Bullets but not Rocks?

[nilkemorya]

So, here's a question. With certain new sci fi shows, we have vehicles capable of speeds that allow for easy short interplanetary travel. Even fighter craft can be seen accomplishing that feat. However, these same fighter craft often use BULLETS to do combat. How could you build a ship which can stand up to the crap in space at the speeds they are traveling, but not a bullet? Or, alternatively, how can you have a bullet pierce that armor without being super high velocity(you never see the fighters getting flung back by firing weapons.)?

I haven't been able to come up with anything, maybe you guys can.

[Shadowfish]

Magic

Or maybe, the ship has an automatic laser that vaporizes small rocks, and it navigates around big rocks.

[Daniel]

Hmm... they tend to have some sort of deflector shield or something similar... Obviously, the reason they use bullets is that they have read Dune, and don't want to accidentally blow themselves to pieces along with their targets...
On the topic of super high velocity bullets, the possible reasons for using them would be that they would be really cheap, since it is going to be a long way into the future before it is cheaper to fire a laser at someone rather than just punching holes in them using little bits of metal...
I don't think that the recoil would be enough to move a space ship, even a fighter, since the mass of a bullet is tiny compared to that of a fighter.

[Strilanc]

It sounds like you need to watch Battlestar more, where they don't actually go very fast.

If you ask me, the main problem is ship design. Why do fighters designed to fight in space need to face their enemy?

[22/7]

It sounds like you need to watch Battlestar more, where they don't actually go very fast.

If you ask me, the main problem is ship design. Why do fighters designed to fight in space need to face their enemy?

I would assume it's just easier than setting up separate fully rotational weapons systems on all sides of the ship and then trying to actually *operate* the thing in a fighter while *also* trying to fly in combat and not get hit by the other people firing at you.

[Pesto]

It sounds like you need to watch Battlestar more, where they don't actually go very fast.

If you ask me, the main problem is ship design. Why do fighters designed to fight in space need to face their enemy?

Why would they need to face the direction they're going?

[skeptical scientist]

It sounds like you need to watch Battlestar more, where they don't actually go very fast.

If you ask me, the main problem is ship design. Why do fighters designed to fight in space need to face their enemy?

Same reason fighters in atmosphere need to face their enemy - so the pilot can see what he's shooting at. Of course, really smart computers or dedicated gunners would let weapons be controlled automatically so the pilot doesn't need to see what he's shooting at, but in Battlestar at least, really smart computers are something to be feared, and many other sci-fi gunfights have weapons shooting from a ship in all directions.

Of course some of the older shows like star trek are really bad about making space (and space combat) more-or-less two dimensional, but some of the newer ones are really pretty good about that.

The biggest problem with ship design in sci-fi is that ships which are never going to enter an atmosphere are quite obviously designed to be aerodynamic and/or generate lift in an atmosphere. This, of course, has a lot to do with the fact that aerodynamic winged ships look cool.

Why would they need to face the direction they're going?

They don't. They have to face the direction they are accelerating in, and they do that because complicated and powerful engines are expensive, so you want to have only enough per ship to power the ship, and you want to point them all in the same direction. That direction, naturally, will be towards the back.

[nilkemorya]

I like what I'm hearing so far, but to address the "They don't actually go fast" Even if they aren't going fast there are bits of interplanetary debris that would be going that fast. Hmmm...I guess those could actually cripple a viper, but I've seen them fly through nebulae and such. As for the not throwing it back much, calculate the momentum of a bullet going at .7c. It's nifty lots. Keep up the good ideas though.

[Strilanc]

It sounds like you need to watch Battlestar more, where they don't actually go very fast.

If you ask me, the main problem is ship design. Why do fighters designed to fight in space need to face their enemy?

Why would they need to face the direction they're going?

My point was that the concept of orientation changes totally once you take atmosphere out of the picture. You don't need to point guns forwards or backwards to ensure you don't cause lots of drag, you don't need to be facing the direction you're traveling in, etc.

In a real space fight, you would want to get your weapons on the enemy as quickly as possible, and turning the whole ship is going to slow you down because of the added moment of inertia and the limits of the pilot.

[Solt]

Same reason fighters in atmosphere need to face their enemy - so the pilot can see what he's shooting at.

QFT. If you think back to the world war I days, it's pretty obvious where that tradition came from. Dogfights are also a thing of the past, with todays super long range radar and self guided missiles, otherwise I'm sure we'd have started putting cannons on the back.

Also, IIRC, some WWII bombers like the Flying Fortress were covered by gun pods on all sides for 360 degree protection. Today though, it's a lot smarter to make the bombers as fast or as invisible as possible, again because long range missiles would own them otherwise; in the air there's no good way to defend against missiles with more weapons.

Of course some of the older shows like star trek are really bad about making space (and space combat) more-or-less two dimensional, but some of the newer ones are really pretty good about that.

The biggest problem with ship design in sci-fi is that ships which are never going to enter an atmosphere are quite obviously designed to be aerodynamic and/or generate lift in an atmosphere. This, of course, has a lot to do with the fact that aerodynamic winged ships look cool.

In Star Trek's defense (and indeed, I do feel as though I must defend Star Trek), they do realize aerodynamics are not necessary in space. Case in point: the Borg Cube.

[yy2bggggs]

Of course some of the older shows like star trek are really bad about making space (and space combat) more-or-less two dimensional, but some of the newer ones are really pretty good about that.

Because in Gallactica, they don't fly ships in place, but planes (they bank when they turn, etc). In Star Trek, they are cars (pretty much at eye level, face up, full stop, etc).

[Jesse]

I like what I'm hearing so far, but to address the "They don't actually go fast" Even if they aren't going fast there are bits of interplanetary debris that would be going that fast. Hmmm...I guess those could actually cripple a viper, but I've seen them fly through nebulae and such. As for the not throwing it back much, calculate the momentum of a bullet going at .7c. It's nifty lots. Keep up the good ideas though.

The same reason that when I fire a rocket launcher I'm not immediately thrown back sixteen feet. Recoil dampeners are already around, I imagine by that time they will have become so advanced that this will not be a problem.

[skeptical scientist]

The same reason that when I fire a rocket launcher I'm not immediately thrown back sixteen feet. Recoil dampeners are already around, I imagine by that time they will have become so advanced that this will not be a problem.

Recoil dampeners don't remove the force of recoil, they just spread it out over a longer period of time. You still have conservation of momentum to contend with.

[skeptical scientist]

Of course some of the older shows like star trek are really bad about making space (and space combat) more-or-less two dimensional, but some of the newer ones are really pretty good about that.

Because in Gallactica, they don't fly ships in place, but planes (they bank when they turn, etc). In Star Trek, they are cars (pretty much at eye level, face up, full stop, etc).

That's true. Even the bigger ships of the fleet are more like an air flotilla than a space fleet. For instance, they are all at different elevations, but they agree on a common orientation of up - there's no reason a space fleet would do that, unless they were sharing the same acceleration and using acceleration to generate gravity.

[OneLess]

Dogfights are also a thing of the past, with todays super long range radar and self guided missiles,

Iiiiiickk...I hate when people say that. They've been saying it since the advent of air-to-air missiles, and I haven't seen it prove true yet (although I admit that I'm fairly ignorant of recent air-to-air conflicts). I'm not saying it isn't or won't be true, but it seems akin to people always predicting that we'll have flying cars in 50 years.

[nilkemorya]

Heh, actually, I thought of a way to solve my own bullet momentum problem. If the shell casings are much more massive than the bullets themselves, you could propel those out the back at a lesser speed and keep the ship momentum the same. It would seem to be a lot of extra mass, but better than being hurled back 20 feet for every bullet fired. Oh, and the reason you aren't hurled back 16 feet when you fire a rocket is that the rocket isn't pushing on you to generate momentum, but throwing fuel out the back. Imagine trying to hand hold an artillery cannon. Considerably more problematic, and that is actually LESS momentum than the galactica projectiles would have to have.

[thecommabandit]

I like what I'm hearing so far, but to address the "They don't actually go fast" Even if they aren't going fast there are bits of interplanetary debris that would be going that fast. Hmmm...I guess those could actually cripple a viper, but I've seen them fly through nebulae and such. As for the not throwing it back much, calculate the momentum of a bullet going at .7c. It's nifty lots. Keep up the good ideas though.

0.7c?! If you can't get the craft itself to half that speed then there's no hope of firing something that fucking fast.

*mumbles* 0.7c? ...bloody fast...

[GMontag]

In Star Trek's defense (and indeed, I do feel as though I must defend Star Trek), they do realize aerodynamics are not necessary in space. Case in point: the Borg Cube.

Even more in Star Trek's defense, the ships need to be "subspacedynamic".

[hobbesmaster]

Of course some of the older shows like star trek are really bad about making space (and space combat) more-or-less two dimensional, but some of the newer ones are really pretty good about that.

The biggest problem with ship design in sci-fi is that ships which are never going to enter an atmosphere are quite obviously designed to be aerodynamic and/or generate lift in an atmosphere. This, of course, has a lot to do with the fact that aerodynamic winged ships look cool.

Many of the Star Trek ships are designed to enter an atmosphere as a part of normal procedure (Voyager, BoP), or in an emergency (Ent-D saucer). As a general principle, its probably a good idea to have your starships designed so that they have some way of landing non-catastrophically in case of an emergency.

As far as the original post goes: magic. Or whatever your target universe calls magic. Really, it doesn't matter, you can go to some fan site for the universe and theres probably already some canon explanation. Its not science so just sit back and look at the pretty explosions or pay attention to the plot (it is fiction afterall!).

[ToLazyToThink]

As a general principle, its probably a good idea to have your starships designed so that they have some way of landing non-catastrophically in case of an emergency.

I doubt that.

Surviving a landing in a gravity well is going to require all kinds of structural demands that will do you no good while in space. Those resources would probably be better spent beefing up your ship so you never have a need for an emergency landing in the first place.

[zenten]

As a general principle, its probably a good idea to have your starships designed so that they have some way of landing non-catastrophically in case of an emergency.

I doubt that.

Surviving a landing in a gravity well is going to require all kinds of structural demands that will do you no good while in space. Those resources would probably be better spent beefing up your ship so you never have a need for an emergency landing in the first place.

How can you ensure you'll never need one?

[hobbesmaster]

As a general principle, its probably a good idea to have your starships designed so that they have some way of landing non-catastrophically in case of an emergency.

I doubt that.

Surviving a landing in a gravity well is going to require all kinds of structural demands that will do you no good while in space. Those resources would probably be better spent beefing up your ship so you never have a need for an emergency landing in the first place.

As a designer of a fictional starship, I would probably want to take one of the most common science fiction plot devices (crash landing on a planet) into account.

[Daniel]

In reality (or what passes for it in sci fi ), the hypothetical fighter will not be thrown back by firing a bullet. I have calculated a hypothetical situation where a fighter with a mass equal to that of a Eurofighter fires a bullet with the specifications of a .44 magnum shell to demonstrate this.

Okay, a .44 magnum shell, with a mass of 11 664 miligrams (0.011664kg), fired at a velocity of 491m/s has a momentum of 5.727024mkg/s.

A Eurofighter has a mass of 11 000kg, so in other words, the fighter has a mass nearly one million times greater.

It gains the same amount of momentum in the opposite direction.

Therefore, the fighter's velocity will become (5.727024mkg/s)/11 000kg, or 0.000520638545 m/s.

That's about equal to 0.5mm/s. Not a lot. Since we have already stated that the fighters must be travelling at speeds allowing short interplanetary travel, then a loss in velocity of 0.5mm/s is so tiny as to be virtually irrelevant.

Of course, the bullets of the future will likely be fired at much faster speeds, but I decided to use real life bullets as an example. It is fairly easy to use the same methods to show that faster bullets will still have little real effect.

I hope that this is all clear, as whenever I write something, it always seems to come out a bit cryptic.

(all info gained from wikipedia, particularly these pages:
http://en.wikipedia.org/wiki/44_Magnum
http://en.wikipedia.org/wiki/Eurofighter)

[ToLazyToThink]

As a general principle, its probably a good idea to have your starships designed so that they have some way of landing non-catastrophically in case of an emergency.

I doubt that.

Surviving a landing in a gravity well is going to require all kinds of structural demands that will do you no good while in space. Those resources would probably be better spent beefing up your ship so you never have a need for an emergency landing in the first place.

How can you ensure you'll never need one?

Well, you can't ensure never.

But you can't always be sure there's a viable planet to crash on (or that it will be in range when disaster strikes). So you're probably better off spending the resources on more redundancy, defenses, weapons, emergency life support, etc.

[ToLazyToThink]

Of course, the bullets of the future will likely be fired at much faster speeds, but I decided to use real life bullets as an example. It is fairly easy to use the same methods to show that faster bullets will still have little real effect.

If the bullet is traveling at .6c, you'd get 261 m/s for the fighter.

So it depends on how much faster they get.

http://en.wikipedia.org/wiki/Momentum#Momentum_in_relativistic_mechanics

[Daniel]

Still, if the bullet can travel at 0.6c, then it is to be assumed that it is possible to get ships to similarly large speeds, where the loss of speed from firing will not throw the ship backwards.

[zenten]

As a general principle, its probably a good idea to have your starships designed so that they have some way of landing non-catastrophically in case of an emergency.

I doubt that.

Surviving a landing in a gravity well is going to require all kinds of structural demands that will do you no good while in space. Those resources would probably be better spent beefing up your ship so you never have a need for an emergency landing in the first place.

How can you ensure you'll never need one?

Well, you can't ensure never.

But you can't always be sure there's a viable planet to crash on (or that it will be in range when disaster strikes). So you're probably better off spending the resources on more redundancy, defenses, weapons, emergency life support, etc.

This becomes a cost/benefit analysis though. It could be that the structural changes required for this can have other benefits, and the costs for increased redundancy, defenses and whatnot would be too prohibitive to sufficiently minimize the chance of a crash landing.

[Solt]

The same reason that when I fire a rocket launcher I'm not immediately thrown back sixteen feet. Recoil dampeners are already around, I imagine by that time they will have become so advanced that this will not be a problem.

Recoil dampeners don't remove the force of recoil, they just spread it out over a longer period of time. You still have conservation of momentum to contend with.

Easy to fix- just dissipate the energy. If you have kinetic energy of some form in some part of your system, it's easy enough to dissipate it through friction or possibly even generate electricity from it.

Iiiiiickk...I hate when people say that. They've been saying it since the advent of air-to-air missiles, and I haven't seen it prove true yet (although I admit that I'm fairly ignorant of recent air-to-air conflicts). I'm not saying it isn't or won't be true, but it seems akin to people always predicting that we'll have flying cars in 50 years.

Well if you live in the US you better hope it's true because that's the premise that the current generation of air-superiority fighters (F-22) is built on. Our assurance of airspace superiority is based on the ability of 2 or 3 F-22s to wipe the floor with 10-20 opposition Soviet or Chinese fighters. That would be very difficult to achieve if we had to enter dogfights on a regular basis. But admittedly, the USAF hasn't engaged in battle against a viable airforce since the Vietnam war so we don't know for sure.

Also, we've had flying cars for several decades now .

As a general principle, its probably a good idea to have your starships designed so that they have some way of landing non-catastrophically in case of an emergency.

I doubt that.

Surviving a landing in a gravity well is going to require all kinds of structural demands that will do you no good while in space. Those resources would probably be better spent beefing up your ship so you never have a need for an emergency landing in the first place.

I refuse to believe that a starship that can accelerate to over a billion miles per second in less than a second can't withstand landing on a planet with a g of a few dozen m/s/s at the most.

[po2141]

There were some comments about rocket launchers and recoil dampeners and some palaver about conservation of momentum:

Rocket launchers (y'know, like your typical russian-made RPG) don't have "recoil dampeners" they are recoil-less, none of the impulse of the rocket is transferred to the launcher. There are also such things as recoil-less guns, where exhaust gases are vented to the rear.

Also, if each round carries a small explosive charge (not like huge bombs, just enough to generate shrapnel from the bullet casing, like a small grenade) then the incident velocity of the round upon the target becomes less important. You could even have a proximity fuse, like AAA in WWII for instance.

[Cosmologicon]

Recoil dampeners don't remove the force of recoil, they just spread it out over a longer period of time. You still have conservation of momentum to contend with.

Easy to fix- just dissipate the energy. If you have kinetic energy of some form in some part of your system, it's easy enough to dissipate it through friction or possibly even generate electricity from it.

You can't dissipate momentum the same way you can dissipate energy.

[evilbeanfiend]

conservation of momentum is not usually that much of a problem for firing weapons as usually the projectile has much less mass than the craft firing it

[zenten]

conservation of momentum is not usually that much of a problem for firing weapons as usually the projectile has much less mass than the craft firing it

Plus the worse case scenario is you just shoot another one out the other end at the same time.

[evilbeanfiend]

please can i not stand behind zenten if xkcdia ever goes to war

[Malkavon]

To the discussion about whether or not to construct a ship with the ability to survive a planetary incident, it is similar to the debate on whether to arm bombers. As someone stated before, WWII-era bombers were often heavily armed, to the point of coining monikers such as the "Flying Fortress" (B-17). The idea was that a large formation of bombers, arranged in three-dimensional boxes, could give maximum defensive coverage to each other, to minimize losses to enemy aircraft. This was possible because the relative speeds of the aircraft in question were low enough to allow humans to track them manually. With the advent of jet aircraft and the rapid increase in both maximum and functional combat speeds, it became near-impossible for a human being to track a moving target except under circumstances where the relative velocities of the aircraft were fairly low - such as chasing positions - which is why some bombers in the modern era, the B-52 Stratofortress until recently for example, mounted manned and later automated tail-guns to deter opponents from slipping into the "kill-zone" behind the aircraft. Even those limited defensive measures have, by and large, been removed.

As the effectiveness of active defenses such as manned and even automated guns became iffy at best, Air Forces around the world have turned to passive technologies to increase aircraft survivability. Right now, there are two factors that are most often exploited to ensure aircraft survivability: speed and stealth. Fast bombers, such as the B-1B Lancer, rely on their high speed and low-altitude capabilities to outrun enemy aircraft. Stealthy bombers, such as the B-2 Spirit stealth bomber, which is neither exceptionally fast nor maneuverable, but which is exceptionally hard to detect even at very short ranges.

The moral of all this is simple: while it is a fine goal to be able to deal with any situation, it is more reasonable and cost-effective to simply design around not being in some situations at all, or else to design your systems in such a way that they fulfill multiple purposes.

Well if you live in the US you better hope it's true because that's the premise that the current generation of air-superiority fighters (F-22) is built on. Our assurance of airspace superiority is based on the ability of 2 or 3 F-22s to wipe the floor with 10-20 opposition Soviet or Chinese fighters.

I take it by Soviet you mean Soviet-produced, not Soviet-operated. In that case, most Chinese aircraft are Soviet-produced designs, either in whole or in part. In fact, the bulk of the combat aircraft in the world are either U.S.-produced or Soviet-era aircraft designs.

That would be very difficult to achieve if we had to enter dogfights on a regular basis. But admittedly, the USAF hasn't engaged in battle against a viable air force since the Vietnam war so we don't know for sure.

Actually, the flight characteristics of the F-22 are designed precisely around both long-range and short-range engagements. It is the most agile air-superiority fighter ever produced, thanks in large part to it's vector-thrust technology. The same thing goes for the stealth technology employed by the F-22. It serves dual roles, giving the F-22 long-range survivability against enemy detection as well as allowing the F-22 to get in close without being detected for a more assured kill.

Wikipedia on the F-22:

In early 2006, after an exercise involving just eight F-22s in Nevada in Nov. 2005, Lieutenant Colonel Jim Hecker, commander of the 27th Fighter Squadron (FS) at Langley AFB, Virginia, commented "We killed 33 F-15Cs and didn't suffer a single loss. They didn't see us at all." [...] In June 2006 during Exercise Northern Edge (Alaska's largest joint military training exercise), the F-22A achieved a 144-to-zero kill-to-loss ratio against F-15s, F-16s and F/A-18s simulating MiG-29 'Fulcrums', Su-30 'Flankers', and other current front line Russian aircraft, which outnumbered the F-22A 5 to 1 at times. The small F-22 force of 12 aircraft generated 49% of the total kills for the exercise, and operated with an unprecedented reliability rate of 97%. [...] The F-22 is extremely difficult to defeat during dogfighting. At Red Flag 2007, RAAF Squadron Leader Stephen Chappell, F-15 exchange pilot in the 65th Aggressor Squadron, commented that "The thing (F-22) denies your ability to put a weapons system on it, even when I can see it through the canopy. It's the most frustrated I've ever been."

The idea behind the F-22 project is an aircraft which can eliminate the majority of it's prospective opponents from long range, and then out-perform the remaining aircraft in close-range combat. It is not simply a long-range missle platform (which, incidentally, is a proposed modification for the B-1B Lancer - a long-range missile platform with a large AAM payload and high speed, but little close-in capability due to it's size).

And yes, I'm fully aware of the comments regarding the cost-effectiveness of the F-22, as well as comparisons to other fifth-generation aircraft such as the Eurofighter. I'm not trying to prove that the F-22 is the be-all end-all of fighter aircraft. I'm just providing counterarguments to the statement that the F-22 is solely reliant on it's long-range missile capabilities and wouldn't stand up in extended dogfighting.

[ToLazyToThink]

I refuse to believe that a starship that can accelerate to over a billion miles per second in less than a second can't withstand landing on a planet with a g of a few dozen m/s/s at the most.

But if your forced to crash land, what are the chances that your ship is structurally sound, still capable of surviving reentry (no holes in the hull letting hot gases inside), and still has propulsion or some other means of slowing your descent/reducing the impact momentum (even if the structure can survive, it doesn't do you any good if the crew is reduced to jam).

Considering the energies these ships would have to throw around, I'm having a hard time imagining a case were your ship is damaged enough to necessitate a crash landing (as opposed to floating around as a cloud of atomic gases, making repairs, or waiting in space for rescue), but still intact enough to survive it.

[hobbesmaster]

Considering the energies these ships would have to throw around, I'm having a hard time imagining a case were your ship is damaged enough to necessitate a crash landing (as opposed to floating around as a cloud of atomic gases, making repairs, or waiting in space for rescue), but still intact enough to survive it.

Uh, thats actually not hard - you lose engine power while executing an orbital insertion, or other orbital maneuver that leaves you without enough thrust to put you into a stable orbit (ie high delta-v while engaged in combat). I'm assuming that this is basically what happened to the Ent-D in Generations - the emergency saucer separation launched the saucer towards the planet, decaying its orbit and due to combat damage or whatever Troi was then unable to bring the impulse engines to correct the orbit, so the ship tumbled towards the planet, at the mercy of gravity and whatever attitude thrusters were still operating.

A large number of shuttle craft in the delta quadrant seem to meet similar fates, as well as runabouts based at DS9. Outside of star trek, the immediate example I can think of is starbuck's raptor in whatever that season 1 episode was. As a designer of fictional star ships, I'd say that its a concern that you'd probably want to take into account - it seems to happen with a good bit of frequency!

[ToLazyToThink]

A large number of shuttle craft in the delta quadrant seem to meet similar fates, as well as runabouts based at DS9. Outside of star trek, the immediate example I can think of is starbuck's raptor in whatever that season 1 episode was. As a designer of fictional star ships, I'd say that its a concern that you'd probably want to take into account - it seems to happen with a good bit of frequency!

But Starfleet is a perfect example of what I'm talking about! How many lives could have been saved it they spent the resources on simple fuses for their consoles instead of spending so much to make sure all their ships were capable of surviving a crash landing? Or providing better fail safes for the warp cores so they wouldn't blow up every other week (or if you can't keep them from blowing up at the drop of that hat, maybe provide some hot spares so you don't lose power when you have to eject them).

[Master Gunner]

They do have other sources of power, just none that provide enough power for warp drive or anything, as that is powered by matter-antimatter reactions in the warp core, so anything that would force you to eject that would also force you to eject any backup power supply that also uses matter-antimatter reactions to produce enough power for warp travel.
Something else to keep in mind, is that what is the point of a spaceship is basically to get from one planet to another. So, a lot of the time your spaceship is going to be in orbit of a planet, so it makes sense to allow it to survive being pushed too far into the planet's gravity well to escape, making it crash to the surface.

[arbivark]

Maybe these TV shows are fantasy rather than science fiction, allegorical horse operas.
Maybe they are bad science fiction - TV shows.
Maybe the bullets are made out of unobtainium.

"unobtanium" is actually the rubber that Oakley use to make the rubbery bits on their sunglasses (the nose and ear bits for example.)

Ah. And being rubber, they aren't deflected by the magnetic shields, or detected by the radar which targets the disintegrator beams... clever.

[po2141]

"unobtanium" is actually the rubber that Oakley use to make the rubbery bits on their sunglasses (the nose and ear bits for example.)