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Gun fire in space


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Silly little thought that crossed my mind and should have kept going out the other side...

Would a conventional gun (rifle or pistol) with conventional ammo fire in space/a vacuum? Clearly a bullet fires due to some form of combustion but does this rely upon the presence of an outside atmosphere or an internal oxidiser (or equivalent - I think of the hypergolic fuels that Apollo used).

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I'm not sure if the weapon would fire or not, but it raises some interesting questions.

If you were free-floating when you fired it (assuming it would fire), would there be a backlash kick that would send you flying off in the opposite direction?

And how long would the projectile sustain a forward motion.. till it hit something?

You too, as a matter of fact.. would you keep flying backwards forever?

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In answer to that, we can thank Sir Isaac. For every action, there is an equal and opposite reaction - hence the recoil of the gun. It should be enough to send you backwards and, in the abscence of friction or air resistance, you would continue to move backwards ad infintum!

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Action and reaction equal an opposite.. and conservation of momentum would apply i suppose...

Depending on the calibre the bullet would have low mass but high velocity...

One of the rounds I use has a mass of 2.9g an a muzzle velocity of 849m/s...

So being a blobby i'd go backwards at about 4.5 m/s.... if my maths are right which they probably aren't

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I do know that some guns vent the exhaust gas in ths same direction as the projectile thus rendering them (to some degree) recoilless, therefore 'negating' Newton (not realy cancelling the effect of course, just acknowledging it and redirecting the motion).

But anyway, my original point - Will a modern conventional waepon actually fire? (should I ever find myself on the ISS on an EVA and feel the need to assassinate my EVA partner - I like to be prepared for every eventuallity and would hate to think I hadn't got this covered in the event that one of the World space agencies feels the desperate need to recruit a 41 year old energy management salesperson with an unhealthy need for astronomy gadgets)

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And how long would the projectile sustain a forward motion.. till it hit something?

This brings back memories..

Newtons First Law..

"A body continues to maintain its state of rest or of uniform motion unless acted upon by an external unbalanced force." This law is known as the law of inertia.

So in the vacuum of space with no external forces to stop your inertia..In theory you could be in motion for ever..

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Reminds me of the 5th Doctor (Peter Davidson) throwing a cricket ball against the outside of a spaceship so he could catch it and use it's inertia to drift to the Tardis.

Not sure if that would work in real life...

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I do know that some guns vent the exhaust gas in ths same direction as the projectile thus rendering them (to some degree) recoilless, therefore 'negating' Newton (not realy cancelling the effect of course, just acknowledging it and redirecting the motion).

But anyway, my original point - Will a modern conventional waepon actually fire? (should I ever find myself on the ISS on an EVA and feel the need to assassinate my EVA partner - I like to be prepared for every eventuallity and would hate to think I hadn't got this covered in the event that one of the World space agencies feels the desperate need to recruit a 41 year old energy management salesperson with an unhealthy need for astronomy gadgets)

Would depend entirely on the propellant. As far as I remember cordite needs oxygen to go bang.

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Thanks, that's what I thought but wasn't sure if the mass had to be equal as well.. a person's quite a bit larger than a bullet. In any case, I'll make a note to keep the safety on. :(

I have a funny feeling the type of weaponry is the answer to this question, but how did Capt. Kirk prevent the Enterprise from reeling backwards when they opened fire on someone?

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Clearly a bullet fires due to some form of combustion but does this rely upon the presence of an outside atmosphere or an internal oxidiser (or equivalent - I think of the hypergolic fuels that Apollo used).

Gunpowder and most modern charges carry their own oxidizer. Therefore it would ignite in a vacuum.

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I expect its something to do with the mass and inertia of a beam of light (for the lasers) :(

Another question though , Surley Space isnt a complete vacumn as there are loads of forces at work (Gravity , Interstella Winds etc) so ther will always be another force acting as well.

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Vihtavuori powders and CCI/ federal/winchester Primers will ignite in a vacuum, muzzle break/compensators work by redirecting the gasses as they come out of the barrel backwards towards the shooter at a 45 degree angle, and also can be adjusted to compensate for muzzle flip usually upwards for large calibre rifles, note never volunteer to be a spotter for a sniper :(

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Vihtavuori powders and CCI/ federal/winchester Primers will ignite in a vacuum, muzzle break/compensators work by redirecting the gasses as they come out of the barrel backwards towards the shooter at a 45 degree angle, and also can be adjusted to compensate for muzzle flip usually upwards for large calibre rifles, note never volunteer to be a spotter for a sniper :(

I used to be a marksman in the Forces, we used rebarrelled Lee Enfields with Vernier sights. I could put a bullet through a two inch square at 500m on a windless day. The interesting bit was being in the butts on the radio calling out the shots. You would hear the crack of the bullet as it went over your head followed by the 'bang' of the rifle........

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Without wishing to divert this thread away from the original topic, is it possible to weld in a vacuum. Gas or Arc.?

Ron.

without wishing to further divert by replying to your diversion....

I would have thought that arc welding would work quite well especially seeing as there is no gasses around to contaminate the weldpool....

As far as gas welding would be concerned the Oxy-Acetylene mix would burn... so... probably yes as well...

Billy...

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Here's a fun one!

I'd think the gun would definitely fire in a vacuum. Your problems would not be just the reverse velocity imposed by the firing, but the rotational vectors as well. As one tends to fire a weapon closer to the top of the body than the middle, the bullet leaving the muzzle would introduce pitch, (up/down) rotation. The venting of the combustion gasses, if deflected in some direction, could introduce yaw. And finally, the spent shell ejection, (for a semi-automatic), could introduce roll.

Final result-a "flat spin" in all directions which would certainly continue until acted upon by some outside source greater than the interstellar medium.

All this assumes you fire while outside the space vehicle. If you're foolish enough to fire from within, your spin would be the last of your problems, as the vehicle would certainly be punctured and you'd be sucked into space through a .44 calibre hole.

Nasty. I'd recommend against firearms in space. 8)

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hhehe, cant you just tell when its been cloudy for a while......... we all get stir crazy.

My question, if I fire my rifle straight upwards, (and asssuming it has enough mv to reach that far) at what point would the round break free of the pull of gravity? You would need to know how fast it would have to leave the muzzle in order to reach space before gravity got the better of it.

BUT! As the effects of gravity will reduce as altitude increases, would the deceleration be uniform, or would it eventually start to slow down more slowly, thus makign it easier for the round to break free of gravity? I'd love to see a graphic on this :(

Peter, what rifle do you shoot? I have a Sako Finnfire Varmint .22LR and a CZ 452 American .17HMR. Also have a 12Ga and .410 up there. Mind you, since I started with the telescope, I hardly get to go out.

Cheers

TJ

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Here's a fun one!

I'd think the gun would definitely fire in a vacuum. Your problems would not be just the reverse velocity imposed by the firing, but the rotational vectors as well. As one tends to fire a weapon closer to the top of the body than the middle, the bullet leaving the muzzle would introduce pitch, (up/down) rotation. The venting of the combustion gasses, if deflected in some direction, could introduce yaw. And finally, the spent shell ejection, (for a semi-automatic), could introduce roll.

Final result-a "flat spin" in all directions which would certainly continue until acted upon by some outside source greater than the interstellar medium.

All this assumes you fire while outside the space vehicle. If you're foolish enough to fire from within, your spin would be the last of your problems, as the vehicle would certainly be punctured and you'd be sucked into space through a .44 calibre hole.

Nasty. I'd recommend against firearms in space. 8)

Nice to see you back Steve. Hope you're keeping well mate.

I guess a good analogy, would be the Apollo 13 event on the way to the moon. The outgassing caused them one hell of a

problem, Similar to what you described. :(

Ron.

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Well a rifle bullet like the SA80's 5.56 mm, looses momentum after about a mile or so, so if you fired your rifle straight up i would take cover.

A modern bullet can fire under water and i reacon it could fire in space because the bullet is in a concealed unit with everything it needs to combust even if there is no atmosphere, I have a german target pistol that has an anti recoil system (basicly a spring that fires forward the same time as the gun gets pushed back = ergo, zero recoil!)

But i aint no scientist so my guess is as good as yours :(

To break free of gravity (plus there is the atmosphere you need to worry about) you need to reach escape velocity which is 17500mph, a bullet travels on average 370 m/s to 460 m/s (depending on what bullet it is of course). The affect of gravity at being just a few miles away from the earth wouldn't change too much i would think.

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