Commonly the protagonists of a science fiction novel will own one of two types of starship. If the protagonists are tramp interstellar traders, they will own a cargo ship. If the protagonists are pirates or privateers, they will own a corsair pirate ship.
First off, a science fiction writer will have to make some assumptions to flesh out the background parameters that determine starship price, size, etc.
Simplistically, becoming the proud owner of a spacecraft or starship will be a process much like what modern-day people go through to own a large sea going vessel. Tramp traders will mortgage their souls to the bank in order to purchase their ship. Pirates will probably avoid the middle-man and instead steal their ship. This also avoids the problem that the astromilitary frowns on civilian ownership of armed starships.
One possible major difference is if the starships are created by a Thalassocracy, who maintains power by keeping interstellar trade clutched in an iron grip. In that case, the interstellar propulsion unit or the entire starship is only available from the Imperial Monopoly. The details about the star-drive are top secret, the drives contain nuclear booby-traps to prevent anybody discovering the secret, and probably contain remote-control self-destruct devices in case the ship-owner does anything that makes the Thalassocracy angry.
Starships are constructed in the yards of shipbuilding megacorporations. There is a selection of standard models, or a custom-designed ship can be constructed at an astronomically higher cost. Used second-hand starships are available from the current owner, or at used spacecraft yards.
Megacorporations and used spacecraft yards can sell ships directly. Sale & Purchase ("S&P") ship brokers connect people in the market to buy a ship with people with ships to sell. Or with people who can build a bespoke ship.
People purchasing ships are generally too poor to pay cash, so they will have to make financing arrangements with a bank or something. The banks will keep an eye on the debtors, and will send Repo persons after debtors on the run.
Using a spacecraft in a transport or other business will be risky, and appropriate insurance will be required.
Spacecraft on their last legs will end up in used spacecraft yards. After their last legs are gone, ships will go to the shipbreakers.
This section is basically a rough outline of Rick Robinson's Interstellar Trade: A Primer. You'd probably be better off reading the full article but some people want executive summaries. This section is duplicated in the Interstellar Trade page because it overlaps the two.
Rick starts with certain assumptions and follows them to various conclusions about the interstellar economy. You can alter some of the assumptions yourself to tweak the economy to suit your science fictional background.
Merchant Starship Costs
Assumption: starships in the interstellar empire are equivalent to present-day jet airliners. They go fast, can carry lots of people and cargo, and are the most advanced technology that can be massed produced.
The ticket prices will not be similar between airliners and starships because FTL interstellar travel will probably take more than a few hours for the trip. Therefore the starships will do fewer trips per year than airliners, so the starship passenger ticket price (and cargo waybill) will have to cover a larger share of the starship's yearly expense.
For comparison purposes we need an airliner's average cost of running, but the corporations are remarkably closed-lipped about that. Using a long series of estimations whose details can be found in Rick's article he concludes that the annual operating cost for an airliner is about $30 million (not counting fuel, landing fees, and taxes). An airliner's purchase price is $100 million so one year's uses costs about one-third of the purchase price.
A cargo jet can carry 50 tons so its purchase price is about $2 million per ton of cargo capacity.
Assumption: starship purchase price will only be about $1 million per ton of cargo capacity instead of $2 million, because starships are orbit-to-orbit, need no landing gear, need no wings, can use lighter structure because they accelerate under 1 g, and we will assume they can carry twice as much cargo per deadweight (inert mass) as a cargo jet.
Assumption: cargo starship operating cost is similar to cargo jet. Therefore it costs $300,000 per ton of cargo capacity per year to run a cargo starship. This ignores taxes, station docking fees, and fuel. Assumption: starship fuel is cheaper than cargo jet JP-4 fuel. Big assumption since JP-4 is about $1.39 per gallon.
(ed note: starships are going to require lots of infrastructure.)
Assumption: the service life of a merchant starship is 30 years. So the starship initial purchase price is about 1/10th of the overall lifetime service cost ($1 million / (30 * $300,000)). Actually it will be closer to 1/5th due to the interest on the purchase loan. With creative maintenance, the service life might be longer than 30 years, see below.
Question: how many cargos can a merchant starship carry in 1 year? That is, assuming a full cargo turnover at each port of call, how many one-way runs can the ship make?
Assumption: a one-way trip takes three months. From departure planet orbit to FTL flight to arrival planet orbit. This is comparable to the Age of Sail.
Assumption: each trip requires one month for servicing, maintenance, selling the cargo, buying new cargo for the next run.
This makes each trip four months from departure to departure, or three cargos per year. This means the ship owner must earn $100,000 of profit per ton of cargo. That is, selling price at destination MINUS purchase price at origin must be $100,000 or more. Therefore if the cargo was available for free at the origin the minimum selling price at destination is $100,000 per ton, or $100 per kilogram. The implication is that only very high value cargo can be profitably shipped interstellar.
Assumption, average of 1/2 of retail price goes to shipping cost. Therefore the minimum price of interstellar imported goods are $200 per kilogram.
The implication is that the only things shipped interstellar would be luxury goods, items with a very high value per weight. Jewelry, spices, fine liquor, designer-label clothing. Maybe some high value per weight industrial goods, such as microchips. Not high mass items such as sports car, not with a $100,000 shipping charge added to the car's price. Bottom line is that you are not going to ship bulk goods like wheat, not at $100,000 per ton you ain't.
Assumption: the Gross Planetary Product (GPP) of a colony planet is $100,000 (about three times that of present day USA). If 2% of citizen income goes to imported luxuries and high-value capital goods, it comes out to $2000 per capita, with $1000 going to shipping cost.
Assumption: Colony planet population is 10 million. Therefore the total shipping cost of imported goods is $10 billion.
Calculating backwards, this implies that 100,000 tons of interstellar cargo arrives at the colony planet annually. The colony must export the same amount or it will run a trade deficit and import prices will rise. This is because if they don't export, the cargo starships cannot find cargoes to transport and sell at the next destination. Starships with empty cargo holds cost nearly as much to run as with full holds. They will have to make up the shortfall somehow, so they will raise the price of what they sell at this planet.
Take simplest model: two planets trading with each other. Each year, 100,000 tons moves in each direction, or 200,000 tons total.
Assumption: average cargo starship carries 1000 tons. This is less than seagoing cargo ships, but more than cargo airplane. This means there has to be 200 annual cargo loadings and unloadings to accommodate 200,000 tons.
Since each ship can make 3 one-way legs per year, then each ship will do three loadings. The implication is that the two planet's combined merchant fleet is between 65 to 70 ships.
Of course if each ship carries more than 1000 tons then fewer ships are needed. If the ships can carry 5000 tons then you would only need 13 or 14 ships. In practice this would not work very well, since the larger the cargo hold, the more difficult it is to find enough cargo on the planet to fill it.A trade network of a dozen colony worlds will support a few dozen to a few hundred cargo ships depending upon cargo hold size.
Airliners carry about four to five passengers per ton of equivalent cargo capacity. However airliner trips are only a few hours. Interstellar passengers cannot live in their seats for three months.
Assumption: Each interstellar passenger berth equals one ton of equivalent cargo capacity. This includes the passenger, their baggage, the berth, apportioned galley/diner space, and food.
The direct result is that the cost of the passenger ticket is the same as the cost of one ton of cargo: $100,000. You are not going to get much tourist traffic, not at those prices. A few rich people and business travellers.
Problem: you must have large scale passenger traffic for the colony network to exist at all. In a word: Colonization.
$100,000 per colonist is prohibitive. Probably several times that for extra stuff like tractors and horses. Even worse, since the new colony will not have any exports, the cargo starship will have not cargo buy for the next trip. So the starship captain will have to charge round-trip prices for a one-way trip. It could total to around $1 million per colonist.
The problem is that our assumptions have made it so that only millionaires can afford the ticket, but millionaires do not want to go live on some jerkwater frontier world. Sending 10,000 colonists to a new world could cost $10 billion, which is a huge amount for private industry or governments to spend, regardless of the potential value of the planet.
Our price schedule has made interstellar colonization unlikely in the first place.
We will have to change some of the assumptions. Lucky for us, there is some room to bring the costs down. We can make the merchant starships cheaper, or make them faster. We shall do both.
Assumption: annual starship service cost is $100,000 per ton of cargo capacity, not $300,000. This is reasonable, since starships are not stressed as much as airliners (at least not orbit-to-orbit starships).
Assumption: starship purchase price is $500,000 per ton of cargo capacity instead of $1 million, since starships are build for long-haul reliability.
With the 30 year service life, the purchase price is now 1/6th of the total lifetime service cost instead of 1/10th. Within interest payments this may be closer to 1/3th.
Assumption: a one-way trip takes 35 days instead of three months. This means the cargo starship can deliver 10 cargoes per year instead of three. Assume 27 days is transit, 8 days is for servicing, maintenance, selling the cargo, and buying new cargo for the next run.
Crunching the numbers, the minimum profit per ton of cargo or passenger ticket is now $10,000 instead of $100,000.
The cost for colonists (provisions and no return cargo) is probably about $100,000 or less. That's more like it. In the reach of the middle class. This price schedule makes interstellar colonization viable.
Note that the same ten-fold cost reduction can be had by making the one-way trip 12 days but keeping the original $300,000 annual cost.
Our colonization-viable starships will also increase interstellar trade. Shipping cost of $10,000 per ton means the threshold cost of imported goods is about $10 per pound. Only $10,000 shipping cost for a sports car. But no bulk cargo, not when oil's shipping cost will be $1500 per barrel. As with all freight the rates will vary. Higher value merchandise will support higher shipping charges. A long-term fixed contract (allowing ship owner to have dependable regular cargoes) will get a lower rate. Standby cargo will get a better rate, if the ship is making a run anyway, it is better to have full cargo holds.
If imports are still only 2% of CPP, the volume of goods will increase ten-fold. The shipping capacity will only have to increase three-fold since starships now deliver three times as much cargo per year. Since shipping costs ten times lower (so a wider range of goods are worth importing) then the import-export sector can expand in total value of goods shipped as well.
Assumption: an inverse square-root rule applies here, so reducing the shipping costs by a factor of 10 will increase spending upon imported goods by a factor of 3.
This means 6% of CPP now goes to imports. High, but not out of reach for a mature trading zone. So a colony of 10 million will have an annual export and import of 3 million tons per year.
Each trade starship can pick up and deliver 10 cargoes per year, so they need a net cargo capacity of 300,000 tons. For a trade network of 12 colonies, the combined merchant marine needs a capacity of some 3.6 million tons. Most ships will still be small (but bigger than jumbo jets) to facilitate filling their cargo holds, but the heaviest-traffic routes will support some bigger ships.
Assumption: say the trade network's merchant fleet is:
|Type of ship||Number|
of one ship
|Total cargo capacity|
|Large||75||20,000 tons||1,500,000 tons|
|Medium||300||5000 tons||1,500,000 tons|
|Small||400||1500 tons||600,000 tons|
If there is no FTL radio, then some of the small freighters will sacrifice cargo capacity for speed (i.e., acceleration), in order to become something like an interstellar FedEx or pony express. The idea is to reduce the normal space transit time. Actually this might be a better job for an unmanned drone, they can take higher acceleration than human beings.
Passenger traffic is only a fraction of total cargo volume (unless there is a colonization effort underway). Freight makes a profit for somebody, passengers are pure expense to whoever pays their ticket. Perhaps passengers are 1% of total volume, makes 360,000 passengers per year. A few routes may support scheduled passenger service (probably in small ships). But most will ride in cargo bays (like railroad sleeping cards), in freighters, or in spare crew quarters.
Ship mass and size
Full load mass and physical size depends upon assumptions about fuel mass ration, fuel bulk, etc.
|Deadweight (inert mass)||1||17%|
Note that total mass is three times the cargo capacity. As you can see, deadweight is the ship proper, structure, engines, anything that is not cargo or propellant.
With this assumption, the big freighters will have a fully loaded mass of 60,000 tons. The largest ships might be twice as big: 120,000 tons.
Our building cost is $500,000 per ton of cargo capacity, the mass assumption makes a building cost equal to $1 million per ton of deadweight. Annual service cost is $100,000 per ton of cargo capacity, the mass assumption makes the annual service cost equal to $200,000 per ton of deadweight. The starship hulls are not cheaper, but they can carry more cargo in proportion to their structural mass.
|Type of ship||Cargo capacity||Purchase price|
|Large||20,000 tons||$20 billion|
|Medium||5000 tons||$2.5 billion|
|Small||1500 tons||$750 million|
At $500,000 per ton of cargo capacity, largest giant freighter cost $20 billion to build, but it it has a cargo capacity of 200 Boeing 747 jets, and accounts for over one percent of whole fleet's cargo capacity all by itself. Small freighter costs $750 million, and has seven time the capacity of 747.
With a 30 year service life, the combined shipbuilding yards of the 12 planet trade network will turn out about 25 ships per year.
Hulls will last longer than 30 years but the equipment wears out and has to be replaced. Ships go back to the yards for an overhaul every decade or so, but eventually the cost of stripping everything and replacing it will exceed the value of the ship. Depending upon overhaul costs the shipyards may make more money on rebuilding than on constructing brand new ships. Some ships will stay in service for many decades. Others will be retained as the futuristic equivalent of naval hulks or the old passenger equipment that railroads use as work trains. Every big commercial space station will have a bunch of these old ships in the outskirts.
If modular design is taken to its limit, "ships" will have no permanent existence. Instead they will be assembled out of modules and pods specifically for each run, much like a railroad train. In that case, a ship's identity is attached to a service, not a physical structure. Example: the Santa Fe "Chief" was identified by a timetable and reputation, not a particular set of locomotive and cars.
The analysis up until now focused on money and economics. Businessmen only care about how long it takes to deliver the cargo and how much transport costs, they could care less about the scientific details of the ship engines. But authors care.
As with everything else, it all depends upon the assumptions. Your assumptions will be different, so feel free to fiddle with these and see what the results are.
Assumption: the time spent in FTL transit is zero (jump drive). For the FTL segment of the transit you can use whatever you want, as long as the details do not affect the analysis. The main thing is that the required time spent in FTL transit will add to the total trip time, and thus the number of cargoes a starship can transport per year.
Assumption: starships use reaction drives for normal space travel.
We know that the mass ratio is 2.0. So the Tsiolkovsky rocket equation tells us that the starship's total delta V will be the propulsion system's exhaust velocity times 0.69 (i.e., ln(2.0) ). Since starships accelerate to half their delta V, coast, then decelerate to a halt, their maximum speed is half their delta V, or exhaust velocity times 0.35 (i.e., ln(2.0) / 2). In practice you would accelerate up to a bit less than half their delta V in order to allow a fuel reserve in case of emergency.
It will be even less if the FTL drive happens to use the same type of fuel that the reaction drive does. Basically part of the fuel mass will have to be considered as cargo, not propellant, which will alter the ship's mass ratio.
|Reaction drive||Exhaust velocity|
|Nuclear powered Ion||~100 km/s|
|Fusion||a few thousand km/s|
|Beam core matter-antimatter||about 100,000 km/s|
( 1/3 c )
We have assumed that the ship spends 27 days in route (with an instantaneous FTL jump), so the outbound and inbound legs are 13.5 days each (1.17 million seconds).
Assumption: the acceleration on each leg is constant. In reality at the same thrust setting the acceleration will increase as the ship's mass goes down due to propellant being expended. The thrust will probably be constantly throttled to maintain a constant acceleration. Makes it easier on the crew and easier on our analysis. The implication is that obviously the average speed will be half the maximum speed (which is half the delta V)
|Reaction drive||Exhaust velocity|
or Early Fusion
|400 km/s||130 km/s||75 million km|
|Advanced Fusion||10,000 km/s||5000 km/s||20 AU|
|c||0.3 c||350 AU|
(x5 Pluto's orbit)
|8 g !!!|
These figures will be lower if time is consumed in FTL flight, maybe be only Terra-Luna distance
Propulsion system's thrust power is thrust times exhaust velocity, then divide by 2. To get the thrust, we know that thrust is ship mass times acceleration. The ship mass goes down as fuel is burnt. As a general rule for ship mass, figure that it only has 2/3rds of a propellant load. That is, multiply the total ship mass by 0.83. So our 120,000 metric ton ship would have a general rule mass of 120,000 * 0.83 = 100,000 metric tons (100,000,000 kilograms).
|Reaction drive||Exhaust velocity|
or Early Fusion
|1.08×107 N||2.16×1012 W|
|Advanced Fusion||10,000,000 m/s|
|4.3×108 N||2.15×1015 W|
|7.65×109 N||1.15×1018 W|
(1 million terawatts)
Where does fuel come from and who does it get into the ship's fuel tanks? Easiest if it is obtained locally at the destination's solar system. The economics of interplanetary transport is same as interstellar (since we did a lot of work making interstellar a cheap as interplanetary).
if fuel from a gas giant at a distance comparable to Terra-Jupiter and round trip is to only take weeks, interplanetary tankers will need speeds of around 1000 km/s. So tankers will be almost as expensive as starships. If tankers use low speed (to make them cheaper), the round trip balloons to a year or more. To service the starship fleet's thirst for fuel, tankers will need to be huge or there will have to be a lot of them. Either way, fuel shipped from gas giants ain't gonna be cheap.
If we forgo interplanetary tankers and instead have starships make extra leg to the local gas giant to refuel, it will cost you more than you will save.
The alternative is shipping fuel up from destination planet. Yes, we know about how surface to orbit is "halfway to anywhere" in terms of delta V cost. But in order to colonize space at all, surface-to-orbit shipping cost will have to be cheap anyway. The industrialization of space will start with using space based resources, but eventually surface-to-orbit will have to be cheap or there is no rocketpunk future. Laser launch, Lofstrom loop, space elevator, something like that.
Assumption: surface-to-orbit shuttle economics are equivalent to current day airliner economics. Round trip to LEO and back is about two hours (not counting loading/unloading). With loading/unloading and maintenance, figure 4 flights a day. Implication is that a round trip passenger ticket is $250 and round trip freight service is $1000/ton (which is +10% added to interstellar transport costs)
Fuel is not round trip, it only goes from surface to orbit, but shuttles have to go orbit to surface in order to get the next load. You will have to streamline the process. High capacity pumps to minimize load/unload times, crew-less shuttle. You might be able to squeeze fuel lift cost to $500/ton. So if starships carry 1.5 tons of fuel per ton of cargo, surface-to-orbit fuel lift costs adds $750/ton to interstellar shipping cost.
So total surface-to-orbit overhead is $1000/ton + $750/ton = $1750/ton or 17.5%. This is an ouch but not a show-stopper.
Back to starships. How big are they?
Present-day maritime tonnage rule: 1 registered ton = ~3 cubic meters.
Assumption: 1 ton = 3 m3 applies to fuel and hull (e.g., crew quarters, engineering spaces, etc) as well as cargo. Therefore, if the absolutely hugest cargo starship in service has a cargo capacity of 40,000 tons (twice that of a large cargo starship), then:
Volume of a sphere is 4/3πr3, so the radius of a sphere is 3√(v/(4/3π)) or
radius = CubeRoot( v / 4.189)
diameter = (CubeRoot( v / 4.189)) * 2
Assumption: a "cigar-shape" for a spacecraft is a six times as long as it is wide, with the proportions indicated in the diagram above. The center body is a cylinder 1 unit in diameter (0.5 units radius) and two units high. The two end caps are cones of 0.5 units radius and 2 units high.
If the monstrous cargo starship is spherical, it would have a diameter of 88 meters. If it is cigar shaped then length = 300 meters and diameter of 50 meters.
A 1500 ton cargo capacity tramp freighter would have a wet mass of 4500 tons and a volume of 13,500 m3. Spherical shape would have a diameter of 30 meters, cigar shaped length = 100 meters long and diameter of 17 meters.
Modular ships dimension would be similar but a bit larger due to being assembled out of component parts.
This is very difficult to estimate.
Since each crew has same berthing requirement as passengers, each crew represents one ton = $100,000/year in lost revenue capacity. Therefore crew will be kept as small as practical.
Operating crew: pilot-navigator and engineer for each watch. Plus life support specialist/medic, cargo-master, and captain. Total of nine. Small ships might squeeze this to four or five. Big ships might double up with assistants and trainees for 20 to 25.
Maintenance technicians will be needed. Ships are en route for a month or so at a time. Unlike aircraft, maintenance can't all be done during layovers. Time is money, you do not want to hold off departure because station tech has not finished some routine servicing. So techs will be carried to do maintenance during the flight. Assume (conservatively) 1 tech embarked per $100 million in construction cost (i.e., stuff to be maintained). So small ships will have a maintenance crew of seven or eight (total crew of ten or twelve). Largest ships in service might have total crews up to 250. Scut work (swabbing decks and peeling potatoes) will be done by junior crew. As has been the case since time began.
Hotel Staff: passenger-carrying ships will need crew for hotel-type services (stewards, chefs, etc.), but not if passengers are colonists (fend for yourselves, steerage scum!). Coach class could make do with one for every 10 passengers. First class would have one for every 2 or 3 passengers (and the ticket price would reflect this). If a typical ship has 1 percent of cargo given over to passengers, the required hotel staff could increase the crew by about a third. Naturally the hotel staff will be looked down upon by the operating and tech crew members. On a passenger ship the hotel staff will vastly outnumber the rest of the crew by some 30 to 1.
Orbital high ports
These are primarily starship ports and service bases, though they may have other functions.
With our current assumptions, at a given time 3/4ths of the ships are en route, the rest are in port. So at the stations of the dozen colony worlds there will be docked about 15 cargo ships. One or two would be large cargo ships. A cargo ship will arrive and depart about three times a day.
Orbit-to-surface traffic is heavy. If each shuttle can carry the load of a 747 jet, about 100 arrive and depart each day. If starship fuel is shuttled up from surface, some 150 daily tankers arrivals are needed as well (if 4 daily flights per shuttle, about 65 physical shuttles are needed).
This is for a typical station. The busiest station in the trade network might have twice the traffic volume.
At any one time we might expect to find 200 to 300 off-duty starship crew at a typical station (probably all in bars). Unlike airports, passenger traffic is small. 200 or so arrive and depart each day. Passenger shuttles will also carry station crew, ship's crew going sightseeing, so there will be a few daily passenger flights.
A station is a ship without a drive engine, so its capacities can be estimated the same way.
If 10% of the overall cost of the merchant fleet goes to support the stations (since the stations maintain the ships) then the stations taken together will have about a tenth of the fleet's deadweight mass, or 180,000 tons all told. A typical station would then have a mass of 15,000 tons, not counting cargo awaiting loading, fuel in storage tanks, etc. But stations are likely to grow by accretions over the years and become sprawling structures extending hundreds of meters in all directions.
Using same estimates for cargo ships, the maintenance crew of an average station would be about 150. However, stations provide the major ship maintenance, so they probably have about as many technicians altogether as the ships themselves do. They alone will multiply the station population by tenfold; support staff and miscellaneous services might double it again, so a typical station could have some 3000 workers. The largest stations might have two or three times as many.
Living quarters will be nearly as expensive ship quarters, but frequent shuttle fare also add up. The income from shuttle fare can be used to subsidize living quarters rent, so many people could live on board, even with families. Station could be a cosmopolitan orbiting town.
The entire space-faring population of the trade network, ship crews and stationers, come to well over 50,000, maybe as many as 100,000 (out of a total population on 12 colonies of some 120 million). The space economy as a whole however employs many times more. If the merchant marine industry accounts for 3% of the economy it will also employ 3% of the workforce, 2 million people. With a similar number employed in the import/export industries.
The expense of a trade-protection navy is an insurance premium charged against trade.
Assumption: the insurance premium to fund the navy is 10% of total value of trade.
Say the 12 colony network is a trade federation and the insurance premium for defense is 10% of total value of trade (this setup could just as well be one planet monopolizing trade, in which case the navy protects the franchise. We will call it a federation anyway). Half the value of trade goes to support the merchant fleet (the other half is initial purchase cost of shipped goods) therefore the cost of the war fleet will be about 1/5 of the merchant marine
Assumption: warships have the same relationship to cargo ships as cruisers do to ocean liners or jet bombers to airliners.
Instead of cargo, warships carry weapons, sensors, armor, more powerful engines, and greater fuel capacity. Ton for full-loaded ton they are more expensive than trade ships (maybe x2) but cost per deadweight ton is about the same since technology going into it is similar. (some present day warplanes have higher cost-to-mass ratio than jetliners. This is due partially to "gold-plating" of weapon systems and partial due to false economies such as small orders that reduce production efficiencies. We will assume that a navy funded by merchants will not allow such expensive stupidities)
Assumption: For first approximation, scale down merchant marine by factor of 5 to get war fleet.
- 1 battlecruiser per 5 heavy freighters
- 1 cruiser per 5 medium freighters
- 1 corvette per 5 small freighters
This will give the following order of battle:
- 15 battlecruisers
- 60 cruisers
- 80 corvettes
This may or may not be balanced, substitute as needed.
(ed note: for a discussion of what Rick Robinson means by those three ship classes see his analysis here)
Space navy combat starships will require auxiliary starships to support them: food supply ships, ammo and missile supply ships, repair ships, hospital ships, fuel ships, etc. So some of the cruisers and corvettes in the order of battle will have to be traded for auxiliaries of various kinds. Some civilian cargo ships can be requisitioned in wartime for auxiliary missions (such as tankers). Depending upon technology and threat level, it might be feasible to fit cargo ships with weapon pods instead of cargo and use them as armed merchant cruisers. And warships might be fitted with cargo pods to become very well-armed transports.
Assumption: a warship's deadweight mass is 1/3rd (0.33) of loaded mass (propellant always dominates a reaction-drive spaceship's mass). You could call the deadweight mass the Washington Treaty Mass.
Assumption: the following deadweight mass values in the following table.
Assumption: warships are always cigar shapes because Hollywood hates spheres
We have already assumed that purchase cost of a spacecraft is $1 million per ton of deadweight. We have also assumed that each ton of loaded mass equals 3 m3 of volume.
Result of assumptions:
|Battlecruiser||30,000 tons||10,000 tons||$10 billion||90,000 m3||200m × 30m|
|Cruiser||7500 tons||2500 tons||$2.5 billion||22,500 m3||120m × 20m|
|Corvette||2000 tons||700 tons||$700 million||6000 m3||75m × 12.5m|
Corvette are the length of a 747 or C-5 Galaxy but larger diameter. Very close to space shuttle in launch configuration. Since corvettes will have a surface landing module (for gunboat diplomacy) they may even look like space shuttle stack (with a big winged thing stuck on the side). Merchant express mail couriers might be a civilian version of courvette.
During peace time war fleet has lower operating tempo than merchant marine. May spend half their their time docked instead of the one-quarter that merchants do. This saves operating expenses. The savings allows greater procurement, so they are replaced and retired from active duty after 20 years instead of 30. Then they go into a mothballed reserve force for another 20 years, so reserve is the same size as active fleet. As with cargo ships, warships might undergo top-to-bottom overhauls and remain in service longer.
Crews are larger in proportion than for cargo ships. Operating crew will be augmented with offensive and defensive weapon controllers, scan/ECM, and communication/intelligence; larger ships will have in addition a command staff.
The maintenance technicians will be larger per unit cost because they have to repair battle damage, during or after the battle.
Of course there is no hotel staff.
Some warships will carry a landing force of marines or espatiers. Due to berthing cost and limited space (mass ratio of 2.0, remember?) there won't be many marines, but they will be highly trained (SEALS).
Crew numbers will be higher if they have a landing strike team embarked
This is not a huge crew force. about 10,000 for the entire fleet, with probably a similar number on shore duty at any given time. Add in the marines and the total wearing uniforms is still no more than 25,000 to 30,000. Perhaps with a similar number of civilian employees.
Defense spending for running the fleet (by far the largest budget item) is a modest $72 billion, 0.6% of trade federation's combined GPP. In a prolonged major war this would expand greatly. But this is supported by trade. If the cost of trade protection (the insurance premium) approaches or even exceeds the value of trade itself, there will be a collapse of political support.
Operations in a trade war will be primarily in space. If large scale planetary landings are required, cargo ships can be pressed into service as troop transports. Light infantry is roughly equivalent to civil passengers: 1 ton equivalent cargo capacity per soldier. However heavier equipment, shuttles to carry troops/gear/provisions to surface, armed shuttles for close air support, will all be required. So for an invasion force, 3 ton equivalent cargo capacity per soldier, not counting the naval escort.
If 1/10th of the entire merchant marine is gathered as an invasion force it can transport and land 120,000 light troops, less if heavy equipment is required. But 120,000 troops is a pretty big force to invade a planet of 10 million people.
Suppose instead of 12 worlds, the empire had a thousand worlds, each with a population of 100 million. Then all the above can be multiplied by a factor of over 800. Improved technology will increase size and number of ships. If typical ships is x3 in linear dimensions they will be x27 greater in mass, and fleet can have x30 as many of them.
Large cargo starships: if spherical 300m diameter, if cigar 1,000 km long. Cargo capacity 1 million tons. Full-load mass of 5 million tons each. Empire will have about 1000 ships of that size (and some larger). It will have 50,000 medium cargo ships with cargo capacity of 20,000 tons, and hundreds of thousands of smaller vessels.
Great hub-route stations will have population in the millions.
Navy battlecruisers will be 1 km long, full-load mass of 3 million tons. Build cost $1 trillion. Crew of 30,000. Empire will have 125 battlecruisers in the fleet. It will have thousands of cruisers with a full-load mass of 100,000 tons. Naval budget can be held down to $60 trillion.
100,000 worlds with average population of few billion each. The scale factor is another x3000. You can do the math yourself.
A used spacecraft yard is sort of like a used car dealership. Generally infested with shyster used-car salespersons, you know the type.
A boneyard is a storage area for spacecraft that are retired from service. Most spacecraft at boneyards are either kept for storage or have their parts removed for reuse or resale and are then scrapped.
Small businesses or even a Maw and Paw team might want to purchase a spacecraft to use in their startup business. A small ship can be used for asteroid mining or small cargo transport. Since spacecraft are going to be incredibly expensive, the happy couple will have to draft a business plan to convince Dealer Dan The Used Spaceship Man or the First National Bank of Ceres to advance them a mortgage loan or other type of financing.
Invariably many of these small businesses will discover that their business model does not capture enough value to keep up with the mortgage payments. They default. Sooner or later (depending upon how lenient the lender is) the business be hit by foreclosure and their ship will be repossessed. The bank will tell them to return the spacecraft or face a replevin lawsuit.
Honest businesses will meekly surrender the spacecraft to the bank and try to get a lift back to the civilized parts of the solar system. Desperate businesses will turn off their automatic identification system, and hope they can get the mortgage money before the bank catches up to them. Businesses that undergo psychotic breaks can "skip": run away from the bank's mortgage and become a full pirate.
For the latter two types of foreclosure, the banks will need specialized employees or contractors to get their spacecraft back. Repo crew and bounty hunters. They are needed since a pirate will just use the bank's replevin as toilet paper. If you are dealing with a pirate, the repo crew will probably need to be armed. The situtation and the local laws will determine whether "armed" means sidearms or ship-to-ship missiles. Tough minded banks might consider the destruction of the forclosed spacecraft to be almost as good as repossession. Potential pirates might think twice if the bank has a reputation for bringing defaulters in dead or alive.
Like any other industry, the spacecraft trade and transport industry is subject to the dreaded spectre of Disruption. Current day examples of technological disruption include how internet delivered news is destroying the printed newspaper industry, how Uber is destroying the taxi industry, how Amazon is destroying the brick-and-mortar dead-tree bookstore industry, and how the advent of self-driving trucks could inflict five million truckers with technological unemployment. Not to mention self-driving automobiles.
This is good from the perspective of a science fiction author. Utopias are boring, but times of massive disruption create lots of angry people and angry people can drive exciting plots for a novel.
As a worked example I mentioned how clusters of boom-towns around orbital propellant depots could suddenly become ghost towns when technologically disrupted by the advent of commercial nuclear rockets, establishment of a laser thermal network, or the like.
More simply, the page about Calculating History shows how the sudden availability of a commercial rocket engine with improved specific impulse can change what trading/transport mission are commercial viable (or even possible). Ship captains stuck with the old obsolete rocket engine are at a severe competitive disadvantage. Plenty of pathos and anger will be created, all grist for the science fiction author's mill.
On the flip side, if a new piece of technology threatens a megacorporation with disruption (or even extinction), you can rest assured they will not go quietly into the night. They will use every means at their disposal to neutralize the threat. Which can make life very exciting for the researchers developing said technology, as they flee for their lives from corporate assassins determined to silence them. This is also grist for the science fiction author's mill.
Shipping cargo via seagoing ships and trans-oceanic trade can be really lucrative, but just one shipwreck or pirate encounter on the far side of the globe will result in a total loss. Spacecraft will be no different, except you will probably be able to spot the pathetic remains of your ship through a strong telescope.
The loss of ones ship is a risk, and the management of risk is the world of Insurance. Anybody who was required to purchase liability insurance for their automobile has a rough idea of how it works. The insurer is betting that they will get more money from you in insurance premiums than they will have to pay out to settle any car wrecks you cause. Which is why they jack your premium if you actually have an accident or get too many traffic tickets. The insurance companies spend lots of money researching methods of calculating the precise amount of risk involved with anything they cover. They also keep a close eye on the behaviour of anybody they are underwriting.
In those times there were over 80 different London coffee houses (selling the "new black liquor from Turkey"), each associated with a different type of clientele. Coffee houses had already become associated with news, conversation, and commerce. The absence of alcohol created an atmosphere in which it was possible to engage in more serious conversation than in an alehouse.Lloyd opened his coffee house in a tiny area between the Tower of London and Thames Street, close to the Navy Office in Seething Lane. This just so happened to be the place where the world of London shipping and London finance intersected. While business was done at the Royal Exchange, news and information were gathered in coffee houses. So for Lloyd, it was a case of the three important parts of a successful business: Location, location, and location.
Lloyd's little coffee house quickly became very popular with ship’s captains, merchants and ship owners due to its location. Lloyd didn't have to listen to the sailor gossip for long to realize that all this intel was very valuable. He started publishing a regular sheet of intelligence on ships, individual ship seaworthiness rating, cargo and foreign events (which is still published to this day), and establishing a network of correspondents in ports across Europe. Coffee houses in general were already known as centers for news. Lloyd's sheet was a shipping list containing each ship's name, owner, captain, port of departure and destination, tonnage, number of decks, guns if any, where and when the vessel was built, and most important of all a rating of the ship's hull and equipment. Hulls were rated by how sound they were by the letters A, E, I, O, and U. Equipment was rated either Good, Middling, or Bad. So the best risk was a ship with the rating AG, the worst was UB. Priceless information for an investor or insurer.
The investors and ship insurers took notice, and Lloyd's became the go-to place where the rich made deals with ship owners. Lloyd soon had to relocate his coffee shop to a larger building closer to the Royal Exchange, and offered the patrons coffee, tea, sherbet, and fruit punch. Not to mention unlimited pens, ink, and paper for deal writing — on the house. I suspect that Lloyd trained his employees to listen carefully to any conversations within ear-shot, and report back, because coffee houses were not only centers for the distribution of news, but also for the gathering of news.
Lloyd also hosted "candle auctions." For instance, say Cyrano Jones has a parcel of Spican Flame Gems for sale. The potential buyers gather at the auction site, the auctioneer sticks a pin into a candle an inch or so down from the top, lights the candle, and the frantic bidding begins. When the candle burns down to the point where the pin drops out, the auction is over and the high bidder has won (this is the origin of the phrase "to hear a pin drop"). The point of the candle is two-fold. First the time limit gets the bidders all frantic, which increases the seller's hopes of a bidding war breaking out. But secondly and more importantly, nobody knows exactly when the pin will fall, making it impossible for somebody to make a last-second bid. A similar method is used in the present day on some online auction sites. The exact ending time is randomly selected in order to foil last-second auction sniping.
Lloyd's coffee house had become an insurance marketplace. Starting with the Lloyd's Act of 1871, it became a partially mutualised marketplace within which multiple financial backers come together to pool and spread risk. This was the origin of the famous Lloyd's of London. Edward Lloyd had spotted a hole in the market and swiftly moved to fill the niche.
The insurance marketplace also attracted an infrastructure of useful specialists, such as shipbrokers, admiralty lawyers, bankers, surveyors, loss adjusters, general average adjusters, etc. To get a cut of the action you had to be where the action is, and all of the action was at Lloyds.
Naturally the underwriters exerted considerable power over the ship owners. If your ship was rated as being a broken-down shipwreck-waiting-to-happen, nobody will be willing to hire you to ship cargo, front you the money for cargo speculation, or insure your ship. Owners had to clean up their act to improve their ship rating, and the underwriters decided what counted as cleaning up. David Drake applied these concepts to the Bonding Authority featured in his science fictional mercenary stories.
The practice of insuring ocean shipping has the quaint name of "underwriting." The name was coined in Lloyd's of London, where under the Lloyd's risk information on the slip of paper the insurers would literally write their names.
Everything old is new again, so science fiction authors can confidently add a futuristic Lloyd's of Luna to their universe. Or even have Lloyds of London still in existence hundred of years from now. Use the way that candle auctions transformed into random online auction end-times as a template to make it more futuristic, transpose the music to a science fiction note so to speak.
This is my Grandfather's ax.
This is my Grandfather's ax.
My Father replaced the handle.
I replaced the ax-head.
This is my Grandfather's ax.
You don't want to just throw old ships away, they are constructed out of expensive titanium and stuff. And abandoning an old ship containing a nuclear reactor so it can decay and start venting hideously radioactive isotopes is a very very bad idea. The old ships should be taken to Ship-breaking Yards.
Orbit-to-orbit ships will be chopped up in orbital ship-breaking yards. Ships that can land will be broken at either orbital or planetary yards, depending upon which is cheaper.
And there will be a lively secondary business of entrepreneurs selling lunch and other items to the hard-working ship breakers. John Reiher wrote about this in his short story Ice Cream Man.
Speaking of cheap, the more bottom tier ground based breaker yards will tend to be in economically disadvantaged areas. These have a plentiful supply of desperate workers who are not picky about things like workplace safety, toxic chemical exposure, and massive environmental damage. Here on Terra, ocean ships are broken on the beaches of India, Pakistan, Indonesia, or Bangladesh.
The game company Blackbird Interactive is working on a game called Homeworld: Shipbreakers. You play a team of mercenaries fighting over control of dozens or hundreds of starship wrecks on the desert planet LM-27.
Then a teaser was released for the new Star Wars movie.
Great galloping galaxies! A star destroyer is about a kilometer long. They will be ship-breaking that monster for generations. Not only that, it is huge enough that an ecosystem could spring up inside. Several ecosystems as a matter of fact. Has anybody here ever played the role playing game Metamorphosis Alpha?
What would it be like to live inside that three-dimensional hell-hole? Well, have you ever heard about the Kowloon Walled City that used to be in Hong Kong? It would be like that, except all Star-Wars like.