interesting things i learned

Oh, and LC?

Did you stop reading my post before you got to this statement?

"Because of the moon's much weaker gravity and the lack of atmosphere the bullet won't slow down nearly as quickly, nor will it "fall" to the surface of the moon nearly as quickly."

:)
 
Where does the oxygen come from for the powder to burn? Is there enough in the cartridge to ignite fully and completely? Would the vacuum of space suck it out when it reached the vacuum leaving no oxygen to burn?
 
Oh, and LC?

Did you stop reading my post before you got to this statement?

"Because of the moon's much weaker gravity and the lack of atmosphere the bullet won't slow down nearly as quickly, nor will it "fall" to the surface of the moon nearly as quickly."
Click to expand...

That is a distinct possibility :o
 
Brian, how can you explain a complete understanding of the physics involved, which prove how the atmosphere, or more precisely the difference in the atmospheres, would effect velocity and then say that because the difference is minute that there is no effect at all?

If you know that the atmosphere has an effect, even if unmeasurable in a specific case, in another case it could be significant.

What would be the difference in firing a rifle on Venus as opposed to the earth?
 
Brian, how can you explain a complete understanding of the physics involved, which prove how the atmosphere, or more precisely the difference in the atmospheres, would effect velocity and then say that because the difference is minute that there is no effect at all?
Click to expand...

I don't claim a "complete understanding". It's extremely complex in terms of getting a precisely correct, exact answer. However, the basic assumptions are not that complex.

Look at the differences in behavior between water and air. How extreme is it? In the grand scheme, it's not very extreme. You're talking about a density change of 800 times. Now think about the effect of taking away just 0.5gr of air and 14 psi in front of 50 or 60,000psi. What effect is that going to have?

Nearly none.

Think about it like this. Look at the effect of adding 400gr of mass in front of that bullet (air versus water) and then think of the effect of subtracting 0.5gr. How much difference is it going to make?
Venus? I don't know. The density is much lower than water but about 55 times higher than earths. The pressure is so high that it's technically a "super critical fluid" though.
 
What would be the difference in firing a rifle on Venus as opposed to the earth?
Click to expand...

50 miles above the surface of Venus I'd think it would be roughly the same, but a rifle is unlikely to even survive, let alone be functional, on the surface itself.
 
Whew! It's been so long since we had a 'guns in space' thread I was starting to get worried.

I can't go into any of the details but I am smug that NOTHING brought up in this thread has made me redesign ANYTHING in my plans for the Lunar Trap and Skeet facility. (Which is a good thing because the Lunar Bowling Alley I designed had SIGNIFICANT problems which I won't go into now.

Venus...isn't the surface temperature about enough to melt lead? You might actually have a problem leaving a Glock in a closed car in the glove box out in the sun on a hot summer Venusian day...course maybe the cloud cover would help out.
 
No, because recoil is a function of momentum, which does not change on the moon. It's related to mass, not weight. It'd be a problem out in space, where you have nothing to brace yourself against to stop the spinning but as long as your feet are on the ground it shouldn't matter.
Click to expand...

So, reduced gravity wouldn't affect the effects of recoil, assuming this theoretical gun was fired from the shoulder?
 
Of course they didn't fire a rifle on the Moon!...>

They fired it on a sound stage in California, (or maybe Elstree studios).

Everyone and their friends who work at NASA knows that!
 
I googled this and there actually is some interesting science behind it. Never thought you could fire w/o O2 but apparently its possible????? Makes me feel better that we can engage potential invading Aliens with a galactic expeditionary force...... or does this administration just give them amnesty and eventual citizenship??:eek:
 
Last edited:
gyvel said:
So, reduced gravity wouldn't affect the effects of recoil, assuming this theoretical gun was fired from the shoulder?
Click to expand...


It really shouldn't make any significant difference. All the relevant formulas are based on mass, not weight. The mass of both gun and shooter are constant, completely unaffected by gravity.

Of course, trying to shoulder a rifle while in a space suit would be interesting. Besides that the glove finger is probably bigger than the whole trigger guard.

Ignoring those real world concerns though, and just figure you could dress like you do on earth, the differences would be minor. Gravity probably helps some with getting the gun back in line after whatever vertical component of recoil there might be, so that might be noticeable. But as long as your feet are on the ground, it's friction that holds you there. That friction is influenced by gravity but it's not as if there's zero on the moon or you're on the ragged edge of going flying away even on earth.

Anyway, I wouldn't say there'd be no noticeable differences at all but it's not as if you'd go tumbling away like you got hit by a car.
 
"Never thought you could fire w/o O2 but apparently its possible?????"

Yes. Chemistry isn't my strong suite, but I think I have all of this GENERALLY correct...

Gunpowder, including black powder and modern smokeless powders, burn too quickly to be able to pull in adequate atmospheric oxygen, especially in the enclosed spaces in a gun.

Gunpowders contain chemical compounds called oxidizers, which supply all of the oxygen the gun powder needs as it combusts.

In black powder, the oxidizer is generally potassium nitrate (KNO3) or sometimes sodium nitrate (NANO3).

Modern smokeless powders get their reaction oxygen from a variety of chemicals based on the formula.

Single base powders are based on nitrocellulose (C6H9(NO2)O5).

Double base powders contain nitrocellulose and nitroglycerine (C3H5N3O9), which also provides oxygen to the reaction.

I believe that other chemicals are also part of the equation, onces that also add free oxygen, but I'm not 100% sure about that.

But, no matter what the formulation, there's enough oxygen generated during the reaction process to sustain it even if it's happening in a vacuum.
 
What would be the difference in firing a rifle on Venus as opposed to the earth?
Well, Venus is way too hot. If the gun itself didn't melt the cartridge would probably cook off. On the moon, who knows what the velocity would be? It's so cold even the least temperature sensetive powder would be seriously affected. I believe that even if you kept the gun in a heated container prior to firing the extreme cold would/could drop the powder temp enough to seriously affect it. You'd most likely need an extremely hot custom primer. Just my probaly unlikely WAG on the question. :eek::D:rolleyes:
Paul B.
 
Gravity probably helps some with getting the gun back in line after whatever vertical component of recoil there might be, so that might be noticeable. But as long as your feet are on the ground, it's friction that holds you there. That friction is influenced by gravity but it's not as if there's zero on the moon or you're on the ragged edge of going flying away even on earth.
Click to expand...

Mind you, it has been decades since I was in a physics classroom, but I think this might be oversimplifying the recoil problem in two respects.

First, there is a higher coefficient of friction when two surfaces are in contact with each other than when the same two surfaces are moving. The lower gravity on the moon (do I remember a figure of 1/6th correctly?) would decrease the force with which the two surfaces contact each other, and you would move from stationary friction to moving friction with less lateral force applied.

Secondly, it seems to me that the force would not be laterally applied, because it would be applied above the center of gravity of the shooter and impart a rotational motion to the shooter's body. The lift thus generated to the feet would be subject to the lower gravitational resistance of the moon.

I am sure my terminology is wrong, but hopefully I communicated my ideas cogently.
 
The principles you mention are more or less correct, the issue is with the magnitude of the forces.

There simply is not enough force to make anything happen.

Take a fairly high recoil rifle, .30-06, .308, etc, load it with one round. Jump up in the air as high as you can (keeping the gun pointed in a safe direction of course) and pull the trigger.

You now have NOTHING impeding your recoil induced motion until you hit the ground again. If anyone does this, I would love to know how much trouble you (don't) have with landing on your back/head/etc.

There's simply not that much force here. I'm not going to do the math again, but as I recall (I have done it before), a fairly powerful rifle will cause a 180 pound man to slide on a frictionless surface at a rate somewhere near 0.1fps. Someone else can figure it out if they want.

This is very much like the popular "knockdown power" discussions. There simply isn't enough power there, moon or earth.
 
I do have one thought on the effect of recoil on the shooter.

Even a golf club swing unbalanced an astronaut, I wonder if the different gravity would cause reflexes to mis-time & flip a shooter off balance in a lunar 1/6th gravity?
 
A 55gr projectile traveling at 160,000fps has about 4.2MJ of energy -- the same as detonating a kilogram of TNT. That's one hell of a bang!
 
There simply is not enough force to make anything happen.
Click to expand...

I was picturing the slow-motion high and long strides of the Apollo astronauts when I wrote my argument, and imagining firing a gun in that environment. Your argument is quite persuasive though, and I think you might be right.

At least I don't have to say that to my wife. ;)
 
You must log in or register to reply here.
Back
Top