Non Sequitur by Wiley Miller for July 27, 2008
July 26, 2008
July 28, 2008
Transcript:
Danae: Whatcha doin', Jeffery? Jeffery: Trying to figure something out. Danae: Wanna talk about it? Jeffery: 'K... If you were on the moon, which is a vacuum, and tried to shoot a gun, would it fire? After all, combustion needs an atmosphere with oxygen... ...Or does the casing of the bullet create its own atmosphere? If so, the bullet would travel farther in the reduced gravity, but would it travel faster than it does here on Earth? Danae: Only a boy would think of bringing a gun to the moon. Jeffery: See? This is what happens every time I try to have a serious discussion with a girl!
Ogmeister about 16 years ago
Almost totally correct, Zod, except for the accuracy part. The entire reason for sleek bullet design and rifling is to overcome the effects of air resistance.
Spin is imparted by the rifling in the barrel for gyroscopic stability; this keeps the bullet pointed straight ahead when the effects of air resistance would otherwise cause it to skew.
Skewing would make the bullet go off course due to aerodynamic forces, and it would be harder to predict where it would impact, and consistency of impact point is the definition of accuracy.
So - no air, no accuracy problems!
queertoons about 16 years ago
^ Boys! :p
1911 about 16 years ago
So, this is why I can’t get a date! Everyone who knows me thinks Wiley must know me and had me in mind when he drew this. Zod’s and Ogmeister’s comments are the same as I was thinking, but since the bullet would weigh 1/6 of its Earth weight, would that change the burn rate of the powder? On the other hand, the powder charge would also be lighter…I think my head hurts. And why wouldn’t anyone take a gun to the moon? I never leave home without mine!
tobybartels about 16 years ago
1911: No, the burn rate will NOT be affected by the 1/6 drop in gravity, since it’s a chemical process, not gravitational. If you like, it depends on the mass but not the force of gravity (what you’re calling “weight”, although that term is ambiguous).
Isn’t science fun, girls?
ds133 over 15 years ago
Science is always fun! Especially when dealing with combustion propelled objects in non-atmospheric conditions and reduced gravity.
SashaW almost 13 years ago
Gunpowder, includes it’s own oxidizer.
Paul_B over 12 years ago
One would presume that Wiley should know these details, in which case he is selling Jeffery substantially short in this scenario.
The whole point of propellants – in armaments and rocketry – is that they are complete, containing their own oxidiser(s). The atmosphere is in all respects an impediment, restricting the travel of the projectile and destabilising its trajectory (with the only possible exception that it may actuallylubricate the bullet as it travels down the barrel ). Other than that, the lack of atmosphere in the barrel would allow the bullet to achieve a greater exit velocity. The bullet would on all counts, travel further – I am not sure whether it could actually achieve escape velocity.
Spin stabilisation would still occur – but be less necessary or more effective as there would be negligible deviation of the projectile’s travel in the absence of atmosphere through tumbling.