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What's in the control room? The most important things are the instruments for Flight Path Control, that is, the controls for the rocket engine and for pointing the spacecraft's nose in the proper direction. This will probably take the form of joystick, er, ah, Translational Hand Controllers. In addition, the control panel will include a radarscope, accelerometer, gyroscope platform, periscope, and chronometer. And maybe an integrating accelerograph. This will display elapsed time, velocity, and distance in dead-reckoning for empty space. If the spacecraft is under programmed controls, the programmed values for the three items will be displayed below the actual values, so the pilot can see how results matched prediction. There might be a brennschluss timer. When a burn is initiated, this is pre-set to count-down to burn stop time.
As far as guidance goes, the accelerometers, combined with the gyros, tell you your exact position, velocity, and orientation during a burn. The pilot's job during a burn is to try and keep those values matching the pre-computed values.
Under high acceleration, the pilot might use controls in a lap panel.
Rotation and Translation
When a spacecraft is falling along a trajectory to its destination, there is no need for a pilot. The ship's course is determined by Newton's Laws of Motion and the effect of gravity, the pilot can go play poker with the atomjacks. It is when the ship has to have its nose pointed in the proper direction so that a scheduled engine burn gives the desired vector that the pilot earns their pay. Or when the ship needs to be docked to a space station or something.
The pilot moves the spacecraft via rotations and translations. A rotation spins the ship around its center of gravity, the ship's orientation in space changes but its position does not. A translation, on the other hand, moves the ship's position but does not affect its orientation. So if you were standing up and pivoted in place to the left, you would be doing a rotation. But if you took a step to the right, you would be doing a translation. Aircraft can do rotations, but they generally do not do translations (with exceptions like helicopters, Harrier jump jets, and unfortunate aircraft in the process of augering in).
For most spacecraft, when they do an engine burn, the exhaust goes directly aft (out the rear of the ship) and the thrust goes forward in the direction the ship's nose is pointing. So the pilot will use the rotation control to aim the nose in the required direction (perhaps with the aid of a coelostat). The translation control is not needed for a burn, it generally is required for a docking maneuver. The pilot might need to make rotational corrections during the burn, if the ship's nose changes orientation due to engine irregularities, crewman Joe Idiot walking around during the burn, or something like that.
Rotation spins the ship around one of its (imaginary) axes. A "yaw" pivots the ship's nose to the left or right, spinning around the Z axis. A "pitch" pivots the ship's nose up or down, spinning around the Y axis. And a "roll" makes the ship spin like a old-style propeller prop, spinning around the X axis. Rotations are created by attitude jets or momentum wheels. It is also possible to do mild yaw and pitch by gimbaling the engine. If you have two or more engines that are off-axis, gimbaling can also do a mild roll as well.
Translations are only done by attitude jets. This is because converting rotary motion into linear motion is impossible (the Dean Drive notwithstanding).
Atomic Rocket Pilot Control Console
This amusing example of 1960's style user interface design is from NUCLEAR SPACE PROPULSION by Holmes F. Crouch (1965). This complements the Engineer's console from the same book. This design assumes that it is for a solid-core nuclear thermal rocket. Mr. Crouch decided that controlling the rocket's trajectory while simultaneously juggling the power levels of the nuclear reactor was a little too much to ask of a single human being, so he split it into two jobs. Each subsystem has too many displays, control functions, and automatic interlocks.
According to Mr. Crouch, there are four independent subsystems involved with flying a nuclear thermal rocket:
- Thrust vectoring (Engine exhaust nozzle)
- Spacecraft orientation and stability (Attitude jets)
- Heat generation for specific impulse (Reactor)
- Propellant flow (Turbopump)
The pilot will be controlling the thrust vectoring and spacecraft orientation, the engineer will be controlling heat generation and propellant flow. So the pilot is flying the rocket, while the engineer is flying the reactor and turbopump.
The "space scanner" is an array of displays showing TV field of vision views fore, port, starboard, dorsal, and ventral; plus radar views.
Above is the collision detector. If anything is on a collision course, the light will flash, the buzzer will buzz, the linear range will display how far away it is, and the range rate will display how fast it is approaching. The way to avoid collision is to do a short thrust in any direction. For reasons explained in more detail here, the simple way to detect a collision is to have the radar watch for any object that maintains a constant bearing while having a range that decreases.
Around the space scanner are panels displaying astronomical data, navigational data (including an accelerometer, chronometer, coelostat, integrating accelerograph, brennschluss timer, and gyroscopic artificial horizon. Not to mention radar plotted trajectories of all other spacecraft and objects in the vicinity), astrophysical data (including solar storm warnings), and radio communications.
The pilot has two 3-axis joysticks, sorry, Translational Hand Controllers and Rotational Hand Controllers. The left is a rotational controller. It activates the attitude jets in order to control the spacecraft orientation (basically which way the nose is pointing and thus the direction of thrust). The right is a translational controller. It controls the thrust vectoring of the engine. This allows "translation control", which is a fancy term for moving the ship left or right without turning the nose in that direction. This also allows thrust neutralization. This means letting the engine blast but with no thrust. You need this because a nuclear thermal rocket relies upon the propellant to cool off the reactor, sometimes the reactor needs coolant when the ship does NOT need to be thrusted. Please not that for translations, an engine is limited to vectoring the thrust to no more than ten degrees or so off-axis.
Each hand controller would be fitted with step and trim buttons to throttle and vernier the maneuver commands as desired. Note that the hand controllers are analogous to the Ship's Wheel on a sea going vessel. The compass and the windows are like the other displays.
Finally there is the Thrust Mode Selector. This is basically a glorified Engine Order Telegraph from the age of steam. The pilot uses it to tell the engineer what sort of thrust is required. It is then the engineer's job to juggle the reactor control rod and the propellant turbines to produce what is requested. When the engineer has the engine configured to the requested thrust mode, they turn on the appropriate yes/no light on the pilot's console (next to the thrust mode line) to indicate the state of nuclear readiness.
On an old-time engine order telegraph, the pilot uses the lever to set the desired engine setting. The engine crew acknowledge the order on their own telegraph. At the pilot's telegraph, the acknowledgement moves the tiny inner arrow. This should move so it matches the pilot's setting, otherwise Something Is Wrong. This includes both no acknowledgement and incorrect acknowledgement. In that case, the pilot repeats the setting on the telegraph. If things are still wrong, the situation is immediately reported to the officer of the deck (unless the officer of the deck is also the current pilot, of course).
Sometimes a situation will develop in the engine, and the engineer will have to alter the thrust mode due to the measures taken to prevent the reactor from melting down or doing something else unfortunate. The engineer will probably not bother manually changing the thrust mode yes/no lights (as you would with an order telegraph on a steam ship), instead they will hit the "discoverer" button and the big red nuclear disaster alarm on the pilot's console will start screaming.
From Rocketship X-M.
From the Boeing B-29 "Superfortress".
From the Convair B-36 "Peacemaker".
From the Boeing KB-50 "Superfortress".
2001 EVA Pod
The pod control panels from Pod control panel from 2001: A Space Odyssey (1968).
In response to the verbal from the autopilot, Dieter Ulans flipped his datavisor in front of his eyes and prepared to take direct command of the massive ring of lasers and reaction engines that was Hercules. He hit the juicer button and felt the rush as the drugs began to wash into his veins. "Com'monn jockey juice!" he whispered and then began to croon: "All my thoughts of you, you, you -- all that I've sought is you, you, you." The tiny green symbols on the datavisor began to zip past his eyes at an increasing speed.
His subconscious easily absorbed and processed the information even as his conscious mind took in the blue numbers and symbols on the main screen that showed the gross situation as Hercules and five other ships of the Martian battlefleet began their final approach to Vesta Main Station. "Joey Kolnichok, I know you're here and I'm going to personally fry your tender little parts." The ship thrummed as the main three o'clock engine cut in and changed vector in response to a movement of Dieter Ulan's right ring finger. It was his former classmate he sought -- Josip V. Kolnichok - the one who had beaten him out his bid for a cushy transport command and who had also cast aspersions on his loyalty to the company. This had cost Ulans two points on his profit sharing plan and that was a deficit he intended to make up by turning J.V. Kolnichok and the DesJardin into a bright, glowing gas.
"80-80. Ready track. Ready main. On my mark FC to you and...mark!"
A second green line began streaming across the datavisor as Ulans took control of the main laser fire control systems. Every time he blinked, the little green symbols paused. Every time he squinted his eyelids, a bright blue bullseye magically appeared where he looked on the main screen. Just tap your foot when your buddy shows, he thought, and you'll make him a star. He began to click his teeth together. His finger tips sweated in the close-fitting control caps. Only eighteen k-k's from Vesta and still no Company. What had they done -- written the station off? The entire ship reached into his heightened awareness. The awesome engines designed to hurl inert cargo on multi-million-kilometer tracks through space. The heavy mining laser converted into a terrifying main weapon now slung in the cargo grapples. The thousands of bits of information from the ship's computers and sensing radars. Where the hell were they? "Come on, you Company fish, swim out into the pan."
Another important item is the control panel lock. When the lock engaged, all the other controls are locked in place. So the pilot can sleep in their chair and not have to worry about accidentally brushing a toggle switch. This also comes in handy if the pilot is forced to allow into the control room a bratty kid who just happens to be the son of the boss.
A control of dubious utility is the three-position control switch. It is available if one has duplicate sets of controls for pilot and co-pilot. The control switch is labeled "Pilot & Co-Pilot", "Pilot only" and "Co-Pilot only". It determines which sets of controls are live. One would expect to find this only on a training spacecraft, or if you would commonly expect a non-pilot to be riding in one of the control seats.
There may also be repeater indicators. Such as a red indicator light from the power room which will change to green when the power officer unlocks the safety on the reactor damper.
The three types of instrument displays are Analog, Digital, and Binary. Analog are typically circular like a clock with hands, semicircular like a multimeter or some automobile speedometers, or tape-like similar to a ruler. Digital displays numbers, such as an automobile odometer or a pocket calculator. Binary are "idiot lights" that are either on or off.
The advantage of analog is in displaying the relationship between the current reading and any "red-line" minimum or maximum. The gas (petrol) gauge on an automobile typically has a red area adjacent to "Empty" as a warning that you'd better fill your tank soon. Analog displays are also good at showing the rate of change. You can tell at a glance if the temperature is rising too quickly. The disadvantage of analog displays is that they can seldom be read with more than three figures of accuracy.
The advantage of digital displays is that it can be read with as many figures of accuracy as there are digits in the display. Disadvantages include having memorize what the red-line values are, and not being able to read the display if the figures change so rapidly as to be a blur.
The advantage of binary displays is the simplicity of an immediate warning. Disadvantages include the necessity of a test mode (so you can tell if an indicator light has burnt out) and the lack of extra information. Airplane pilots have many worries when they hit the "lower the landing gear" button and the "landing gear down" binary display fails to light up. Is the gear still up, or is gear actually down but the light is burnt out or the sensor wiring connection loose? All you can do is make a low pass by the control tower so they can look at the status of your landing gear. An analog or digital indicator with the angle of gear would avoid that worry.
Heinlein short stories have rockets with a coelostat on the control panel. This is a series of prisms used for navigation. For each burn of the engine, the astrogator will calculate the direction of the axis of acceleration (i.e., where the ship's nose points). Then they will calculate how to set the prisms on the coelostat. When the pilot sets the coelostat, each prism will reflect a "guide star" onto a screen with cross hairs. (say, three prisms using Vega, Antares, and Regulus) When the ship is pointed in the correct direction, all the guide stars will be dead center in the cross hairs. G. Harry Stine calls this instrument an "astrostat".
During the burn, the pilot will
- keep the stars in the astrostat centered
- ensure that the burn starts and stops at the proper time according to the chronometer or brennschluss timer
- keep the thrust at the pre-calculated rate according to the accelerometer, and
- keep an eye on the radar to be sure that space is clear
Remember that the spacecraft has to be balanced or it will tumble. Any crewmember who unstraps and upsets the balance by walking around will receive a free trip out the airlock sans spacesuit when the pilot catches up with them.
The computer, his calculations complete, watched the pilot with interest, for, accustomed as he was to traversing the depths of space, there was a never-failing thrill to his scientific mind in the delicacy and precision of the work which Breckenridge was doing -- work which could be done only by a man having had long training in the profession and possessed of almost instantaneous nervous reactions and of the highest degree of manual dexterity and control. Under his right and left hands were the double-series potentiometers actuating the variable-speed drives of the flight-angle directors in the hour and declination ranges (ed note: in the "hours" of Right Ascension and the "degrees" of Declination, which is the longitude and lattitude of celestial navigation.); before his eyes was the finely-marked micrometer screen upon which the goniometer threw its needle-point of light; powerful optical systems of prisms and lenses revealed to his sight the director-angles, down to fractional seconds of arc. It was the task of the chief pilot to hold the screened image of the cross hairs of the two directors in such position relative to the ever-moving point of light as to hold the mighty vessel, precisely upon its course, in spite of the complex system of forces acting upon it.
Whoever invented dynamic configs deserves a medal - I'd give him all of mine. Imagine the chaos we'd have without them. A kid joins the Navy on Viand, learns the ropes, and then musters out and joins a merchant company operating out of the Marches.
So what happens? The merchant vessel he's on was built by a company light-years away from the yard that fabbed the dreadnought. All the controls are different: the power switch that was under the thumb of his left hand is now under the third finger of his right. The heads-up attitude display is now flat on the board, and the blue light that signaled a problem is an amber one on the merchant. If he doesn't scuttle her first time out of the dock, you're lucky.
With a dynamic config, he keys in the layout he likes, and if he wants to further customize the panel, he moves the controls around and logs it in the computer so he can call it up any time he wants.
There are moments on the bridge, too many moments, that call for split-second thinking. You set that panel up to your liking - you live with that panel - you marry that panel - and it will always be right there when you need it. Your fingers (and feet, if you use them, but I never do) learn every inch of the board, and you can fly a ship in your sleep. A skilled crewman never looks at the controls - his eyes are on the tell tales and other displays.
If a man's skilled with the configs, too, he can handle any board in a crisis. Commo needs help set ting up a line-of-sight during a battle? Fine, if he's not tied up it takes him a second to pull up commo's board at his station. That's why it's so critical that your bridge crew be skilled at several tasks.
Personally, when I configure a panel I always ignore the leg controls. I don't stop my crew from using them, because a man knows what he likes or he doesn't know anything. But I was never much of a dancer, either, and I feel like my legs just flail around under the console.
I keep the most common controls under my index fingers, but I won't overlap. If there's two things I need to do at once, they've got to lie under different fingers. I'm left handed, so I put anything I need quick under those fingers. I use my thumbs as anchors, mostly. If controls need locked, sure, I'll put in a toggle where I want it, but if the control needs a sensitive touch but still must be held down, l put it under a thumb so the rest of my hand can still swivel around to all the positions.
Another good place for anchors is the little fingers. Little fingers are good, too, to set up alternative controls. For example, on my commo board I like my left index to handle fine tuning of radio frequency, but once I've zeroed in on what I want, that spot's wasted. So when I'm ready to transmit the burst, my right pinkie holds what I call my "second set". Then the burst pad is under my left index where fine tuning normally is. Once the burst is through, I let up my pinkie and I can reset the frequency if I want to. (ed note: In other words, the "second set" button is like the shift key on a computer keyboard.)
I keep any displays I want in front of me, using heads-up holo. If the station can't handle a holo, I'll use a data-display/recorder headpiece, but I don't like to because I get tired faster.
The main displays are right in front all the time. I map telltales to the center in a contrasting color - for the important ones, I use a mixture of red and green, chosen so they clash with each other. I don't like `em to blink, because I want to look at them and catch the info at any time. The split second between blinks might be the split second I need to make the decision. Choose your own colors; your eyes are different from mine.
I use my right third finger to move the telltale once I've spotted it, and I never use this finger for any other purpose on any board. The warning light appears, in the center as I said, then once I've noted it I punch the board and the light moves off to one side. They're all set so that if the condition lasts over a certain time, the telltale will reappear, and I'll just punch it over to the side again if I'm handling it. I want to know, but once it's in my brain I don't need to keep staring at the light all the time.
Burn start and stop might be under autopilot control. But the pilot will still keep their hand hovering over the manual start key (or cut-off switch), as they never quite trust the auto-pilot. The co-pilot and the power officer will also have their hands hovering over their manual keys, since they never quite trust the auto-pilot nor the pilot.
Acceleration depend upon the ship's mass. However, the ship's mass will be decreasing during the burn (as propellant is expended) so the acceleration will go up. The amount of thrust will have to be reduced in proportion in order to keep the acceleration constant. There will be some sort of control that will do this automatically.
How do you keep the ship from spinning, tumbling, or otherwise stationary? Equip the ship with a massive stabilizing gyroscope. If you cannot construct or otherwise use a single massive gyroscope, you can use a series of smaller ones. The International Space Station can limp along with only two, but three is preferred, and the fourth is a back up.
The technical term is "control moment gyroscope." You mount each inside a spherical framework which rotates inside a slightly larger spherical framework. This larger framework is anchored to the ship's structure. The ISS gyros spin at about 6,600 revolutions per minute and take eight hours to rev up to full speed.
Once you spin up a given gyro, the inner framework will stay in one orientation. If the gyro frame is "unclutched", the inner frame can freely rotate (actually it stays stable while the ship rotates around it). When you "clutch" the gyros, the inner frame is clamped onto the outer frame, and the gyro cage will do its best to keep the ship from changing orientation.
Aerospace Engineer Bill Kuelbs Jr corrected an error on an earlier version of this page. I mistakenly stated that the control moment gyroscopes had to be mounted at the center of gravity of the ship. Mr. Kuelbs pointed out that due to a force known as a 'moment couple' the the translative forces are balanced out (i.e., you can mount the gyros anywhere inside the ship and they will work).
Some spacecraft designers will try to economize by specifying gyros that are too light for the spacecraft's moment of inertia (i.e., the rotational analogue to mass ). Such ships will tend to wobble under acceleration. This will also happen if a gyro's bearings start to go bad.
Since gyros heavy enough to stabilize the entire spacecraft are rather massive, a more elegant solution is to use tiny gyros to detect changes in the spacecraft's orientation and connect this to an attitude control system to automatically counteract it. In the old Heinlein novels ships had gyros massive enough to keep a landed ship from tipping over, but this might not be realistic.
How does the pilot aim the ship? The Apollo spacecraft used attitude jets. A more elegant way is with a large precessing flywheel on a gimbal (these are also called reaction wheels or momentum wheels) Aim the axis of the flywheel so it is parallel to the desired axis of rotation, start spinning it, and the spacecraft will start to yaw, pitch, or roll in the opposite direction. Keep an eye on the astrostat to see when the stars overlap, telling you that the ship is pointed in the correct direction. Stop the flywheel and so will the ship. Be sure to unclutch the gyros first. Trying to use the precessing flywheel while the gyros are clutched is like trying to drive a car with the emergency brake on.
Rapidly changing the ship's attitude is a problem, it will require unreasonably powerful attitude jets. A possible solution is using Cascade Vanes instead. Of course exploration and merchant spacecraft generally do not need to rapidly change attitude, this is only needed with warships.
You may or may not need thermal protection on the hull to shield it from the thruster exhaust. Depends upon how the thrusters are angled, and how hot the exhaust is.
Rapidly changing the ship's attitude is a problem, it will require unreasonably powerful attitude jets. A possible solution is using Cascade Vanes instead. Of course exploration and merchant spacecraft generally do not need to rapidly change attitude, this is only needed with warships.
Hop David has an exceedingly clever arrangement of attitude jets on his Tetrahedral spaceship concept. This takes the "jet on a long lever arm" arrangement of Babylon-5 Starfuries to the logical ultimate.
Since the spacecraft has far more mass that the flywheel, the ship will rotate far more slowly than the flywheel does. So if you want the ship to rotate faster than the hour hand on an analog watch the flywheel will have to spin like a x100 CD-ROM drive. It might be prudent to put an armored cage around the flywheel, in case of "explosive delamination". This will ensure that the deadly shrapnel from the delaminating flywheel will shred the armored cage instead of shredding the unlucky crewmembers who happened to be in the plane of the flywheel. Unfortunatly the mass of the armor cuts into payload mass.
A flywheel is too slow to be used during a burn. For that one will use gyros, either massive ones to prevent tumbling by brute force or a tiny ones connected to gimbaled nozzles on the propulsion system.
For complicated maneuvers, one programs the controls with an autopilot. Nowadays one uses computers. In pre-computer days, they "cut a cam". A cam operates in a similar fashion to the paper roll on a player piano. When I was little they were all the rage in motorized toys, to program various movement patterns. But those have gone the way of eight track tapes and slide rules.
Currently the only place one is likely to encounter a cam in on the camshaft in the engine of your automobile. Each cam is a "program" that controls the state of the intake and exhaust valves, synchronizing them to the position of the pistons.
Cargraves yelled, "Hang on to your hats, boys! Here we go! He turned full control over to Joe the Robot pilot. That mindless, mechanical-and-electronic worthy figuratively shook his non-existent head and decided he did not like the course. The image of the moon swung "down" and toward the bow, in terms of the ordinary directions in the ship, until the rocket was headed in a direction nearly forty degrees further east than was the image of the moon.
Having turned the ship to head for the point where the moon would be when the Galileo met it, rather than headed for where it now was, Joe turned his attention to the jet. The cadmium plates were withdrawn a little farther; the rocket really bit in and began to dig.
Ross found that there was indeed a whole family on his chest. Breathing was hard work and his eyes seemed foggy.
If Joe had had feelings he need have felt no pride in what he had just done, for his decisions had all been made for him before the ship left the ground. Morrie had selected, with Cargraves' approval, one of several three-dimensional cams and had installed it in Joe's innards. The cam "told" Joe what sort of a course to follow to the moon, what course to head first, how fast to gun the rocket and how long to keep it up. Joe could not see the moon -- Joe had never heard of the moon -- but his electronic senses could perceive how the ship was headed in relation to the steady, unswerving spin of the gyros and then head the ship in the direction called for by the cam in his tummy.
The cam itself had been designed by a remote cousin of Joe's, the great "Eniac" computer at the University of Pennsylvania. By means of the small astrogation computer in the ship either Morrie or Cargraves could work out any necessary problem and control the Galileo by hand, but Joe, with the aid of his cousin, could do the same thing better, faster, more accurately and with unsleeping care -- provided the human pilot knew what to ask of him and how to ask it.
Joe had not been invented by Cargraves; thousands of scientists, engineers, and mathematicians had contributed to his existence. His grandfathers had guided the Nazi V-2 rockets in the horror-haunted last days of World War II. His fathers had been developed for the deadly, ocean-spanning guided missiles of the UN world police force. His brothers and sisters were found in every rocket ship, private and commercial, passenger-carrying or unmanned, that cleft the skies of earth.
Trans-Atlantic hop or trip to the moon, it was all one to Joe. He did what his cam told him to do. He did not care, he did not even know.
Last but not least is the pilot's logbook in the corner. Or log tape. Or DVD. Or holographic crystal. Or whatever.