[Lucky Jim]

Just wondering, as oft I do, what would happen if an Astronaut fired a .45 acp pistol in space? Would the bullet go 850fps in one direction and the Astronaut 850fps in the other direction or would a gun even shoot in space? Since there is no resistance to bullet travel would a gun that shot a bullet 850fps here on Earth shoot the same bullet at a much greater velocity?I just had the idea that maybe shooting in space would be a way to get around up there. Just a dumb idea but heck who knows. I have never heard of it being tried. Y'all know how us Texicans are. Always wondering about this or that.

[Psssniper]

425 fps each in opposite directions??

assuming the gun would fire with no oxygen

physics class was oh so long ago in 1976 .........sigh

[Norm357]

Jim you have too much time on your hands. :D

[Dregan]

The energy of the charge would be equally split by both.

But each wouldn't go flying off at the same speed. Since the bullet is much smaller than the astronaut, and has much less mass, the bullet would go faster. The same amoung of force would be applied to the astronaut, but he would move much slower. The force expended to each would be the same, although their speeds would be radically different becasue of the massive difference of mass between the two.

This is of couse assuming that someone can get a cartridge to go bang in space. No air. No O2 for the gunpowder to burn. Wouldn't even hear a click, b/c no air for the sound to move through.

2 cents.

-D.

[kudu]

Since gunpowder makes it's own oxygen when it burns it would fire in space.
As for recoil propeling the astronaut in the opposite direction, it would, but to a much smaller degree. You just have to figure out the differnces in mass between the bullet weight and the astronaut weight and do the calculus. :confused:

[Dregan]

didn't know that gunpoder made oxygen as it burns... gonna have to look into that...

the formula's easy = force (newtons of energy released by the gunpowder) times mass = acceleration. F x M = A.

You need to know exactly how many newtons are released by the gunpowder, and divide that number by two. For the bullet, it's easy. You'd express it like this F/2 X M (bullet) = A.

The astronaut is a little trickier, because you also have to figure in the recoil action of the gun (i'm going to assume that he had his arms locked rigid for the shot, because figuring his strength to absorb kinetic energy in his arm and shoulder is impossible without using a real person and doing some real tests) - Anyway. If he's using a 18 pound recoil spring, that spring will absorb the square of that amount of energy (during compression and release) and that figure needs to be removed from the force actually propelling the astronaut backwards. In this case, "r" is the strength of the recoil spring, and don't forget to convert to metric! [F/2 - (F/2r^2)] X M = A.

Easy!

[kudu]

Back in an old shooting magazine they were shooting a 1911 .45ACP in a swimming pool underwater. They went on to explain that as long as there was no air bubble in the barrel of the gun when it was fired that it would not blow up. Cool pics of the bullets going about 7 ft in the water. Went on to explain that gunpowder makes it's own oxygen as it burns.

[Mal H]

Dregan is correct that the bullet will go much faster than the astronaut due to large diff in mass. Bullet would still go about 850 fps just as in the earth's atmosphere (actually a tiny amount faster due to no air to be pushed out of barrel). Big difference is that it would continue to go 850 fps as long as it remains in space. Lots of different definitions of "space" though. Near earth, there is still a fairly large amount of gases. Interplanetary, less. Interstellar, lots less. Intergalactic, practically none. So depending where it is fired, it can slow down a little to not at all. Let's not even think about how gravity will affect it.

kudo is sort of correct about why the round will fire in space. The gunpowder (or smokeless powder) doesn't make it's own oxygen, but the oxygen is contained in the chemicals making up the powder. No outside oxygen is required.

[rrader]

To clear up one thing:

Newtons Law; Force = Mass* Acceleration

so: A = F/M


As far as the motion of the bullet and astronaut:

This is assumed to be a system where energy is conserved, i.e., is the same at all times, so the initial potential energy stored in the gunpowder is converted perfectly to an equal amount of kinetic energy of the bodies after the gun is fired.

As for the motion of the bodies before and after the gun is fired, making the usual assumptions that the system exists in perfect isolation with no net energy input or friction, and that the bodies travel in pure linear motion:

Start with: momentum = mass * velocity

Momentum initial = momentum final = zero with respect to a local frame of reference

Let:

Mb = mass bullet
Ma = mass Astronaut
Vbi = initial velocity of bullet
Vbf = final velocity of bullet
Vai = initial velocity of astronaut
Vaf = final velocity of astronaut


so we get:

MbVbi + MaVai = MbVbf + MaVaf = 0 total momentum = 0 always

or simply:

MbVbf + MaVaf = 0

MbVbf = -MaVaf

So the bullet and astronaut have equal and opposite momenta after gun is fired, so the less massive bullet goes away with much higher velocity than the more massive astronaut, and in the opposite direction.

(This neglects the momentum of the gas produced)

[Mike Irwin]

Oxygen is NOT required for gunpower to ignite and burn.

Think about it.

Given the ability to push a bullet from zero to several hundred, or even thousand, feet per second, you'd need a LOT more oxygen than you'd find in an enclosed cartridge case.

Black powder contains 3 ingredients, Sulphur, which is an element, Charcoal, which is carbon with some oxygen, and Potassium Nitrate, Kn03.

Potassium Nitrate in gun powder is called the oxidizer -- it provides the free oxygen needed for the rest of the reaction to take place.

To provide enough oxygen, the formula for black powder contains roughly 75% Potassium Nitrate.

During combustion, the sulphur and carbon in the charcoal act as fuels, and the KnO3 gives up its oxygen to fuel the process.

The effect is roughly similar in nitrocellulose, although the chemical formulae are much different.


Mal

"Big difference is that it would continue to go 850 fps as long as it remains in space."

Wouldn't a bullet fired in space be subject to very very slow, very long term gravitational slowing?

[rrader]

Mike Irwin

Wouldn't a bullet fired in space be subject to very very slow, very long term gravitational slowing?


Maybe it had escape velocity from our solar system, in which case it would begin to gain velocity by gravitational attraction to the next nearest star system.

[C.R.Sam]

Mal got it covered.

Robert Goddard worked it out bout 90 years ago, even makin a really big bell jar so he could fire a handgun in a vacuum. He measured velocity, energy, recoil effect etc.

Gravitational deceleration ....not necessairily...could be gravitational acceleration ....difference being the the direction fired in relation to the most influential mass in the area.

Sam

[Loaded]

In outer space there is no up, there is no down, there is no left, there is no right. Off the bullet would go in a straight line until it is pulled into a gravitational path of a larger object. And wouldn't the bullet be traveling slo compared to the speed at which the Shuttle and other crafts soar through space?

[C.R.Sam]

And wouldn't the bullet be traveling slo compared to the speed at which the Shuttle and other crafts soar through space?

Again, depends on direction of fire in relation to the shuttle or other craft it is fired from.

Sam

[Blueduck]

I just like the idea of plinking with a 45/70 at 3,000 yards and not having to worry about compensating for bullet drop :D

[Moparmike]

Fly me to the moon, let me play among the stars...Oh, sorry.

As the bullet travelled out of our solar system, it would be slowed down by the gravity of our sun assuming that no planets' gravity wells affected its path. What would be really cool is the top velocity of the bullet on its way to a black hole.

Or the velocity of an unladen swallow on its way to a black hole. :D :rolleyes:

[Blueduck]

African or European swallow????


;)

[Randy63]

I'd like to see Michael Moore shuttled into space and fired out of one of those big circus cannons........Hopefully he'd just keep going.

K22

[Mike Irwin]

Just shoot a .45 ACP at that black hole.

That'll stop it! A .45 will stop ANYTHING! :rolleyes: :D

[Orthonym]

MOMENTUM IS CONSERVED!
E= 1/2 Mv^2!
Momentum is a vector, energy a scalar.
No more stupid questions, please?
I thought they taught this in the 8th grade.
There was an excellent article on this subject in Astounding in about 1940.

Oh, and F=Ma.:cuss:

[Lucky Jim]

Wow. That is way to deep for me. Think I will go back to work with the old shovel. I know how fast it will dig here on Earth in 105 degree heat or myself X 105 degree heat X shovel X 8 hours = pooped. Thanks for clearing that thought up for me guys.

[Mal H]

Mike: Wouldn't a bullet fired in space be subject to very very slow, very long term gravitational slowing?Yes. No matter where in "space" (see my list of spaces) you are, gravity will have an effect on the velocity and trajectory of the bullet. The effect might not be negative though, it could increase the velocity just as easily as it decreases it. That's why I said, "Let's not even think about how gravity will affect it."

On escape velocities: A .45 at 850 FPS will not be able to leave the earth's gravitational field. The escape vel required is around 37,000 FPS. The escape velocity of the Solar System is much much higher. I don't think Man has ever built a gun that could fire a bullet that would escape from the Solar System. The energy required would be astronomical, so to speak.

[rrader]

Mal H:

On escape velocities: A .45 at 850 FPS will not be able to leave the earth's gravitational field.


That would depend on the distance the gun was from earth when the bullet was fired.

For escape velocity the bullet's kenetic energy must be at least greater than its gravitational potential energy at all times:

Let:

Mb = mass of bullet
Me = mass of earth
Ve = escape velocity
G = universal gravitational constant
R = distance from earth's center

Kenetic Energy must be > Gravitational Porential Energy

1/2Mb(square of Ve) > GMeMb/(R)

so Ve > square root of (2GMe/R)

so as R increases Ve decreases.

[bedlamite]

Orthonym is right, momentum is conserved. Disregarding any gravitational pull and the ejected case, the sum of mass times velocity before will equal the sum of mass times velocity after, and this is vector addition.

MI x VI = (MB x VB) + (MA x VA)

Assuming initial velocity is 0, the astronaut weighs 250 lbs with gear, the bullet is 230 gr, and the bullets velocity is 850 fps we have:

0 = (0.00102 slugs x 850 fps) + (7.764 slugs x VA)

VA = -.112 fps

This also assumes the barrel is lined up exactly with the COM of the astronaut. Not exactly the best method of propulsion.

[rrader]

Bedlamite:

Orthonym is right, momentum is conserved. Disregarding any gravitational pull and the ejected case, the sum of mass times velocity before will equal the sum of mass times velocity after, and this is vector addition.

I stated several times that momentum doesn't change here (remains at zero), i.e., is conserved. :banghead:

The formulation I gave assumed linear motion, so that it's unnecessary to use vector addition to resolve the motion ot two bodies relative to one another, i.e., along a straight line. A simple + or - suffices to account for directionality.

Systems may be conservative with respect to scalar quantities like energy, I mentioned that to obviate use of mass energy equivalency which seems kind of unnecessary given these very slow speeds and heavy objects

[Fly320s]

But then we have to think about the back stop.

Should we aim at the Earth knowing that the bullet will burn-up on reentry or should we aim toward (presumed) empty space?

If we fire off into nothingness there is a possibility that the bullet will return toward us at some future time.

New headline for the NY Post: "Man killed by bullet fired 1 year ago."

[bedlamite]

:rolleyes:

I reread everything, you did mention it once (not several times). You also went overboard in defining the problem, while neglecting to solve it.

Linear motion, even with a defined positive direction, is still a vector.

[griz]

The biggest problem is collecting your brass.:D

[Newt]

I'm no rocket surgeon, but I do have a question to clear something up for us here in the office. The ingredients in a powder charge will support any type of discharge from a weapon without supporting O2 in the air because of it's ingredients? I ask because some of the people in the office say that the vacuum of space will either 1) crush the shell or 2) pull all of the supporting O2 out of the shell so that it cannot ignite. From what I'm reading on here 1) it doesn't have to have the supporting O2 in the shell because of the ingredients in the powder and 2) I believe the projectile is sealed inside the casing enough so that the vacuum of space cannot pull the remaining O2 out of it. Input is welcomed.

Newt

[ShaiVong]

Could a bullet survive in a DP of ~24psi? PSIg~24PSIa right? Or was that 14? Ugh.

I would imagine that unless the brass is sealed, then the gasses would leach out.

Edited to add:

The DP of a vacuum is less than 25ft of water, right? which is two atm. I'm sure the brass could take the stress NP.

[J Miller]

:confused: :uhoh: :what: = MIGRAINE HEADACHE + Excedrin = Relief.
Where's that green bottle.............:scrutiny:

[2nd Amendment]

Supposedly our astronauts played with this very thing on the moon, firing a .45 in a series of experiments. I read an article on it a few years back, but I ALSO read NASA denied it(???). Regardless, the only real questions are the ones regarding gravitational effects, the ammo and firearm will function fine.

[FireInTheHole]

What about center of gravity? If you shoot your pistol normally chances are you would be sent into a tumble... whould have to place the gun someplace over your abdomen(or hip?) to prevent it.

Anybody see that movie "MoonTrap"(?) had what's his face from Ghostbusters in it. Ya Dan Achrod (?). They fire off uzis while in orbit for thrust!

Oh... and your gun would likely explode due to the extreme heat/cold of space and the lack of atmospheric pressure playing havoc on chamber pressures... now there's a thought.

[Mute]

Mama don't let your children growup to be gun owning physicists!

[willyjixx]

pretty irresponsible to be launchin lead into the outer regions. bound to raise the voices of liberal aliens an why they should take over earth because were a danger.

so its a safe assumption that an pump action air-rifle is pretty dang useless in space. but how bout a C02?

[DigitalWarrior]

The ultimate space weapon is a 55 gallon drum filled with sand (and a 1/2 pound high explosive) launched into high orbit then detonated.

Ships, sattelites, and spacesuits are vulnerable to micrometeorite puncture. Communications, spy sats, etc would be hosed. As sats get shredded debris increase.

I think about this and terrorists in rocket science majors in universities.

[lee n. field]

Just wondering, as oft I do, what would happen if an Astronaut fired a .45 acp pistol in space? Would the bullet go 850fps in one direction and the Astronaut 850fps in the other direction or would a gun even shoot in space?

Proportional to the different masses. 230 grain bullet takes off at 850fps. Astronaut + suit massing maybe 2.8 million grains (guessing 400 pounds for the astronaut plus suit) takes off the opposite direction quite a bit slower.

Since there is no resistance to bullet travel would a gun that shot a bullet 850fps here on Earth shoot the same bullet at a much greater velocity?

Nope. it just wouldn't slow down. It would follow whatever path Newton decrees for it.

[atek3]

most cartridges don't use gunpowder these days. 45 ACP generally uses single base propellent which is basically nitrocellulose and binders. Nitrocellulose burns so rapidly because it doesn't need outside oxygen, the Nitro groups (-NO2) within the molecule supply the oxidizing component of the chemical reaction. The net result is that the oxygen in the nitro group forms water and carbon dioxide (with the carbon and hydrogen present in the molecule) and the nitrogen atoms form N2 (nitrogen gas). So basically a 45 ACP will fire in space. However, the gun would be so cold and possibly brittle the chamber pressure might rupture the gun. Also if the sun came out the rounds would likely cook off inside the gun leading to a catastrophic failure sending shrapnel through your suit killing you. Long story short, don't bring your colt into space. A simple but effective design for space based anti personnel weaponry is basically a recoilless rifle firing clusters of flechettes. (A recoilless rifle has holes on both ends, out one end comes the cartridge and out the other comes a blast equal in momentum such that the impulse given to the shooter is minimal)

atek3

[ShaiVong]

A simple but effective design for space based anti personnel weaponry is basically a recoilless rifle firing clusters of flechettes. (A recoilless rifle has holes on both ends, out one end comes the cartridge and out the other comes a blast equal in momentum such that the impulse given to the shooter is minimal)

Where can i get me one of those!?

[Lord Grey Boots]

Don't forget that most of the reaction momentum will go into cycling the gun and be absorbed by the recoils spring. I suspect that our intrepid space hero may have to stabilize himself to avoid going head over tail very slowly, but he could put repeated rounds on target fairly easily.

[Black92LX]

Hmm shooting in space. i wonder if the Government would make us get a special permit to shoot in space, since shooting in space would be completely silent, you wouldn't even hear the bolt action.

[Guy L Johnson]

you analisis is correct except that the astronaut has a far grater mass not to be confused with weight as such his oposit velocity would be far less example if the astornught has 1000 times the mass he would move away at 1/1000 th of 850 fps this dose not count for the recoil that is absorbed by the slide spring and yes a gun will fire in space as the propelant contains its on oxidzer a sealed cartrage fires.
Guy L Johnson

The worlds worst typist

[atek3]

Where can i get me one of those!?

you can't, all non-shotguns over 0.5" are 'destructive devices'.

atek3

[zpo]

How fast was Voyager (I or II?) going when it left the solar system?

[Combat-wombat]

Come to think of it, I'll bet that's how the Brady Campaign can say that a .50 BMG rifle has a 4-mile range! In outer space! Just think of it! Do you know how easily a moon terrorist can pick off a satellite? Also, .50 caliber rifles can easily shoot down a galaxy!. Think of the space children! Think of the space children!!!

[Orthonym]

I recall reading a book by (James?) Oberg about the recent US-Russian space adventures. No, I didn't read all of it, I did read most of it while standing up in the bookstore.:) While Mr. Oberg was talking about the corrupt subsidies we've provided to the Russkies to keep them in the space business, he (almost parenthetically) mentioned, and showed a picture of, a Nudelmann 23mm (?) cannon which went up with the Russian space station, just in case we had designs on the thing.

[ShaiVong]

you can't, all non-shotguns over 0.5" are 'destructive devices'.

Couldnt I get a 10 or 12ga recoilless rifle then? I hear the term thrown around alot, but ive never seen any exact info about them. Anyone have a good link?

[280PLUS]

someone (or two) figures out that unless the astronaut were to hold the gun in precisely the right spot he would begin to tumble slowly off into space where he will then continue on into infinity until some gravitational force like the sun took hold upon him/her and sucked them in

so now, all you brainiacs (dating myself, where does the term "brainiac" come from??)

at what speed would the astronaut tumble and also, given the forces absorbed by creating the tumble, at what speed would he NOW be traveling away from the point at which he discharged the projectile?

and would his direction be exactly the opposite of the direction of the projectile or would he assume another direction due to some of the forces being used to create the tumble?

let's assume he's firing from a weaver stance, that oughta simplify it a little

yes, you may have time to go get your tin foil hats

heck, i'm not even smart enough to word the question correctly...

:neener:

[Mal H]

zpo - I've forgotten exactly, but I think their vel was somewhere in the ballpark of 10 miles per second. However, there was a lot of celestial mechanics involved in achieving that speed. It would have taken a lot more energy if the rocket had been fired directly toward the edge of the Solar System instead of in an orbital configuration and without using the outer planets for a little help.

As rrader correctly pointed out, the escape velocity required depends a whole lot on where you are when you try to escape from a massive something.

280PLUS - Brainiac was one of Berkeley's early monstrosity "computers". "Brain Imitating Automatic Computer".

I'm not even going to make a feeble attempt at your question - too many variables.

[280PLUS]

the term braniac is earlier than that, they stole it,,,

:evil:

i'll give you a hint, jerry seinfeld would know...

anyhow, way too many variables,

even if we defined bullet mass and velocity and the astronauts body mass and even eliminated any outside gravitational interference there are still an infinite number of possible points and directions in space to point the muzzle each one necessitating a fresh set of calculations

but what if we defined those terms too??

c'mon, i know somebody out there can do it

oh and don't forget the forces imparted to the gun as the projectile is being spun by the rifling :what:

then my buddy standing here just says,

"what if you put your back against the spaceship?"

ok, whos got that exedrin?? pass it over

:rolleyes:

[JohnBT]

When taking the really long shots...what kind of windflags should I use to read the solar wind?

John

[FireInTheHole]

280PLUS:
Ack math... I've had the whole summer to pickle my brains... :banghead: I'm not going to mess with this one. Interesting prob though.... might pop it on my physics teacher this fall. :evil:

[Smoke]

I am not a scientist, n do I play one on TV.

Proportional to the different masses. 230 grain bullet takes off at 850fps. Astronaut + suit massing maybe 2.8 million grains (guessing 400 pounds for the astronaut plus suit) takes off the opposite direction quite a bit slower.

There is no air in space to provide resistance. THere is no gravity (work with me here...) Isn't the size of the object irrelevent. Wouldn't thebullet and the hapless astronaut travel at the same speed? They don't use massive rockets to move the shuttle when its up there.

Please explain this as you would to your three year old...thats my intelect level. And don't show me the math...I'm dyslexic and hated algebra.

[C.R.Sam]

Smoke...
Try concept;
Hit 13,000 pound locomotive with a one pound hammer, see how far locomotive moves.

Not accurate but similar to 3,000,000 grain object launching 230 grain projectile.

Now if the recoil were sustained....effect would become important.

Sam

[Mal H]

280PLUS - Are you thinking of the Superman character? If so, that came later.


Smoke: There is no air in space to provide resistance.
For the most part, that's true. But there is quite a lot of air in the space of the low earth orbits the shuttles are in compared to the space between stars, for example. There is enough air resistance to degrade even the most perfect orbit over a long period of time.
THere is no gravity (work with me here...)Not true. Contrary to our intuition and watching the astronauts float freely in the shuttles, the gravity where the shuttle is is almost the same as when standing on earth. The thing that creates the illusion of no gravity is that the shuttle and everything in it is in "free fall". It is orbiting the earth at the speed required to keep it in orbit. In effect it is falling to the earth very rapidly, but its forward speed keeps it from actually hitting the earth. When it has fallen the distance required to hit the earth, the earth isn't there! So it keeps falling and moving forward = it's in orbit. Isn't the size of the object irrelevent. Wouldn't thebullet and the hapless astronaut travel at the same speed? See Sam's good analogy. The size (actually the mass) is relevant, very relevant.They don't use massive rockets to move the shuttle when its up there.True. They use relatively small rockets to adjust the orbits and attitude, etc. The big difference is that they don't have to move the shuttle very far or very fast with those rockets. Even a small rocket like an amateur rocketeer's rocket could move the shuttle in orbit given enough time.

[ShaiVong]

When taking the really long shots...what kind of windflags should I use to read the solar wind?

Really thin tinfoil. The same kind demos put on their heads to prevent us of the vast right wing conspiracy to read their thoughts. Damn you tinfoil!

[JohnBT]

I gave up trying to remember the details. I knew though that the wind flags would have to be huge.

Solar wind -> 400 km/sec, but only 6 ions per cubic centimeter.

A quick Google search turned this up:

"The solar wind shapes the Earth's magnetosphere and supplies energy to its many processes. Its density at the Earth's orbit is around 6 ions per cubic centimeter--far, far less than that of the "best vacuum" obtainable in labs on Earth. The distribution of ions in the solar wind generally resembles the distribution of elements on the Sun-- mostly protons, with 5% helium and smaller fractions of oxygen and other elements. (There are electrons too, of course, counteracting the positive charge of the ions and keeping the plasma electrically neutral.) All this flows away from the Sun with a mean speed of about 400 km/sec, and as shown by the Voyager 2 space probe, this flow extends past the outermost planets, more than 30 times more distant from the Sun than Earth, and it probably continues much further than that."

[Billll]

Here's my shot at the Brainiac thing: The earliest computers had names like Eniac which was an algorythm for something involving integrated analog computing. The -iac suffix was grafted to the word 'Brain' to yield the new word 'brainiac'.
As it happens, there was a science fiction story from some time back involving a conflict between two astronauts on the moon. The baddie held the station, and had acquired the good guys .45. The good guy, knowing that the baddie was unfamiliar with firearms, stood on a low ridge, some distance out, and let the baddie empty the gun at him, then engaged the fellow in arguement for a few minutes. Now, the gun was delivering muzzle velocity of 1100 FPS, and, it turns out escape velocity from the moon is also 1100 fps. This means that objects launched from the surface at 1100 fps, in a tangential direction will go into a very low orbit. Sure enough, after a few minutes the bad guy got several slugs in the back, from his own gun! I can think of several practical reasons why this is unlikely to actually happen, but the physics is OK.
I seem to have stumbled into the Mad Scientists wing of THR. Cool!

[telomerase]

>I gave up trying to remember the details. I knew though that the wind flags would have to be huge.

>Solar wind -> 400 km/sec, but only 6 ions per cubic centimeter.


Solar wind is orders of magnitude less powerful than the light pressure from the Sun, so your main long-distance windage correction will be for light pressure. Search on "solar sailing" or look in your Physics book for the equation for the momentum of reflected photons; if I remember right there's about 1.4 kilowatts per square meter of photons at the Earth's orbit.

Of course you're living in a country that doesn't recognize private property rights to extraterrestiral property (with the notable exception of geostationary orbit slots), and whose government owns exactly three 1970s "manned spacecraft". So the question isn't likely to be important soon... unless some other country decides that the near-Earth asteroids might be a teensy bit more important than Saudi Arabia, and decides to use the NERVA technology that the US developed in 1965...
http://freedom.orlingrabbe.com/lfetimes/neil_armstrong.htm

[Orthonym]

grumpy? Like me?;) Yes, another old Space Cadet here, also very annoyed at the way NASA has systematically sodomized any serious space development. I still get hoppin' mad when I think of that Saturn 5 lying on the ground at the Cape, covered in grackle poop!

[Andrew Wyatt]

Heinlein did a story where a bunch of High school kids with garands and 1911s fought nazis on the moon, and i wlawys wondered if a properly lubed for the conditions garand would work on the moon.


do they need a smaller gas port?


would you still hear the "pling"?

[Mal H]

I don't think you'd need to do anything special, including a lube change, to the Garand or a 1911 to make them function on the moon. They should work just fine as is. The loss of 14+ PSI outside pressure is just a rounding error compared to the pressure it takes to operate the Garand. For both, it's the mass of the bolt/slide that counts. I doubt that the weight change would make much difference.

You wouldn't hear the "pling" unless the clip hit your helmet. You might, however, hear the shot. I'm not sure what it would sound like, but some of the escaping gases might make it to your helmet. It would probably be a faint "poof". Anyone standing near your muzzle would probably hear it a little louder.

Man, that sure would give a whole new dimension to "point blank range"!

[Phyphor]

given that astronauts CAN communicate in space by touching helmets (the vibrations travel through the air in the helmets, into the hardened material in the helmets, and finally, reach the ears,) isn't it quite possible that the vibrations of your shot being fired would travel up your arm and be heard?
Obviously, it wouldn't sound the same.

[Mal H]

Possibly, but I think it would be faint sound at best since there would be a lot of soft, non-sound-conducting, material between the gun and your ears. And the sound from the gun vibrations would most likely be at a very low frequency.

[Loaded]

Getting back to the original question -- A bullet would travel in space forever, with the liklihood that it will get pulled into a gravitational pull of a planet and even "slingshot" its way back out again until it is pulled back once againa and forever stay in an orbital path around said planet.

[Mal H]

We know that Vic. We were talking about sound traveling through things other than air. Or sound coming from the escaping muzzle gases impinging on a suit helmet. etc.

Everytime I see the opening of Star Trek, past and present, I wonder where the "whoosh" comes from when the Enterprise goes by. :) I guess they needed it for effect, but it's far from what you would really hear, namely nothing.

[Moparmike]

Its the "woosh" generator. The impulse engines double as wooshers at warp.:D :neener:

[Lord Grey Boots]

The woosh generator also powers the doors on the Enterprise.

[280PLUS]

came before Brainiac the evil scientist and superman arch rival??

are you sure??

now here's something that needs serious research...

:neener:

oh, i just realized that GRAVITY here on earth helps control recoil, right?

so i'm going to correct myself because i now believe the tumble imparted will actually be rather rapid instead of nice and slow like i first thought

AND

does the bullet take precisely the track of initial poa or is there a variance there?

i know if we define ALL the variables it then becomes a doable problem

not by me, of course :rolleyes:

math?? i hate math... :barf:

it would be interesting to figure it on paper and then actually try it to see how the results compare (i know, "Paper, What's paper?")

:D

[Mal H]

I just did the research for you. :)

Brainiac the computer was invented by Ed Berkeley in 1955 (http://www.blinkenlights.com/pc.shtml). Brainiac the villain was introduced (http://www.thekryptonian.com/comics/bios/brainiac.htm) in Action Comics #242 (http://www.supermanhomepage.com/comics/pre-crisis-reviews/c-review-pc-act242.html) in 1958.

[MeekandMild]

In outer space there is no up, there is no down, there is no left, there is no right. Off the bullet would go in a straight line until it is pulled into a gravitational path of a larger object. There are no straight lines. Larry Niven discussed this problem in his fiction book "The Integral Trees" some years ago. If you are in orbit and throw something down it will go forward, if you throw it forward it will go up, if you throw it up it wil go backwards and if you throw it back it will go down, relative to you in your orbit.

[280PLUS]

"Brainiac the computer was invented by Ed Berkeley in 1955. Brainiac the villain was introduced in Action Comics #242 in 1958."

well i'll be...

i always thought it was the other way around,,,

probably cause i saw brainiac the villian way before i ever heard of brainiac the computer

280plus was introduced to the world in the may 1957 issue... :rolleyes:

:D

good lord,,,i even remember the story now that i read it again...

:what:

the miniature city of kandor...wooowwwwww...talk abouta mental time warp,,,

[benEzra]

oh, i just realized that GRAVITY here on earth helps control recoil, right?
so i'm going to correct myself because i now believe the tumble imparted will actually be rather rapid instead of nice and slow like i first thought
The magnitude of the recoil impulse is not affected by gravity; gravity just gives you your grip on the ground. If you were to jump up in the air at the shooting range and fire the gun while in the air, you wouldn't tumble violently with most guns (.577 Tyrannosaurs notwithstanding), even though you would be momentarily weightless.

[280PLUS]

the pull of gravity on the mass of the gun and your arms absorbs some of that recoil energy, gravity helps pull it back down after recoil right?

in space there would be no such force, therefore all that new found energy would then be directed to the mass of the body holding the pistol

and would relate directly to how stiff you held your arms

the stiffer the hold, the faster the rotation

duh,,,i think...

:rolleyes:

:D

[Stevie-Ray]

Everytime I see the opening of Star Trek, past and present, I wonder where the "whoosh" comes from when the Enterprise goes by. I guess they needed it for effect, but it's far from what you would really hear, namely nothing. If you see the episode where they use that shot many times, where a human-like race led by Warren Stevens has taken over the Enterprise and makes it go even faster than it's maximum speed of warp 9, it makes no noise at all, as it should be. It's always been one of my favorite scenes, the big E blistering to a dot on the screen. Of course then in '79 we got the first movie where Isaac Asimov as technical consultant gave them the impression of what a ship might look like going into warp. Quite impressive at the time.

[ShaiVong]

Ill tell you what the whoosh is! Ah HA! I've thought about this myself!

Naturally there is no sound transmission in the form of compression waves of a gas; buuuuuuut, consider the sound that of ions striking the hull of the ship your viewing from emitted by the fusion drive of the starcraft, and the large magnetic field and shields it creates! HA!

[Mal H]

Vic - yes there is sound in space. Lots of things will make sound that you can hear if you are in a position to hear them and the sound can be conducted to your ears. You don't need air in every situation for there to be sound. If an asteroid hits your spacecraft, I can guarantee you will hear it. You won't hear it for long since you will be vaporized, but you will hear it hit asuming you are in a normal atmosphere inside the craft. On second thought, maybe you won't hear it since there is a very good possibility that the asteroid will be traveling much faster than the speed of sound, but it won't be because of a lack of air outside the craft.

ShaiVong - I had a very similar thought after I posted the Star Trek whoosh thing. There has to be several different fields that would be generated by a spacecraft passing nearby at extremely high speed. In fact, meteors will create sound on earth, even though they are anywhere from 30 to 100 miles up. They create an electromagnetic field that tends to affect things on earth if you listen carefully. Some who have heard it describe it like the rustling of leaves. The sound has definitely been attributed to the passing meteors.

[SelfProclaimedExpert]

Sound and air have no connection. Sound can, and does travel through any matter that is either a fluid (liquid or gas) or a solid. The denser the material, the better sound travels.

There is no sound in space. A gun is not "space". The astronaut is also not made of space. Therefore, anything that is composed of a material that can produce sound IS making sound, and if a listener is in fluid or solid contact with it they will hear that sound.

Space doesn't cause sound to not happen, it just insulates one sound making object from another.

No astronaut has ever reported the lack of sound they experienced. Everywhere they were was just as noisy as any other man made place.


On the bullet velocity/astronaut velocity thing: The recoil of the astronaut is directly proportional to his mass relative to the bullets mass and velocity. If the astronaut masses one thousand times the bullet, he will recoil at 1/1000th the speed of the bullet. That simple.

[Mal H]

Vic - It sounded like you thought there would be no sound in space no matter what due to the lack of air. In every instance we were talking about things (clips, expanding gases, ions, etc.) impinging on your spacecraft, spacesuit, helmet, etc. You implied that we were incorrect and that those things could not be heard. You are correct that a sound producer cannot be heard by the ear or a microphone if there is absolutely no conducting material to carry the sound.

I haven't reread every post, but I don't recall anyone suggesting that they would be able to hear sounds that travel through empty space.

[280PLUS]

would the expanding gases of the round create an impulse that could be felt and/or heard by the shooter as well as others floating nearby? theres your fluid

i had another thought, what would the anti gunners think of introducing a handgun to space, where, at one time, space was considered "off limits" to weaponry

imagine the debate as to whether we should put a handgun on the next shuttle flight to test our theories and calculations...

:what: :uhoh:

oh and while where at it, has anyone here ever figured out how many angels really DO fit on the head of a pin?

:eek:

:D

[SelfProclaimedExpert]

Vic,

Are you asserting that if an asteriod hit the Enterprise, and you were IN the Enterprise, you wouldn't hear it? You would be in space, after all.

Of course there is no sound in a vacuum. There's nothing in a vacuum except radiation. However, if there is matter (the stuff that can make noise), there is going to be noise in that matter and any adjacent matter.

And if noise is identified by the ability to observe it, you will observe sound in space due to the listening device's ability to produce its own. A man will hear his pulse, a microphone will measure its own AC current vibration.

From the beginning, we have been talking about making noise with objects in space (guns, as it so happens). If you want to argue that one can't make noise out of a vacuum, you're right, but that's not what anyone was saying.

[benEzra]

i had another thought, what would the anti gunners think of introducing a handgun to space, where, at one time, space was considered "off limits" to weaponry
Actually, I believe there's already a handgun in space. It's in the emergency survival kit on board the Russian Soyuz "lifeboat" docked to the International Space Station. (Mostly for defense against wolves if they land off course; the gun was added after a pair of cosmonauts spent a cold night in the spacecraft due to a wolf pack outside . . .)

[telomerase]

> at one time, space was considered off limits to weaponry

No, only to "weapons of mass destruction", and then only if they were based in space (the Soviet FOBS was an orbital weapon, but was allegedly only based on the ground). ICBMs and even IRBMs pass through space on their way to their targets. And there have been many generations of anti-satellite and anti-missile weapons which operate in space.

Anyway, the idea of everywhere in the universe (except Earth!) being off limits to weapons is hilarious anyway... wouldn't it make more sense the other way around?

[Mal H]

Vic - But I still believe you will not hear an astroid hittiing your craft because the craft and the asteroid are in a vacuum. You will certainly feel the collision, but sound? Nope, you won't hear it.

I guess you and SPE and I will just have to agree to disagree on that one. I know that you are an intelligent gentleman, so I think we are just not getting our point across sufficiently. Besides it is getting us further afield from the original "shooting guns in space" query.

[Andrew Wyatt]

Vic: what happens if ia bounce a rock of a car while you're in it?


you'll hear the thunk of the rock hitting the windshield.



same thing with spacecraft.