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Could something similar to a naval battleship main gun work in the vacuum of space?

Let me set the stage: A turret of 2-3 large caliber guns, loaded with an explosive shell. Artificial gravity keeps the round and the powder bags seated properly, and the loading chamber is isolated from the inner atmosphere of the ship to prevent loss of atmosphere during firing. The level of technology in this setting is very advanced, an approximation would be Star Trek/Star Wars levels, where there are interstellar starships with shields and nice thick hulls, and a form of FTL travel utilizing wormholes.

Now to the specific questions:

What would need to happen for the gun to fire the projectile? Would there need to be atmosphere around the shell? Without oxygen would the firing generate the gasses needed to push the projectile out?

Would an explosive round, like a conventional naval weapon, have a considerable effect in space? Would there be an explosion? What could be done to improve the effectiveness of such a round?

My goal is to have a navy that is slowly adopting more...advanced...weaponry, like railguns, but has a strong love of their old projectile weaponry and is wont to give them up. I'm just not sure how feasible that is in the real world, and how much handwavetonium I'm going to have to add to the guns to make it feasible.

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    $\begingroup$ Any navy that had that attitude towards modern weapons would have long since lost to another that didn't. $\endgroup$ – GrandmasterB Jun 29 '16 at 2:47
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    $\begingroup$ Not always historically true. The USN during pre-ww2 thought battleships were the major naval powerhouse. They were rapidly proven wrong and had to adapt. I am emvisioning this navy as slow to adapt new things and surviving through skilled captains and a lack ofa serious opponent. Coming to terms with the need to use different weapons than they traditionally do is the driving force behind conflict in thestory $\endgroup$ – Marshall Tigerus Jun 29 '16 at 3:35
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    $\begingroup$ That's not even remotely similar to the technological disparity you're describing in your question. You're talking space ships using weapon technology hundreds of years out of date. How well would a Spanish galleon from the 1600's handle the USS Zumwalt? It would not end well for the galleon. $\endgroup$ – GrandmasterB Jun 29 '16 at 4:57
  • $\begingroup$ Just a little detail to expand the previous answers: There was a gun-armed spacecraft, the Salyut 3. $\endgroup$ – o.m. Jun 29 '16 at 5:16
  • $\begingroup$ You'll want to look at How, if at all, can space battleships mitigate gun recoil?. $\endgroup$ – Schwern Jun 29 '16 at 6:09
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Your projectiles would have to utilize chemical explosives, which don't require oxygen.

So no, your shell would not need an atmosphere.

Would an explosive round, like a conventional naval weapon, have a considerable effect in space?

This depends completely on what you're hitting and the design of your round. An explosion can happen in any environment - including the vacuum of space. An explosion is the result of a very quick combustion that produces a sudden extreme increase in gas pressure. If that gas pressure is contained in a container that is not strong enough to hold it, the container violently ruptures and parts of the container and its innards are propelled by the gas pressure outward.

A gun cartridge being fired is a controlled explosion with one particle propelled - the bullet. This is also why any sort of bomb needs a container like a pipe or a pressure cooker. Without the container the gas just expands out into the environment as its created rather then in a violent outburst.

Would there be an explosion? What could be done to improve the effectiveness of such a round?

As written above, explosions can happen in space. So yes, it's possible to have an explosion. But the effectiveness of these rounds depends solely on what you make the rounds out of - but then you have to ask yourself, whats the point of making these rounds minutely better when you could just adopt a better form of weaponry (given that you have star wars/star trek tech, almost any Laser or Photon weaponry is way more powerful).

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  • $\begingroup$ So it sounds like shrapnel would be doing the damage instead of heat/explosive force if the shell were to detonate against a solid ship hull. $\endgroup$ – Marshall Tigerus Jun 29 '16 at 3:36
  • $\begingroup$ @MarshallTigerus well, pretty much, yea. Unless you're firing solid projectiles in which case it's just pure kinetic force. $\endgroup$ – Aify Jun 29 '16 at 3:53
  • $\begingroup$ I'm reasonably sure that a round of ammunition can be fired in space if the rounds of ammunition have enough oxygen in them. On the show Mythbusters they fired a handgun in a vacuum. I don't really know, though. $\endgroup$ – Xandar The Zenon Jul 3 '16 at 21:26
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The main issue with chemical artillery weapons like a 16" battleship gun is simply too slow for any serious combat in space.

Consider the ISS, a very non-military spacecraft. It is in Low Earth Orbit, so moving at a velocity of @ 7km/sec. It is moving so fast that if you were standing on an American Football field with a .45 automatic pistol aimed at the opposite goalpost and fired when the ISS was directly overhead, it would cross the other goal line before your bullet reached the 10-yard mark. The obligatory XKCD comic is here.

That other repository of space-related wisdom, Atomic Rockets, has some commentary on their space war pages, and I believe the figure they quote is an enemy spacecraft could move 3 miles before the shell travels the length of the barrel http://www.projectrho.com/public_html/rocket/index.php.

So while a shell is actually a good idea (for reasons I will get into), a cannon to fire them out of is not.

The true killer in space is the kinetic energy that moving at orbital speeds delivers to an object. The American Space Shuttle sometimes needed the window replaced because it had impacted a speck of paint moving at 7km/sec. If they had been hit by a washer, nut or bolt, then the window would not have just been starred, but totally shattered and the space shuttle would have been destroyed by abrupt explosive decompression and the instant death of the crew. And that is just in Earth orbit. Once you move into interplanetary space, speeds simply increase in order to achieve transfer orbits. The fastest unpowered objects can move and still remain in the Solar System is 72km/sec, but since Ke=1/2Mv^2, the increase in energy is not 10X that of an object orbiting the Earth, but over 100X! So an artillery round detonating in front of a spacecraft will have its relatively immobile shrapnel hitting the moving spacecraft with the energy of a freight train. Old style artillery often burst into large pieces, so the enemy spacecraft isn't being showered with flecks of paint at lighting like energies either...

Since the real issue is getting on target, your space battleship will need to use some pretty impressive energies simply to get the round on target. Nuclear explosions have been used to drive pellets at speeds approaching 100km/sec, and Atomic Rockets describes a weapon developed in the late 1950s here

If your space battleship ever gets in the way of these things, it will be toast.

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  • $\begingroup$ That doesnt seem to take into account the velocity of the firing platform. If the guy with a gun was running forward at the same speed as the ISS the fired bullet would be travelling at ISS velocity + firing velocity. Your points also seem to suggest flak rounds might be very effective provided you can get them in front of a ship $\endgroup$ – Marshall Tigerus Jun 29 '16 at 11:53
  • $\begingroup$ Even if the firing platform is moving at the same speed as the enemy spaceship, the shell is still too slow. You will also be in serious trouble if your enemy shoots back with a modern weapon with shells or KE rounds moving at spaceship velocity; you will not have time to get out of the way of his shell, while he has a long time to get out of the way of your shell. $\endgroup$ – Thucydides Jun 30 '16 at 3:08
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    $\begingroup$ Relative velocity is the important bit, so Marshall would be correct assuming the two ships are fighting A) not that far away and B) on VERY similar orbital trajectories. Also, be warned about firing anything into space like those projectiles... If war was common enough where dozens of ships were firing flak rounds, the cumulative effect would be unpredictable and catastrophic, as the shrapnel would likely enter a number of different orbits at high speeds. You can't "fire and forget" in space... $\endgroup$ – Pyrotrain Dec 15 '17 at 16:28
  • $\begingroup$ If the two ships are moving at similar velocities, then the relative velocity between them will be small enough that whoever had the faster railgun or hypervelocity missile will still have a huge advantage. Cluttering up space with debris is a problem, but once again, hypervelocity fragments should be moving faster than escape velocity, so the area will become cleared soon enough. If you are firing inside the Solar System faster than 72km/sec, you have surpassed Solar escape velocity, and the particles will leave for interstellar space. $\endgroup$ – Thucydides Dec 16 '17 at 15:28
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I don't know specifically about the chemicals used in naval guns, but modern handgun bullets have the oxidizer included in the chemicals inside the cartridge, so they ought to work in a vacuum. I suspect naval guns are the same for the same reasons, but I'll defer on that to anyone on here who actually knows. Even if present naval guns require atmospheric oxygen to ignite, the technology to include the oxidizer in the cartridge is clearly there, so there's no reason why it couldn't be done on a spaceship.

Presumably an artillery gun would work better in the vacuum of space than on Earth, because it doesn't have to overcome air resistance. Once the projectile leaves the barrel, it will continue moving in a straight line at a constant speed until it hits something. Not quite in real life, because space isn't 100% vacuum. It will hit dust particles etc that will eventually slow it down. But it will go a long way before that makes a significant difference.

If the battle is taking place in orbit, then gravity may eventually pull the shell toward the planet, where it will either burn up in the atmosphere, or not and hit the ground. I say "may" because if the shell is travelling faster than escape velocity it will just fly off into space.

I don't think losing air when you fire would be a big issue. Yes, you have to open the barrel to load another shell. I'd assume this would be done by machinery and not by people hand-carrying shells, in which case the whole mechanism could be in a part of the ship separate from the crew quarters, and where everything operates in a vacuum. Or if people need to hand load it, fine, you have airtight doors on the gun barrels. They'd presumably have to be pretty well sealed anyway so the force of the blast is directed outward, to propel the shell out of the barrel, and not into the firing ship, killing the gun crew.

Yes, you can have explosions in space. The key difference is that with no air, you won't produce a shock wave. If you want the shell to do more damage than just punching a hole in the enemy ship, it will have to be loaded with shrapnel.

Yes, the speed of an artillery shell is slow compared to orbital velocities. But if you and the target are both in the same orbit going in the same direction, your relative velocity is zero, and so the artillery shell will have the same effective velocity that it does here on Earth. The operative question is the delta-V of the target: how fast can it maneuver out of the way when it sees the shell coming. If you're at close enough range that the shell hits within a couple of seconds, maybe the target doesn't have time to react.

An artillery shell is limited in speed because all the impetus to get it moving has to come from one blast, and there are practical limits to how fast you can release energy. And even if you could impart a very high velocity very fast, the g-forces would damage or destroy the projectile. A rocket can go faster than a shell because it continues to expend energy to accelerate over time. That acceleration can add up to a higher total velocity.

Thus, I tend to doubt that space war will use artillery shells. Rockets seems more likely. Assuming that overall lasers or other "beam weapons" don't prove more effective.

An advantage of a simple projectile is that it is more difficult to counter. Guided missiles can be neutralized with electronic counter measures, i.e. doing something to confuse or disable the guidance system. But a simple dumb projectile isn't vulnerable to that kind of defense. If someone fires an artillery shell at you, the best defense is probably jumping out of the way. Maybe some kind of anti-missile.

Oh, I presume someone capable of building spaceships is capable of building targeting systems for their projectiles that can deliver them to the desired point with a high degree of accuracy, and make due allowance for movement of the target. As long as the target doesn't see the shell coming and take evasive action, I'd expect you'd hit almost every time.

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Recoil is going to be an issue. Lets assume you are able to launch low cost, aimable projectiles (so you give it an initial boost through chemical or electromagnetic means) for longer range use, or slam a slug the size of a standard 1 TEU container right through an enemy ship (or into it). Any force imparted to the slug will be imparted to the ship. A launch along the axis of the ship will slow you down. A launch at an angle will make you slow down and potentially roll, so you'd need to compensate for that.

There's some situations where oldschool projectile artillery makes sense. Surface bombardment is a role similar to what the last battleships excelled at. It may make sense with short range combat with high velocity rounds, essentially the space equivilent of a dual to the death inside a elevator, and for point defence. There could be unusual uses for a large ship gun - first stage launch for self guding type rounds. The initial boost saves propellent on the torpedo itself, saving mass for longer range and course correction (which is a idea 'modern' artillery has embraced) Unlike a torpedo, these rounds would be smaller (and harder to detect), have great range (since they already have a sizable launch velocity) and fairly cheap.

As for the rounds themselves. I'd consider a few options. The oldschool bag and projectile design is silly. You don't want debris floating around your ship. Something self contained would be a great idea and if you can reduce recoil it would be awesome. The design of the Armburst might be an idea - having a 'standard' propellent canister that acts as propellent, and counterweight. You'd load a round, and this instead of a 'bag' - fire, and the propellent

  1. pushes a piston that launches the missile
  2. fires a counterweight that's shredded, and dispersed safely, or somehow trapped over a longer period of time.
  3. keeping the need to adjust the ship's thrust to compensate minimal, greatly simplifying the process.

It would be low tech, allow for a variety of rounds to be used and simple for a oldschool navy to adapt to. Considering the missiles coast most of they way, they'd also possibly be harder to spot thermally, which might be handy.

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  • $\begingroup$ I like the guided round idea a lot $\endgroup$ – Marshall Tigerus Jun 29 '16 at 11:57
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Guns work in space already i don't know the process but they do. But if you are thinking about advanced technology what about a rail gun operated with electro-magnets? it packs a hell of a punch and would not require any explosive (safer to store) and if you have evolved technology i am sure you'll find a way to gather energy for the electro-magnets. Besides, no gravity means your projectiles will have a lot of acceleration. More than with a gun. Also, you'll be able to throw anything that is magnetic.

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Late to the party but let me add another angle.

Railguns are far superior to explosive propellants for the reasons given elsewhere but could be handwaved as more complex or difficult to engineer for whatever reason. Missiles are trickier to explain away but could be supporting elements of any attack.

Dependant on who you're fighting against, explosive weaponry could be exceedingly potent against aggressors. Spaceship hulls just need to be able to withstand the pressure of internal atmosphere vs external athmosphere plus any strain from take off or landing. If they're solely exo-athmospheric they just need to be able to withstand the internal pressure vs a vacuum.

Add a pressure wave to this and you could do major damage. Not sure 100% on the science of this but you'd probably damage significant areas of plating which would then "pop" from the internal atmosphere (think submarine vs depth charges in reverse) - could be useful to explain the success of such primitive weaponry in space. Adaption of hulls designed to contain such damage could also explain why the navy are starting to pursue rail guns. With the advent of pressure plates, the aim of any gunfight the navy gets into isn't to pop them open like a bubble, but to fill the enemy ships full of holes till they can't fight any more.

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If you had a problem with the force of the gun firing vs the firing ship then all you would need to fix that is a gun not connected directly to the ship like by magnets.

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  • $\begingroup$ Welcome to worldbuilding.SE! What you're talking about is recoil compensation. However, the energy must go somewhere. Could you expand your answer to explain where the energy is going? Will it be absorbed as heat? electricity? or is the kinetic energy diffused throughout the ship? If so, how is it done such that the ship isn't repositioned or structurally damaged? Thanks! $\endgroup$ – JBH Jan 7 '18 at 18:39
  • $\begingroup$ If you wanted the gun to still be near the ship instead of flying away from it after firing this won't solve the problem. Most guns are designed to be fired more than once. $\endgroup$ – sphennings Jan 7 '18 at 18:40

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