Out with the streamlining, in with the RL physics

November 2, 2006 6:28 AM

Let's say you're thrust headlong into a dogfight engagement in space. Era and galaxy of your choosing. What would the real-world physics look like?

Fessing up here. I'm a dedicated, white-knuckled fan (er, on occasion) of the dogfights in Star Wars and Battlestar Galactica, with their dopplering sound effects, banking fixed wing aircraft, and atmosphere-based physics in "space." All the same, I sometimes wonder what a real-world engagement would look like. In particular:

-Fighter design: Streamlining is out the window, of course. But what would an optimal design be? Spherical, cubical? Riddled with gun emplacements (due to the lack of air friction)?
-Tactical issues: Assuming we want manueverability, what types of rockets and thrusters would be used? Problems with inertia in a gravity-free environment?
-Strategic issues: Would a space dogfight even be feasible -- or desirable? How about those dreadnought-class battleships, a la Star Wars. Would these be useful platforms for battle? (You'd assume they'd exert gravitational pull on smaller craft).
-Non-Classical physics: Particle entanglement, extra dimensions, quantum effects -- any way to exploit these?

posted by Gordion Knott to science & nature (58 comments total)

It's important to note that dogfights you cite (Star Wars and BSG) contain crafts which are designed to fly in space AND atmosphere. So it's not surprising that the crafts look the way they do.

BSG gets a nod for noting that they're figther ships can, if the pilot isn't up to par, kill the pilot from all the gforces/thrust etc.
posted by Brandon Blatcher at 6:41 AM on November 2, 2006

Also, streamlining is NOT out, and not just for atmosphere travel capability.

A streamlined ship is able to attack an enemy while presenting the smallest possible target. A sphere or cube is equally big from any angle.

Also, you may want to state what problem you're trying to solve before someone jumps in here with the chatfilter flag.
posted by utsutsu at 6:45 AM on November 2, 2006

Space is big. Relative velocities can be enormous and occur in arbitrary directions. It's stupidly hard to make Star Wars work even at low-Earth-orbit speeds. I can't see how a space dogfight could actually work.
posted by flabdablet at 6:49 AM on November 2, 2006

Drive systems would want to be as much like a rocket as possible. While the ion drives of TIE fighters are real technology, they work over a long time and aren't maneuverable in the least.
posted by cowbellemoo at 6:58 AM on November 2, 2006

A few sci-fi authors have tried to model what a "real" space fight would look like.

Since velocities are likely to be extremely high relative to each other, the consensus seemed to be something like:

Fleets approach each other. Hours pass. Both fleets launch out clouds of metal BBs. In a fraction of a second, the fleets pass. Many ships are destroyed by collisions with metal BBs. The remaining ships maneuver into orbit, around a planet, whatever. Likely enough they don't pass each other again for days or weeks, even if both sides still want to fight, which is unlikely.

There are a few basic things at work here: mass is always going be the enemy of space flight, so ships will always be as fragile as possible. A bowling ball moving at ten miles per second is going to go through your space ship like it wasn't there, so why bother trying to armor the ship? Clouds of BBs are cheap and deadly weapons... why mess around with more sophisticated weapons. Lasers sound like a good idea, until you realize the most powerful laser ever, from a distance of thousands and thousands of miles, spreads out enough to barely warm the target.
posted by jellicle at 7:05 AM on November 2, 2006 [2 favorites]

A real world space engagement (assuming slightly higher levels of tech than the real world and less than star wars) would involve a lot of old fashioned trajectory plotting to intersect ships and/or long range (think light hours or days) laser strikes.

If I know your big ship is traveling on a certain trajectory I would move my ship to a point where I can launch my long range weapon (assume a laser) and shoot at a point where you will be in the next few minutes or hours. Your ship intersects with my laser and you'll die. Not very exciting.

I would imagine it would be like how old time ocean going ships fought. Do we have enough fuel to do this? Can we make this trip? Where should we shoot from? Have we been spotted? Does the target have a support ship or backup? How far from port will we be if we engage them? Do they have better weapons systems and detection than we do?

You'll probably get a kick out of realistic space combat games like this one.
posted by damn dirty ape at 7:06 AM on November 2, 2006

If you're doing orbital manoeuvres within a gravity well then you'll run into some interesting counter-intuitive situations. the conditions known as "above" and "below" are actually energy states. In some scenarios, applying too much thrust to dive "down" to someone below you could result in you moving further out, or "up" into a higher orbit. You have to reduce your momentum to move "down", which means targeting your thrust in just the right direction relative to your instantaneous momentum. In many cases, its easier to imagine yourself in a stationary frame of reference and regard everything else as free bodies.

You may want to play with the Orbiter space flight sim to see what this feels like. Pretty much every commercial space sim and media entertainment abandons "true" Newtonian dynamics for some version of aeronautical direct-line space flight, including Galactica.
posted by meehawl at 7:07 AM on November 2, 2006 [1 favorite]

Weaponry possibilities should be much more insane than in space opera. You basically have to either figure out some kind of armor or shielding that would block atomic weapons, or it's going to be a nuke-fest. Once you stop nukes, it's a matter of figuring out how to aim a relativistic kill vehicle at a target (sufficiently big ship or planet). Or a laser (assuming that you don't, you know, put mirrors all over your ship). Space fights would be large, armored ships launching stuff at each other.
posted by graymouser at 7:11 AM on November 2, 2006

Weapons that you'd probably use:

1. Lasers - A nice coherent beam is too useful to pass up, although you're going to have to hold it on your target for quite some time (several seconds) and if they're more than a few light-seconds away that could become problematic. Power requirements might be an issue, but if you're zipping around in space at enormous velocities then you probably have power to spare.

2. Missles - If you're already fighting in space then you can add a few (thousand) missles. Only a few have to get through to destroy your opponent, and since space is big and missles are small, it's going to be hard for your opponent to get them all.

3. Dumb bombs - If you're dealing with really large relative velocities then dropping a load of ball bearings in your opponents path will be sufficient to shred any current spacecraft. Of course, this is at some point in the future where it's possible that our spacecraft will be made of transparent aluminum, diamond, or an impervious General Products material, so this might not be a viable weapon.

4. Exotic weapons - Instead of dropping a load of ball bearings, how about a bunch of quantum black holes? The actual gravitaional forces probably won't do that much, but the black holes will be able to pass through any normal matter and if they're small enough they'll be putting off some pretty fierce Hawking radiation.



Generally, though, "dogfights" in space wouldn't really work. You'd want to hide behind a large mass (asteroid, planet, star) until the last minute and then blast your opponent as soon as they came into view. Getting really close would be impossible and wouldn't be all that useful.
posted by bshort at 7:15 AM on November 2, 2006

Fighter design:

Streamlining isn't necessarily out the window.

On the one hand, some ships may be designed for in-atmosphere work as well, or at least be capable of diving into an atmosphere briefly without ripping itself to pieces (something that, say, an Omega-class destroyer from B5 couldn't do). This wouldn't be just stupid, either -- having the ability to aerobrake might radically expand your maneuvering envelope and let you do stuff that the enemy doesn't expect.

Also, having a fighter that just plain looks mean and badass might be an important part of maintaining a psychological edge for the pilot. As long as it's not actively interfering with some other goal, a nod towards streamlining or badassness might be useful.

A normal Starfury might be a good compromise. Put the pilot near the center of mass, put the thrusters in positions to maximize torque on the center of mass, have "wings" that are big enough for various emplacements but not so big that it really slows rotation, and it still makes you feel like God to sit in it and blow shit up.

All of this assumes that stealthing is not needed or is useless against magic sensors. If it's important, that probably leads back to effective streamlining as you minimize radar (or whatever) cross-section from a preferred attack angle.

Tactical issues:

You'd want the biggest fuck-you rockets (or magic thrusters) you could pack into the ship, subject to the minimal constraint that you can't break any people in the ship too badly (this makes ships driven by an AI or downloaded human mentality a real plus). Problems with inertia: I'd just bet that combat maneuvering in that setting would be strongly counterintuitive and highly three-dimensional. Whether you'd deal with this with training or computers or both, who knows.

Strategic issues:

I'd bet that whether a dogfight is feasible depends a lot on the balance between offensive weapons, and their size, and defensive weapons and armoring/shielding. And, at a secondary level, on the strength of automation available.

If weapons useful against a capital ship can be carried on a fighter or small attack ship, like now, then having them (and their motherships) might make a lot of sense. Then you'd get "dogfights" as the attacking fighter cloud tried to take out the fighter cloud defending a capital ship or group thereof.

But I bet you'd also only get a real "dogfight" if the tech developed so that missiles were less useful and beam-weapons and railguns -- gun equivalents, that is -- were the preferred weapons. Otherwise the ships are just missile platforms. And if automation is really good, you can dispense with the platforms and just have very intelligent missiles and antimissile missiles in a cloud around your ship, sort of like a dispersed immune system.

A ship would have to be really gigantor to have a noticeable grav field, barring weird shit.
posted by ROU_Xenophobe at 7:15 AM on November 2, 2006

You basically have to either figure out some kind of armor or shielding that would block atomic weapons, or it's going to be a nuke-fest.

But a nuke in space isn't that bad. It's a big burst of radiation near your ship, and some chunks of metal moving at great velocity. A thickness of metal or rock/earth will stop the radiation, and alternating hard and soft layers will minimize damage from the impact.

ISTR that a lot of the actual blast energy of a nuke on Earth comes from the interaction of the radiation and the atmosphere -- the xrays heat the holy fuck out of the air, and it's the air itself that makes a earth-shattering kaboom. Take away the air, and you're left with defeating a big xray flux.

What you'd probably want to do is either use nukes to pump x-ray lasers, or worse, or use them to accelerate very hardy projectiles to very high speed. In the latter case, using nukes like gunpowder.
posted by ROU_Xenophobe at 7:21 AM on November 2, 2006

One thing is for sure, the dogfight would be silent.
posted by theinsectsarewaiting at 7:21 AM on November 2, 2006

It's all out the window if anyone has gridfire, of course.

\me swivels effectors and CAM-dusters menacingly
posted by ROU_Xenophobe at 7:21 AM on November 2, 2006 [2 favorites]

Banking's not that implausible. It'd be handy to rotate as you enter a turn so that you put the acceleration through your body in the right way, letting you maybe get higher accelerations in.

Sound: people keep saying that space battles will be silent. This seems to me insanely stupid assuming that it's real human pilots going at each other. What better way for a radar system or whatever to tell you there's someone sitting on your tail than having a speaker making engine noises behind you. Surround sound all the way!

However, if you're chucking rocks at each other at high speed then it's probably not so useful. I doubt there's much weaponry and countermeasures that sit in the gap between knowing about something so early you can just have a dialog box pop up and knowing about something so late that your ship is in bits.

On the exotic physics front - it's either so exotic it might not exist or it's not worth using in favour of more conventional methods I suspect.
posted by edd at 7:28 AM on November 2, 2006

You need to think of it more like Asteroids than Star Wars. The dogfighting in those things is modeled after ww2 dogfighting - relatively slow moving highly maneuverable craft. Also, they are planes which operate on the basic principle of flying through air to create lift. Spacecraft don't need lift, because there's no air, and their in orbit or interplanetary space where they aren't under a constast gravitational pressure.

Also, if you puncture a wing with a bullet, you may survive. If you puncture a spacecraft, you lose air, pressure, and the expulsion of air creates a thrust which affects the movement of the plane.

The BB's are a fine idea, but even today's cruise missiles, relying on vectored thrust rather than wings to guide them would be deadly. And maneuverability in space is very low unless you have a lot of fuel to burn (which makes craft larger and bigger targets).

In space, an object in motion stays in motion. Turn the rocket on for 2 seconds, then turn it off and you keep going. To stop, you have to turn on a rocket facing the other direction with power enough to cancel out the momentum of the craft.

Jellicle brings up BB's but I recall an Arthur C. Clarke story in which a very fast moving craft (like 60% of c) had a giant cone of water ice in front to aborb the impact of small particles that are normally harmless but would be deadly at those speeds. So if you have a craft that you know is going to get shot at (with bullets or bbs or whatever), ice makes a fine shield. If they use an explosive weapon, you are basically screwed with or without the ice. Also, ice is very light.

From a materials standpoint again, if you are not expecting to get shot (like the Apollo missions), you use a thin skin of aluminum and you're fine. If you expect to get shot or blown up, you'd use something heavy like steel or depleted uranium (what armor piercing shells are made of).

Again, that's extremely heavy, and now you need a ton of fuel.

The shape of the craft does not matter, what matters is where the center of mass is, because that's the point the ship will rotate around when it tries to turn.

BTW, every time you shoot a projectile weapon, that equals thrust in the opposite direction every action has an equal an opposite reaction. so the bullet moves forward fast, and the ship moves back slowly, but it keeps moving back because there's nothing to slow it down.

Weapons -magentic rail guns would work nicely.

Ships - what I said above - life support functions would have to tucked deep inside so a stray bullet doesn't puncture the air tank.

In short, a dogfight is impossible. Hell, with modern fighter planes dog fights are basically 40 minutes of chase and 2 seconds of target and fire.
posted by Pastabagel at 7:28 AM on November 2, 2006 [1 favorite]

Non-Classical physics

Considering relativistic motion as a Special case. If you are moving close to c then, as well as time dilation effects, you are going to perceive a "squeezing" of events into a cone in front of and behind your line of travel. As you move nearer to c, more and more events to your side will simply not reach your point of reference "in time" to be seen and your available information will resemble more and more two points of highly dense information, front and rear. If you eventually travelled "at" c, then you would in effect be a photon and "see" only a along your single path of motion, front and back.
posted by meehawl at 7:29 AM on November 2, 2006

One thing is for sure, the dogfight would be silent.
posted by theinsectsarewaiting at 10:21 AM EST on November 2

Not for someone sitting inside a craft. The ship is all metal, which means you are going to hear every vibration, every impact, every creak as forces are exerted on and spread across the ship. Think how noisy a commercial airliner is, or even a car. Most of those sounds are the vibrations of the engines an various mechnical motors transerferred along the metal hull.

The reason shuttle flights and apollo mission were relatively silent is that those craft were in orbit or in free flight, not operating under any engine power.
posted by Pastabagel at 7:34 AM on November 2, 2006

In a nutshell: Less like "Star Wars", more like "Asteroids".
posted by Wild_Eep at 7:35 AM on November 2, 2006

Larry Niven's PROTECTOR has a detailed dogfight between several ramjet spaceships travelling at speeds that are a significant proportion of the speed of light. The dogfight takes several years, and largely consists of throwing things out of the back of ships at pursuers, hoping they hit the obstacles at their relativistic velocities and are therefore vapourised.
posted by alasdair at 7:37 AM on November 2, 2006

It's not even as straightforward as meehawl makes out. There are relativistic raytracers however, this for example, and it might be possible to have cameras doing the observing and have a computer remove many of the relativistic abberations so that you get a view of things that is more like that people expect.
posted by edd at 7:38 AM on November 2, 2006

dangit PastaBagel.
posted by Wild_Eep at 7:38 AM on November 2, 2006

Yes, I undertsand that the pilots might hear something, but the battle itself would be silent. Or are the soundwaves rebounding off something I don't know about in the vaccuum of space?
posted by theinsectsarewaiting at 7:47 AM on November 2, 2006

To get a handle on Newtonian spaceflight with futuristic, non-fuel-constrained thrusters, outside of a gravity well, play Independence War or Independence War II. Make sure you turn off the fly-by-wire computer sometimes.

A book I once read with an interesting, realistic view of spaceflight was Allies and Aliens by Roger Macbride Allen.

A lot of it depends on the propulsion technology. If two space shuttles tried to have a dogfight, they'd most likely soon find themselves without enough fuel to properly deorbit.

I also think the detection / stealth technology will be important in determining the existence of dogfights. If you can only see your enemy when he's a couple hundred miles out, it makes a dogfight much more likely than if you see him coming from ten thousand miles.

I think it would take something special, like a weapon very powerful only at very short range, to get dogfights close enough to actually see each other out the cockpit window.
posted by TheOnlyCoolTim at 8:01 AM on November 2, 2006

Yes, I undertsand that the pilots might hear something, but the battle itself would be silent. Or are the soundwaves rebounding off something I don't know about in the vaccuum of space?
posted by theinsectsarewaiting at 10:47 AM EST on November 2

The battle itself would be silent, you're right. Think 2001, not Star Wars. Sound is vibration of a medium. Space has no medium, hence nothing for sound waves to propagate in.
posted by Pastabagel at 8:04 AM on November 2, 2006

Pastabagel --

The one thing I'm having trouble with in your description is the railguns. How do you shield them so they can spray out (whatever) at relativistic speeds but can't just be targeted for quick obliteration? Or are tactics a "wreck their weapons before they wreck yours" kind of proposition?
posted by graymouser at 8:17 AM on November 2, 2006

There is something else to consider - whaling. Small manned craft are inefficient in space All that metal and protection just to protect a person who's sole job is to drive all that metal around???

The only reason we build small space craft is because we have to get it off the ground. Look at the Saturn V rocket. All that fuel just to get an orbiter and lander on a trajectory to the moon.

But if you build the craft in space, it is more efficient to build them huge. Look at the size of supertankers, cargo vessels, cruise ships and aircraft carriers - the only limit is the budget.

So a dogfight with these things is going to be more like the tall ships of the 17th and 18th century. Model it after the defeat of the spanish armada.

A nuclear detonation would be a pretty big problem in space - electromagnetic pulse - gamma rays, x-rays, etc. The smaller the electronics - transistors, circuits etc. the more likely they are to get fried by EMP. EMP is why we do not have atmospheric nuke tests. An atmospheric nuke test in 1962 took out a number of satellites in orbit not directly affected by the blast.

Also, nuclear blasts put out a ton of radiation that is going right through all that metal into everyone's soft and squishy bodies. And the metal is going to stay radioactive long after the blast is over with. You could make the ship out of lead, but lead melts at low temperatures, and nuke blast are pretty damn hot.

The thing to consider is that humans are so fragile, and space is in fact so hostile an evironment to us, that a tiny robot with a power daw could pretty much kill everyone on board the ISS if it started cutting willy nilly.
posted by Pastabagel at 8:37 AM on November 2, 2006

David Gerrold's "Star Wolf" series describes space battles as being more like submarine battles than dogfights. He's got some excellent points.
posted by kindall at 8:44 AM on November 2, 2006

The battle itself would be silent. Sound doesn't travel in a vacuum except for through a medium like metal or air. So yes, a pilot would hear something.

I'm going to take this question as 'with current or currently possible technology' ...

A dogfight -- Ok. Point 1) Space is big. No, REALLY big. ... ok, you're not understanding me. SPACE IS REALLY FRIGGING BIG. It'd be easy, unless you've got a system-wide radar network, to hide completely.
Point 2) Maneuvering. Keep in mind space is BIG. Also, keep in mind that we haven't developed a propulsion technology that's effective enough to propel a lot of mass (i.e. a fighting ship with armor or whatnot) efficiently enough and at a high enough velocity to make combat effective. What we end up doing is using gravity 'pathways' through the solar system to get a velocity boost from falling into a planet's gravity well and maneuvering so that we 'slingshot' out. It would be difficult to copy that effect in a 'dogfight', and that's all our long-range propulsion systems could handle. It's more likely that a 'battle' will happen in orbit around a planet, because it'd be difficult to arrange a deep space battle. Also, it would be disasterous if you ran out of fuel in deep space, so it's more likely to use fighter type craft (or remotely controlled fighter craft) that could refuel at an orbital station or a 'carrier' ship.
3) Weapons -- Lasers have become siginficantly more focused and effective in recent years. We can now do a lot in atmosphere with lasers (see the new antimissile 747's); space is even easier because you don't have the decollimating effect of the atmosphere. The problem with missile launchers, railguns, and other projectile means of propulsion is that every force has an equal and opposite reaction in zero gravity -- so you fire a big cannon and you push your ship away from the cannon and off of your intended path, and then need to expend precious fuel to get back on course. Since we've stipulated that most battles will happen in the orbit of a planet (potentially inhabited), and we're not dealing with relatavisitc velocities, you're also not going to see a lot of nuclear munitions unless you just don't care what the heck happens to everyone within EMP range of the planet. Lasers, or missiles launched after separation from a ship, would be much more likely.

With current technology, if we developed a way to quickly and easily get materials in orbit or someone finally started manufacturing things in space, deep space maneuvering would be like submarine service -- as few emissions as possible, hide in the vastness of space, don't let them know we're coming. They would carry fighters or other external munitions packs (possibly remote control fighters, since trained pilots would be a pretty short supply) for use in orbit of a planet.
posted by SpecialK at 8:49 AM on November 2, 2006

"The smaller the electronics - transistors, circuits etc. the more likely they are to get fried by EMP. EMP is why we do not have atmospheric nuke tests. An atmospheric nuke test in 1962 took out a number of satellites in orbit not directly affected by the blast."

Heh. You made me read all the way down to the end of the thread, with the EMPs in my mind...

I always figured that space combat would probably happen with EMPs and clouds of debris (and I'd think that with water so relatively scarce in the universe, it'd be prohibitively expensive to just make ice shields).
posted by klangklangston at 8:57 AM on November 2, 2006

Read Larry Niven's earlier Known Space stuff. Protector as mentioned above has a great dogfight between a couple of bussard ramships .

But, my own speculations...

General Setup: I suspect that combat in space will take place between two fleets of largish ships, not single-person fighters, at great range. Great amounts of energy and money will be spent on creating really badass ballistics computers to predict the flightplans of enemy ships.

One thing I can tell you is that space combat will be wasteful. When you're five light-seconds from your target, with relative velocities in the thousands of km/s, it's going to be very difficult to hit them with a single shot. You're going to need your computer to define multiple possible predictions of target location, and then attack all of these locations simultaneously in order to maximize the probability of a hit. This means that if you fire against N probable locations, you're very likely to miss with all N shots, and the very best you can hope for is to miss with N-1 shots.

Ship Design: Enormous engines. Assuming this ship is for deep-space service only, I would build the thing as a sphere, despite the issues of cross-section mentioned above. At the range and velocities we're discussing, having a 40% smaller target area really can't help that much--targetting will already be the biggest issue.

The value of a spherical design, with multiple thruster nozzles arrayed over the surface of the sphere, is that lateral thrust can be applied without having to first rotate the ship. Since the best defensive manuevering would be to thrust laterally at random (thus throwing off your course just enough to avoid laser and dumb weapons fire), you want your thrusters always available.

Weapons: Oooh boy. I like the steel BB idea. Actually, a marshmallow at the right velocity works just as well. The problem is that, unless you're headed directly toward the enemy ship, your steel BBs will never hit them.

The real core of your space armament would be guided missiles. Really smart, multi-million-dollar guided missiles. Like our latest gen cruise missiles, except fitted with badass computers and sensors. I would also modify the warhead so that it's an atomic bomb with plenty of mass around it to vaporize.

Your ballistics computer would pick a set of trajectories of highest probability, and you would launch a missile along each of those trajectories. These missiles would then do their own ballistic tracking and modify their thrust vectors to increase probability of hit.

If you're behind someone and chasing them, you need lasers. I don't suggest a standard laser tube, but rather a single-use, bomb-pumped laser. Jettisson the laser alongside your ship, run it out to a few kilometers, tell your computers to find a good heading to fire along, manuever the laser pod, and then detonate the bomb.

I suspect, however, that the idea of a space dogfight will not be to destroy their ship, but to capture it--those sons of bitches are expensive. As such, expect extensive electronic warfare.

This could actually be a situation in which something like a fighter could be useful. Launch a team of two people in a small, manueverable, low-inertia craft loaded up with lightweight jamming equipment and computers. One's a pilot, the other's a hacker. Intercept the other craft, dodge its fire, and attach yourself to the hull. Then, start fucking with their sensors, computers, and everything else you can think of.

Furthermore, you'd almost certainly have countermeasures on the ships themselves. Radar stealthing, jamming, decoys --drag a shell of a ship a thousand kilometers behind you. If your technology is similar to your enemy's (or identical in our increasingly monopolated world economy), there're all manner of things you could try.

Also, by the time we're having space warfare that is more than astronaut-marines throwing junk at one another in geosynchronous orbit, we're going to have some awfully smart computers. Probably not conscious, but certainly with powerful solvers for all sorts of difficult problems.

Perhaps space warfare is never conducted by humans for an attack, since it might be tactically desireable to put the attack craft on a one-way vector to the galactic core. A swarm of small, nimble craft piloted by computers could be sent out on a suicide mission and left to autonomously attack the target for months on end. Since you don't have to keep humans comfortable, or even alive, these ships can consist of nothing but a giant rocket, a big fuel pod, and weapons.
posted by Netzapper at 8:58 AM on November 2, 2006

The way I see it, the big balancing act is between detection and defenses. Your best weapon is going to be an energy beam. It doesn't require munitions beyond an energy supply, travels at light speed, and without an atmosphere to distort the beam, it pretty much kills the thing you point it at. So whoever sees the other guy first wins, assuming a sufficiently powerful weapon.

If your opponent tries to defend himself with a reflective coating, he becomes more susceptible to detection by active scanners or passive light reflection from a nearby sun. Or he can go "stealth," although painting himself black, he makes himself more vulnerable to the beam weapons.

So really, the issue is, how do two vehicles get close enough to have a real melee? Ambush, maybe, by hiding in an asteroid (see "Last Starfighter"), but IMHO you really need to examine the reasons why dogfights occur (or occurred) on Earth, and see if they're applicable.
posted by condour75 at 8:59 AM on November 2, 2006

Railguns are the coolest thing ever, and they are very real. The operating principle is that energy is energy whether it's kinetic energy or explosive energy.

A magnetic rail gun is basically a long rack of electromagnets (ideally on two equidistant sides or three sides spaced 120 degress apart, like a Y), and a small metal conductive object as a projectile, like a ball bearing or a cube. The magnets turn on and off (or more precisely power up to one pole and switch to the other) in carefull timing to accelerate the projectile along the length of the rack. Becasue the projectile isn't resting on anything (the magnetic filed suspends it in midair) in can be accelerated as fast as you can switch the current through the electromagnets.

The thing is, they can be very small. The projectile could be as small as a baseball or a die. The thing is to fire them at insane speeds. You aren't going to get it at relativistic speeds but you could easily get it over a few times the speed of sound, expecially in space which is naturally cold and where there is no air resistance.

Kinetic energy is 1/2mv^2. So the velocity is far more important than the mass. You double the speed and you quadruple the energy. Double the mass and you just double the energy.

A final note: in science fiction, I personally think it's acceptable to solve any engineerying problem (better materials, more precision, no budgetary constraints, faster computers, etc.) but it is really annoying to change or ignore the laws of physics (wormholes, dimensions, time travel etc). If you change the laws of physics, then it's just fantasy set in space. In star wars, people moving objects with their minds was just as plausible as jumping to hyperspace.
posted by Pastabagel at 9:00 AM on November 2, 2006

I agree with Pastabagel that fights in space will be less Star Wars and more High Seas. James Michener gives a pretty decent account of near-earth orbit manouvering in Space - fighter pilots were trained with jeeps driving in circles. You have to slow down to drop to a lower orbit and speed up to move to a higher orbit.

In open space, think about the manouvering done in Apollo 11. Turn on right thruster for 10 minutes. Turn it off, measure deviation from intended position, and redo. Of course, computer navigation software would make this process a lot easier, but I think even at slightly sub-light speeds, positioning is going to be very important.
posted by muddgirl at 9:00 AM on November 2, 2006

You can always have a dogfight wherever there's a debris field. It forces people to stay at slower speeds and make more calculated maneuvers.
posted by cowbellemoo at 9:05 AM on November 2, 2006

Actually, it is very very hard to hide in space. The reason subs are hard to detect is because of the environment. The ocean is noisy, light doesn't penetrate it well, radar doesn't work well, the water wicks off and disperses heat, and the general planet earth puts out so much electromagnetic noise that makes those instruments difficult to use.

In space, where the environment is emplty but for radioation which is easy to filter out by frequency, finding things is easy if you know where to look. We can find planets hundreds of light years away.

If you have a space craft that is 450 degrees C warmer inside than out, and you have electricity and motors and whatever, you are as easy to spot as a floating TV station on fire. Radar works wonderfully in space. Hell, 35mm cameras work great in space. There is nothing in sapce every remotely like a spaceship, so finding them is easy.
posted by Pastabagel at 9:07 AM on November 2, 2006

Go find the video game "Descent". Thrust and roll/turn in all three dimensions, in a zero-G environment. Broad banking turns _are_ possible, if you can turn as you thrust. I've had some fabulous dog fights in that game.

For me, the biggest challenges were figuring out how to combine actions (thrust and turn in various axes) to acheive the effects I wanted, AND learning how to think about movements in three dimensions. When you're used to looking for opponents front/back and side/side, attacks from above and below are devastating.
posted by browse at 9:12 AM on November 2, 2006

So really, the issue is, how do two vehicles get close enough to have a real melee? Ambush, maybe, by hiding in an asteroid (see "Last Starfighter"), but IMHO you really need to examine the reasons why dogfights occur (or occurred) on Earth, and see if they're applicable.
posted by condour75 at 11:59 AM EST on November 2

This is a great point. They occurred on earth in WW2 as bomber support. You control the sky to control the high ground so you can bomb the regular ground from up there. The WW2 dogfights were forward air support for the b17s, etc.

Now, you use stealth bombers and cruise missles to take out ground based radar, you use fighters to maintain control of the air by taking out their fighters and their airfields, and then you send wave after wave of bombers until you run out of bombs or targets.

As an aside, the air force has plans to control the Lagrange points (L2, L3, etc) because they are the ultimate high ground). Lots of info here about how the a military would use space to maintain control of a planet.
posted by Pastabagel at 9:14 AM on November 2, 2006

Ambush, maybe, by hiding in an asteroid (see "Last Starfighter")

Asteroid fields are a lot more sparse than the movies would have you believe.
posted by edd at 9:38 AM on November 2, 2006

Kinetic energy is 1/2mv^2. So the velocity is far more important than the mass. You double the speed and you quadruple the energy. Double the mass and you just double the energy.

It's not clear to me that one is more important than another. You're pumping whatever energy you have available in - you can't just decide between doubling one or doubling another.

In fact, increasing the mass may be better as then your projectile is moving more slowly and you have more time to pump more energy into it.
posted by edd at 9:42 AM on November 2, 2006

To get a feel for it, you should try Terminus . Published in 2000, it simluated space combat with pretty accurate Newtonian physics. There's no drag, you can spin your ship independently from your axis of motion (which Viper pilots in BSG frequently do too), you have a "top speed", but it's ludicrously high for most ships. Your real limiting factor is your max acceleration. It makes some comprimises on technology to make combat recognizable to players, so the dropping BB's weapons talked about above don't make an appearance that I remember. It's still mostly mass drivers (kind of like BB's), lasers, and missles.

Rail guns are great but getting the efficiency up on them is really challenging. There's a reason the military doesn't use them much. Explosives are still way more effective for moving bits of metal at very high speeds.

Also, edd is right about it not being a choice. Yes, an object moving twice as fast has four times the kinetic energy, but it took four times as much energy to get it moving that fast, so it's not a short-cut to doing more damage. Though, since space combat would probably be all about relative velocities, you can count on everyone else going fast enough that the mass isn't going to matter that much.
posted by heresiarch at 10:27 AM on November 2, 2006

In fact, increasing the mass may be better as then your projectile is moving more slowly and you have more time to pump more energy into it.
posted by edd at 12:42 PM EST on November 2


Increasing mass means increasing the mass you have to carry around all the time. That's more fuel, you need to burn in every maneuver. What makes railguns appealing is that you are turning electricity into propulision, so you aren't storing anything other than the projectile. The difference is that you have this energy (electricity) anyway.

The railgun doesn't require much in the way of facilities beyond what will be present to provide electrical energy to a craft anyway.

True explosives are effective, but you have to carry them around, which creates an accident risk.
posted by Pastabagel at 10:57 AM on November 2, 2006

I thought that a nuke has to explode in a magnetic field (such as the earths) so that they won't be effective in deep space. Wikipedia concurs.
posted by doozer_ex_machina at 11:10 AM on November 2, 2006

Oops, thats what happens when you try to post with a baby on your knee. My point is that you won't get an EMP from a nuke in deep space.
posted by doozer_ex_machina at 11:29 AM on November 2, 2006

My point is that you won't get an EMP from a nuke in deep space.

That's absolutely not true, and if you read the wikipedia article that you linked to, you'd see that it doesn't agree with what you're claiming.
posted by bshort at 11:47 AM on November 2, 2006

Regarding lasers:

No way. Useless as a space weapon. Laser beams diverge; it's a fundamental physical limit, and it cannot be defeated with improved technology. As you decrease the wavelength of the laser light, the angle of divergence decreases, but even with some kind of exotic gamma ray laser your beam will spread out, and the further away your target is, the less engery per surface area you'll be able to deliver to it. By the time you get close enough to use your laser, the other guy will have already lauched a bowling ball through your hull at 10,000 miles/hour. Bowling balls don't diverge.
posted by mr_roboto at 12:46 PM on November 2, 2006

Um. Doesn't mean it's right, but it does say that:

Beyond a certain height a nuclear weapon will not produce any EMP, as the gamma rays will have had sufficient distance to disperse. In deep space or on worlds with no magnetic field (the moon or Mars for example) there will be little or no EMP. This has implications for certain kinds of nuclear rocket engines. See Project Orion.

I suspect y'all may be using different definitions of "deep space."
posted by ROU_Xenophobe at 12:51 PM on November 2, 2006

RE: Railguns ... Sure, but you have the issue with any other explsoive-launched projectile cannon: The force to launch the projectile is commuted back through the hull (Newtonian physics, peeps...) and pushes your ship around. Then you need to burn your limited fuel to get back on course.

If laser collimation was truly an issue over 'dogfight distances', then we wouldn't be actively shooting missiles down with lasers in our own atmosphere. As I said, a laser works as a *short range* space weapon. We're talking about dogfight here, which is by nature a short-range battle.
posted by SpecialK at 1:06 PM on November 2, 2006

SpecialK writes "If laser collimation was truly an issue over 'dogfight distances', then we wouldn't be actively shooting missiles down with lasers in our own atmosphere. As I said, a laser works as a *short range* space weapon."

Current laser weapons have a maximum range of a few miles tops. "Short range" in a space dogfight would be thousands of miles.
posted by mr_roboto at 1:40 PM on November 2, 2006

Check out any of the earlier of David Weber's Honor Harrington novels...I believe they're more accurate than a lot of stories in showing battles between fleets. A lot of time passes as combatants get close enough to fight, then gagillions of intelligent kinetic weapons and masers are unleashed, countered by defensive weapons. There are a lot of battles in those books.

I got way tired of Honor Harrington long before I reached the end of the series, but feel a sudden nostalgia for the first two or three novels, before she saved the universe yet again...
posted by lhauser at 5:11 PM on November 2, 2006

A cloud of BBs is a totally useless weapon in Space, except at very close range. All you have to do is detect them coming at you and move in the opposite direction a very easy thing to do in space.

As I see it a war in space would be very much like naval warfare in Napleonic times. You would have the biggest ships running blockades and defensive actions around important planetary systems, they wouldn't see much action except in a few major fights. Most of the action would take place between "frigate" size vessels and would be focused on stopping commerce and recon.

In space like on the ocean it is very easy to run away, so the whole point of a fight after detecting your enemey would first be to determine whether to run or fight. This would then be followed be a long chase in order to get close enough to attack. Attacks over long range don't work because dumb projectiles are easy to avoid and smart projectiles have a limited fuel source. You would have to get close enough to the other ship in order to luanch your smart rocket and maybe shoot it with particle weapons.

This is were dogfights could come into play. As swarms of fighters surrond the capital ships and try to prevent missiles from hitting them.
posted by afu at 6:21 PM on November 2, 2006

here's an article on the subject, previously seen on the blue
posted by jepler at 8:29 PM on November 2, 2006

Elite First Encounters had real-world physics dogfights, as I recall, if you're looking to get a sense of what it's like. It was not fun to play as a result.
posted by greycap at 12:07 AM on November 3, 2006

All you have to do is detect them coming at you and move in the opposite direction a very easy thing to do in space.

Easy... assuming you have a magical instant inertia-cancelling drive.
posted by meehawl at 5:04 AM on November 3, 2006

Easy... assuming you have a magical instant inertia-cancelling drive.

All you would have to do is slightly change your course in order to avoid a BB cloud. Why would spacehips be forced to travel on some fixed path?
posted by afu at 7:31 AM on November 4, 2006

Except that bbs would be hard to detect (being small), and if spread diffusely would be hard to avoid unless you detected them from thousands of miles away if you're actually going at space speeds.
posted by klangklangston at 8:15 AM on November 4, 2006

Even if the BBs would be hard to detect, the space ships firing them would not be. In order to lauch a BB attack you have to see your enemy first and assuming both sides have the same technologu they would see you at the same time, and could start immediatly start doing evasive manouvers to avoid any dumb kinetic weapons. Guided missiles would be a much better weapon, at least over long range.
posted by afu at 8:48 AM on November 4, 2006

Unless the bbs were laid like chaff, at which point they'd effectively block pursuit and movement in a wide swath. Or if you grant that they wouldn't necessarily be fired straight on, ans would rather be fired as broadsides.
The biggest danger with bbs is that you can't return to that area, lest your own ship take the hit (like dumb mines). But dumping bbs like that would also have the advantage of not requiring course correction.
posted by klangklangston at 8:56 AM on November 4, 2006

If you were stupid enough to put an acceleration limiting factor like a human being into your fighter it would probably look like the ones in Babylon 5 did. I think a hive of small one purpose vehicles that parallel process strategy and tactics would be the way space battles are fought. A cloud of 5 million missile drones, augmented by nuclear explosive pumped x-ray lasers, fast firing railguns, and ships that fire interfering clouds of sand. All separated by miles of intervening space.
posted by BrotherCaine at 1:45 AM on July 25, 2007