller craft would be less visible to radar, more maneuverable, and could achieve higher accelerations for constant engine thrust. As with just about any military force, the role of the craft would be tailored to the tactical operations required, so the Space Force would probably include several sizes of craft.

Enemies could come at your ship from any direction in space, which means that you would want to react, strike, and counterattack in any direction. So, you would either have to mount weaponry all around your starfighter, put the weapons on gimbals so that they could rapidly point in any direction, or make the fighter maneuverable enough that it could rapidly point in any direction. Gimbals would be a bad option, because they would introduce points of increased vulnerability, unless they could be very well-armored. I conclude that the big ships would have many weapons, pointed in many directions; the small ships would have a few weapons, with the main weapon systems pointed in one direction.

Maneuverability (angular acceleration) you could achieve with gyroscopes, or by mounting engines or thrusters away from your fighter’s center of mass. For the highest levels of maneuverability, the spacecraft should be close to spherical and these engines should be as off-center as possible, which might mean putting thrusters on long booms or struts. The problem with this kind of Firefly-like engine layout is that it becomes very vulnerable. If a fighter can achieve high maneuverability with gyros, those are probably the best option.

So, I think the small fighter craft would be nearly spherical, with a single main engine and a few guns or missiles facing generally forward. They would have gyroscopes and fuel tanks in their shielded centers. It would make sense to build their outer hulls in a faceted manner, to reduce their radar cross-section. Basically, picture a bigger, armored version of the lunar module. The larger warships would also probably be nearly spherical, with a small cluster of main engines facing generally backward and a few smaller engines facing forward or sideways for maneuvering. Cannons, lasers, and missile ports would face outward in many directions. On a large enough space cruiser, it would even be a good idea to put docking ports for the small fighters, so that the fighters don’t have to carry as many consumables on board.

I think it’s time to sketch some pictures and write some stories!]

I certainly hope we don’t get into any space wars. Human nature being what it is, though, and given how scarce a lot of resources really are on the scale of a solar system or a galaxy, I don’t think it’s out of the question. I would like to think that when we start colonizing other worlds, we will be sufficiently enlightened to do so from on board the Ship of the Imagination, and not as futuristic conquistadores. Still, the part of me that loves science fiction has fun with these thought experiments.

• 

      The center of gravity of a liberty ship is the singularity, the pinpoint black hole that powers the ship and also serves as the focus for its hyperstate nodule. The singularity masses as much as a small moon and can be accurately located by even a low-power gravity wave scanner out to a distance of several light hours.
     The singularity is held in place by a singularity bottle, a spherical magnetic cage three stories high; this is the ship’s engine room. Three hyperstate fluctuators are focused on the singularity; one from above, one from either side. They are spaced 120 degrees apart. The fluctuators extend out through the hull of the ship and into three massive spines that give the starship its characteristic spiky look. The length of the fluctuators is a function of the size of the ship; it is necessary for precise focusing of the projected hyperstate bubble around the vessel. Hyperstate is also known as irrational space, producing the oft-quoted cliche, “To go faster than light, first you have to be irrational.”¹

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     ¹The singularity itself is tended by the “Black Hole Gang,” generally an insular crew with their own jargon and mystique. On most ships, the singularity team regard themselves as the masters of a particularly arcane and esoteric discipline; they do not casually welcome outsiders to their domain. Relationships with the “Front Office,” their name for the Bridge crew, are occasionally strained.

---

     For sublight acceleration and deceleration, the liberty ship has three mass-drivers mounted around her hull. A mass-driver is a long thin tube, lined with superconducting magnetic rings. Ions are introduced at one end, accelerated to near-lightspeed, and shot out the opposite end, producing the necessary thrust. The direction of particle acceleration can also be reversed for braking maneuvers. While the operation of the mass-drivers is not as easily detectable as that of the singularity stardrive, the vessel’s wake of accelerated ions can be detected by a ship with sophisticated scanning gear.
     Aft of the engine room, you will find crew’s quarters, storage areas, aft torpedo bay, cargo bays, and the internal shuttle bay. The shuttle bay is equipped to function as a cargo lock; but there are also smaller airlocks at the stern of the vessel. A liberty ship usually carries two shuttles and occasionally a captain’s gig. Used as lifeboats, the shuttles can carry ten individuals each; fifty if they are put into short-term hibernation.
     Forward of the engine room, are officers’ quarters on the top deck, the ship’s brain and main mess room on the second deck, and the keel and equipment storage bays on the bottom level. Forward of that is the Operations complex. This is built around a large U-shaped Operations deck; the forward half of which is a sophisticated viewer. At the rear of the Operations deck is the Bridge, a high, railed platform overlooking everything. Directly underneath the Bridge is the Operations bay, where the ship’s autonomic functions are maintained.
     Forward of the Operations complex are more crew’s quarters, sick bay, the weapons shop, forward torpedo bay, forward access and airlock. Running the length of the ship is the keel, a utility corridor which also functions as the ship’s primary channel for cables, ducts, and optical fibers.

     On the hull of the ship, you will find three large arrays of scanners, detectors, cameras, and other sensory apparatus. There are also twelve arrays of disruptor-beam projectors. The ship is double-hulled, with both hulls required to maintain 99% or better atmospheric integrity. Both hulls are also internally and externally shielded against particle-beam weapons. Class V magnetic shields are standard on most liberty ships, although most captains upgrade to Class VII or better whenever the equipment is available.
     The liberty ship has a multiple-redundancy, optical nervous system. Autonomic functions are maintained by an array of Systems Analysis boxes. Higher-brain functions are handled by one or more HARLIE series synthesized-consciousness modules. The HARLIE series has been designed to be more anthropomorphic than other constructed identities, and therefore tends to perceive the starship as its own body; this produces a measurable increase in the unit’s survival motivation.
     Standard crew on a liberty ship is 120 persons.

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     The LS-1187 was three years old and had not yet earned a name.
     She was a destroyer-class starship, a liberty ship, one of many. On her side, she wore the flag of New America: thirteen horizontal stripes, alternating red and white, and a dark blue field showing seven white circles around a single bright star.
     The liberty ships came off the line one every eleven days. There were seven assembly lines building ships. This one was like all the rest; small and desperate, fitted with just enough equipment to make her survivable, and sent as rapidly as possible out toward the frontier. It would be up to her port of assignment to install her secondary fittings, internal amenities, auxiliary systems, and weaponry—whatever might be necessary for her local duties.
     The LS-1187 had not yet earned her name because she had not yet “bloodied her sword.” Until she did, she would remain only a number.

     She was a lean ship: a dark arrow, three hundred meters long. Two thirds of the way back along her hull, three sharp fins projected out and forward. These were her fluctuator spines. The end of each one culminated in a bulbous stardrive lens.
     Her cruising speed was subluminal, but the realized velocity of her hyperstate envelope was 750 times the speed of light.
     Her orders were the simplest possible: a time, a location, and a vector.
     Translation: Proceed to The Deep Rift. Arrive at a specified here at a specified now, pointed in a particular direction and traveling at a particular speed. Don’t be followed. Do all this and you will be part of the Grand Convoy of a thousand ships: a thousand separate vessels all arriving at their respective places in formation at the same moment.
     It was a daring gamble, but if it worked ... the outworlds would have the protection they needed against the raids of the marauders.
     If it failed ...

• 

      Two months before not a one of the ships now afloat behind them in the waters of Scapa Flow had even slipped down the ways at Falkirk. Duncan called back anguished memories of those days when he and Logan and MacLeod fretted impatiently at the old shipyards wondering if the new, prefabricated battlecraft being constructed at obsolete shipyards could ever be as effective as the older, handcrafted types.

     As the last of the Argylls passed and he received the salute of the Black Watch, Duncan could look back shudderingly on the thousands of headaches of those hectic months. New troops to replace the cadres moved out to form new battalions and regiments. Transfers from infantry to space units. Inadequate housing. Insufficient uniforms and equipment. Occasionally even shortages of food. And worst of all, not enough qualified instructors to do the job properly. Commercial computers substituting for genuine battle gear as men were trained in the elements of space navigation and programming. Dummy guns and torpedoes substituted for working models. Dummy mines were armed and disarmed a thousand times as raw recruits labored sixteen hours a day learning not only their specialties but the basic fundamentals of soldiering at the same time.

     And besides all this, there were the details of ship construction to be attended to. Harried engineers argued desperately in futile efforts to stabilize construction against changes being incorporated daily. MacLeod, Logan and Duncan had pushed for the maximum amount of weaponry. The logistics people had argued for a maximum of supplies and fuel capacity. The xenologists had added a supplementary computer and sensing system designed to afford insight into the aliens’ purposes. Theoretical physicists—those who were prepared to accept the reality of a faster-than-light drive—had placed aboard their own computer and specialized communications relay systems in hopes of learning something of the characteristics of a hyperdrive.

     Bureaucrats wanted to incorporate a number of “lifeboats” as a sop to worried constituents who lacked the least idea of the fundamentals of space war. Someone in the Admiralty office, no doubt left over from the Napoleonic Wars who had somehow been overlooked by Father Time, had tired to persuade the War Office to install plastic sails capable of catching the solar wind and sailing home if the conventional fuel gave out! It was with some difficulty that MacLeod had been able to convince the Admiralty that while the idea might conceivably be technically feasible it could only work if the men aboard carried a thirty-year supply of food!

     Then there had been more subtle problems. How much should be included aboard each ship in the way of PX supplies? What number of men would be a minimum for round-the-clock operation of the fleet over an extended period of time? How many microfilmed books and how many cassette projectors? Assume a crew of six for one of the new scouts; how long could those six he expected to remain in isolation before relief became necessary? How many tours could a single crew the expected to make before rotation hack to Earth became necessary? these were only a few of the problems.

     MacLeod, Logan and Duncan had won most of their arguments so faras armament was concerned. The cruisers had a double pair of torpedo launchers added to their “chin blisters” to allow for lengthy stern chases. Two additional mine-laying ports graced each flank. Six additional 37 mm and two more 90 mm machine rockets had been placed in the bow turrets.

• 

Liberty ships were a class of cargo ship built in the United States during World War II. Though British in concept, the design was adopted by the United States for its simple, low-cost construction. Mass-produced on an unprecedented scale, the Liberty ship came to symbolize U.S. wartime industrial output.

The class was developed to meet British orders for transports to replace ships that had been lost. Eighteen American shipyards built 2,710 Liberty ships between 1941 and 1945 (an average of three ships every two days), easily the largest number of ships ever produced to a single design.

Their production mirrored (albeit on a much larger scale) the manufacture of "Hog Islander" and similar standardized ship types during World War I. The immensity of the effort, the number of ships built, the role of female workers in their construction, and the survival of some far longer than their original five-year design life combine to make them the subject of much continued interest.

Construction

The ships were constructed of sections that were welded together. This is similar to the technique used by Palmer's at Jarrow, northeast England, but substituted welding for riveting. Riveted ships took several months to construct. The work force was newly trained — no one had previously built welded ships. As America entered the war, the shipbuilding yards employed women, to replace men who were enlisting in the armed forces.

The ships initially had a poor public image due to their appearance. In a speech announcing the emergency shipbuilding program President Franklin D. Roosevelt had referred to the ship as "a dreadful looking object", and Time magazine called it an "Ugly Duckling". 27 September 1941, was dubbed Liberty Fleet Day to try to assuage public opinion, as the first 14 "Emergency" vessels were launched that day. The first of these was SS Patrick Henry, launched by President Roosevelt. In remarks at the launch ceremony, FDR cited Patrick Henry's 1775 speech that finished "Give me liberty or give me death". Roosevelt said that this new class of ships would bring liberty to Europe, which gave rise to the name Liberty ship.

The first ships required about 230 days to build (Patrick Henry took 244 days), but the average eventually dropped to 42 days. The record was set by SS Robert E. Peary, which was launched 4 days and 15​¹⁄₂ hours after the keel was laid, although this publicity stunt was not repeated: in fact much fitting-out and other work remained to be done after the Peary was launched. The ships were made assembly-line style, from prefabricated sections. In 1943, three Liberty ships were completed daily. They were usually named after famous Americans, starting with the signatories of the Declaration of Independence. In the 1940s, 17 of the Liberty Ships were named in honor of outstanding African-Americans. The first, in honor of Booker T. Washington, was christened by Marian Anderson in 1942, and the SS Harriet Tubman, recognizing the only woman on the list, was christened on 3 June 1944.

Any group which raised war bonds worth $2 million could propose a name. Most bore the names of deceased people. The only living namesake was Francis J. O'Gara, the purser of SS Jean Nicolet, who was thought to have been killed in a submarine attack, but, in fact, survived the war in a Japanese prisoner of war camp. Other exceptions to the naming rule were SS Stage Door Canteen, named for the USO club in New York, and SS U.S.O., named after the organization itself.

Another notable Liberty ship was SS Stephen Hopkins, which sank the German commerce raider Stier in a ship-to-ship gun battle in 1942 and became the first American ship to sink a German surface combatant.

The wreck of SS Richard Montgomery lies off the coast of Kent with 1,500 short tons (1,400 tonnes) of explosives still on board, enough to match a very small yield nuclear weapon should they ever go off. SS E. A. Bryan detonated with the energy of 2,000 tons of TNT (8,400 GJ) in July 1944 as it was being loaded, killing 320 sailors and civilians in what was called the Port Chicago disaster. Another Liberty ship that exploded was the rechristened SS Grandcamp, which caused the Texas City Disaster on 16 April 1947, killing at least 581 people.

Six Liberty ships were converted at Point Clear, Alabama, by the United States Army Air Force, into floating aircraft repair depots, operated by the Army Transport Service, starting in April 1944. The secret project, dubbed "Project Ivory Soap", provided mobile depot support for B-29 Superfortress bombers and P-51 Mustang fighters based on Guam, Iwo Jima, and Okinawa beginning in December 1944. The six ARU(F)s (Aircraft Repair Unit, Floating), however, were also fitted with landing platforms to accommodate four Sikorsky R-4 helicopters, where they provided medical evacuation of combat casualties in both the Philippine Islands and Okinawa.

The last new-build Liberty ship constructed was SS Albert M. Boe, launched on 26 September 1945 and delivered on 30 October 1945. She was named after the chief engineer of a United States Army freighter who had stayed below decks to shut down his engines after a 13 April 1945 explosion, an act that won him a posthumous Merchant Marine Distinguished Service Medal. In 1950, a "new" liberty ship was constructed by Industriale Maritime SpA, Genoa, Italy by using the bow section of Bert Williams and the stern section of Nathaniel Bacon, both of which had been wrecked. The new ship was named SS Boccadasse, and served until scrapped in 1962.

Several designs of mass-produced petroleum tankers were also produced, the most numerous being the T2 tanker series, with about 490 built between 1942 and the end of 1945.

Problems

Hull cracks

Early Liberty ships suffered hull and deck cracks, and a few were lost due to such structural defects. During World War II there were nearly 1,500 instances of significant brittle fractures. Twelve ships, including three of the 2,710 Liberties built, broke in half without warning, including SS John P. Gaines, which sank on 24 November 1943 with the loss of 10 lives. Suspicion fell on the shipyards, which had often used inexperienced workers and new welding techniques to produce large numbers of ships in great haste.

The Ministry of War Transport borrowed the British-built Empire Duke for testing purposes. Constance Tipper of Cambridge University demonstrated that the fractures did not start in the welds themselves, but were due to low temperature embrittlement of the steel used; the same steel used in riveted construction did not have this problem. She discovered that the ships in the North Atlantic were exposed to temperatures that could fall below a critical point at which the steel changed from being ductile to becoming brittle, allowing cracks to start easily. The predominantly welded hull construction allowed small cracks to propagate unimpeded, unlike in a hull made of separate plates riveted together. One common type of crack nucleated at the square corner of a hatch which coincided with a welded seam, both the corner and the weld acting as stress concentrators. Furthermore, the ships were frequently grossly overloaded, increasing stresses, and some of the problems occurred during or after severe storms at sea that would have placed any ship at risk. Minor revisions to the hatches and various reinforcements were applied to the Liberty ships to arrest the cracking problem. The successor Victory ship used the same steel, with improved design to reduce potential fatigue.

After the war

More than 2,400 Liberty ships survived the war. Of these, 835 made up the postwar cargo fleet. Greek entrepreneurs bought 526 ships and Italians bought 98. Shipping magnates including John Fredriksen, John Theodoracopoulos, Aristotle Onassis, Stavros Niarchos, Stavros George Livanos, the Goulandris brothers, and the Andreadis, Tsavliris, Achille Lauro, Grimaldi and Bottiglieri families were known to have started their fleets by buying Liberty ships. Andrea Corrado, the dominant Italian shipping magnate at the time, and leader of the Italian shipping delegation, rebuilt his fleet under the programme. Weyerhaeuser operated a fleet of six Liberty Ships (which were later extensively refurbished and modernized) carrying lumber, newsprint, and general cargo for years after the end of the war.

The term "Liberty-size cargo" for 10,000 long tons (10,200 t) may still be used in the shipping business.

Some Liberty ships were lost after the war to naval mines that were inadequately cleared. Pierre Gibault was scrapped after hitting a mine in a previously cleared area off the Greek island of Kythira in June 1945, and the same month saw Colin P. Kelly Jnr take mortal damage from a mine hit off the Belgian port of Ostend. In August 1945, William J. Palmer was carrying horses from New York to Trieste when she rolled over and sank 15 minutes after hitting a mine a few miles from destination. All crew members, and six horses were saved. Nathaniel Bacon ran into a minefield off Civitavecchia, Italy in December 1945, caught fire, was beached, and broke in two; the larger section was welded onto another Liberty half hull to make a new ship 30 feet longer, named Boccadasse.

As late as December 1947, Robert Dale Owen, renamed Kalliopi and sailing under the Greek flag, broke in three and sank in the northern Adriatic Sea after hitting a mine. Other Liberty ships lost postwar to mines include John Woolman, Calvin Coolidge, Cyrus Adler, and Lord Delaware.

In 1953, the Commodity Credit Corporation (CCC), began storing surplus grain in Liberty ships located in the Hudson River, James River, Olympia, and Astoria National Defense Reserve Fleet's. In 1955, 22 ships in the Suisun Bay Reserve Fleet were withdrawn to be loaded with grain and were then transferred to the Olympia Fleet. In 1956, four ships were withdrawn from the Wilmington Fleet and transferred, loaded with grain, to the Hudson River Fleet.

Between 1955 and 1959, 16 former Liberty ships were repurchased by the United States Navy and converted to the Guardian-class radar picket ships for the Atlantic and Pacific Barrier.

In the 1960s, three Liberty ships and two Victory ships were reactivated and converted to technical research ships with the hull classification symbol AGTR (auxiliary, technical research) and used to gather electronic intelligence and for radar picket duties by the United States Navy. The Liberty ships SS Samuel R. Aitken became USS Oxford, SS Robert W. Hart became USS Georgetown, SS J. Howland Gardner became USS Jamestown with the Victory ships being SS Iran Victory which became USS Belmont and SS Simmons Victory becoming USS Liberty. All of these ships were decommissioned and struck from the Naval Vessel Register in 1969 and 1970.

USS Liberty was a Belmont-class technical research ship (electronic spy ship) that was attacked by Israel Defense Forces during the 1967 Six-Day War. She was built and served in World War II as SS Simmons Victory, as a Victory cargo ship.

From 1946 to 1963, the Pacific Ready Reserve Fleet – Columbia River Group, retained as many as 500 ships.

In 1946, Liberty ships were mothballed in the Hudson River Reserve Fleet near Tarrytown, New York. At its peak in 1965, 189 hulls were stored there. The last two were sold for scrap to Spain in 1971 and the reserve permanently shut down.

Only two operational Liberty ships, SS John W. Brown and SS Jeremiah O'Brien, remain. John W. Brown has had a long career as a school ship and many internal modifications, while Jeremiah O'Brien remains largely in her original condition. Both are museum ships that still put out to sea regularly. In 1994, Jeremiah O'Brien steamed from San Francisco to England and France for the 50th anniversary of D-Day, the only large ship from the original Operation Overlord fleet to participate in the anniversary. In 2008, SS Arthur M. Huddell, a ship converted in 1944 into a pipe transport to support Operation Pluto, was transferred to Greece and converted to a floating museum dedicated to the history of the Greek merchant marine; although missing major components were restored this ship is no longer operational.

Liberty ships continue to serve in a "less than whole" function many decades after their launching. In Portland, Oregon, the hulls of Richard Henry Dana and Jane Addams serve as the basis of floating docks. SS Albert M. Boe survives as the Star of Kodiak, a landlocked cannery, in Kodiak Harbor.

SS Charles H. Cugle was converted into MH-1A (otherwise known as USS Sturgis). MH-1A was a floating nuclear power plant and the first ever built. MH-1A was used to generate electricity at the Panama Canal Zone from 1968 to 1975. She was also used as a fresh water generating plant. She is anchored in the James River Reserve Fleet.

Fifty-eight Liberty ships were lengthened by 70 feet (21 m) starting in 1958. This gave the ships an additional 640 long tons (650 t) of carrying capacity at a small additional cost. The bridges of most of these were also enclosed in the mid-1960s in accordance with a design by naval architect Ion Livas.

In the 1950s, the Maritime Administration instituted the Liberty Ship Conversion and Engine Improvement Program, which had a goal to increase the speed of Liberty ships to 15 knots (28 km/h; 17 mph), making them competitive with more modern designs, as well as gaining experience with alternate propulsion systems. Four ships were converted in the $11 million program. SS Benjamin Chew had its existing condensers modified and a new superheater and geared turbine installed to give the ship 6,000 shp, up from 2,500. SS Thomas Nelson had its bow lengthened, diesel engines installed in place of the original steam engine, and movable cranes outfitted in place of the original cargo handling gear. The GTS (Gas Turbine Ship) John Sergeant had its bow extended, and its steam engine replaced with a General Electric gas turbine of 6,600 shp, connected to a reversible pitch propeller via reduction gearing. John Sergeant was considered overall to be a success, but problems with the reversible pitch propeller ended its trial after three years. GTS William Patterson had its bow extended and its steam engine replaced with 6 General Electric GE-14 free-piston gas generators, connected to two reversible turbines and capable of 6,000 shp total. William Patterson was considered to be a failure as reliability was poor and the scalability of the design was poor. All four vessels were fueled with Bunker C fuel oil, though John Sergeant required a quality of fuel available at limited ports and also required further treatment to reduce contaminants. Three were scrapped in 1971 or 1972 and the diesel-equipped Thomas Nelson was scrapped in 1981.

In 2011, the United States Postal Service issued a postage stamp featuring the Liberty ship as part of a set on the U.S. Merchant Marine.

      From time to time it is necessary to guess the performance of a warship whose approximate dimensions are known and it is usual to do so by comparison with the performance of a similar one. This frequently calls for interpolation and the problem becomes tedious. The nonograms given have been prepared from existing data, with most helpful assistance from members of D.N.C. and D.O.R's. staff, and are designed to simplify the problem of interpolation; they are based on the performance of a large number of foreign as well as British warships.

     The speed of a ship of known length and displacement depends upon the shaft horse power (S.H.P.) of her engines; this relationship for warships of typical length/displacement ratio can be found with reasonable accuracy from the charts given in figs. 1-4.

For Destroyers, Sloops, and Frigates: 25, 30, 35 knots

For Destroyers, Sloops, and Frigates: 15, 20 knots

For Cruisers, Carriers, and Battleships

Supplement for Figure 3

For Vee-Bottomed Planing Boats

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     For example, consider a 2,500 Ton destroyer. In fig. 1, by drawing a straight line from the 2,500 Ton point on the left hand scale through the centre of the 30 knot band, a figure of 36,000 S.H.P. is obtained from the right hand scale. This is the figure for the power which would be required to drive a 2,500 Ton destroyer through the water at 30 knots if her length were 375 feet.

     If the length is less than that indicated on the left hand scale (a "short ship"), the power required will be more than 36,000 H.P. for 30 knots and it may be as much as 44,000 H.P (the upper limit of the 30 knot band should be used). For a “long" ship, the lower limit of the 30 knot band should be used.

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     The chart in fig. 3 covers a wide range of ships and has, for simplicity, been prepared to give the S.H.P. required for 30 knots only. If the S.H.P. is required for 35, 25 or 20 knots the letters on the right hand scale must he used in conjunction with the table in fig. 5.

     For example, consider an 11,000 Ton cruiser, depending upon her length she will require between 67,000 and 79,000 S.H.P. to drive her through the water at 30 knots, e.g. a ‘Long Ship‘ design will require less than 72,000 S.H.P. and a 'Short Ship‘ design more than 72,000 S.H.P.

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     From the 35 knot band and using the letters in conjunction with the table in fig. 5 it is seen that the ‘Long Ship‘ cruiser would require between 105,000 and 150,000 S.H.P. while the ' Short Ship ’ design would require considerably more to steam at 35 knots.

     The power required for speeds other than 20, 25, 30 or 35 knots can be obtained by interpolation if the necessary curve is plotted.

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     From considerations of the perfomance of typical machinery and using suitable figures for specific consumption, a guess at the fuel consumption can be made, thus:

Miles-Steamed-Per-Ton-Of-Fuel = K * ( SpeedInKnots / SHP-Required)

where SpeedInKnots is input into the appropriate nomogram for the ship type, SHP-Required is the output of the nomogram, and values of K are given below:

K Values

Fuel	Speed in Knots
	15	20	25	30	30+
Petrol Driven	4,000
Diesel Driven	6,000
Diesel Electric	4,000
Steam Driven	2,000	2,500	2,800	3,000

     It is, however, necessary to bear in mind that there are so many unknown variables that the answers obtained can only be called "intelligent guesses, based on wide experience." But they are likely to be more accurate than guesses which are based on limited experience only.

If you want to use the same hackneyed, stale, and totally wrong ship types that everybody and their brother have been using since the Battle of the Jutland, here ya go. Just remember to wash your hands afterwards and don't brag about it.

• 

• 

Long ago we (Larry Niven and Jerry Pournelle) acquired a commercial model called “The Explorer Ship Leif Ericson,” a plastic spaceship of intriguing design. It is shaped something like a flattened pint whiskey bottle with a long neck. The “Leif Ericson,” alas, was killed by general lack of interest in spacecraft by model buyers; a ghost of it is still marketed in hideous glow-in-the-dark color as some kind of flying saucer.

It’s often easier to take a detailed construct and work within its limits than it is to have too much flexibility. For fun we tried to make the Leif Ericson work as a model for an Empire naval vessel. The exercise proved instructive.

First, the model is of a big ship, and is of the wrong shape ever to be carried aboard another vessel. Second, it had fins, only useful for atmosphere flight: what purpose would be served in having atmosphere capabilities on a large ship?

This dictated the class of ship: it must be a cruiser or battlecruiser. Battleships and dreadnaughts wouldn’t ever land, and would be cylindrical or spherical to reduce surface area. Our ship was too large to be a destroyer (an expendable ship almost never employed on missions except as part of a flotilla). Cruisers and battlecruisers can be sent on independent missions.

MacArthur, a General Class Battlecruiser, began to emerge. She can enter atmosphere, but rarely does so, except when long independent assignments force her to seek fuel on her own. She can do this in either of two ways: go to a supply source, or fly into the hydrogen-rich atmosphere of a gas giant and scoop. There were scoops on the model, as it happens.

She has a large pair of doors in her hull, and a spacious compartment inside: obviously a hangar deck for carrying auxiliary craft. Hangar deck is also the only large compartment in her, and therefore would be the normal place of assembly for the crew when she isn’t under battle conditions.

The tower on the model looked useless, and was almost ignored, until it occurred to us that on long missions not under acceleration it would be useful to have a high-gravity area. The ship is a bit thin to have much gravity in the “neck” without spinning her far more rapidly than you’d like; but with the tower, the forward area gets normal gravity without excessive spin rates.

And on, and so forth. In the novel, Lenin was designed from scratch; and of course we did have to make some modifications in Leif Ericson before she could become INSS MacArthur (from novel The Mote in God's Eye); but it’s surprising just how much detail you can work up through having to live with the limits of a model.

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ed note: so please follow my line of reasoning here.

The Galactic Cruiser Leif Ericson was originally a plastic model that came out in 1968.

Larry Niven and Jerry Pournelle got a Leif Ericson plastic model. They examined it and tried to design a spacecraft based on it, the INSS MacArthur. The MacArthur was streamlined and had scoops. This meant it was a Cruiser class, capable of independent operations. If need be, it could harvest hydrogen fuel by scooping the atmosphere of a nearby gas giant. This is what NASA calls In-situ Resource Utilization.

In 1974 Niven and Pournelle wrote the science fiction classic The Mote in God's Eye. It featured the INSS MacArthur.

Marc Miller read The Mote in God's Eye. He thought the fuel scooping ability of the MacArthur was a good idea. So when he wrote the Traveller RPG in 1977, he put that into the game under the term "wilderness refueling."

So what I am telling all you fans of the Traveller RPG is the reason there is wilderness refueling in Traveller is because of the plastic model Leif Ericson!

One of the problems with figuring out how ships are going to fight in space (assuming that we have ships in space, which isn't as likely as I wish; and, that we're still fighting when we get there, which is unfortunately more probable) is that there are a lot of maritime models to choose from.

It's also true that some of the maritime models came from very specialized sets of circumstances; and a few of them weren't particularly good ideas even in their own time.

And it's also true that some of the writers applying the models have a better grasp of the essentials than others.

As you have probably noticed, the ships placed at our disposal correspond reasonably well to the means utilized in armies on Earth. Fast and lightly armed corvettes are our chasseurs, the frigates are our hussars (light cavalry) and dragoons (medium cavalry). The (heavy) cavalry (Cuirassier) is replaced by heavily armored vessels, not as fast as the others. As for the artillery, it has been replaced by missile launchers. Finally, the light vedettes with short-ranged laser-disintegrators can be compared to the infantry. It was by making use of such equivalences that I planned the battle of Usk.

CORVETTES

We were interested to see that a number of “corvette” – i.e. sub-frigate – classes of warship have emerged since our last edition, especially since the role of the frigate is already extremely limited, due to the limitations of its available mass and volume on its capacities, to wolf-pack deployments for light anti-piracy control, scouting, minor system pickets, and civilian system-security functions.

On examining the three primary examples of corvette-class vessels seen in use, the Vanknir-class from Nal Kalak State Arms (we admire, incidentally, the gall of the Orsten System Navy in officially designating essentially unmodified Vanknirs as “system defense frigates”), the Auberwuth-class from Eilish Star Armories, and the General Svanek-class from the Empire’s own Islien Yards/Artifice Armaments, several key differences from frigate-class vessels, and ones which render them even more impractical as ships of war, are apparent.

Specifically, the defining characteristics of these sub-frigate ships are a particularly light armament (one barely sufficient for civilian system-security functions, if that), a greater emphasis on armor and shielding (although the kinetic barriers and hull armor mounted by any corvette-class vessel would be inadequate against even lightly armed warships firing for effect), and an emphasis on technological simplicity, focusing upon ease of field repair in the absence of equivalent-technology infrastructure, often by the replacement of modular components. This is to say that the corvette appears to be designed for ease of maintenance in the low-technology field first, survivability – such as is possible at this scale – second, and warfighting ability third.

In the light of these unusual features, and of its emergence after the case of Sarine v. Galactic Volumetric Registry, the true purpose of the corvette becomes clear. They are a political ship class, not a military one. In other words, they are not intended to put up a practical system defense; rather, they are intended to permit a single-system polity which does not wish to bear the expense of a viable star nation’s naval establishment to claim system sovereignty – by virtue of policing their own space – using a few corvettes at a fraction of the expense of actual warships.

Certainly, in the event of any serious territorial incursion, these ships could do little more than fire off a few warning shots for the honor of the flag and surrender immediately thereafter, but this may be sufficient to establish their intent to assert system sovereignty in the eyes of the legal authorities.

(The name of the Islien Yards/Artifice Armaments General Svanek-class may also suggest the correctness of this analysis, the historical General Svanek Arctorran being known primarily for presiding over two surrenders in the War of Banners without any decisive battle preceding.)

We await the first legal decisions on this point with considerable interest.

- Naval Starships of the Associated Worlds, INI Press, Palaxias, 421^st ed.

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Alistair Young commented later:

My general rule on that is that they're sufficient to do that for values of lightly-armed equal to "a merchant hull with some improvised weapons strapped onto it", mostly because that's helpless against anything capable of firing back, including the better class of reaction drive.

Pirates lightly-armed in typical military terms — using, say, a naval auxiliary frigate of one dubious provenance or another, on the other hand, will slice and butter a corvette unless it brought some friends to the party. And even then, not all of 'em will go home.

• 

• 

So, in today’s piece of worldbuilding, have an analysis and explication of the different classes – or the different types, rather – of military starships operated by the Imperial Navy. (The basis for the ternary plot I’m using is, of course, Winchell Chung’s analysis here, so you might want to go read that first if you’re not familiar with the concept, then come back here.)

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Types

The chart ... illustrates the differences between the various types and classes of warship in common use by the Imperial Navy by their P/D/W ratio – i.e., the relative trade-off between propulsion, defenses, and weapons (i.e. offensive armament):

“in common use” should be read as “not counting all the weird-ass specialist ships we build for special cases”; also, it doesn’t include auxiliary vessels (oilers, hospital ships, etc.) since they’re not operated by the IN, but by the Stratarchy of Military Support and Logistics.

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Battleships, Dreadnoughts and Superdreadnoughts

“I am an Imperial Mandate-class dreadnought, and you are within a million miles of me. Ergo, you continue to exist solely on my sufferance.”

- an early experiment in AI captaincy

Battleships, dreadnoughts, and superdreadnoughts (B, D, S on the chart) are capital or supercapital ships mounting heavy long-range firepower as their primary function.

These types, the ships of the wall, are the kings of the outer engagement envelope, engaging each other with powerful weaponry at ranges of up to two light-minutes, and rarely closing beyond one to two light-seconds range (a zero/zero intercept at this residual range is considered a “set-piece” battle). They are the purest of all naval vessels in function, existing simply to counteract each other in the battlespace of major fleet actions, or to own the volume of space they can dominate if not opposed; the ultimate argument of star navies.

The principal difference between two of the three types is simply mass and volume; doctrinally, the majority of the ships of the wall of any given time should be of battleship classes, with their larger cousins the dreadnoughts providing heavier stiffening formations to the wall and occasional nasty surprises.

Because while it sure would be nice to build nothing except dreadnoughts, even nearly-post-scarcity economics doesn’t stretch to overbuilding everything just in case.

Superdreadnoughts, while sometimes referring to particularly large dreadnought classes, more typically refer to ships falling in the dreadnought type by mass, while using much of their internal volume for specialized systems: typical examples would include the command superdreadnought, the information-warfare superdreadnought, the anti-RKV superdreadnought, and so forth.

Mauler Superdreadnoughts

One example of this listed separately (L on the chart) since its P/D/W ratio moves it well outside the standard range is the mauler superdreadnought. In this case, the specialized systems in question are a very, very large mass driver or laser, with propulsion and defensive systems stripped back to accommodate it.

Mauler superdreadnoughts are not considered ships of the wall, but rather are specialized vessels used to attack specific hardened targets. Since their low speed and weak defenses render them vulnerable “glass cannons”, they are typically operated as part of a task force including close-in point-defense cruisers, and only brought up once opposing fleets and mobile defenses have been cleared away; however, in their specialty role of cracking hardened fixed bases, they’re unequalled.

Hyperdreadnoughts

The “hyperdreadnought” is a peculiarly unique version of the superdreadnought type, of which the Empire fields three, each unique within its class; Invictus, Imperiatrix, and God of War. In order, they are the home of Admiralty Grand Fleet Operations, the Imperial Couple’s personal flagship, and the literal embodiment of the archai/eikone of war. Any one of them turning up in the battlespace would have implications that, by and large, no-one wants to think about thinking about.

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Battlecruisers and Cruisers

The backbone of the fleet, battlecruisers and cruisers (C on the chart) are middle-weight combatants, more heavily armed than destroyers and frigates, and yet more maneuverable than battleships and larger ships of the wall. Most cruisers also maintain limited AKV facilities. They are perhaps the best balanced (between operational aspects) of any of the Imperial Navy’s standard types. The distinction between cruisers and battlecruisers is simply one of mass and volume, with battlecruisers identifying the significantly larger and heavier classes of the type.

In fleet operations, battlecruisers and cruisers serve as screening elements and operate on the fringes of the close-in battlespace, maneuvering aggressively for advantage. For the most part, however, these middle-weight combatant types are intended for patrol operations and long-endurance “space control” missions, sometimes alone and sometimes in flotillas, as well as serving as the IN’s go-to types for independent missions of almost any type. In areas of heavy patrol activity, cruisers may lead destroyer or frigate flotillas into action.

Cruisers are also the type within which most variation exists, and cruiser classes may wander quite far from the indicated P/D/W ratio. Of particular note here is the point-defense cruiser (“pd” on the chart), the one type which you might see as a ship-of-the-formation, stripped of most of its offensive armament in exchange for point-defense enhanced to the point of augmenting that of other ships, but many other specialized varieties exist: the assault cruiser (optimized for planetary assaults, i.e., heavy on the ship’s troops and capable of launching drop shuttles and drop pods into atmosphere; some of these are aerospace cruisers, which atmospheric interceptors can sortie from before there’s an orbithead established); the diplomatic cruiser (a big stick to transport the softly-speaking); and the interdictor cruiser (specializing in the volume-security mission, which is to say, to chase down, capture and board other starships). The primary battlecruiser variants are the command battlecruiser (optimized to carry the admiral commanding a CC/BC task force) and the carrier-battlecruiser (which carries AKVs – see below – as well as its internal armament; this is the type of battlecruiser usually found operating alone, due to its significantly enhanced operational envelope and capabilities).

Due to their versatility, the IN maintains a greater tonnage of battlecruisers and cruisers in commission than starships of any other types.

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Destroyers and Frigates

Destroyers and frigates (D, F on the chart) are small, fast, maneuverable ships used for screening larger vessels, as escorts, and for patrol work. On their own, their capacity is severely limited, for which reason they typically operate in flotillas assigned together.

As with the above two types, the most obvious difference between destroyers and frigates is their mass and volume. That said, the strict difference between these two types is that while a destroyer may possess very limited broadside armament, due to its limited volume, it does possess it. A frigate, however, possesses no broadside armament; its spaceframe is essentially constructed around its primary gun.

Like cruisers, destroyers and frigates are designed for the “close-in” battlespace – with the understanding that close-in, in space terms, means anything under one light-second of separation. Indeed, these types arguably dominate this battlespace, since they form the majority of the IN’s screening forces, whereas cruisers are largely incidental to “set-piece” naval engagements. In this area, they use their superior maneuverability to both engage each other with wolf-pack tactics and to swarm larger ships at close-in range. Their lesser defensive capabilities than their larger cousins reflects the intention that they should substitute speed and maneuverability, avoiding being hit, for the ability to withstand taking one.

Destroyers and frigates are also intended to serve in escort and patrol roles in relatively safe space, where antipiracy patrol is the main concern (a flotilla of destroyers or frigates is considered an effective counter to a single cruiser-class vessel, which would be a rare high-end encounter under such circumstances); and in small numbers and specialist classes as scouts, avoiding engagement entirely.

Some frigate classes, uniquely among naval vessels, are capable of atmospheric entry and landing. Such frigates occasionally serve an additional role with Imperial Naval Intelligence.

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Autonomous Kill Vehicles (AKVs)

AKVs (A on the chart) – autonomous kill vehicles – are extremely smart multi-bus, multi-munition, multi-mission missiles. An AKV is, in effect, a small, stripped-down, AI-piloted starship – capable of much higher acceleration and greater maneuverability than a standard design, albeit with much less endurance – designed to act in multiple roles: as a mobile reconnaissance platform; as a “fighter craft” used to swarm and destroy larger starships from inside their own point-defense zones; or, when it loses all other fighting ability, as a kinetic energy weapon in its own right.

As indicated on the chart, AKVs have essentially no defensive weapons of their own; the intent is that they should substitute their vast advantage in speed and maneuverability for armor and point-defense.

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Monitors

A monitor (M on the chart), in essence, is a fixed base – an orbiting station or asteroid base – used for local defense. Their W/D ratio is skewed more towards defense than the ship-of-the-wall types, since unlike those, they lack even minimal maneuverability to avoid incoming fire or to retreat from the battlespace; on the other hand, their lack of concern for acceleration or other propulsive matters means that there is effectively no upper limit on the mass of the weapons or defenses that a monitor can mount, and asteroid-based monitors may make extensive use of the asteroid’s mass as armor and heatsink both.

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Carriers

Carriers (V on the chart) are battleship or dreadnought-sized vessels which eschew armament of their own in exchange for carrying a large number of AKVs, along with AKV replenishment supplies, strap-on AKV thruster packs, observation platforms, etc. Since they are not generally maneuverable enough or well enough protected (the massive flight deck of a carrier is essentially a corridor through the armor into the heart of the vessel) to survive heavy attack, they are usually held back from engagements, and as such their designs heavily emphasize point- and local-space defense over additional propulsion.

Assault carriers

Assault carriers – i.e., those carrying dropships rather than AKVs – also fall into this category. The same general operational rules apply; they are held well back from any engagements, and do not move in to the target area until the high orbitals have already been cleared of the enemy.

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Starfighters / Scouts

Starfighters (“sf” on the chart) are not manned fighter-class vessels. (The intersecting rules of physics, economics, and tactical effectiveness do not, in the general case, support a fighter-class of spacecraft in direct analogy to fighter aircraft. Rather, such craft can be replaced trivially by an equivalent vessel removing the biosapient pilot, their life support, and the ensuing limitations on maneuverability, acceleration, and computational performance, and replacing them with a computronium block; in effect, converting the spacecraft into an unmanned AKV.)

Rather, starfighters and scouts are essentially mini-carriers, suitable for operation by a very small crew, or even on occasion a single sophont, dedicated to the special operations and reconnaissance roles. They are small, no-frills starships designed to carry a limited, but still useful, number of AKVs or observation probes in exterior clamps. On arrival at their target, the AKVs or probes are then released to carry out the mission, while the starfighter itself serves as a command post, repair and replenishment depot, and coordination node in the tactical ‘mesh.

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Couriers

Couriers (“o” on the chart) are simply militarized (in construction standard) versions of the equivalent civilian type. While remaining, for the most part, “all engine”, military couriers add limited defensive and extremely limited offensive capability to give them at least minimal survivability in the event that they must pass through an engagement envelope; doctrine, on the other hand, demands that couriers should avoid engagement at all costs utilizing their superior acceleration and maneuverability to any other warship type.

• 

• 

LEVIATHAN-CLASS DREADNOUGHT

Operated by: Empire of the Star
Type: Dreadnought, General Operations
Construction: Palaxias Fleet Yards

Length: 3 km
Beam (avg.): 0.8 km
Z-Beam (avg.): 0.6 km

Dry mass: 2,500,000 tons

Gravity-well capable: No.
Atmosphere-capable: No.

Personnel: 6,736

• 4,968 crewers
• 1,768 espatiers
• Thinker-class AI

Drives:

• Imperial Navy 4×2 “Neutrino Dawn” antimatter pion drive
• Nucleodyne Thrust Applications 4×4 “Nova Pulse” fusion torch

Propellant:

• Deuterium slush/metallic antideuterium
• Deuterium/helium-3 slush blend

Cruising (sustainable) thrust: 7.2 standard gravities (6.7 Earth G)
Peak (unsustainable) thrust: 8.4 standard gravities (7.8 Earth G)
Maximum velocity: 0.3 c (rated, based on particle shielding)

Drones:

• 144 x AKVs (loadout varies by mission, typically Daggerfan-class)
• 144 x add-on thrust packs for AKVs
• 72 x “Buckler VI” point-defense supplementary drones, Artifice Armaments, ICC
• 72 x “Rook” tactical observation platforms, Sy Astronautic Engineering Collective (with supplementary IN hardware)
• 72 x general-duty modular drones

Sensors:

• 3 x independent standard navigational sensor suite, Cilmínar Spaceworks
• 18 x [classified] enhanced active/passive tactical sensory suite, Sy Astronautic Engineering Collective
• Imperial Navy tactically-enhanced longscan

Weapons (Primary):

• 4800/2400 mm custom axial heavy mass driver, Artifice Armaments, ICC

Weapons (Secondary):

• 4 x 4800/2400 mm custom heavy mass drivers, Artifice Armaments, ICC
• 4 x “Black Lightning” axial grasers, Artifice Armaments, ICC

Weapons (Tertiary):

• 64 x 2400/1200 mm turreted mass drivers (32 capable of broadside use), Artifice Armaments, ICC
• 8 x 2400/1200 mm turreted mass drivers (rear-firing for kilt defense), Artifice Armaments, ICC
• 32 x “Flashburn” turreted heavy lasers, Artifice Armaments, ICC
• Artifice Armaments, ICC “Popcorn” point defense/CQB laser grid

Other systems:

• 3 x Artifice Armaments, ICC cyclic kinetic barrier system
• Biogenesis Technologies, ICC Mark VII regenerative life support (multiple independent systems)
• 3 x Bright Shadow, ICC custom-build megaframe data system, plus multiple EC-1140 information furnaces for sectoral control
• Class IV starship repair facilities
• 8 x Extropa Energy, ICC “Calviata” second-phase fusion reactors
• Flag bridge
• 4 x Imperial Navy command communications/tactical networking suite
• 4 x Imperial Navy DN-class vector-control core and associated technologies
• 3 x Metric Engineering, ICC “Gloaming” ray shielding system
• 3 x Nanodynamics, ICC “Phage-a-Phage” immunity
• 32 x modular swapout regions (large)
• Systemic Integrated Technologies, ICC high-capacity thermal sinks and dual-mode radiative striping

Small craft:

• 8 x Reaver-class starfighters, with own AKVs
• 8 x Nelyn-class modular cutters
• 4 x Ékalaman-class pinnace/shuttle (atmosphere capable)
• 16 x Élyn-class microcutter
• 16 x Traest Sargas-class troop transport
• 32 x Adhaïc-class workpod
• 32 x Marlinspike-class boarding torpedo
• 32 x Sledgehammer-class drop shuttle

From without, the Leviathan-class dreadnought resembles a slender wedge, a dagger-blade without a hilt. It is, of course, rather larger than virtually all equivalent dreadnought classes and even some superdreadnought classes seen elsewhere, in keeping with the Empire’s naval construction policy of “shock and awesome”.

This should come as no surprise to anyone, since the realities of armoring such a vessel mandate such a glacis, and as such virtually all ships of the plane, of whatever origin, share this common feature. The Leviathan mixes this up slightly, having a change in ratio along its length that gives the hull a subtle curve and the ship entire a forward-leaning, sleek and hungry look.

(Although those who serve aboard Leviathans, especially back in the maneuvering sector, tend to describe their workplace as the ship’s “fat ass”.)

As is also usual, the apparent outer hull of the vessel is entirely composed of armor plating, which in the case of the Leviathan is a little over 30m thick, comprised of multiple layers of heavy plate, Whipple foam, radiation-absorbent material, thermal superconductors, dilatant shock gel, flexible spreader trusses, and other necessities for survivability in the modern high-energy battlespace, many of which remain classified.

(The important thing to remember about this armor plating is that it is not there to protect against a direct hit from an opposing capital ship. No practicable material will do that. It’s there to protect against the spallation debris left behind after your point-defense grid sweeps the sky like the hand of an angry laser-spewing god.)

This armor serves as a backup to the triple-layered cyclic kinetic barrier system with which the Leviathan is equipped, along with the likewise triple-layered ray shielding to protect against photonic attack.

The majority of the space within this outer hull is unpressurized volume, occupied by machinery space, bunkerage, stores (tanks and unpressurized cargo holds), accessways, robot hotels, and magazines. The habitable volume is represented by a relatively small (roughly equivalent to a 232-storey building, laid out tail-lander style) cylinder buried deep within this, above the axial passage for the primary mass driver, with two attendant counter-rotating gravity rings providing space for gravity-requiring special facilities. Below and to port and starboard of this passage can be found the eight fusion reactors providing non-thrust power to the Leviathan.

In addition to the primary (axial) heavy mass driver, the Leviathan mounts four secondary heavy mass drivers of only slightly lower power along its dorsal-ventral centerline, spread out at 15 and 30 degrees off-axis (although with off-bore firing capability), along with four heavy grasers clustered around, and aligned to, the axial primary.

Tertiary weapons systems consist of 64 turreted mass drivers and 32 turreted heavy lasers, of which half can slew far enough to be capable of broadside firing. An additional eight turreted mass drivers are mounted on the stern for kilt defense, should the prospect of attacking through, or at best in close proximity to, the emissions plume of the Leviathan‘s 24 torch drives not be sufficient deterrent. Finally, the Leviathan is equipped with the Artifice Armaments “Popcorn” laser grid for point-defense and CQB purposes, ensuring that anyone foolish enough to close to point-defense range will have mere microseconds to contemplate their folly before vaporizing in one of the most spectacular coruscations known to sophontkind.

Also pressurized are portions of the “docks and locks” sections to port and starboard, 500 meters for’ard of the drives, which house the Leviathan‘s small craft complement. These are buried beneath the starship’s outer hull armor, which is designed to retract under non-combat conditions to provide ingress. In light of this, the multiple AKV wings and drones are launched via dog-leg tubes through the dorsal and ventral armor, and recovered – if this is necessary during an engagement – when circumstances permit turning broadside to the enemy and recovering through the far-side landing bay.

As a dreadnought, the Leviathan is equipped with a flag bridge and communications/tactical mesh suite for task force command; with the capability to effect repairs on smaller vessels of its task force; with the ability to deploy starfighters for patrol or remote operations missions; and with a substantial espatier force and the means to deploy them, whether in boarding operations or for groundside raids.

• 

• 

Just to clear up a few misconceptions that may have crept in:

David Weber, alas, has done me no favors by convincing much of the SF-reading world that the standard interstellar badass is the dreadnought (DN).

And, yes, you may remember me saying “it sure would be nice to build nothing except dreadnoughts [for ships-of-the-plane (3D version of ships-of-the-line)]” back when we discussed ship types, but what I did not say is that if they did, they wouldn’t be dreadnoughts. They’d be battleships (BB), because the modal ship classes for engaging in big set-piece space battles are always designated as battleships. Says so right in the name. Battle. Ship.

Or, to put it another way, there are a lot fewer dreadnoughts than there are battleships. (And a lot more cruisers than there are battleships, for that matter, because most missions don’t have any major fleet engagements in them. But that’s another story, already told.) This is principally for economic reasons: when you examine the requirements for a ship of the plane, the battleship sits right at the bang/buck sweet spot, so that’s what you build.

A dreadnought (and to an even greater extent, a superdreadnought (SD)) has four virtues, which is why they’re built at all:

1. It benefits in internal space from volume increasing faster than surface area, which makes it a convenient class to carry extra stuff, from complete flagship suites through shipyard-class repair facilities for its cohorts and prisoner-of-war blocks to all that is required for the many, many specialized variants on the books.
2. It can afford a hell of a lot of extra armoring, so you are significantly less likely to get your admiral shot off and your fleet coordination suffering if you give him a DN to ride around in.
3. It can mount a Really Big Gun of the kind you’ll rarely need to use, but you might miss if you didn’t have any of in your plane of battle.
4. It’s bloody terrifying. When naval architects are told to draw up plans for a DN or SD, the unspoken requirement is that it dominate the battlespace like Conan the Barbarian at a convention of preadolescent pacifists: it dreads nothing, and everything dreads it.

So there aren’t all that many in service, relatively speaking. There don’t have to be – say, speaking non-canonically and off the back of the envelope, eight squadrons in the Capital Fleet (mostly in the Sixth Flotilla, which is the IN’s heavy-hitting force), four squadrons in Home Fleet, two for Field Fleet Spinward (which borders on the Seam), and one for each of the other field fleets: say, 228 in total, not counting specialist classes and the reserve.

You can assume at least four times that in BBs.

• 

• 

So let’s talk about the layout of that mainstay of the Imperial fleet, the Drake-class frigate. (The numbers are for deck plans. My own sketches are far too horrible to publish, but… well, there they are.)

External

Like most starships, one could conveniently divide the Drake-class into a pressure hull and a drive bus. It’s a little harder to spot the connection than it is on many ships (like, say, the Cheneos-class freighter) because of the armor, but it’s still there.

The pressure hull is, essentially, the front half of the ship, a round-fronted, slightly-flattened cylinder, for the most part unbroken in its organic curves except for the few openings (stellarium, gun port, airlocks) mentioned below, for the six geodesic spheres – three on each side, arranged fore-to-aft along the mid-line – clamped to the hull, which contain redundant sensor suites, best not placed inside the armor, the four paired cheek-mounted light mass drivers to for’ard, the ship’s secondary weapons, and an antenna suite projecting from the dorsal pressure hull near its after end.

Behind this, the pressure hull stops, but the armor which covers it continues on past the aftmost pressure bulkhead, broadening the hull to port and starboard even as it narrows into the starship’s stubby “wings”. (Which are of course not wings – they’re the secondary radiators; double-sided radiative striping under transparent light armor, encapsulating more bunker space. These are considered the secondary radiators because they’re designed to carry only the life-support and low-power heat load.) The armor back here serves as a cowl wrapping around the propulsion bus, which is the usual tangle of structural trusses, cryocels (for the ship’s limited supply of afterburner antiprotons), spherical and cylindrical tanks (for deuterium/He3-slush fuel and heat-sink goo), auxiliary machinery, and at the aftmost end of that (such that the bunkerage provides additional shielding for the crew), the fusion torches sticking out the open back of the cowl.

(This is, of course, a weak spot in the starship’s armor, but such would the drives be wherever you put them. In practice, the argument goes, when you’re in the furball – well, million-degree drive plasma provides a poor approach vector even for a kinetic weapon, and when you’re not – well, just watch where you point your kilt, okay?)

The external parts of the primary radiators sit on top of and below the cowl; they’re liquid-metal droplet radiators, which extend perpendicular to the secondaries when in use. They’re intended to support full power-and-some-more on the reactors, such that you can make a fast retreat and chill down your heat sinks at the same time.

The lowest deck extends, squared-off and flat-bottomed, a little below the main body of the pressure hull and extends back some way below the cowl; as the large doors at front and aft would indicate, it’s the landing bay.

The hull itself is gorgeous in shimmering military indigo; naturally, leading edges and other salient points are highlighted in intricate swirls of embedded gold-filigree brightwork, just because the IN can and wishes to emphasize that small point. (Close inspection will also note the apertures of attitude-control system thrusters, especially to outboard for the largest moment arms, and scattered black, glassy domes concealing the point-defense laser grid.)

Internal

Internally, the Drake has five decks dorsal-to-ventral. It uses the classic belly-lander arrangement because it’s considered possible to land a frigate planetside, or at least small-planet-side, or operate in atmosphere. (In the latter case, under the “with sufficient thrust, pigs fly just fine” principle.) Frigate captains rarely want to, though.

Despite that, there’s no artificial gravity on a Drake; while in space, the starship operates in microgravity.

Communication between decks is provided by a pair of elevators/shafts running between decks 1 to 4, and a staircase providing access to deck 0, along with various maintenance ladderways and such (especially in engineering). The elevators don’t run under microgravity conditions; they’re only for use under gravity. Rather, the elevator car is open-topped and is locked down on deck 4 in flight, allowing the shafts to be used as any other passageways.

As far as possible, auxiliary machinery, further storage tanks, etc., are wrapped around the outside of the ship, between the decks and the hull, to use as additional protection in the event of an armor-penetrating strike.

Deck 0

Deck 0, “the loft” is the smallest deck, squeezed in between the ceiling of deck 1 and the hull. Fortunately, it contains (for the most part) spaces which will be unmanned at general quarters or higher readiness states.

Specifically, at the fore end, there’s (1) the captain’s cabin, including a small office and private ‘fresher, from which a central corridor runs aft past (2) and (3), VIP staterooms which include the ‘fresher but not the office, ending at (4) the auxiliary sensory and communications room (approximately beneath the antenna suite mentioned above. Outside this room, a foldaway spiral staircase (i.e. serving as a microgravity shaft in flight) descends to the main corridor of deck 1.

Deck 1

Deck 1 is the first of the three “main” decks of the pressure hull.

Starting from the for’ard end, we begin with (5) the stellarium, which is literally the only room on the ship with windows, of which it has a continuous strip around the periphery and overhead. It also, being intended to entertain visitors and provide somewhere to get away from inside for a moment, comes with comfortable microgravity-adaptive seating, a few potted plants, and a wet bar.

More important for military purposes, while the windows are tough, they aren’t that tough, and as such the armor layer passes comfortably behind it, and access is through a sequential pair of spacetight doors. Naturally, it’s unmanned at general quarters or higher.

Behind this, another central corridor runs aft past (6), a conference lounge to port, and (7) an office for ship’s business – usually the Flight Administrator’s domain – to starboard, reaching the for’ard entrance to (8) the bridge/CIC, which takes up the full width of the ship in the center of the deck.

The aft entrance to the bridge/CIC opens into a second central corridor, this time passing (9), the server room containing the ship’s primary “dumb” servers and avionics systems to port, and (10), the ship’s AI’s cogence core and primary mentality substrate to starboard, terminating in a five-way junction containing the access to deck 0. To port and starboard, a cross-corridor terminates at the elevators/shafts, each with a ‘fresher located adjacent; aft, a door provides access to (11) the maneuvering room, in the form of a well-insulated gallery overlooking (12) the engineering space, which spans all three main decks.

(Secure backups for the cogence core and the substrate also exist buried in the middle of the propulsion bus section.)

Deck 2

Deck 2 is the central deck of the ship, and to a large extent is divided into two non-communicating parts. As a frigate, the Drake-class is built around its main gun, which occupies the axis of the ship and thus the center of the deck. While access is possible to the mass driver chamber (which can even be pressurized, with the gun port in the bow closed, for maintenance), it’s normally kept evacuated and is not, in any case, a very comfortable place to be.

The mass driver runs down the center of the deck from the gun port at the bow to (13) its “breech”, which sits directly against the engineering space bulkhead. Straddling it on either side are (14), the magazines for its k-slugs, which are also kept evacuated under normal conditions for ease of autoloader operation.

Starting this time from the aft end of the ship, at far port and starboard against the engineering bulkhead are the elevators/shafts and the associated adjacent ‘freshers, and the accesses directly to the engineering space. Corridors lead forward from these against the inner hull until they pass the magazines, at which point they turn inwards to reach, and proceed to the bow against, the central mass driver (for ease of accessing the driver coils for maintenance from these corridors).

On the port side, the majority of the space for’ard of this corridor is given over to (15) the medical bay, and at its for’ard end (16), the nano/cryostorage unit, used both for patients in need of return to fuller hospital facilities and doubling as the ship’s brig.

(It should be noted that the medical facilities are quite limited; the nature of the space combat environment is such that the window between “fine” and “chunky salsa” is quite narrow, and as such the medical bay is oriented more toward treating illness and minor injuries among the crew than it is to handling massive combat casualties.)

On the starboard side, the equivalent space is used for (17), a combined laboratory, workshop, and engineering support area.

The remainder of the space for’ard of these, behind the avionics area at the bow, contains the equivalent of two small rooms on either side (18, 19, 20, 21), connected by double spacetight doors; this is the modular function area. With sufficient engineering support and at a yard, these independently-encapsulated areas are designed to be disconnected from the ship’s infrastructure and framework, pulled out as a whole – along with their associated outer-hull plate and armor – and replaced with other modular capsules of equivalent specification. This feature permits the Drake-class to be customized for special functions – such as the electromagnetic radiation shielding we saw at the Battle of Eye-of-Night – much more flexibly than would otherwise be possible.

As mentioned, main access to the (12) engineering space is on this deck, although catwalks lead up and down to the lower level and to the maneuvering room gallery. The nearer part of the engineering deck contains a variety machinery, although also housing to port and starboard the two auxiliary fusion plants used to provide power to the starship when the drive is shut down. Beyond it, a half-octagon wraps around the bulk of the vector-control core and the reaction wheels, containing in their own sections the (22) life support systems to port, and the (23) robot hotels for the ship’s mechanicals to starboard.

Amidships between these, a small airlock and external robot hotel provides access to an unpressurized maintenance crawlway running through the propulsion bus. Normally, this is only used by robots or for occasional yard maintenance; radiation levels are unhealthy back there with the drive running, to say the least, but access may be necessary in emergencies.

Deck 3

Deck 3 is primarily the crew deck. At the for’ard end, along the centerline, is the (24) mindcast receiving room, allowing visitors received as infomorphs to borrow one of the ship’s spare bodies for the duration of their visit; aft of that, a cross-corridor links the (25) port and (26) starboard airlocks, each of which is accompanied by a small conning station (usually disabled) for use while docking.

Aft of that, another small room serves as a quarterdeck/reception area and security post. From there, a central corridor leads aft through the (27) crew quarters – the corridor itself is lined with access hatches to what are, in effect, double-sized personnel capsules – to the (28) comfortably furnished mess deck, which incorporates a (29) standing galley to port, and the (30) ship’s locker to starboard. Beyond the mess deck, hatches to port and starboard – a design choice permitting a large screen to be mounted on the mess deck’s after bulkhead – lead through inner-hull-hugging corridors past the (31) accumulator room to port, and the (32) auxiliary control room and (33) a small gymnasium to starboard, to another cross-corridor against the engineering bulkhead, providing access to the elevators/shafts and the ‘freshers on this level. However, there is no routine access to the engineering space on this deck.

Deck 4

Deck four, slung beneath the ship, is primarily its (33) landing bay; one large space, extending fore to aft. Space is reserved at port for the (34) armory, used to equip shore parties if necessary, and at starboard for a (35) second workshop space. These are each located for’ard of the elevators/shafts which open into a small hallway offering access both to these, and to an airlock opening into the landing bay. There are no associated ‘freshers on this deck.

A Drake-class frigate is typically equipped with a single cutter, an interface vehicle, or both; the relatively large landing bay permits it to also store the frigate’s complement of drones, and to serve as a cargo bay to such extent as space permits. Overhead manipulators permit vehicles to be moved to engage with either the fore or aft mass catapult for launching, reshuffling of the cargo, or retasking of the cutter, as desired.

Flight operations are handled from the bridge/CIC. The bay can be pressurized with both doors closed, but at general quarters or higher readiness states operates unpressurized to expedite operations and avoid unnecessary risks.

(For those paying attention to the implications: yes, the very same vector control tech that lets you make kinetic barriers lets you make nice air curtains that would hold air in even with the door open, while still letting you fly in and out. [Well, mostly: for molecular statistical reasons, they leak, but it’s manageable.] Some civilian ships use those for the convenience. Military ships prefer not to have unexpected depressurization incidents when someone gets a lucky shot in on the emitters when they don’t have to. Sure, it’s a pain to have to wear a skinsuit all the time, but you’re in the Navy now! Also, you’re less likely to get brained by a flying spanner if there were to be a curtain oops.)

We've come a long way in our discussions about building a space navy forces and the combat considerations thereof. At this point, we can start actually designing some spacecraft, or at least start focusing in on the specific needs our space forces will have to address when designing spacecraft.

First off, and remember that in the case of Conjunction, this is the most important, is the fact that the UN Space Force is not a military in the conventional sense. It is a law-enforcement body primarily and a search and rescue service secondarily. Military action, as will occur in the dark years of the Great Conjunction War (or whatever they decide to call it) are all new and uncomfortable roles forced onto the majority of the commanders, mission planners and spacecraft designers of the future.

That last part brings up an interesting point, however: Spacecraft have a horrendous amount design time, and spacecraft as big and complex as the ones in Conjunction can easily take years to develop and build. This fact, along with the multi-year travel times from the Inner System to the combat theater, will make it all to likely that the spacecraft developed for the Conjunction War will not be available until the war is over. This leads to our first design consideration, one mentioned by Heinlein in the past: The weapons of this war were designed to win the last war.

Specific to Conjunction, the weapons of this war weren't made for war at all, but police actions and purely theoretical combat scenarios that our ornery Jovians have no moral requirement to follow. Hilarity ensues.

• 

So, what would the UNSF have available, at the start of the war, and what would they have in the slips or on the drawing board? As far as what the UN have available, it's mostly Patrol Rockets like the Class-A, little utility rockets like the Cygnus, and the big, trans-Chronian transports. The Class-A and the Cygnus have been mentioned before — just click on the link for a reminder. The big transports need a few words, as these classes of spacecraft will have been well established prior to the war and really are the backbone of not only the UNSF, but of all space travel in Conjunction.

Annie and Chris mention the Mekong in the comic strip, as the ship the two will have share for the two year trip to Saturn. This is a River-class logistical ship, of a kind similar to the ones Rick Robinson describes in his Rocketpunk Manifesto. However, the Mekong is not a military ship; it is a civilian-run transport that is heavily subsidized by the UN in exchange for ferrying personnel and patrol craft across the black. This kind of compromise is to be expected, given that the UNSF is not a military, is not at war, and is only mandated to keep the peace. It also has to do this in a sphere of operations roughly a billion kilometers in diameter, They can't have a large number of purely peacekeeper spacecraft of this size, It isn't cost effective.

That being said, there are a lot of convoys moving between Titan and Terra in a constant stream of methane, and you can't just station a fleet in the shipping lanes, so each convoy needs some escort, and that escort needs the delta-v and the life support to move across a large chunk of interplanetary space. Therefore, I postulate the creation of a logistical carrier and a stripped-down variant made for civilian use. The UN Carrier — call it the Gagarin class and name it after astronauts, will be armored and armed with large defensive lasers, carry a half-dozen patrol rockets a dozen or so Cygnus rockets, and two crews for itself and each rocket it carries. That's a lot of people, but a spacecraft of this type is more starbase than spaceship anyway. In addition, the Gagarins will need large repair spaces for the patrol craft, a fleet reserve of propellant, and space to carry any kinetic vehicles that will be used in combat.

The civilian version — our River-class — will only carry a pair of patrol rockets, maybe for utility craft, a correspondingly smaller propellant reserve, and most likely no kinetics for deployment during travel. weather or not they carry kinetics as cargo depends on how easy it is to manufacture KKVs at Saturn and weather or not the UN wants it's colony to make its own WMDs or not.

How do these behemoths move between the worlds? Chemical rockets — or even nuclear ones — are right out as they are too inefficient. A nuclear electric drive, delivering constant boost at minimal acceleration, is the best option. The disadvantage to such a drive is that minimal acceleration thing. To alleviate this, the logistical craft could have NTRs — after all, they got the reactors anyway — and thus be able to hit the gas when needed. In fact, there is even a way, albeit a very expensive and inefficient one, for our logistical craft to move from the inner system to a hot spot in the outer worlds much faster than normal. This involves the technique upon which naval legend Chester Nimitz credits the American victory over the Japanese in the Pacific — underway replenishment.

To perform underway replenishment, we need another class of spacecraft: The Tanker. This need not be too complicated, as ice is a more effective medium for transporting hydrogen than hydrogen is. As a purely practical matter, the propellant tanks of the interplanetary ships will have to be full of water anyway, as you can't expect to carry cryogenic hydrogen under pressure for two years. So our tanker will basically be a gigantic plug of water ice with a nuke at one end and an electrolyzer at the other. The heat from the nuke serves to melt the ice for conversion into propellant. The logistical craft and the tanker will have to dock nose-to-nose in order to prevent irradiating one another, and will spin around their common access to make enough force to let the propellant pump in between the two. I'm not a hundred percent on this, but I don't think the pair of craft could dock nose-to-nose under acceleration, seeing as their rumps would be at cross-purposes.

• 

It goes without saying that the logistical craft have spin gravity. This is in the form of two rings, spinning in opposite directions to cancel the gyroscopic effect. I imagine that the rings will sit inside a huge, globular water tank — that fleet reserve I mentioned — as a way of making the propellant do double duty as cosmic radiation shielding. Because the ship will sometimes spin end-over-end while taking on reaction mass, the logistical craft must either halt spin on the gravity rings — a pain in the butt — or use a species of Winchell Chung's Ezekiel's Wheel. If this looks like it could be a maintenance nightmare, let me reassure you — yes, yes it is. Any spin-gravity system is high maintenance, and one that must spin along two axes is high maintenance squared. However, with a large number of crew, literally half of which will be out rotated out at a time, lengthy and complex maintenance cycles are a feature, not a bug.

So, we have patrol rockets, utility craft, logistical carriers, and tanker already available for the UNSF at to play around with. What about what is on drawing board? Mission planners and saber-rattlers are all too aware that the Great Conjunction will come and put the UN&Cs most troubling possession in between the oil-hungry masses of the inner system and the oil-rich oceans of Saturn's moon, Titan. They must have made some plans ahead for the eventuality that Jupiter, which in our scenario is self-sufficient in terms of power and many other commodities, is ready to go its own way. What have the UN developed to counter this?

• 

Enter the Laserstar.

Even for Conjuction, my Laserstar concept is an oddity in the annals of space combat. Usually the biggest, most heavily armed and armored ship is the "battleship" right? In this case our basic assumptions about combat and the tactical considerations thereof make the Laserstar the opposite of that: The ultimate defensive system in our arsenal. It boasts a Violet wavelength laser with a twenty meter mirror on the nose and six ten-meter mirrors on its flanks. These monsters are uncrewed, controlled by on-board AI, and nuclear powered. They are named after the native countries of the first astronauts and cosmonauts, with The Union of Soviet Socialist Republics being the flag ship. The Laserstar's purpose is to provide cover fire for the logistical craft it is assigned to defend. With the number of lasers on these leviathans, the goal is to make a successful kinetic attack impossible.

That's a lot of ships. A lot of different ships. And given the nature of space and its peculiarities, how they come together as a cohesive fighting unit will be equally peculiar.

• 

There's a decent functional space to discuss here.

Most navies really have three sizes of ship.

• Small ships
• Medium sized ships
• Capital ships

Most navies have two roles that ships are designed for:

• Independent patrol
• Main battle fleet

Independent patrol sacrifices firepower (and sometimes protection) for cruise endurance and multi-mission capabilities.

Main battle fleet requires ships to be 'honed to the bone' - anything that doesn't make the ship more capable in a fight is usually a luxury.

History hasn't been kind to independent patrol capital ships. They're generally too expensive for the benefit they give the navy (something that eats independent cruisers for lunch and can do commerce raiding. Jackie Fisher's Battlecruisers in WWI and the German pocket battleships are two examples.

So this leaves:

• Frigate (Small ship, independent patrol)
• Destroyer (Small ship, main battle line)
• Cruiser (Medium ship, independent patrol)
• Armored Cruiser (Medium ship, battle line)
• Battlecruiser (Capital ship, independent patrol)
• Battleship (Capital ship, battle-line)

Within each role, you have specific missions, and you'll have different sizes of ships within each niche, depending on what specific navies did with their doctrines.

The frigate is the smallest thing that can be armed with guns capable of doing shore bombardment.

The destroyer may have less armament than a frigate; it's job is to shoot down threats to the bigger ships in the battle fleet.

The cruiser is a frigate that's generally got more armament, more armor, and more survivability. It usually has greater endurance.

The armored cruiser trades endurance for enough armor to maybe survive a hit from a capital ship's gun without being mission killed, and usually has the same number of guns as the cruiser with heavier throw weights.

The capital ship has Massive Firepower and the armor to stand up to it. Endurance is usually traded off somewhere.

	Independent patrol	Main battle fleet
Small sized ships	Frigate	Destroyer
Medium sized ships	Cruiser	Armored Cruiser
Capital ships	Battlecruiser	Battleship

• 

It's a common trope in sci-fi that Space is an Ocean [WARNING - TV TROPES LINK], and so when we talk about spacecraft classification, naval terminology creeps into our work. I think some of this is unavoidable. For one, the Space is an Ocean meme is a powerful one, and it's been heavily reinforced over decades of use. The other is that while I personally expect any future space forces to evolve from the Space Commands of existing Air Forces, once you get the ability to build large space-going warships and send them days or weeks out of contact from home, the Navy's organizational model starts making more sense over the Air Force model (pace, SG Universe.)

But that's not what I want to write about.

I think this 'creep' has extended so far that we've forgotten (or just didn't know), what all of those ship classifications even mean, or haven't taken a good look at whether a particular wet navy ship type even makes sense in space. The term 'destroyer' is perhaps the worst offender. We get destroyers in sci-fi that range from small escorts to titanic capital ships. (I'm looking at you, George.)

Since sci-fi Space is an Ocean models invariably build upon conventions established for such recent events as the Battle of the Jutland, the rock-paper-scissors paradigm of naval combat that dominated in that period may have been lost, and with it, just what exactly made a destroyer what it was and why. Battleships rule the waves, with armor that only another battleship could defeat, and large bore cannons which could in theory strike their targets over the horizon. If you wanted your Navy to compete, you needed to build battleships, which were crushingly expensive burdens. (Look back to the period for commentary on how the naval arms race prior to WW1 was driving countries to ruin for examples of this.) Then along came the torpedo, a powerful, relatively cheap weapon that could sink one of these behemoths, and could be deployed by relatively tiny, fast, and cheap swarms of torpedo boats. The Battleship, especially the post-Dreadnought models of the type, could not effectively engage torpedo boats with their big guns. Thus entered the Destroyer, short for Torpedo Boat Destroyer. It was much smaller and cheaper to build than a ship of the line, was fast enough to chase after its quarry, and had lighter guns that could track and sink the torpedo boats. Battleships sink Destroyers and other Battleships, Torpedo Boats sink Battleships, and Destroyers sink Torpedo Boats. Rock, Paper, Scissors. The Destroyer had a specific purpose, otherwise it would have never existed. Submarines being torpedo boats that could go underwater just meant that the Destroyer still had a reason to be as naval warfare technology moved on.

Does your Destroyer have such a purpose? It's something to think about. A Destroyer in a space setting could be a 'Fighter, Drone, and Missile' Destroyer, heavy on the point defense systems and acting as a consort to a larger and more important vessel. That makes perfect sense and justifies the class. If your Destroyer can stand in the line of battle, with a primary anti-ship armament and good protection, and even carry a few of its own fighters or troops along for the ride, you might want to reconsider its classification. Make it a cruiser, or, if it really is just a battleship in destroyer clothing, call it something that reflects that role.

I think one of the reasons why the trope has been so enduring is that audiences can relate to them easily. 'Battleship' is fairly clear in peoples' minds, so a battleship in space is an easy mental gearshift for them. For better or worse, so too 'Destroyer.' People can relate to a 'battleship' or 'carrier' in a way that a 'system control ship' or 'parasite (craft) tender' do not relate. For one thing, there is a certain elegance to the wet navy terms that the clunkier if more apt 'system control ship' and 'parasite tender' are clearly lacking. And let's face it, frigate commands were romantic and exciting in the days of Wooden Ships and Iron Men, more so in the sea-romances written about them, and if you're going to write a sci-fi romance in the days of Alumo-Titanium Ships and Diamondoid Men, they probably have a place there, too.

As creative types, we love the worlds we create. We love our fluff. I'm no exception to that. What I find disturbing, even objectionable, is when I find so little consideration put into the fluff. I think the caveat of de gustibus non est disputandum applies, but as someone who enjoys sci-fi games, books, movies and TV shows as much for their fluff as their primary contributions to the visual and literary media, a well reasoned and internally consistent fluff is a signifier to me that the creative person behind their works actually cares about what they are doing, is as interested as me in the genre, and isn't just doing this because this is how they earn their daily crust.

For my own setting, I've adopted naval ship classes that seem to have a purpose. Here's a list and the reasons for their existence.

Battleship

Space Control ship. Heavy armament and stout protection. If you don't have anything that can stand up to it available, you have to concede the space it can control. Thus, Battleships can take control of orbital spaces, or even entire solar systems without firing a shot if the defenders don't have a comparable amount of tonnage and throw-weight to resist them and the willingness to do so.

Carrier

Interface Fighter and Strike Craft mothership. In my setting, there is nothing a Space Fighter can do that a drone missile carrier can't do better, but when it comes to planetary real estate, a fighter that can operate in low orbit as well as within the deep atmosphere has greater utility. They can be Johnny-On-The-Spot for close air support, ISR, and air superiority in a way that orbiting warships providing for these roles cannot. For one thing, in low orbit, a warship will only pass over a given location on the ground for about 10 or 15 minutes, maybe 4 or 5 times a day depending on the latitude and the inclination of the orbit. Because Interface Fighters and Strike Craft have a reason to be, so too the Carrier, to bring them to low orbit, recover them after their mission, and return them to service.

Cruiser

A cruiser is more or less a scaled down Battleship. Battleships are expensive to build, man, and maintain, and if your setting has lots of places to go, the amount of space you can actually control will be limited by your ability to put something there that can take care of itself. The Cruiser, being smaller, is less expensive to build, man, and maintain, so you can build more of them to control more space, reserving the Battleships for the really important locations and to keep them available to mass for a decisive engagement. Wet Navy cruisers tended to be faster than battleships, but in a Newtonian physics based space setting like my own, one's 'speed' in the end comes down to propellant fractions, which can be the same for any given size or class of spacecraft. Instead, a Cruiser is built for long endurance independent operations, trading a little firepower and protection for the ability to maintain a presence somewhere and control space where a Battleship isn't worth sending instead.

Assault Ship

A troop carrier. Their job is to transport ground based combat power to target worlds and deliver them with organic interface craft. They may carry interface fighters and strike craft as well as landers, they may even have their own space to surface weaponry for fire support, but most of their displacement is given over to housing troops, their vehicles, their gear, and their supplies.

Tanker

Just what it says on the tin. The Tanker carries reserves of propellant and reactor fuel to replenish the fleet. Since propulsion within a system is by reaction drive, massive quantities of reaction mass get consumed, and it is the Tanker's job to keep the fleet fueled. Tankers usually carry harvesting craft to find sources of hydrogen, deuterium, and helium-3 and have their own processing plants to turn raw materials harvested into useable propellants/reactants. An army marches on its stomach, and so too a fleet maneuvers on what is in its tankers.

Logistics Ship

A military version of a freighter, usually identical to existing civilian merchant classes, with perhaps a slight upgrade to armament, communications, and protection. Warships need spare parts, replacement missiles and other expendable stores, water, and food.

Tender

A repair ship. These carry fabrication plants, raw materials, and technical shops to maintain, repair, and in some cases even rebuild parts of spacecraft to keep the fleet in the fight away from their home stations.

Frigate

A scaled down Cruiser. You can build and operate 2 or 3 frigates for the same expense as a Cruiser, so you can at least 'show the flag' in more places, and in remote systems even control them. Most Frigates have a small organic troop contingent embarked on board as well as small landers to transport them, allowing them to occupy or provide security for outposts and small colonies. The Frigate is the Swiss Army Knife of the fleet. It doesn't do any particular job very well, but it can do a little of everything, and because you can build lots of them for the same price as a Battleship, your ability to at least influence large volumes of space is much greater than a powerful warship that can only be in one place at a time.

Destroyer

Also called an Escort. The purpose of the Destroyer is to eliminate any missiles or small craft which threaten its consort, usually a Battleship, Carrier, Assault Ship, Tanker, Tender, or Logistics Ship. It does not have an appreciable anti-ship armament, and would be helpless against even a Frigate. They have to be fairly agile in order to provide coverage, or if necessary, position themselves to eat an anti-ship missile instead of letting their charge get hit.

Corvette/System Defense Boat

A scaled down Frigate, usually optimized for an anti-ship role. Since a corvette/SDB is unlikely to have a direct fire armament that can seriously threaten larger warships, they typically incorporate a significant fraction of their weapons displacement as anti-ship missiles and will engage in packs. This gives them limited combat endurance, but offers a cheap way to punch well above their weight in an engagement. Think of them as the wet navy Torpedo Boat. (Ironically, Destroyers are not built to engage them, but a Frigate or another Corvette/SDB would serve admirably in this role.) Corvettes and SDBs may also be assigned to convoy escort duties, sometimes led by a Frigate or a Destroyer. Their job is to intercept commerce raiders away from the convoy, and destroy them with salvos of anti-ship missiles. The original wet navy Corvette was meant to operate in home waters in a patrol role, and with a fairly strong for its displacement anti-ship capability. A System Defense Boat is simply a Corvette without an FTL system, making them more in line with the original wet navy concept.

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I don't think there would be a huge variation in the types of warships seen. You'd have the big battleship which would dominate everything it fights, and then maybe smaller ships that could cover more area at once and engage in light combat, but wouldn't stand up to the battleships. Red called these 'frigates' in his Humanist Inheritance fiction, probably because their role is similar to the ship of the same name from the age of sail, and it is a term I like, so I will use it here. However, note 'cruiser' may also be an applicable moniker for these ships, probably depending on its specific mission rather than its design goal.

I feel these would exist due to economic efficiency rather than speed or range difference like those seen in the real sailing frigates. Let me explain.

Many of the arguments against space fighters can actually be used when talking about other capital ship classes as well. Let's look at what the roles of various naval ship classes basically were, and see if they could have an analog in space.

You had corvettes, which were small, maneuverable ships used close to shore. This role doesn't really apply in space. You might argue low orbit around a planet could be seen as a shore, but the problem is combat ranges would be rather large. If you have a stationary asset in LEO that you want to attack, you could put your battleship arbitrarily far away and attack it at will. If you have a mobile asset in LEO you want to attack, you can still attack it from some distance away, probably around one light second, to avoid too much light speed lag targeting issues and diffraction of your laser beams over the distance.

For comparison, the moon is about one and a half light seconds away from Earth. So, the battleship could be sitting out two thirds the distance to the moon and easily engaging the LEO target with precision and power. Corvettes being there wouldn't be of any help on defense, and the battleship can do their job on offense just as well, and at longer range.

A corvette type ship might be useful to the Coast Guard for police and search and rescue work, but that is an entirely different realm than a warship.

How about cruisers / frigates? The historical usage of the term referred to a small but fast warship, capable of operating on their own, and often assigned to light targets or escort duty. I do see an analog to this role in space.

A frigate would be no match for a battleship, however they would be useful in force projection, due to presumably being cheaper to produce and operate, thus more numerous. I'll be back to this in a moment.

And of course, battleships would be the backbone of the war fleet, able to swat down anything that comes at them except other battleships. If it were economically feasible to build a huge fleet of battleships, I see no reason not to. Let's investigate some of their traditional disadvantages and see if they apply in space.

The big one is speed: the huge battleship can take just about anything dished out to it and dish out enough to destroy nearly any other class of ship, but its huge size makes it slow. This isn't so much of a concern in space. Allow me to elaborate.

There are two things in space that are relevant when talking about "speed": delta-v and acceleration.

Delta-v is determined by the specific impulse (fuel efficiency) of the ship's engines and the percentage of the ship's mass that is fuel. Tonnage of the ship doesn't really matter here: it is a ratio thing. If the specific impulse is the same and the fuel percentage to total mass the same, any size ship will eventually reach the same final speed. Thus, here, if fuel costs are ignored, small ships have no advantage over large ships. (And indeed, if you are going on a long trip, the large ship offers other advantages in how many supplies or for war, how many weapons it can carry at no cost to delta-v, again, if the ratio remains constant) So the question is how fast can they reach it, which brings me to acceleration.

Acceleration is determined by total engine thrust and the total mass of the ship. At first glance, it seems that the smaller ship would obviously have the advantage here, but there are other factors that need be observed.

One is the structural strength of the materials of which the ship is constructed. This becomes a big problem on insanely huge ships with larger accelerations, since the 'weight' the spaceframe must support goes up faster (it cubes) than the amount of weight it can handle (it squares). Mike talks about this on the main site when he debunks the silliness of giant insects. However, steel is strong enough that with realistic sizes and accelerations, this should not be an issue before one of the other ones are.

One that is a much bigger problem is how much the human crew can handle. In the space / atmospheric fighter thread we had the week before last, Broomstick discussed the limits of the human body to great accelerations. Well trained people in g-suits can handle 9 g's for a short time, but much more than this is a bad thing to just about everyone - their aorta can't handle it. In fact 5 positive g's are enough to cause most people to pass out, as she explains. If the crew is passing out, the ship is in trouble. This problem can be lessened by the use of acceleration couches: someone laying down flat can handle it much better for longer, but even 5 g's laying down is going to be very uncomfortable, and the crew will have a hard time moving their arms. Extended trips would probably be best done at 1 g so the rocket's acceleration simulates Earth normal gravity, with peak acceleration being no more than 3-5 g's for humans in the afore mentioned couches if possible.

That is probably the most significant limit on acceleration, since it is an upper limit of humans. No matter what technology exists, this cannot be avoided.

The third limitation will be based on the technical problem of generating this much thrust for the mass. This, too, can provide an upper limit, since adding more engines on to a ship will eventually give diminishing returns. The reason for that is the available surface area on the back of the ship where the engine must go increases more slowly than the mass of the ship as it grows. But, for a reasonably sized ship, this should not be a tremendous problem, especially when nuclear propulsion techniques are used, many of which have already been designed and proven feasible in the real world. Fission nuke pulse propulsion can provide 400 mega-newtons of thrust according to the table on Nyrath's Atomic Rockets website (see the row for Project Orion).

Three gees is about 30 metres per second squared acceleration. F = ma, so let's see what mass is possible. 4e8 / 3e1 = 1e7 kg, or about 10000 metric tonnes. Incidentally, this is the number Sikon used for his demonstrations in the October thread about brick vs needle. I think it a reasonable number for a battleship, so rather than repeat the benefits of this, I refer you back to that thread and the posts of GrandMasterTerwynn and Sikon on the first page, who discussed it in more depth than I am capable of. I agree with most of the views Sikon expressed in that thread.

So, for these sizes, the speed argument against battleships is very much sidelined.

You also pointed this out later in your post that these advanced propulsion techniques do not necessarily scale down very well, which may also serve as a lower limit on ship size, which is probably more relevant than the upper limit it causes.

You might ask if pushing for a greater peak acceleration would be worth it, and it is not, in my opinion. The reason again goes to the human limitations. Even if your warship is pulling 10 gees, it most likely won't help against a missile, which can still outperform you.

An acceleration of even 1 g should be enough to throw off enemy targeting at ranges of about one light second. By the time the enemy sees what you are doing, you have already applied 10 m/s change to your velocity. Then, if he fires back with a laser, you have another second to apply more change. This would be enough to help prevent direct, concentrated hits. Having even five times more acceleration will offer little advantage over this in throwing off targeting or wide spread impact of lasers of particle beams, due to the ranges and the size of your warship, which is certain to measure longer than 50 metres. For missiles and coilgun projectiles, it matters even less, simply due to the time the enemy fire arrives, you have plenty of time - minutes - to have moved. 1g is plenty for that, attainable by a nuke pulse engine for sizes around 30,000 metric tonnes.

Long range acceleration would again be limited to around 1 g or less due to the humans, mentioned above. However, even at 1g constant acceleration (which would probably not be used due to fuel concerns anyway), an Earth to Mars trip could be measured in mere days. More offers little advantage there either.

Lastly, there may be a question of rotation. A more massive and longer ship would have a greater moment of angular inertia than a smaller ship, thus requiring more torque to change its rate of rotation. Again, I don't feel this will be a major concern. At the ranges involved, you again have some time to change direction. However, this does pose the problem in quick, random accelerations to throw off enemy targeting.

Going with the 10,000 metric ton ship, let's assume it has an average density equal to that of water: one tonne per cubic meter. For the shape, I am going to assume a cylinder, about 10 meters in diameter (about the same as the Saturn V), with all the mass gathered at points at the end. The reason of this is to demonstrate a possible upper number for difficulty of rotation (moment of inertia), not to actually propose this is what it would look like. Actually determining an optimal realistic shape for such a ship would take much more thought.

With this, we can determine the length of the cylinder to be 10000 / (π r²) = about 130 metres long. Now, we can estimate the moment of inertia, for which, we will assume there are two point masses of 5000 tons, each 65 meters away from the center. So moment of inertia for the turning axis (as opposed to rotating), is 2*5000 * 65^2 = about 4e10 kilogram meters squared.

Now, let's assume there are maneuvering jets on each end that would fire on opposite sides to rotate the ship. Let's further assume these have thrust about equal to that found on the space shuttle, simply because it is a realistic number that I can find: about 30 kilo-newtons. Let's determine torque, which is radius times force, so 3e4 * 65 * 2 (two thrusters) = about 4e6 newton meters. Outstanding, now we can determine angular acceleration possible.

Angular acceleration = It, where I is moment of inertia and t is torque. So, we have 4e6 / 4e10 = 1e-4 radians per second squared. This is about a meager 10th of a degree per square second. Remember this is acceleration - change in rotation rate. Once spinning, it would tend to continue spinning. This is also a lower limit: most likely, the thrusters would be more numerous than I assumed, and probably more powerful as well, and the mass probably would be more evenly distributed. But anyway, let's see if it might be good enough.

As I said when discussing linear acceleration, you would want some quick randomness to help prevent a concentrated laser beam from focusing on you, and you would want the ability to change your path within a scale of minutes to prevent long range coilgun shells from impacting. There isn't much you can do about missiles except point defense: a ship cannot hope to outmaneuver them due to limitations of the crew, if nothing else.

Some unpredictable linear acceleration should be enough to do these tasks, unless the enemy can get lined up with you, in which case, you will want to change direction to prevent him from using your own acceleration against you, and blasting you head on. So the concern is can you rotate fast enough to prevent the enemy from lining up with you. So, let's assume the enemy can change direction infinitely fast, and can thrust at 3 g's. The range will still be one light-second.

We can calculate how much of an angle he can cut into the circle per second if he attempted to circle around you. His thrust must provide the centripetal acceleration, so we can use that as our starting point. Centripetal acceleration is equal to radius times angular velocity squared, thus, sqrt(30 / 3e8) = 3e-4 radians per second.

So, its angular velocity is three times that of the acceleration of the battleship. Thus, it would take the battleship three seconds to match that rotation rate. It would also want to spin faster to make up for lost time, thus lining up on your terms again. I feel this is negligible because of two factors: if the enemy actually was orbiting like this, its position at any time would be predicable, thus vulnerable, and the battleship can probably see this coming: the enemy's tangential velocity must also be correct to do such a burn - he can not randomly change the orientation of his orbit due to his limitations on linear acceleration. This means you can see what he is doing and prepare for it with a small amount of time of him setting the terms. In this small time, he would not even move a degree on you: still easily within your armor and firing arc. (Also, weapons turrets on the battleship would surely be able to rotate at a much, much faster rate, so outrunning them is impossible anyway).

Thus, I feel neither linear acceleration nor angular acceleration are significant limiting factors as size increases within this order of magnitude.

Long story short: unlike marine navies, speed is not a significant factor in space warship design, unless you are getting into obscene sizes.

And, since I find it interesting, I want to finish talking about possible ship classes, so back to the comparison list.

Submarines depend on stealth, and since there is no stealth in space (barring pure magic like the Romulan cloaking device), there are no submarines in space.

Destroyers operated to protect larger ships against submarines and small, fast ships, like torpedo boats. Since speed is not a significant factor and stealth impossible, there are no fast ships nor subs, meaning the destroyer has nothing to do, thus would not exist. (Though, you might chose to call what I call frigates destroyers if you prefer the name, but IMO the role is different enough that is isn't really accurate. But the US Navy somewhat does this, so it is up to you as the author.)

A cruiser is simply a ship that can operate on its own. Frigates, destroyers, and battleships can all also be called cruisers depending on their mission.

A battlecruiser is a ship meant to be able to outrun anything it can't outgun - it had the speed of a lighter cruiser with the guns of a battleship. In real navies, this was usually achieved by taking armor off a battleship. However, since speed is not limited by mass in the given order of magnitude, a battleship and battlecruiser would have the same speed: the battleship would be a clearly superior vessel. Thus, no battlecruisers. (Now, if you have FTL, then that might create a battlecruiser class, but I am trying to avoid talking about magic in this discussion, since as the author, it is entirely up to you what the magic can and cannot do.)

A destroyer escort is a small, relatively slow ship used to escort merchant ships and protect them against submarines and aircraft. But, in the real world, aircraft can threaten a ship due to its superior speed and submarines due to stealth. So neither of them are there, making the destroyer escort worthless. Frigates or battleships would have to be doing the escorting, since they are the only things that can stand up to what they will be fighting: other frigates or battleships.

Now, a little more on what I mean by frigate. It is basically a smaller battleship, built simply because I am presuming they will be cheaper to produce and maintain, thus allowing more of them to exist. With more of them, they can be in more places doing more things. Cost is the only real benefit I can think of: if for some reason you could crank out and operate / maintain battleships for the same cost, I see no reason why you would not.

The 10,000 ton proposal might actually be the frigate, with the battleship being larger than that, or it might be the battleship with the frigate being smaller than that. The relationship would remain the same, however.

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The design of the ships of fleet are driven by requirements. Requirements are driven by mission and threat. The Royal Navy of the 18th century had one mission (control of the seas through destruction of the enemy fleet and blockade of his ports) and one threat (the muzzle loading black powder cannon). And it remained pretty much that way until the late 19th century. Battleships were for the destruction of the enemy fleet, and frigates (or later "cruisers") were to be where ever power was needed that didn't rate a battleship. Then newer threats showed up (the torpedo boat, the mine, the submarine) and new ships (the torpedo boat destroyer, the minesweeper, and the subchaser) appeared to counter those threats.

As those threats grew more sophisticated, and others appeared (aircraft), the design of ships and ship types changed to match. Aircraft carriers, and ships designed to counter the air threat (the Atlanta and Iowa classes) appeared. Existing ships adapted to the new threats, as destroyers became the primary defense against subs, and anti-aircraft batteries sprouted on every ship. Specialized amphibious ships were developed as the mission of projecting power ashore through troops grew more important.

After the war, the carrier was supreme, not the least because its aircraft could deliver nuclear weapons. In the US Navy the offensive mission centered totally on the carrier, and the various escorts (cruisers and destroyers) became almost purely defensive, putting up a barrier of guns, then missiles against air, and then missile attack.

(In contrast, the Soviets worked almost solely on carrier killers - cheap platforms with powerful missile armament).

For the US Navy of the future, things are changing again - the next generation "destroyer" - the DDX - will be optimized for deep attack missions against shore targets (and some of the capability will be usable for sea control). The next 'cruiser' will be a dedicated air defense platform. And a new class of ship, the "sea fighter" will take the fight close inshore, to deny the enemy the ability operate in shallow waters.

To think about what the Loroi fleet should look like, we should ask:

• What is the mission of the Loroi fleet, strategically?
• How does the fleet carry that mission out?
• What are the threats to the ships?
• How can those threats be countered?

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The Little Giant had been forced to identify itself three times earlier: security was tight in the Kingdom of Talnar, especially here at its center. Mourn had kept the ship decelerating at 200 G’s ever since the jump back into normal space. The Little Giant had a healthy power reserve, another hundred Standard Gravities, but Mourn saw no point in advertising the fact. He knew he would be in time, and the slower deceleration cost him only a few hours.

The Little Giant was not a big boat, but size is relative. What had once served adequately as a five-man gunboat more than sufficed as a one-man Speedster. Mourn had kept a good portion of her original armament, had installed a pair of oversized engines (both primary and secondary drives—the Little Giant was to remain a star-hopper), and had done a great deal of internal rearranging.

One-man speedsters are rare birds. Comparatively speaking, not many individuals can afford a spaceship—a starship, that is, not merely a planetary yacht. Those who can—generally, successful businessmen and star lords—have little use for a one-man boat. They carry with them a retinue of servants, associates, and what-not, all of whom need space to live, air to breathe, food to eat. Such men can afford and demand service, comfort, luxury … and company. Those are not the virtues of a tiny speedster.

Mourn was a confirmed bachelor and also a loner. He would have been by temperament, even if his job did not necessitate it. The Little Giant suited him admirably.

Mourn had wanted 400-G acceleration badly, but it just was not in the cards. The primary-drive engine required would occupy nearly two-thirds of the ship, and, with no defensive screens and a water pistol for armament, the Little Giant might manage to amble through pseudo-space at all of three light-years a day. It could outrun a freight barge—but not by much. Oars would be as practical.

At the other extreme, with the use of a smaller primary and the acceleration cut to a bare 200 G’s, the ship could, with correspondingly larger secondaries, increase its pseudo-velocity from its present six to a possible eight light-years a day … and in a tight spot never get far enough to make the jump.

As it was, with acceleration limited to 300 G’s, he could, on primary drive, neither outrun nor out-fight a destroyer. On the other hand, a destroyer could not catch him, and on secondaries no military craft in the Empire could touch him (military ships max out at 5 light-years a day). The compromise was not satisfactory in every respect; it was the best he could manage. He learned to live with it and avoided destroyers whenever possible.

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The trip itself was not long; indeed, Victor jokingly said that they would be spending more time within the two systems than they would in interstellar space. This was not quite true. The Hand of Tyr was designed essentially for intrasystem travel and consequently boasted a high primary acceleration rate: three hundred Standard Gravities, as good as a destroyer. At three kilometers per second per second constant boost, the ship took just under eighteen Standard Hours to travel the necessary twelve billion kilometers or so before being far enough out to switch over to the secondaries. They could have lazed out at two hundred gravities and lost only about four hours of acceleration time, but Victor liked to travel fast and did not believe in wasting potential: he saw no point in having such big primaries if he did not use them.

The size of the star-drive engines suffered, however, from the space occupied by the primaries, and the jump through pseudo-space to the Regalio system, nearly nine light-years away from Syrtax in the direction of Aldebaran, thus lasted two days, five hours (4 ly/day), GS (galactic standard). As an eighteen-hour deceleration period at the Regalio end was necessary to shed the ship’s acquired sub-light velocity, the entire trip took just over four days.

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Most defense missiles, including the space stations’ Wesson-Rockwell Mjollnir V’s and the Puritan Pacifiers around Sanctuary, are relatively stupid but are even faster than offensive missiles. Their 5 km/sec² acceleration, made possible by the lack of shielding and the small size of both the guidance system and the warhead, makes even a destroyer look like a freight barge.

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He saw what might have been the Marquis climbing into the Patrick Henry. The Marquis’ ship was not much taller than the Hand of Tyr but was more nearly spherical and lacked the Hand's atmosphere fins. Victor felt a flicker of hope: “credit-gobbling crate” or not, the Patrick Henry was a real warship. With a little luck, they might yet raise hell.

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“My Lord?” said Jalandra. “I didn’t want to slow things before by asking unnecessary questions, but what exactly is a war cruiser?”

“Hmmm?” said Victor absently. “A war cruiser is a cruiser-sized battleship.”

“Your pardon, my Lord. Isn’t that what an ordinary cruiser is?”

“What? I’m sorry; I forget you don’t have my background. There are three basic types of capital ships: destroyers, cruisers, and battleships. The names of the ships are holdovers from ocean navies; no matter. The three types are technically defined by certain performance and armament standards. A destroyer has 300 Gravity acceleration and five light-year pseudo-speed; a battleship has 200 Gravity acceleration and four light-year pseudo-speed. Cruisers are somewhere in the middle. With me so far? Good.

“As a corollary to the performance characteristics, a cruiser, for example, with comparatively smaller engines than a destroyer, devotes comparatively more of its space, and mass, to armament: about twice as much, in fact. Still more so for a battleship. Thus the definitions say nothing whatever about the actual size of the types. Hypothetically, one could have a battleship twenty meters long. Practically, of course, the three types have evolved into pretty standard sizes, consonant with their functions and the economics of ship building: a hundred, a hundred and fifty, and two hundred and fifty meters in diameter, respectively.

“But this theoretical quirk of the definitions leads to the possibility of various strange types. The most common is the light cruiser—more accurately termed a heavy destroyer only no one calls it that. It is simply a destroyer a hundred and fifty meters long; it possesses destroyer performance but it can afford bigger guns simply because it has more space for them.”

“Sounds like a good idea,” said Jalandra.

“Under certain circumstances, it is. But it costs about as much as an ordinary cruiser, and though it can outrun one, it can’t out-fight a real cruiser, because the cruiser can afford still bigger guns because it has smaller engines.” (as it says above, the cruiser devotes about twice as much space to armaments)

“I think I see,” said Jalandra slowly. “So what’s a war cruiser?”

“A battle cruiser is a cruiser the size of a battleship; a war cruiser is a battleship the size of a cruiser.”

After a moment, Jalandra said, “What’s the matter with them?”

Victor smiled. “A battle cruiser suffers from the same problem a light cruiser does; it’s fast, but it’s no match for other ships of its size—in this case battleships. Some marquises and barons use them, because they need speed but occasionally want something more powerful than an ordinary cruiser.

“War cruisers are, for my money, the weirdest of the lot. They’re expensive, and they can neither outrun a cruiser nor out-fight a battleship. A few of the wealthier counts have them because they’re useful in certain defensive situations. I don’t care much for them, myself; I’m an advocate of speed in ships. The faster ship can dictate the when and where—and even the whether—of an engagement.” He thought of his present situation. “Most of the time, anyway.”

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“Better, I guess,” Victor said somberly. “Considering… Even a light cruiser out-guns a destroyer by at least three-to-one.”

“But its defensive screens are only fifty per cent better.”

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(The protagonists have three ships: the destroyer R.N.S Victor, the small gun-boat Hand of Tyr and the gunboat Patrick Henry.)

Despite Ronal’s cheery fatalism, Victor was worried. The Hand of Tyr and the Marquis’ ship had a combined firepower perhaps equal to a destroyer, but that still left them well shy of the enemy’s strength. The crucial period would come when the three ships were concentrating on the destroyer, leaving themselves open for unreturnable fire from the cruiser. The Hand of Tyr was most vulnerable in that respect, not only because it was the smallest of the three—the Patrick Henry was at least a fifth larger (x1.2)—but also because of its shape.

Defensive-screen strength is dependent on only two factors: the proportionate size of the generators and the surface-to-volume ratio of the ship being shielded. A sphere has the largest volume-to-surface ratio of any geometric figure. Ergo, the invention of the defensive-energy screen nearly two centuries ago made spherical warships a necessity. Any other shape—a cylinder, for instance—possesses, for the same mass and volume, a greater surface area. The larger the area the screen must cover, the thinner it is: sending semicylinders against spheres is suicide.

(ed note: Defensive-screen-strength is in units of defensive-screen-power per square meter. So to calculate the defensive-screen strength you take the screen power output from the generators and divide it by the surface area of the ship. Screen strength of a given ship design is increased by increasing the number of generators or decreasing the surface area of the ship.)

Unlike the other two, the Hand of Tyr was only vaguely spherical. Victor’s ship was designed to function adequately as an atmosphere cruiser; hence its fins. Whatever advantages the aerodynamic shape had in atmospheric maneuvering, it was decidedly dangerous in a real battle.

The light cruiser they were facing illustrated one other quirk of that governing surface-to-volume ratio. It was simply a destroyer with a diameter one and a half times normal. It devoted proportionately the same percentage of its mass to screen generators. Although the mass of the light cruiser and its generators was twenty-seven eighths (x3.375) of that of a normal destroyer, its surface area and, hence, screen “size” was only nine-fourths (x2.25) that of a destroyer. As a result, it boasted fifty per cent greater screen strength using generators of proportionately the same size (x1.5).

(ed note:
Light cruiser diameter 150m, so volume is 4/3 πr³ or 1,770,000 m³
Destroyer diameter 100m, so volume is 524,000 m³
Assume both have same density, so mass is proportional to volume. So mass of light cruiser relative to mass of destroyer is 1,770,000 / 524,000 = 3.375 or twenty-seven eighths. Assuming screen generator proportion of total light cruiser ship mass is the same as for a destroyer, the light cruiser's screen generator power is also x3.375 that of a destroyer.
Light cruiser diameter 150m, so surface area is 4πr² or 71,000 m²
Destroyer diameter 100m, so surface area is 31,000 m²
Light cruiser surface area relative to destroyer is 71,000 / 31,000 = 2.25 or nine-fourths
Light cruiser screen strength relative to destroyer is screen generator power (relative to destroyer) divided by surface area (relative to destroyer) or 3.375 / 2.25 = 1.5 or fifty percent greater screen strength)

By the same token the weapons proportion will also be x3.375 that of a destroyer. Since a standard cruiser has a diameter of 150m, but devotes twice the proportional mass to armaments, a standard cruiser's weapons power will be 3.375 × 2 = 6.75 times that of a destroyer.

Thus, size, although it did not necessarily limit speed, did increase a ship’s offensive and defensive capabilities. Only economic considerations prevented all three warship types from growing into unstoppable juggernauts of satellite size.

      Right, serious history, that’s why I’m here and why a chunk of you follow me so...

     Today I thought I’d describe the differences between the type of warships engaged in the First World War starting with battleships:

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Orion class Super-dreadnought

     Super dreadnoughts: starting with the Orion class (1911) was basically a much bigger dreadnought (see below) as over time displacements had grown by 2000 tons, the new 13.5” gun became available with turrets arranged to superfire over each other. This was the pinnacle of design

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HMS Dreadnought

     Dreadnought: The commission of HMS Dreadnought was ground breaking in 1905-6 and was one of those developments that made all else obsolete. It embodied long range gunnery of the more numerous main heavy Cali remains guns with the smaller secondary armament.

SMS Prinz Eugen

     Dreadnoughts evolved overtime to get larger secondary armament to deal with the more pressing destroyer threat. More importantly a fresh naval arms race around the world (notably Britain and Germany) began and even Austro-Hungary built 4 to combat Italy.

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HMS Canopus

     Pre-dreadnought: these “obsolete” battleships were smaller with a main armament in turrets, with slightly smaller calibre guns in emplacements along the hull designed for fleet actions at close range. By 1914 very vulnerable to a battle with Dreadnoughts

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SMS Moltke

     Battle-cruisers; These were the cream of the cruiser force and were a hybrid of battleship and armoured cruiser carrying large calibration guns but with the speed of a cruiser. Hipper and Beatty’s bore the brunt of the fighting in the North Sea.

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SMS Scharnhorst

     Armoured cruisers; First built in 1873 in Russia the Armoured Cruiser was designed to pack a punch against other cruisers but be able to escape a battleship and was defined by a thick armoured belt on the mid to upper hull.

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HMS Bristol

     The Light Cruiser was a very lightly armoured but quick warship often used for scouting & patrol duties. By 1909 they also sported a similar but lighter armoured belt to the Armoured Cruiser.

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SMS Kaiserin Elisabeth

     Protected cruisers; Much older and fairly obsolete for fleet action the Protected cruiser only sported armoured decks and a protective shield around vital ship’s machinery and armoured gun emplacements

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SMS Cormoran

     Unprotected cruisers; The only armour these lightly armed (and very obsolete ships) carried was the protective shell around vital machinery. SMS Cormoran had been downgraded to the status of gun boat

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HMS Eden

     Destroyer/torpedo boat. During the late 19th century there was a growing belief that fast lightly armoured ships could cut through cruiser screens & torpedo the vulnerable below the water armour of battleships. Also used for escorting convoys.

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SMS Iltis

     The Gunboat; basically designed for bombarding small shore targets as naval support such as the battle of the Taku forts during the Boxer rebellion where SMS Iltis got the Pour le Mérite.

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Cadmus class

     Finally, Sloops; very lightly armed & armoured not meant for fleet engagements but used for convoy escorts and light naval duties. The Cadmus class were used effectively as gun support from the rivers during the Mesopotamia campaign.

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HMS Raglan

     Additionally, Monitors: Unlike the 19th Century variants these were lightly armoured but fitted with large calibre guns for shore bombardment. Their shallow draft allowed them to get closer to shore & small size harder to hit by enemy gun emplacements.

Yup, spaceships again. Between Star Citizen, the new Halo, the new Star Wars, a couple of key mods for Sins of a Solar Empire that I keep up with and have done some voice work on, and Destiny, my mind has been buzzing with them. I’m a huge nerd who thinks of things in my free time like “if I were a shinigami what kind of Zanpakutō would I have?” and “I wonder if I’d rather be a ranger or a mage” and “if I were a Jedi in the New Jedi Order, what kind of ship would I have?” And alongside that sort of inane theorycrafting and imagination comes obvious questions, like “would I want to captain a cruiser or a carrier?” But then, what exactly is the difference?

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There are lots of different ship classes in science fiction, and I’m not talking about the designated name for a particular frame (like Victory-class or Firefly-class). I’m talking about classification of ship roles; or ship types. You have your cruisers, your destroyers, your frigates and corvettes, your dreadnoughts, and all sorts of other roles. But something that always confused me is exactly what the differences are between them. If you had shown me two ships and claimed one was a destroyer and one was a cruiser I wouldn’t have really understood what that actually means and what roles they employ in a battle. How is a battleship different from a battlecruiser? Is there any difference between a star cruiser and an assault cruiser, and if so what is it?

So like any good geek I did research and actually enjoyed doing it! And the knowledge I’ve gained I want to spread for anyone who is interested, whether that be due to simple curiosity or you’re developing a story or RPG setting. Because knowledge is power.

Before we get to the meat of the topic let’s look at a bit of history. When science fiction writers were exploring space they drew a natural comparison between space travel and the maritime Age of Sail; both feature long voyages on large vessels through “alien” terrain that human beings can’t freely traverse. As such, naval terminology entered the lexicon very quickly, and as a result spaceships are classified by similar naval systems. That’s also likely the reason why the branch of the military that deals with spaceships in fiction is very commonly called the Navy.

Naval warfare, particularly way-back-when in the 17th Century or so, was rather stringent and refined. The British in particular had very strict guidelines on ship classification, roles, and tactics. As time went on the definitions for particular warships and roles blurred until we hit modern day navies. Back in the day, like 17th Century back, a common tactic was the naval “Line-of-Battle,” introduced by the Portuguese in the 15th Century. The idea is that your fleet would very literally line up in a single-file row and turn their broadsides toward the enemy. This gave all ships within the line free sight to fire on the enemy fleet without fear of hitting an ally. Battles could play out with enemy fleets sailing parallel to each other and firing into one another, though the ideal situation had your line slicing perpendicularly through the enemy’s line at some point. Ships that could survive standing within the line were thus referred to as “ships of the line (of battle)” or “line-of-battle ships.” Other ships existed that were not ships of the line, and they usually had other tactics to employ and jobs to fulfill. (This is important information for later; I promise.)

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Let me touch a bit on capital ships and flagships. William S. Lind explains the concept of a capital ship extremely well; “These characteristics define a capital ship: if the capital ships are beaten, the navy is beaten. But if the rest of the navy is beaten, the capital ships can still operate. Another characteristic that defines capital ships is that their main opponent is each other.” In short, a capital ship is a ship that doesn’t need the rest of the fleet to function, and can operate independently of a fleet while being the main target of other capital ships (not that they are impervious to the fire of other ships, but that generally capital ships will seek each other out for direct confrontation). Note that this definition refers strictly to independence in a large-scale engagement. Plenty of other vessels can operate independently in other scenarios, such as patrol, but in a large-scale battle they would not be able to combat the enemy fleet if the capital ships fell. Capital ships are generally some of the largest and most heavily armored ships in a fleet. However, they should not be confused with flagships. A fleet can have multiple capital ships within it; the term simply describes the capabilities of a particular vessel. But an individual fleet will only ever have one flagship at a time, the “lead” ship, which the admiral/general/fleet commander resides on and operates from. Flagships are often capital ships (as they generally want to be the biggest, most powerful ship in the fleet), but by definition whichever ship has the fleet commander on board will fly the flag and thus be considered the flagship. Usually, this is a specifically designated vessel but the title can jump around as needed between ships.

So, from here on out I’ll be explaining the various classes of ships, their histories, and how I would personally define what the role a spaceship of that kind would take. I’ll also provide specific examples of each ship type as I go. A word of warning, though; even in the real world rules are and were constantly being broken. Ships technically designed as one type of vessel may perform the operations of another type equally well, or some countries may have different rules from each other and thus classify two vessels of almost identical capability differently. Not only that, but as technology improves the various types can become so alike that it can be very difficult to draw a line. A further problem (which comes up very often in sci-fi) is technological superiority; that is, a ship classification in one species’ navy may not be equal to the ships of the same classification in another species’ navy. For example, one navy’s corvette may be large enough and powerful enough to be more than a match for another species’ destroyer or cruiser. What’s important when we talk about ship classification is the comparison of ships within the same navy. So while that corvette may be a cruiser as far as the alien race is concerned, what’s important is that the species that built it considers it a corvette.

Just remember that this guide exists as just that; a guide. It is not a strict law, the rules of which can never be broken. Feel free to break these rules if it makes sense for you to do so.

Let’s go from the smallest ships to the relative largest. For each type I’ve bolded particular characteristics that stand out to me and help cement the ship’s role. I’m just going to be going over warships, so things like freighters or single-pilot ships will not be getting the once-over.

Corvette

The word “corvette” comes from the Dutch word corf, which means “small ship,” and indeed corvettes are historically the smallest type of rated warship (a rating system used by the British Royal Navy in the sailing age, basically referring to the amount of men/guns on the vessel and its relative size; corvettes were of the sixth and smallest rate). In complete honesty I have not found much information on what role corvettes tended to employ; or at least nothing extremely concrete. By all rights, early corvettes are essentially just smaller, less effective frigates; they were more lightly armored and armed than frigates, while not being as quick or maneuverable. They were usually used for escorting convoys and patrolling waters, especially in places where larger ships would be unnecessary. Corvettes could also be used for taking out larger vessels already crippled by other ships, almost making them akin to scavengers. Later corvettes in modern navies (around WWII) started filling a niche as antisubmariners, minesweepers, and trawlers (it might be more accurate to say that those kinds of vessels started being called corvettes, but the effect is the same). In many ways, corvettes existed just to have a ship or two (or ten) available; being smaller and more lightly armed meant that they were cheaper to construct, and that is important when discussing anything in history. It takes money and resources to build things, so you can’t just build a bunch of the best thing.

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In Sci-Fi – Corvettes would be the smallest warships, designed for escort and patrol, anti-mine, or anti-stealth. They would be used where larger ships with more firepower are not deemed necessary (such as backwater worlds or low-risk areas) or where a larger ship would be unsuitable for deployment. Corvettes might be outfitted to have some sort of stealth or cloaking system for reconnaissance or spec ops missions; naturally it would be easier to cloak a smaller ship than a larger one (though plenty of examples of large stealth ships exist). In some series they are likely to be diplomatic vessels due to their small size and speed, particularly seen in Star Wars, and can commonly act as blockade runners (again; their small size and speed makes them ideal for slipping through a blockade, where a larger ship presents more of a target). They would, ideally, never be used for direct combat in large scale engagements due to their extremely light armor and weapons, but may be employed in a battle to lay down or destroy minefields, uncover stealth ships, act as stealth ships on their own (for whatever purpose needed), or for dispatching already crippled vessels.

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Frigate

“Frigate-built” was a term used in the 17th Century describing a warship that was built to be quick and maneuverable. They were often too small to stand in the “line of battle” and usually had only one weapons deck (but sometimes two). By the 18th Century the term had been modified slightly to include ships that may be as long as a ship of the line but were still designed for speed and had lighter weaponry, making them useful for patrols and escorts. The 19th Century brought armored frigates to the world, which were actually regarded as being the most powerful warships at the time. They were still known as frigates because they were lightly armed with only one deck of guns. Modern frigates are generally used as escorts for other warships and convoys. As I mentioned earlier, frigates and corvettes really are very similar in their designs and roles; frigates just tend to be larger (and thus more expensive to build) and had more firepower, so they could engage in direct combat more effectively.

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In Sci-Fi – Based on their history, space frigates would probably be best defined as smaller vessels with light armament and armor (but more powerful and larger than a corvette), suited for speed and maneuverability. They’d often act as patrol and escort vessels, whether for a merchant convoy, a single capital ship, or a fleet. Their agility and maneuverability means they can move to redeploy and protect other ships better than larger, slower moving vessels. You’d likely see a strength-in-numbers strategy with them. Frigates, unlike corvettes, would more commonly see direct battle and would probably not be found with stealth drives in most settings; they are simply getting too large by that point.

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Destroyer

Destroyers are comparatively modern ships. Historically, they were designed after the emergence of torpedo boats (quick, frigate-like ships which employed newly invented self-propelled torpedoes as their main arms) in the late 1800s. Torpedo boats were faster and more maneuverable than larger ships, able to bear down on a battlecruiser and take it out with its torpedoes. Destroyers were originally designed as, and named, torpedo boat destroyers, but at some point became referred to simply as destroyers when their roles expanded. They went through many iterations, but were essentially smaller cruisers designed with the sole purpose of hunting down and destroying torpedo boats, and had much more powerful weaponry as well as torpedoes to fulfill this purpose. As such, they were employed as escorts for larger, slower warships (to protect those warships from torpedo boats). They were designed to have the long range and speed to keep up with their fleet, and over time this fact plus their multi-purpose capabilities meant that destroyers began seeing more use as advanced scouts for a fleet as well as direct fleet combatants, anti-submariners, and anti-submarine patrol. Destroyers operated in destroyer divisions or units composed of multiple destroyers in order to carry out these tasks. By WWII destroyers began filling in a niche as (what I’ll very simply call) anti-everything vessels, extremely powerful high-value targets due to the number of guns they would field. In fact, this pushed several countries to develop smaller corvettes and frigates as anti-submariners in order to take some of the heat off of destroyers.

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In Sci-Fi – Destroyers would be much like their naval counterparts; ships smaller than cruisers (and usually larger than frigates, though not always) but armed to the teeth with a multitude of weapons. They’d mostly act as escorts for larger fleets (and likely not for single warships, but exceptions would certainly exist) but can be seen operating in destroyer-only divisions as well. You could expect to find destroyers fulfilling all sorts of roles because of how multi-purpose they are, even roles that could be fulfilled by other types that are designed for that purpose. It would, however, be rare to find a destroyer acting on its own in most circumstances; destroyers are not capital ships and do not operate as patrol craft. They do not operate independently as a rule, though I know of at least one case in fiction where a super-destroyer acted as an independent ship. Science fiction, as I mentioned previously, breaks a lot of rules.

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Cruiser

In the Age of Sail “cruiser” was a term used to describe ships which underwent “cruising missions;” that is independent scouting, raiding, and commerce protection missions. These “cruiser warships” were normally frigates and sloops because there simply wasn’t anything else available at the time. By the mid 1800s ships began being constructed that were specifically designed for this sort of work, and as such were called “cruisers”. They could be smaller, like a frigate, or larger, but it was not until the 20th Century that they were consistently scaled to be larger than a destroyer but smaller than a battleship.

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Cruiser roles in the late 20th Century included anti-air defense, shore bombing, and commerce raiding, depending on the navy. However, the increasing firepower of aircraft made it so that individual cruisers could no longer operate safely, pushing navies to have their cruisers operate in fleets. Because of this, cruiser fleets were also specialized for particular roles (like anti-submarine or anti-air) and the generalized cruiser fell out of use.

In Sci-Fi – Cruisers are medium-sized vessels, able to operate independently but also commonly seen within a fleet. They would have the capacity to be used as anti-fighters, planetary bombers, raiders of enemy supply lines, and scouts. However, they would also be the type of ship most likely to engage in non-combat roles such as exploration or even colonization due to their ability to operate independently for extended periods. I would not expect cruisers to commonly be used in front-line assaults of an enemy fleet; that role is better left to other ships. However, they have the firepower, size, and better defensive capability to go up against other ships when needed and it’s not uncommon to see cruisers making up the bulk of fleets in some settings. It is however, in my admittedly amateur opinion, not the ideal choice; better to fill in that space with destroyers or battlecruisers and battleships. Cruisers can be considered capital ships in some settings (and in fact, some settings treat any ship over a certain size as a capital ship, regardless of role).

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Battlecruiser and Battleship

Battlecruisers (or battle cruisers) are the first vessels in this article to commonly be considered capital ships. They are similar to battleships, having a similar armament and size, but were generally faster and not as heavily armored by comparison. Originally fielded by the UK in the early 20th Century, battlecruisers were designed to combat and destroyer slower, older armored cruisers through heavy gunfire. As time went on (around WWI) they began seeing use as general-purpose ships alongside battleships by all manner of countries. Unfortunately, battlecruisers were generally inferior to battleships, and in the Battle of Jutland this was perfectly exemplified as both navies lost battlecruisers but no battleships; the light armor of the battlecruisers made them easier targets for heavy guns. As technology improved battlecruisers were designed with heavier armor. At the same time, battleships began becoming faster. These similarities would ultimately cause a blurring between the two types, and by 1922 the Washington Naval Treaty considered battlecruisers and battleships functionally identical. The Royal Navy continued to refer to pre-treaty battlecruisers as such, and WWII saw a re-emergence of modernized “cruiser-killer” battlecruisers. However, only one such vessel actually survived the war, cementing again their general inferiority to battleships.

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The term “battleship” is a contraction of phrase “line-of-battle ship” from the Age of Sails. If you remember, ships of the line were the largest and most powerful ships that a navy could field and were strong enough to stand within the line of battle. Modern battleships arose from ironclad battleships in the late 19th Century, and battleships were for decades considered the most powerful type of naval warship. They were characterized by very heavy armor and large-caliber guns, making them key capital ships. So influential were they that treaties such as the Washington Naval Treaty were designed, partially, to limit the number of battleships that a particular country could have. They represented naval might and power, and battleships were so influential in their strength that the simple existence or presence of a fleet, even without leaving port, could create psychological victories for a navy (called a fleet in being). Battleship tactics often saw other vessels, such as destroyers or cruisers, employing scouting and raiding missions in order to locate enemy fleets before the battleships came in to sweep aside the enemy. Despite these strengths, battleships were susceptible to smaller weapons such as torpedoes, mines, and aircraft missiles (and thus required the presence of smaller escort ships such as frigates and destroyers to protect them; it’s all circular). If your battleships fell the fleet would fall, as is the accepted definition of a capital ship. Presently there are no battleships currently in service anywhere in the world.

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In Sci-Fi – Despite their unfortunate history, battlecruisers in space tend to operate similarly to battleships, and I would argue there is not much distinction between the two owing, partly, to the blurring of both vessels in our history. Battlecruisers and battleships, thus, often act as the heavy hitters in a fleet; they are the main combatants and are protected by other vessels such as frigates and destroyers. Being that they are capital ships, an engagement is usually won through battlecruisers and battleships. If a distinction is made between the two types then battlecruisers would likely be quicker and less heavily armored than battleships, and in some settings are not even considered capital ships at all. But again; rules can be blurry and broken at the whim of any author. Regardless, battlecruisers and battleships are the truly massive, anti-“large vessel” ships in a fleet. They are meant to take a lot of punishment and dish out that punishment in kind. One particular term I see fairly often is “star cruiser.” In my mind, a star cruiser could either be the equivalent of a cruiser or a battlecruiser; that distinction is likely decided by whether or not star cruisers are considered capital ships, since that then determines the general capabilities of those vessels. As a general rule I would be bold enough to claim that star cruisers are equivalent to battlecruisers, and named as such because space.

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Carrier

Aircraft carriers, like destroyers, are very modern classifications. They are the one vessel in today’s navies that almost anyone can pick out at a glance without fear of mistaking them for something else. This is due to their extremely obvious design; a very large, flat deck suitable for landing and deploying aircraft. Put as simply as possible, carriers carry aircraft (whether plane or helicopter depends on the ship). Historically, the concept of utilizing seagoing vessels for airborne operations was considered as far back as the early 1800s (though with balloons rather than planes). It was not until the early 1900s, with the invention of seaplanes, that actual aircraft launched from a ship become prominent. Back then, an aircraft with floats was launched from a modified cruiser or capital ship with a catapult, then recovered by a crane after it would later land in the water. Semi-successful uses of ship-borne craft in 1914 showed the world how effective such assets could be in war, and heavier-than-air craft started becoming more valuable for the world’s navies. By 1922, with the Washington Naval Treaty, battleships and battlecruisers (which most navies had too many of to be legal under the new treaty) were being converted into carriers. The flat-topped design did not become prominent until the late 1920s.

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No one can deny the value of single-fighter aircraft. Planes provide a new dimension from which to attack and defend, and can carry payloads ranging from missiles to bombs to supplies for ground troops. Aircraft were extremely effective compared to even the best guns as they were more accurate and had the benefit of extreme maneuverability. That said, carriers suffered from a lack of personal offensive and defensive ability, and relied on their aircraft or the rest of their fleet to protect them. Even so, their aircraft can be considered an extension of themselves and the reign of the battleship was brought to a close when U.S. ship-borne craft sunk numerous Japanese super battleships, the largest battleships ever made.

In Sci-Fi – Carriers tend to be some of the largest capital ships around due to the need to hold and transport large numbers of fighters, bombers, and other craft. Typically, though not always, their hull-mounted armaments are light; carriers usually rely on the large numbers of fighters they carry (when operating solo) or their fleet for defense and attack of other ships. The ability to carry craft does not make a ship a carrier by default; many frigates and cruisers, for example, will carry a complement of fighters or a few ground vehicles. In order to be considered a true carrier the vessel’s main role needs to be the transport and deployment of smaller craft (or troops; as far as I’m concerned not all carriers are extremely large and I would classify troopships and assault ships as small carriers).

Dreadnought

It’s difficult to talk about historical dreadnoughts without also talking about battleships. The first dreadnought was the Royal Navy’s HMS Dreadnought, a large and heavily armored battleship that ran on steam turbines (and thus made her the fastest battleship at the time). Dreadnought operated on an “all-big-guns” philosophy, giving her more heavy-caliber guns than any other ship at the time instead of smaller, quicker-to-fire secondary guns. Her creation was extremely influential in her time, and she spawned a new variant of battleship called “dreadnoughts” (and battleships made before her were designated “pre-dreadnoughts”). Thus, strictly speaking, dreadnoughts are just particularly large and powerful battleships. As such they carry the same characteristics of battleships; they are capital ships, represent naval power and influence, and would need a fleet to protect them from smaller vessels and weaponry.

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In Sci-Fi – Dreadnoughts are just about always gigantic ships; massive vessels that dwarf even the largest battleships or battlecruisers. The role they fulfill is exactly like a battleship or battlecruiser; complete dominance and superiority. Intimidation, even more so than with battleships, is the name of the game when it comes to dreadnoughts. When you have a multi-mile long ship bearing down on a fleet you know the enemy’s morale is precarious at best. Due to their large size they can often carry a large number of secondary craft, like a carrier, but their extremely powerful armament would tend to exclude them from that definition. A dreadnought carries a bunch of craft because it can, and this adds to its lethality. But its true strength is its overwhelming firepower, plus its usually resilient armor.

Other Terminology

Whew. We’re about 5000 words in and I’m starting to lose steam, but let’s go over a few other things before I end today. You may have noticed some terms floating around that I’ve used but not really elaborated on, like “heavy” and “assault.” Those terms actually mean something, and so I’m going to take the last part of this article to explain them.

Armored: This is very self-explanatory and I don’t think I have to spend many words on it. An armored vessel is one with more resilient-than-normal armor than others of its type. They can, theoretically, take more punishment.

Assault: By definition, an “assault” in warfare is usually the first phase of any particular attack. You can have aircraft assaults, or spaceship assaults. However, sci-fi lexicon also seems to borrow the term from the concept of amphibious assaults. These are operations where ships land ground (or air) forces upon a particular location through some sort of landing site like a beach; D-Day in World War II is a prime example of this. Assault vessels, therefore, are designed for assaulting an enemy planet, installation, space station, etc. They are usually designed to carry large numbers of troops, vehicles, drop ships, supporting aircraft, and the like; they assault the planet by being the first ships to touch down and dispense their payload and then get the hell out of dodge while the ground forces do their thing. Sometimes they need the brunt force of a fleet to allow them to get to the planet in the first place, but then you have ships like the Covenant’s CAS-class assault carrier that can do that job themselves.

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Light and Heavy: I described the Halcyon-class (from Halo) as a light cruiser, while the later Autumn-class is a heavy cruiser. So what’s the difference there? Generally speaking, whether a particular vessel is light or heavy refers to the payload of its weapons. Sometimes the resilience of its armor may come into play (again; exceptions exist), but overall a vessel’s status as light or heavy is dependent on its guns. A light vessel has a lighter armament, while a heavy vessel, naturally, has a heavy armament. As such, you’d expect heavy vessels to be more useful in an engagement. Light vessels, meanwhile, would probably see more use in non-combat and support roles. At the very least they are less specialized for direct large-scale engagements. The various frigate classes in Halo are perfect examples of this; the Paris-class is a heavy frigate and very specialized for space combat. The Charon-class and Stalwart-class light frigates, meanwhile, were more jack-of-all-trades ships that saw more use as ground-support vessels and fleet support. Of course remember; sometimes you gotta make do with what you have available.

Super: I think this one is fairly self-explanatory as well. A super vessel is, for lack of a better word, just a bigger version of whatever classification of vessel it is we are talking about. Because of their increased size they almost always have much better armor and much stronger weapons than the “normal” variant.

• 

And there you have it. Hopefully you have a better understanding of space combat and ship classification. I know I learned a lot by doing this; already I’ve starting thinking about things differently. Just the other day I finished the Ciaphas Cain: Hero of the Imperium omnibus and I had a better appreciation for some of the scenes in the last book (The Traitor’s Hand) that described a battle taking place in the planet Adumbria’s orbit.

Please don’t hesitate to use this information however you see fit. I hope it brings a sense of realism and authenticity to your games and I hope you appreciated my attempt at a comprehensive guide to ship taxonomy. With any luck it did someone somewhere some good.

• 

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BATTLE CRUISER A large COMBAT SPACECRAFT; almost always a STARSHIP. As the name implies, it combines the firepower of a BATTLESHIP with the high speed, large cruising radius, and general dashing flavor of a cruiser. Although larger space warships exist (TECHJARGON terms being Dreadnought, Annihilator, etc.), Battle Cruisers seem to do most of the work, and are the mainstay of most interstellar battle fleets.

Their type name is seldom hidden behind Techjargon; people in future centuries (and even wholly alternate universes) apparently find this First World War-era terminology irresistable. Battle Cruisers do have one important similarity to their prototypes at Jutland: they frequently blow up with spectacular explosions.

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BATTLESHIP A large COMBAT SPACECRAFT, intended to be the primary backbone of a fleet. Battleships have somewhat fallen out of use, being largely replaced by BATTLE CRUISERS, though for no very obvious reason. (But see TRADE FEDERATION.)

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BATTLE STATION The largest class of COMBAT SPACECRAFT, these may range from a few kilometers in diameter to the size of a small planet. TECHJARGON terms include Orbital Fort and Death Star. A few are in fixed parking orbits, as you would expect of such massive constructions, but most Battle Stations are remarkably mobile, and are liable to turn up anywhere. Their firepower is in line with their size; most can SLAG a planet with their secondary batteries, and the main armament must be intended to make stars go supernova.

Battle Stations also have multiple layers of defensive weapons and protection, and can easily hold off entire fleets of BATTLE CRUISERS. However, all Battle Stations have a critical design weakness. They can easily be blown up, but only when attacked by the smallest of all Combat Spacecraft, SPACE FIGHTERS. Indeed, the primary mission of Space Fighters seems to be to destroy any enemy Battle Station they happen upon.

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CLOAKING DEVICE This is the usual TECHJARGON for stealth technology used in SPACE WARFARE. When used, it converts Space combat from a stand-up drag-out into submarine-style lurk-and-shoot action more like "Das Boot." Cloaking Devices, alas, are almost pure HANDWAVIUM, whereas hardly any of that costly stuff is needed for the other guy's SCAN gear that is searching for you.

The closest you can get to a Cloaking Device without piling on too much Handwavium is to surround yourself with some sort of opaque mini-nebula, like a sea destroyer laying smoke. The enemy's Scan will still give your approximate position, and how much energy you're putting out, but at least this will fuzz things up a bit and make it harder for him to score a hit. Of course, if the enemy can't see in, you can't see out, either. This is inconvenient.

In any case, Cloaking Devices never work as advertised. Someone on board — either a particular dumb ensign, or the Science Officer — invariably hits the wrong button, sending out a transmission that pinpoints your location to the centimeter.

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COMBAT SPACECRAFT Space vehicles, generally with crews, designed and used to zap or otherwise blow up enemy Combat Spacecraft in the course of SPACE WARFARE. Classes in common service range from SPACE FIGHTERS up to BATTLE STATIONS. Except for the last, TECHJARGON is seldom used to characterize them. Instead, most have type names that could have been found at the Battle of Jutland (e.g., BATTLE CRUISERS).

Even though the earliest interplanetary exploration, in the late 20th century CE, made extensive use of automated, crewless spacecraft, these seldom appear as Combat Spacecraft. This is odd, because not only would use of drones reduce casualty lists, but it would save on the cost and bulk of life-support. But who wants to see, or read about, battles between drones? (See also ROBOTS.)

Combat Spacecraft must require a good many auxiliary support vehicles, the equivalent of tenders, repair ships, oilers, and so forth. But these seldom get much attention, any more than their seagoing counterparts do.

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DESTROYER A class of fairly small to medium-sized, fast COMBAT SPACECRAFT. Usually they are STARSHIPS. The mission of Destroyers, as of their ancient oceanic namesakes, seems primarily to be escorting larger Combat Spacecraft such as BATTLE CRUISERS.

What they are protecting their larger consorts against, or why Destroyers can defend such powerful ships better than they can defend themselves, is not altogether clear. (On ancient Earth, seagoing Destroyers evolved to counter specific threats, such as submarines, which have no obvious equivalent in Space.) Escorting Destroyers might be most useful in protecting gigantic BATTLE STATIONS from the one threat they are helpless against, namely SPACE FIGHTERS.

Like their ancient prototypes, however, Destroyers often serve mainly as general-purpose light combatants, in which case they are more or less equivalent to FRIGATES.

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FRIGATE A medium-sized class of COMBAT SPACECRAFT, normally a STARSHIP. Frigates are widely used for escort, scouting, and general patrol duties; in overall configuration they probably resemble scaled-down BATTLE CRUISERS. Alternative TECHJARGON usages are Scout, Cruiser, etc., though sometimes a DESTROYER serves essentially the same function.

This term, which most people associate with Horatio Hornblower or "Old Ironsides," might seem a curious choice to apply to an interstellar Combat Spacecraft. But there were oared fregatas in the 16th century CE, and guided missile frigates through at least the early 21st century, so the type has had a remarkably long run. Only triremes had a longer service life, but their DRIVE did not prove adaptable to operations in SPACE.

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SPACE FIGHTERS Small, fast, highly maneuverable COMBAT SPACECRAFT. They have very limited range (never FTL), and no crew habitability to speak of; they can only operate for at most a few hours at a time. The crew is limited to one person, or occasionally two. At least among EARTH HUMANS and ALIENS WTH FOREHEAD RIDGES, these are usually males in their early twenties, known for their swagger, coolness, and fast moves on any attractive female of an INTERBREEDABLE species. (Who REALLY ALIENS use to crew their Space Fighters is not known.)

Because of their short range, Space Fighters usually must be carried into action by TRANSPORTER ships, though in some cases they will be carried piggyback on other, larger Combat Spacecraft. Their tactical value is unclear, since the are really just small spacecraft themselves. Since they don't operate in an essentially different medium, the way aircraft operate in a different medium from surface ships, there is no fundamental reason why they should be all that much faster. In naval terms they are more analogous to motor gunboats than to airplanes.

Mostly Space Fighters fight each other, which is logical enough in itself but doesn't explain why they are used in the first place. Only two other missions can be identified for them:

1. To destroy gargantuan BATTLE STATIONS, which are vulnerable only to attack by Space Fighters.
2. To give prominent roles to young males in their early twenties, so they can display their swagger, coolness, and fast moves on any attractive female of an Interbreedable species.

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SPACE WARFARE This is what the general public thinks of as WARFARE in SF: COMBAT SPACECRAFT zapping away at each other in deep Space. In HOLLYWOOD SCIFI they whoosh and gyrate like atmospheric aircraft, in blithe indifference to the vacuum of space and the laws of physics. They also seem to fight at astonishingly close range, more like Trafalgar than Midway. Written SF is somewhat more careful — the audience is more sophisticated, and anyway a book doesn't need a sound track for battle sequences...

...Whatever the Techlevel, however, the organization of Space Warfare is almost invariably based on naval usage. Most Combat Spacecraft (except for the largest and smallest) are called ships, and service ranks will include crusty Chief Petty Officers, naive Ensigns, capable Captains, and anxious Admirals. This is broadly reasonable, if — as is usually the case — space travel is assumed to involve journeys of days or weeks, so that crews necessarily live on board (unlike, say, tanks or aircraft).

However, space fleet organization is usually based specifically on 20th century CE naval organization, especially the first quarter of that century. This one brief period in the distant past seems to be taken as a model by planners everywhere in the Known Galaxy. BATTLE CRUISERS and DESTROYERS abound in fleets, and while you will sometimes be attacked by a FRIGATE, you'll never encounter a dromon or a pinnace in space combat. And, while on rare occasions you may encounter EMPIRE fleets commanded by Consuls, I have not yet heard of one commanded by a Captain-General — even though the 16th century CE might be a better model than the 20th for a civilization expanding into open space. (This, by the way, is a deficiency I intend to remedy.)

It is also a curious fact that Space Warfare has tended to lag real-world naval developments by a few decades. BATTLESHIPS and (especially) Battle Cruisers continued to be the queens of the space fleets right through the 1960s, long after their prototypes had been relegated to amphibious gunfire support, or the scrapheap, by the dominance of aircraft carriers.

This changed abruptly a long time ago (1977 CE) in a galaxy far, far away (20th Century Fox). Suddenly deep Space — especially Hollywood Scifi deep Space — became infested with X-wing, Y-wing, and Z-wing SPACE FIGHTERS. Squadrons of Battle Cruisers contended futilely against them, zapping away in vain with their heavy weapons like someone trying to swat flies with an axe. Oddly, though, Battle Cruisers remain in production; evidently fleet staffs have noticed that Space Fighters can't actually damage anything except each other (and of course the occasional behemoth BATTLE STATION).

It may now be just about time for Space Warfare to catch up to the 1970s, in which case we should see a proliferation of medium-sized Combat Spacecraft armed to the teeth with MISSILES. In fairness, some fleets have been using Missiles as primary weapon for years (and I will be joining their ranks).

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TRANSPORTER This is a TECHJARGON term that may be applied to either of two entirely unrelated technologies.

2) A COMBAT SPACECRAFT used to carry short-range SPACE FIGHTERS into action. This type of Transporter is essentially a spacegoing aircraft carrier, except that it doesn't need a flight deck. If the civilian TRADE ships in use carry their cargo in external pods, they can be easily converted into Transporters for war service. Alternatively, larger Space Combat Vehicles can carry Space Fighters themselves, reducing the need for a specialized ship to do it.

• 

      Rumors are being heard about a civilian study of Imperial naval doctrine which may cause a major explosion in the Navy's methods of ship procurement.

     This study was conducted by Interstellar Technical Consultants of Mora, in response to an IN request for an analysis of the relative merits of battle riders and battleships in naval policy. This has always been a difficult subject, with many partisans on both sides but no agreement. All that can be said of the ITC study is that it will undoubtedly provoke quite a reaction.

     Details are not available for the most part, since much of the report is classified, but the broad outlines are now known.

     The controversy surrounding the two types of capital ship has been built on one key point: that a battleship derives much of its value from the fact that it has a jump drive, for which advantage it pays a considerable cost in terms of mass that could otherwise produce energy or house weapons. A battle rider — essentially a battleship without a jump drive, delivered on target by a mother ship, which usually carries a full squadron is more powerful, kilogram for kilogram, and frequently less expensive, as well.

     Thus it is argued that a 70,000-ton battleship will always be severely handled by a 70,000-ton battle rider, which demonstrates the superiority of the battle rider concept.

     The ITC study contradicts this view, labelling it "specious" and a "sophistry".

     The argument is that in truth, the strategic value of a 70,000-ton battle rider is nil; it is merely a very large system defense boat. Only when it is mated with the mother ship's jump drive does it acquire strategic value. Therefore, in comparing the relative combat effectiveness of a battle rider and a battleship, the battle rider's share of the mother ship's mass should be added.

     In the example being used, it is not fair to compare a 70,000-ton battleship to a 70,000-ton battle rider; after including the equal share of the mother ship's jump drive and fuel, the battle rider would actually be equivalent to something like a l20,000-ton battleship.

     The ITC report drily notes that it comes as no surprise that a 70,000-ton battleship would be defeated by a l20,000-ton battleship.

     Furthermore, the report cites other disadvantages to battleriders.

     Among these is the well-known vulnerability of a battle-rider squadron to the loss of its mother ship. Whole squadrons can he cut off and forced to surrender by a few well placed shots, The mother ship cannot adequately defend itself without becoming a major warship itself, a self-defeating design philosophy. Furthermore, using the battle riders to defend the mother ship restricts them to a defensive role. Lack of iniative is to some extent rewarded, a lethal mode of thought in a naval battle.

     Another disadvantage is difficulty in deploying battle riders. If an objective or mission calls for the presence of a single capital ship, or perhaps two or three, battle riders are difficult to use in such a role, because they can generally only be deployed as integral squadrons of a half-dozen or more. The only way to send a single battle rider on a mission is to send a mother ship with it. Battle riders thus must be deployed with the main battle fleets, and during times of peace, cannot be used for the "gunboat diplomacy" so often seen on the Imperial fringes.

     The ITC study also claims that battle riders are, contrary to current opinion, actually undergunned in comparison to battleships. This rather esoteric argument relies on the fact that the number and caliber of weapons carried by a warship is determined not by available power, since there is generally enough power available for many more weapons than the ship can carry if a trade-off in maneuverability is accepted but, by the mass, surface area and shape, and crew size of the ship involved. All other things being equal, in other words, to the sheer size.

     Therefore, even though a 70,000-ton battle rider is equivalent to a 120,000-ton battleship, the battle rider is armed like a 70,000-ton battleship, not a larger one. It is exceptionally well-armed and has vast reserves of power — but it is still armed only to the scale of a ship half its equivalent size, which would ensure that a l20,000-ton battleship would be able to crush it in a starship duel.

     The only way to recover the difference would be to arm the mother ship, making full use of the true size of the battle rider, not merely the small combat portion of it. However, again, arming the mother ship is self-defeating: with the weapons would have to go more power production, more powerful computers, better defenses and more acceleration, all reducing its ability to carry battle riders. The end result would be something like a carrier which carried a few extraordinarily large fighters rather than many small ones.

     Although the ITC study was not commissioned to do more than compare the two design philosophies, it did include several recommendations for long range planning of naval construction. It called for a shift to a fleet composed exclusively, or almost exclusively, of battleships and the relegation of battle riders to main fleets in quiet areas.

     It also recommended that studies be conducted into the feasibility of a hybrid sort of ship: essentially a battle rider with a limited jump capability, Jump-1 or Jump-2. lt is pointed out that such a design might prove valuable, The battle riders would no longer face total defeat if their mother ship was disabled, for one thing. For another, the mother ship could in some situations not even be exposed to danger; it could be used to ferry the battle riders to within a parsec or so of the target world and let the battle riders complete the the journey under their own power.

(ed note: see rebuttal below)

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THE NAVY REPLIES

     In a previous issue of this magazine, Paul Montgomery Crabaugh reported the results of a study conducted by Interstellar Technical Consultants of Mora, ostensibly at the request of the Imperial Navy, regarding the relative merits of battle-riders and battleships. The results of the study, if valid, reveal the total bankruptcy of the Imperial Navy’s force structure (pro Battle-Rider); it is therefore incumbent upon the Navy to explain its position to the public.

     First a disclaimer: the ITC study was not commissioned by the Navy; indeed, the Navy has been unable to procure a copy of the study’s final report, and this reply is necessarily based wholly on Mr. Crabaugh’s article. (Although he fails to so state, Mr. Crabaugh is an officer of ITC.)

     Mr. Crabaugh begins with a common misconception of the traditional argument for battle-riders: this being that a battle-rider, unburdened with a jump drive, can defeat a battleship of equal tonnage. As Mr. Crabaugh states, this is both obvious and meaningless. The true argument, which the Navy has always used, is that a fleet composed of battle-riders (and the necessary number of fleet tenders) can defeat a fleet of battleships constructed at the same cost.

     It is profitable to analyze the costs of starship design. Separating the jump and combat functions saves costs in several areas and adds costs in others. In order to fulfill its strategic role, a battle squadron must be capable of jump-4; jump drives and (especially) jump fuel make up 53% of the tonnage in a jump-4 ship. Battle-riders save the cost of armor, meson screens, and high-agility maneuver drives for this immense tonnage. There are additional costs for some duplication of hulls, power plants, computers, and maneuver drives for the fleet tender (which Mr. Crabaugh calls the mother ship). On balance, however, the battle-rider squadron comes in at a considerable cost saving.

     Another useful sqadron comparison is that of survivability. Many starship systems are tonnage-dependent; they take up a certain percentage of the ship’s tonnage regardless of its size. These systems all fight for space within a design. Battleships, with their 53% of dead space (for battle purposes), a.re at a severe disadvantage in this fight. A battleship cannot simultaneously possess the best armor, best meson screen, and a high agility; with the jump drive and fuel, these components would add up to more than 100% of its hull space. Compromises must be made in the design of a battleship, while a battle-rider requires no such compromises. A battle-rider, being smaller than a battleship, is also somewhat harder to hit. This adds up to a much higher survivability for the battle-rider.

     The ITC study presents several further arguments against the battle-rider/fleet tender system, none of which have been borne out in practice.

     It is claimed that battleriders are undergunned in comparison to battleships. True, a 120,000 ton battleship can carry more total weaponry than a 70,000 ton battle-rider (assuming the weaponry and power supply therefore will fit), but the majority of a capital ship’s offensive power is contained in its spinal mount weapon, and no ship, whatever its size, has so far proven capable of mounting more than one spinal weapon. The battle-rider can mount the same spinal weapon as a battleship; their relative offensive strengths are much closer than mere tonnage would indicate. Moreover, 70,000 tons is very large for a battle-rider; most are between 30,000 and 50,000 tons, yet possess as powerful a main weapon as the largest battleship at a fraction of the cost.

     The report claims that unarmed tenders are vulnerable in battle. Actual battle experience has shown that a fleet’s battle-riders are fully capable of protecting the tender from enemy fire while simultaneously engaging in offensive action. Only if the battle line were broken would the tenders be exposed to fire (and in such a case most of the battle-riders would necessarily be crippled or destroyed already). An admiral who feels that tenders restrict his tactics is fully capable of releasing the riders from a jump point far from the area of battle and leaving the tenders to remain there; it is very unlikely that a patrolling enemy would locate them given such a large volume of space to search. Battle-riders are fully capable of operating on their own for periods of a month or more (indefinitely if there is a source of fuel).

     Finally, the study claims that a battle-rider/tender-based fleet is inflexible. One rider cannot be sent to a trouble spot the way one battleship can; the smallest unit is a tender transporting four to eight riders. While true, this has not proven a major drawback. The study correctly states that the main use of single capital ships is in what Mr. Grabaugh indelicately terms “gunboat diplomacy.” (The Navy uses the less emotionally loaded “deterrent demonstration.”) The purpose is to safeguard the lives and interests of Imperial citizens in the various smaller states beyond the Imperial borders by a public (though non-threatening) display of the Navy’s power. However, a large cruiser is generally sufficient for these demonstrations. There are enough battleships in the fleet to cover the few instances in which a cruiser will not serve, and most of these are concentrated in the appropriate frontier regions for just such uses.

     The conclusions to be drawn is that the Navy’s current construction and deployment policies are indeed the best possible solution to our defense needs. Any return to a battleship navy would have disastrous consequences; be assured that the Zhodani and the e so-called Solomani Confederation (whose fleets are also composed of battle-riders) are well aware of this.

Sir John Harshman
Captain, Imperial Navy

By Direction:
Vice Admiral Baron Mtume,
C-in-C Corridor Fleet

• 

Many of the absolutes described above become much more fluid in the early days of space warfare.  Depending on the circumstances prevailing at the time, the first space forces could be entirely different from those described as ideal above.  After the first war, such forces would have a significant impact on the course of development, although if the solution was very sub-optimal it would likely be overtaken by better ones.  An alternative is a case in which space warfare forces are constructed, but not used for a long period of time.  This could lead to sub-optimal forces being dominant and built for multiple generations of forces before real-world experience grounds them in reality.

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Space warfare forces can grow in several ways.  First, there is the possibility of improvisation due to warfare.  This would probably be the case during war between colonies.  Second, there is the possibility of forces being produced by major powers before a war.  These would probably grow from patrol and law enforcement roles (see Section 11), but the creation of purely military forces cannot be ruled out.  Such forces could also grow from aerospace forces, most probably aerospace fighters (see Section 1).  Oddly enough, all three of these avenues initially lead to fighter-type craft, despite their long-term problems.  It is unreasonable to expect that all powers in a given scenario would develop in the same way, or to the same ends.  To illustrate a possible sequence of parallel developments among different powers, consider the following scenario:

In the year 2283 there are two superpowers on Earth (the US and China) and space colonies on Mars, Calisto and Ganymede. The US and China have OPVs (Orbital Patrol Vehicles) to inspect the traffic in Earth orbit. The OPVs are small craft, with a crew of half a dozen and a dozen-man boarding party, along with a few small lasers. They're chemfuel, and operate from orbital bases.

Calisto and Ganymede get into a feud over volatile mining on Europa. Both have mines there, and Calisto says that Ganymede is taking more than they are allowed to. Eventually, they mount weapons on a transport, and stop a Ganymedean ship for inspection. The Ganymedean response is putting a missile rack, a chemfuel rocket, and a hab module in a cargo module, and carrying it with their freighters. They're manned, as automation is hard to set up quickly. In other words, space fighters.

Calisto responds with similar craft. Soon the situation escalates, with both sides converting a few transports full-time. Fighters remain the primary warcraft because neither side can afford that many full-time transport conversions.

The US and China get annoyed at this, and decide to do something about it. The Jovian McGuffinite is too valuable to allow the supply to be threatened. Not having anything better, they cobble together a carrier and attach a bunch of OPVs to it. When it gets to Jupiter, there are two problems.

1. Neither side wants the crisis solved by Earth, at least the way Earth wants it solved. The carrier has no local supplies, sharply limiting its use.
2. The Jovian fighters are more powerful than the OPVs.

Eventually the crisis is solved somehow. Ganymede and Calisto remain at odds. Each body set (Earth, Mars, Ganymede and Calisto) develops its own set of space forces. Earth keeps the OPVs for orbital patrol. It also develops a deep-space fleet composed of classical laserstars, kinetistars, command craft, and so on. Ganymede and Calisto develop nuclear-thermal and chemfuel craft better suited for warfare around Jupiter.  They're more worried about each other than Earth, so their forces look more like fighters, although they generally don’t need carriers. Weapons fits are similar to those of the Earth fleet, although each craft might be a little smaller.  Mars looks at what had happened and decides that they don't want Earth meddling in their affairs. They build a fleet that's similar to Earth's but lacks much deep-space capability. It's more kinetic-heavy as well.  Each has a separate, parallel fleet because they had different starting points, but all of them work in the same setting.

A brief analysis of similar scenarios leads to the conclusion that manned warcraft, and even manned fighters, will have their day. That day will be brief, but it will happen.  The day in question is likely to be limited to the first war in any given sphere, possibly excepting Earth. The term sphere is used to reference any area of space that involves multiple powers in close proximity.

The reason why is quite simple. Setting up a secure laser comm setup isn't impossible, or even that difficult, but it does take time. At a guess, it might take 6 months or more with very large amounts of money and lots of technically-adept people, which a colony would be unable to afford during a war.  After the war, when more time is available, the cost would drop dramatically, but before the automated system can be deployed, manned fighters would rule.  This era would be brief, just like many eras that are commonly romanticized, but it seems likely to occur in some form or another.

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The improvised space warcraft are the type that seems to hold the most story potential.  These would, as mentioned, likely be built by colonies that are in conflict.  As they do not have to operate in an atmosphere, and are built by relatively poor colonies, they are likely to be rather crude.  The basic components required are structure, propulsion, weapons, life support, power, sensors, control, and communications, and each will be briefly discussed in turn.

There are two methods of assembling an improvised warcraft, either adapting an existing vessel, or constructing a new one from parts.  The use of an existing vessel removes the need for some, though not all, of the various components.  The structure will obviously be preserved, and propulsion and life support are almost certain to remain unchanged as well.  Weapons would obviously be added, along with their associated control equipment.  Existing power supplies might or might not be sufficient, depending on the weapons fit chosen.  Sensors and communications are gray areas, depending on the tasks required of the vessel, and the existing fits in these areas.

Structure is one of the easiest components to create.  So long as the builder does not mind the craft being somewhat heavy, slapping a few beams together should be sufficient.  Existing structures, such as cargo containers, could easily be modified, or simple new ones fabricated.  In any case, this is not likely to be a driving factor in construction or conversion of vessels.  Any group incapable of creating basic structure is also almost certainly incapable of surviving if it were to win a rebellion.

Propulsion for improvised craft is likely to be chemfuel due to the fact that it is by far the simplest to implement, and has sufficient delta-V for any operations that do not involve transiting deep space.  It is entirely possible that a colony will have standard chemfuel engines used in various places, and one of them, with appropriate fuel tanks, would be fitted to the vessel.  Nuclear propulsion is much more expensive, and might well involve detailed engineering to avoid killing the crew.  The performance advantage over chemfuel for nuclear-thermal is probably not significant enough to justify the problems involved, and nuclear-electric is only practical for vessels intended for deep space use.  

Weapons are a tricky issue. These are likely to be improvised as well, and would fall into the same categories already discussed.  Improvised lasers are highly unlikely.  Industrial lasers lack the optics trains required for weapon use, while any optical trains available (probably from astronomical or other scientific sources) are unlikely to be able to handle the high powers output by the lasers.  With some time, an appropriate optical train could be designed and mated to an industrial laser, and it is even possible that colonies could design and test such things in case of war.  Kinetic projectors are in largely the same boat.  While small mass drivers could be adapted to such a task, it is difficult to see a role for such devices on a colony.  There is also the issue of targeting, which, while not insoluble, requires good pointing accuracy and possibly the creation of guided projectiles, which have even less peacetime use then the launchers themselves.  

This leaves three options, missiles, lancers, and unguided kinetics.  Unguided kinetics can be as simple as junk thrown out of the airlock, but they are of very limited effectiveness, as shown in Section 8.  Missiles and lancer projectiles face many of the same issues, and the only practical difference is the motor, which should be relatively easy to improvise.  A missile or lancer will require sensors, thrusters, and guidance logic of its own.  As this force is presumably facing another more or less improvised one, complicated guidance logic is probably unnecessary, and proportional navigation is quite easy to implement.  The sensor might well be adapted from another role, which means that the likely problem is in the thrusters.  These must be well-balanced and integrated with the guidance logic.  Depending upon the materials available, this could range from very easy (if there are large numbers of small, self-propelled objects that can be used as warheads lying around) to extremely difficult (if the entire system must be designed from scratch).  Small thrusters themselves are an unknown.  There are some systems that might use small thrusters, such as thruster packs for spacewalkers, in which case the actual integration is all that is required.  However, the number available might well be strictly limited, forcing the builder to start from scratch.  Note that this is not as easy as it seems.  While a primitive kinetic could probably be built with the simplest of systems, it would be inefficient, of dubious reliability, and probably quite large.  In the end, this is an area in which the specific situation plays a very large role, leaving us unable to anticipate exactly what might occur.  

Life support should be straightforward to build into a vessel.  Any space colony will undoubtedly have small, portable habs that can be used for surface expeditions or what have you.  Mounting one of those would be relatively simple, and the actual mechanisms for short-term life support are fairly rudimentary, easing implementation if for some reason a hab had to be constructed from scratch.

Power is a rather tricky proposition.  Unless a nuclear propulsion system is used, power is likely to be at a premium.  Most non-nuclear power studies assume that solar panels will be used, but these have significant drawbacks for space warfare.  The biggest problem is that solar panels are vulnerable to damage from opponent’s lasers or powder weapons, and cannot be angled for protection, unlike radiators.  Radiators, discussed in Section 7, are both somewhat less vulnerable to damage, and can be kept edge-on to the enemy.  A clever opponent could manage to create a dilemma between getting power and preserving the panels from damage.  Alternatives include fuel cells and batteries.  Fuel cells are the current solution for short-duration spacecraft, due to their possessing higher specific energy than batteries.  The problem is that fuel cells are somewhat involved to manufacture and are not likely to be common on space colonies, unless the colony is far enough from the Sun that solar panels are not effective.  Batteries are somewhat more likely to exist, but are heavy for their power output.  The only bright side is that a truly improvised spacecraft is unlikely to need much in the way of power, particularly when compared to a nuclear-electric laserstar.

Sensors are probably the biggest unknown.  A proper space warcraft needs some form of active sensor to localize the enemy, although it is possible that a simple passive sensor would be adequate for simple missiles.  The sensors might or might not be readily available.  Sensor suites for existing spacecraft are the most likely source, although cobbling sensor suites together from other uses might be possible.

Control is mostly a matter of systems integration.  Depending on the nature of the systems involved, control setup could range from simple running of cables and plugging together a few modules, to having to write all of the code to make everything talk, or simply doing without an integrated control system.  While it is certain that some systems will have to talk (sensors and weapons spring to mind) a large portion of the integration could be skipped, with a resulting loss of efficiency due to the crew having to move around.

Communications is fairly simple, as one thing people in space will have to do is talk.  This should ensure the availability of communications modules, which can be attached to the vessel.  The most likely cause of problems is lack of strong encryption and particularly electronic warfare capability in such modules.  Depending upon the capability of the opposition, this may or may not be a serious hindrance.  The encryption capabilities should be a reasonably simple fix, involving mostly software updates.  The EW work will be harder, as there are likely to be physical changes required to ensure freedom from interference by enemy radio transmissions.  This is not likely to be a problem if the communications module is radio-based.

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One crucial point about warfare in general that is often overlooked, but is particularly relevant to the origins of space warfare, is that warfare is almost never just about destroying things.  Space colonies will likely place a premium on resources, doing their best to keep them intact during a war.  For that matter, the earliest space warfare might be police actions, security, or even filibusters (amateur attempts to take over other countries) instead of the sort of all-out warfare that has been described in this section so far.  Those forms of conflict tend to happen as much on the ground as in space, making the previous discussion on infantry weapons even more relevant.  Particularly at such low levels of conflict, space weapons will be very primitive, leading them to be either incredibly destructive (ramming ships into things) or almost totally ineffective (throwing unguided debris at other ships).

Part of this is that in many cases, warfare may resemble the formal, positional wars of the 18^th century, with a premium placed on outmaneuvering the enemy and a minimum of destruction of assets.  This has been alluded to in other sections.  Both sides would have a strong incentive not to destroy anything, as they would be hoping to take enemy material for themselves.  For instance, an invasion could consist of one side sending a group of ships to the other’s world, with the space battle based around their attempts to run each other out of delta-V.  It’s possible that the attacker would go in without abort delta-V, in the knowledge that this gives their enemies an incentive to not go for the kill, as they can expect to take the ships if they win.  Unguided kinetics are likely to be common in these battles, as they are excellent for forcing maneuvers.  However, the equilibrium may not be stable, and both sides would have to be fighting over fringe issues, and not their very survival.

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Note that all of this has only addressed the origins of space forces from scratch on colonies.  There are two other potential sources for space forces, existing Air Forces and the law-enforcement organization that will inevitably spring up to police human space presence (see Section 11).  This organization will be called the ‘Space Guard’ as it will likely be broadly analogous to the modern-day US Coast Guard.  The Air Force solution is somewhat unlikely, as it requires there to be a reason for current Air Forces to move into orbit in a major way, and the author cannot come up with a plausible explanation for this, even as an extension of their current responsibility for space operations.  The Space Guard would be unlikely to grow out of the Air Force, as it would initially be something more like transport police, and by the time actual military operations begin to occur, it would be the obvious candidate to become the Space Force.

This could have a major impact on the structure of Space Force.  In most sci-fi, there is a tendency to model Space Forces on Navies, although in reality, this is unlikely.  Even though it might bear more resemblance to a modern Navy than a modern Air Force, the Space Force will have evolved from whatever origin it had.  Either the force would have to have been split off from an actual wet Navy at the beginning (unlikely, as the Air Force would normally be given responsibility for the task) or it would have to consciously choose a naval model for itself.  There are two reasons why the later might occur.  If the space force is being created from scratch, it is possible that those responsible, likely influenced by sci-fi, will choose a naval model.  The alternative is that if the split between the Air and Space forces is acrimonious enough, the new Space Force might choose a naval model to distinguish itself from the Air Force.

The structure of a Space Guard-derived Space Force is much less predictable.  While they will likely evolve into something recognizably military, it is difficult to see what path they will take.  To use the US of today as an example, there are several different agencies (Department of Transportation/FAA, NASA, Department of Justice, Department of the Treasury) which might give birth to the Space Guard.  The use of police ranks is not unlikely, although they might transition to a more traditional military structure as they move into that role.

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A final point that needs to be raised is the difference between ‘armed ships’ and proper warships.  While this may seem like an academic distinction, history has shown that experience in design and operation of combat equipment, particularly warships, is vital to the successful design and use of such equipment. As we are obviously lacking such experience, it is impossible to speculate on what lessons might be learned.  The point of this reminder is that ships are not measured by their weapons counts and delta-Vs alone, but also by the skill of their crew and design teams.  This obviously favors established spacefaring powers, but that is only to be expected.

... One thing which I notice you haven't touched on is the origins and early development of a space navy. No one is going to be able to operate a heavy space cruiser the size of an OSCAR class submarine (much less the Polaris) without climbing a fairly steep learning curve.

Military access to space is probably the route that will take us there. The first step is already here; the recent introduction of operational ABMs. Assembly line production of ABM systems (since they will eventually be needed to cover both the east and west coasts of the United States, as well as the polar routes and deployed to protect bases in Guam, Diego Garcia etc.) should lead to standard "busses" and launchers for critical space hardware and will certainly drive down the price of getting into space and operating in LEO. The experience gained by assembly line production will increase the reliability of this hardware and associated systems.

The ever growing amount of critical space infrastructure and hardware will demand the ability to "surge" large numbers of satellites into space in response to a crisis or to replace damaged and destroyed assets in the early stages of a war, and one or more manned "garages" to service orbital hardware and extend its useful life. The ABM launcher will be produced in such quantities to make it the cheapest and most reliable vehicle for lightweight orbital hardware and many military and commercial systems will be designed to take advantage of this. Mass production of ABMs and their interfaces might make this the common standard for most space hardware into the future. Manned launchers and spacecraft to operate in LEO that are derived from these systems will share the cost and reliability attributes of the base system.

Given the base launcher is a solid fuel missile with a fairly narrow diameter, the eventual manned spacecraft will resemble the one man space cruiser concept from the 1980 era "High Frontier" proposals (i.e. a very minimal one man spacecraft), rather than the luxury yachts or tourist ships some people think would lead to space access. Since the one man "space cruiser" would have limited supplies and on orbit time from direct launch, military space stations would be required for in orbit refueling and replenishing. The space stations themselves will be pretty Spartan, given each section has to be sized to fit on the standard launcher in folded or deflated form. They may even operate unmanned for a large part of their life times to extend their limited supplies. Since these garages would be vulnerable to enemy ASAT weapons if left in a fixed orbit, they would have to be spacecraft in their own right, capable of manoeuvre and orbital changes, and at the very least treated to minimize visual, radar and thermal emissions.

While small military garages will be the starting point, eventually there will be a need and desire for larger and more capable systems. Clustering garage segments together to make larger space stations will be a first step. Several cylinders ganged together provide a sheltered "dock" for spacecraft, while the upper surface can be utilized for tank farms, solar panels and other systems.

For protection against space debris, inflatable wake shields will be common equipment on long duration space hardware. Using high density foam to "blow up" the wake shield and supporting struts, the wake shield is either made out of metalized Mylar film (civilian spacecraft) or "dark" materials which are absorbent over a broad range of wavelengths in order to render the spacecraft less visible. The adoption of inflatable Mylar wake shields provides the experience needed to create inflatable high gain antennas and optical mirrors. The mirrors can be used as concentrators for solar furnaces, solar thermal engines, solar power generators (either using photovoltaic cells at the focus or a thermal generator) and they can also be used as "one shot" fighting mirrors for ground and space based laser weapons.

As the space force grows in size and importance, the need to ferry larger amounts of supplies and create more capable space forces drives the development of the ARES heavy lift launcher, a "C-130" for space. Resembling an overgrown Space Shuttle External tank with an engine cluster, the ARES has hard points along the side to house payload pallets or strap on boosters, as well as an upper collar for nose mounted upper stages. The ARES launchers would be retained in orbit to become the building blocks for second generation space garages, larger space structures or as the elements of commercial or Space Navy spaceships. In time, these space stations/space ships might also be home to space bombardment weapons and a form of Glider Infantry using a variation of the SUSTAIN concept to insert forces on the ground in times of crisis.

The internal tankage of the ARES can be subdivided by inserting a series of balloons after orbital insertion and hardening them with epoxy. For space station building blocks this is sufficient, the ARES shell has hard points for payload attachment that double as connectors for attaching these units together. These attachment points also serve to connect various systems to the budding space structure, such as trusses, solar panels or the inflatable wake shield. Larger structures can be joined "nose to nose" and rotated about a common centre of axis to provide artificial gravity for the crew on extended missions. A permanent space station would have a vast wake shield in the direction of orbit, a series of ARES stages spinning on a common axis and one or more ARES units "trailing" for the docking station and zero g workshops, etc.

To create a spaceship, one or more units are connected, and a nuclear thermal rocket (NTR) is attached. Some of the tankage is retained to hold the reaction mass for the NTR; for logistical reasons the preferred reaction mass would be LOX from lunar sources. To gain access to this resource, ARES stages would be refitted and refueled in orbit and sent to the moon, where they become part of the ground infrastructure or serve as tankers to bring LOX back to Earth orbit. A crew cabin and landing legs are the normal retrofits for ARES lunar systems. While not as efficient as liquid Hydrogen, LOX is easily available from regolith, can be boosted at low expense from the moon, can be stored for long periods of time in orbit (since it is a "soft cryogen"), and also doubles as an emergency source of breathing oxygen for the crew. At least one of the balloons near the center of the ARES is covered in radiation shielding to act as the "storm cellar" during solar storms and other radiation events. The NTR must be made of materials which can withstand the effects of exposure to high temperature oxygen, or be a "nuclear light bulb" (since I suspect no one will allow open cycle nuclear reactors to operate in Earth Orbit or even Cis Lunar space).

As time goes on, Lunar resources become inadequate (since they are deficient in most light elements) and the moon itself would be considered vulnerable to attack from Earth. Greater strategic depth is achieved by establishing bases among the Near Earth Asteroids, since they provide both the needed light elements to sustain life and industry in space, and also provide time and distance to protect deployed elements of the Space Navy from rival forces on Earth and in space. This also allows the reaction mass to become water mined from asteroidal sources, since it is even easier to deal with than LOX. The simplified logistics suggests that "steam rockets" using nuclear light bulbs as the energy source and water as the reaction mass would be the system of choice for military and commercial spacecraft. Operations in deep space will create a different paradigm for operations (as so many people have noted). My take on the matter revolves around the requirement for protection from cosmic radiation and debris in transit, as well as the provision of artificial gravity for the crew(s). The cycler concept of having a large space station traveling between the planets is a good starting point, and the "Ice spaceship" provides many of the features a Space Navy might desire. The 215m diameter ice ship is protected by 40,000 tonnes of water ice, a vast thermal sink against energy weapons and a pretty hefty shield against kinetic energy impactors as well. Since the basic structure can be created with a 60 tonne "bladder" and filled with water extracted from asteroids, large numbers of cyclers can be assembled in space.

The actual warships would be clustered in the middle, connected to the structure to provide thrust and electrical power with their engines, while drawing water as reaction mass from the ice spaceship, or using the ice as a thermal sink for the engines and energy weapons while clustered together. The large size of the ice ship also serves as a means of supporting a large sensor array, which can support operations both while clustered with the warships, or when the mini fleet is dispersed. This sort of arrangement would work well when dealing with planetary sized targets like Mars or the Jovian moons, you have a base to maintain and preserve your ships to and from the theater, but can disperse independent warships with full tanks and weapons load when you reach the area of operations. (presumably the Fleet HQ has sent several empty ice ships to intersect the planet at different times so you can refit, rearm and go home, but the ships are capable of doing so independently if necessary). In effect, the Space Navy would be based on a series of "submarine pens" moving between planets.

This isn't such a far fetched analogy. I suspect the actual warships by that time would resemble an OSCAR class submarine in size and function. Even construction of the spaceship would be broadly similar, with the outer casing being used to house reaction mass (in the form of water) and the missile racks or beam weapon emitters, while the inner hull would probably be very small and heavily automated like an ALPHA class submarine. Since the crew would be inside the 214m ice ship during the cruise portion of the flight, they would have their gravity and cabins there, while in combat they would be in the warship cycling between zero g and "forward is up" orientation, spending their time strapped into acceleration couches.

For small targets like an asteroid, the smaller 100m ice ship might actually be the warship. It has 8000 tonnes of ice to act as a heat sink or reaction mass, is powered by three NTR's (according to the author. This could be reduced if more powerful nuclear light bulbs were substituted), and has lots of interior room for a large crew, supplies and so on. Rather than carry independent warships in the center cavity, it might be loaded with hundreds of missile busses; a space going arsenal ship. For mass fleet actions (i.e., conquering the Uranus system to seize the Helium 3 facilities), a combination of 100m arsenal ships and 214m cyclers carrying independent warships seems to provide the balance of firepower and flexibility a Space Navy would want.

An interesting timeline, radically different from what I usually assume. I tend to assume civilian development of space will occur before development of military spacecraft beyond spy satellites.

Arthur Majoor's analysis starts with a couple ideas which would never even cross my mind. First, he assumes ABM missiles would use rockets suitable for orbital launch. I always assumed such missiles would lack the delta-v for orbit, but honestly I never checked.

Second, he assumes a future need to be able to "surge" orbital military hardware at times. I actually think the opposite to happen. I believe that improved technology would make each spy satellite more capable, reducing the number needed and thus reducing military launch demand. At the same time, I expect UAVs to become cheaper and more capable. Since they can fly underneath clouds, they can provide better tactical intelligence and better 24/7 coverage.

So, I'd expect a small number of spy satellites used for long term missions during peacetime, along with mostly aerial UAVs for a "surge" of intelligence capabilities during wartime.

If you presume normal ABM tech in use, you also have to have a corresponding capability to surge useful satellites to replace those shot down by the other side. They kind of go together.

ABM technology is different from ASAT technology. There might be some overlap in that a low Earth orbit satellite may be engaged with ABM missiles, but generally the tasks are very different.

An ABM missile doesn't need orbital velocity, but it does need to intercept its target on the first pass and it needs to intercept with a very high relative velocity. In contrast, an ASAT missile probably needs orbital velocity, but it can use a closely matching orbit to intercept at relatively low velocities. Depending on the closing velocities and the amount of thruster propellant available, an ASAT can even get multiple attempts to hit a target. An ASAT requires much more delta-v to reach the target, but the job of actually hitting the target is easier.

Because chemical rockets are only efficient up to around 4km/s, there's a strong incentive to design an ABM missile without orbital capability. This is good enough to take out ballistic missiles because you can always count on ballistic missiles coming back down.

Such a weapon could be used against satellites in low Earth orbit, but the enemy will quickly adapt by launching his spy satellites into a higher orbit instead. The marginal costs of sending a spy satellite into a higher orbit are rather modest, considering how much delta-v is required just to get it into orbit at all. The extra costs of the higher orbit and more powerful optics are mitigated by the fact that these higher orbiting satellites now have a better field of view.

With higher orbiting satellites, ASAT missiles would need to have orbit capability. An arms race between ASAT launchers and spy satellite launchers is thus a conceivable scenario for bulking up orbital launch capability.

That said, I would be against it. The main appeal of spy satellites is that they can overfly other countries during peacetime without starting a war. But during a shooting war, UAVs provide continuous coverage which isn't blocked by clouds, and they're a lot cheaper. If an enemy shoots down some spy satellites, I'd bet the response would be to replace them with spy UAVs rather than more spy satellites.

Of course, this is all assuming the use of missiles rather than lasers. At the rate solid state laser technology is progressing, I think it's entirely possible they will become the de facto dominant ASAT weapon within a few decades. Research into high energy lasers has traditionally been promoted as a missile/rocket defense, but the unspoken fact is that these lasers will be able to shoot down satellites, as satellites are easier targets than missiles/rockets. While nobody wants to talk about it, it wouldn't take much to point a high energy laser into the sky to damage a satellite.

In this case, many countries could end up possessing potent de facto ASAT capabilities without much--if any--orbital launch capability. This is a contest which military spy satellites probably just lose. At that point, cheap expendable UAVs become the only sustainable option. Spy satellites can still be useful for long term missions during peacetime, but they'll be the first things to go if a shooting war starts.