Ephelides Posted August 11, 2006 Report Share Posted August 11, 2006 Re: Stupid firearms question Standard propellents for firearms (and also standard explosives) do not use air in the chemical reaction' date=' they have their own oxidizer. That is why explosives work under water.[/quote'] I know that. What I tried to say is-=-=-what I've heard is that the ingredients won't mix together well if there's no air to make sure all it mixed together, and the powder will not burn so well. It will burn, but not so well. Unless someone has actually "set off" gunpowder in a vacuum...? It does not need to be in "outer space" you know. Quote Link to comment Share on other sites More sharing options...
gewing Posted August 11, 2006 Report Share Posted August 11, 2006 Re: Stupid firearms question it is generally not the heat that fires shell. If I remember correct the primer need to be wacked to go off. in a fire the round expands which allows the powder to be contacted by the fire which sets off the bullets ect. this is one reason that the rounds go off at different times and some never go off in the fire. Now heat might cause the powder and the primer to become more unstable eaisier togo off with less force. Lord Ghee Rounds can cook off and fire in the chamber (or even magazine!) it the weapon becomes too hot. This is most common in automatic weapons that fire from a closed bolt. It is true, that unconfined cartridges in a fire will not cause significant damage, in most cases. However, larger cartridges, particularly HMG rounds and up, some with explosive projectiles... There is a drive to make all military munitions fall under the "Insensitive Munitions" standard, so they are less likely to catastrophically blow up if hit by bullets or shrapnel, or if a fire breaks out. The reason so many Iraqi tanks have been photographed with their turrets blown off is that the propellant in the loose cartridges in the hull burned/deflagrated (slow explosion, basically aiui) but this was plenty of force to blow the turret as much as a hundred yards. If they rounds were not confined by the tank, the damage would not have been catastrophic. Kind of like the difference between lighting a propane barbecue with the top open, or with it closed. I want to see my son grow up, so I only light it with the top open! Quote Link to comment Share on other sites More sharing options...
gewing Posted August 11, 2006 Report Share Posted August 11, 2006 Re: Stupid firearms question I know that. What I tried to say is-=-=-what I've heard is that the ingredients won't mix together well if there's no air to make sure all it mixed together, and the powder will not burn so well. It will burn, but not so well. Unless someone has actually "set off" gunpowder in a vacuum...? It does not need to be in "outer space" you know. afaik, conventional gun powders have adequate ozidizers to burn completely. It would be possible to make propellants that did need external oxygen, but unless you are making a solid propellant ramjet, I don't see why. Though there are rocket motors that burn by adding liquid oxygen to a solid propellant, iirc. Quote Link to comment Share on other sites More sharing options...
Toadmaster Posted August 12, 2006 Report Share Posted August 12, 2006 Re: Stupid firearms question I know that. What I tried to say is-=-=-what I've heard is that the ingredients won't mix together well if there's no air to make sure all it mixed together, and the powder will not burn so well. It will burn, but not so well. Unless someone has actually "set off" gunpowder in a vacuum...? It does not need to be in "outer space" you know. I'd have to take a guess and say this is a myth, not alot of air in barrel to mix with between the cartridge case and the bullet. once the gases exit the barrel and contact the atmosphere it is another story but that has no effect on the bullet but makes a nice fire ball in short barreled weapons. One factor on the recoil in space not being accounted for is the escaping gas, "supposedly" (as in I recall reading somewhere) this has the effect of a small rocket pushing away from the direction of the target. It is probably fairly minimal but is an additional factor to consider than simply the bullets energy. Maybe we could get the guys from Myth busters to try this one, of course they will probably need a bigger budget or at least a surplus rocket from NASA. Quote Link to comment Share on other sites More sharing options...
gewing Posted August 12, 2006 Report Share Posted August 12, 2006 Re: Stupid firearms question I'd have to take a guess and say this is a myth, not alot of air in barrel to mix with between the cartridge case and the bullet. once the gases exit the barrel and contact the atmosphere it is another story but that has no effect on the bullet but makes a nice fire ball in short barreled weapons. One factor on the recoil in space not being accounted for is the escaping gas, "supposedly" (as in I recall reading somewhere) this has the effect of a small rocket pushing away from the direction of the target. It is probably fairly minimal but is an additional factor to consider than simply the bullets energy. Maybe we could get the guys from Myth busters to try this one, of course they will probably need a bigger budget or at least a surplus rocket from NASA. the gasses can apparently make up a very large percentage of the recoil force. I'll try to find the formulas tomorrow, I need to finish up, go home, and get some sleep! Quote Link to comment Share on other sites More sharing options...
Mantis Posted August 12, 2006 Report Share Posted August 12, 2006 Re: Stupid firearms question Important point: Vacuum is not "cold". Vacuum is an *insulator*. This is the biggest problem for a weapon in a vacuum - guns are all air-cooled. A gun fired in vacuum will not be able to lose the heat generated due to being surrounded by a perfect insulator, so the barrel will overheat more quickly than it would in atmosphere. Maybe not a big problem for single-shot weapons, but definitely problematic for auto-fire weapons. I'm dubious as to whether it matters what type of lubricant (wet or dry) is used, again vacuum is neither hot nor cold and a viscous liquid will stick regardless of the presence or absence of air pressure. I am 100% certain that cordite propellant will work fine in vacuum, however, since it works underwater. Quote Link to comment Share on other sites More sharing options...
Toadmaster Posted August 12, 2006 Report Share Posted August 12, 2006 Re: Stupid firearms question the gasses can apparently make up a very large percentage of the recoil force. I'll try to find the formulas tomorrow' date=' I need to finish up, go home, and get some sleep![/quote'] I think its just a matter of the weight of the powder being added just like the weight of the bullet. Quote Link to comment Share on other sites More sharing options...
gewing Posted August 12, 2006 Report Share Posted August 12, 2006 Re: Stupid firearms question I think its just a matter of the weight of the powder being added just like the weight of the bullet. yeah, but the velocity of the gasses are something like 5000fps, iirc. Quote Link to comment Share on other sites More sharing options...
BobGreenwade Posted August 12, 2006 Author Report Share Posted August 12, 2006 Re: Stupid firearms question You know, this is exactly the sort of question I'd hope to have answered in The Ultimate Environment.... Quote Link to comment Share on other sites More sharing options...
Tom Carman Posted August 16, 2006 Report Share Posted August 16, 2006 Re: Stupid firearms question I'm dubious as to whether it matters what type of lubricant (wet or dry) is used' date=' again vacuum is neither hot nor cold and a viscous liquid will stick regardless of the presence or absence of air pressure. I am 100% certain that cordite propellant will work fine in vacuum, however, since it works underwater.[/quote'] I seem to recall reading that dry lubricants are not necessarily good for use in space. If air allows the lubricant particles to easily move about, then those particles may jam against each other in vacuum. Quote Link to comment Share on other sites More sharing options...
Zeropoint Posted August 16, 2006 Report Share Posted August 16, 2006 Re: Stupid firearms question Okay, a nitpick: smokeless gunpowder has a nitrocellulose base. It does not burn, in the sense of oxidation: it decomposes. It does not require any oxygen. Black powder contains potassium nitrate as an oxidizer, and does not require any external oxygen supply. And yes, the gasses DO create a significant portion of the recoil. A good muzzle brake, even though it does not direct gasses backward, can significantly reduce recoil impulse. Zeropoint Quote Link to comment Share on other sites More sharing options...
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