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JohnRich

Freefalling Bullets

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In physics, the laws say that an object fired into the air will come down with the SAME force as it was lanched with...



Negative. Muzzle velocity of a rile bullet is 2,500 to 3,500 feet per second (about mach 3). Terminal velocity on a freefall back to earth is only about 80 to 150 mph, depending upon the size of the bullet. They do not accelerate continuously while in freefall. Skydivers should know that.

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First off, it is almost never the case that a bullet is fired straight up into the air. It is more likely on a high arc. Therefore, the bullet never looses full motion and rifling of the bullet should continue, thus allowing greater speed than what you experienced.



Even fired straight up, the spin from the rifling can continue. There is a tendency to think that when apogee is reached, that the spin must stop also. Not so. It can lose it's upward momentum, and still be spinning like crazy.

But as you say, a spin-stabalized bullet is likely to fall nose-first, presenting less drag than a tumbling bullet, and therefore greater freefall speed.

All of this has been discussed in the previous thread messages. Newcomers here should perhaps take the time to read the entire thread, even though it is several years old.

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The other thing is that there is probally some disfiguration due to firing, which the test bullets didn't have, which would make them more ball shaped and they wouldn't tumble as much.



Not neccesarily. If a fired bullet doesn't hit anything hard it will maintain it's original shape.



The only "disfiguration" of a fired bullet while in-flight would be the shallow channels impressed into the sides of the bullet by the rifling as the bullet squished itself from the firearm's chamber into the barrel. Thus, it substantially retains it's original shape, until it hits something hard.

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The other thing is that there is probally some disfiguration due to firing, which the test bullets didn't have, which would make them more ball shaped and they wouldn't tumble as much.



Not neccesarily. If a fired bullet doesn't hit anything hard it will maintain it's original shape.



The only "disfiguration" of a fired bullet while in-flight would be the shallow channels impressed into the sides of the bullet by the rifling as the bullet squished itself from the firearm's chamber into the barrel. Thus, it substantially retains it's original shape, until it hits something hard.



When considering the size and balanced shape of a bullet, would it be same to assume the rifled scratches on it would help cause it to rotate in FF?

Also, if you could fire rounds into water with out damage it would rifle the bullet and then you could retry the experiment... Just for shits and giggles!!!

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Sometimes it is more important to protect LIFE than Liberty

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When considering the size and balanced shape of a bullet, would it be same to assume the rifled scratches on it would help cause it to rotate in FF?



That sounds logical to me, assuming that it was nose-down and spinning to start with. The airflow through those channels I would think would keep it rotating to some degree.

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Also, if you could fire rounds into water with out damage it would rifle the bullet and then you could retry the experiment... Just for shits and giggles!!!



Excellent idea! However, the problem I encountered is trying to release the bullets in freefall in a nose-down attitude, with spin. You just can't do it. They all tumbled end-over-end.

Now if I could carry a gun with me on exit, from 25,000 feet up, fire the bullet downward, then chase after it, find it, and catch up with it when it slows down to terminal velocity... Ahh, I'll have to work on that idea a bit.

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I just watched Episode 50 of Mythbusters the other night, and they did some experiments on this very issue :D.

They fired freefalling bullets at freefall speeds at a pigs head, and it bounced off (but would definitely have hurt). Basically, if it's fired at a shallow enough angle that it keeps spinning, it'll keep its ballistic trajectory and go much faster; it can kill then (they interviewed an LA doctor who has X-rays). But if it really goes straight up, where it's just freefalling down (like John's experiment), then it just keeps tumbling, and ends up going about 100 mph.

Wind tunnels, desert firings, pig heads -- it was a great show :ph34r:. Not to mention the vodka myths they busted. They're my new heroes :D

John, I think you oughta email them.

Wendy W.
There is nothing more dangerous than breaking a basic safety rule and getting away with it. It removes fear of the consequences and builds false confidence. (tbrown)

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John, I think you oughta email them.



Yes, it's interesting that with all their resources they just confirmed what I figured out with a single skydive.

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Remster: I seem to recall John having a shrine devoted to one of the assistants on the show...



Oh yes, the red-head babe that welds. She can bust my myth any time.

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But if it really goes straight up, where it's just freefalling down (like John's experiment), then it just keeps tumbling, and ends up going about 100 mph.


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I know know..but I STILL think that would leave a mark!:ph34r:;)

Several years ago during the Xmas / New Years holidays, I was cleaning the hangar and noticed a ray of light coming through a hole in the steel roof.

Some idiot must have been shooting a .45 into the air...the projectile came down on a straight vertical path punching through the hangar roof....the top skin (Fabric) of the Great Lakes...and made a dent in the top of the fuel tank. The bullet wasn't deformed very much...but it was still going fast enough to do some damage.










~ If you choke a Smurf, what color does it turn? ~

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Several years ago during the Xmas / New Years holidays, I was cleaning the hangar and noticed a ray of light coming through a hole in the steel roof.

Some idiot must have been shooting a .45 into the air...the projectile came down on a straight vertical path punching through the hangar roof....the top skin (Fabric) of the Great Lakes...and made a dent in the top of the fuel tank. The bullet wasn't deformed very much...but it was still going fast enough to do some damage.



As stated also on the myth busters that a bullet not fired dead straight up still maintains a trajectory making it deadly



http://www.swoopstudios.com/videos/videos-rex.php

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That reminds me of a call I had around eleven years ago when I was a rookie cop in Winter Park. I responded to a call on the midnight shift of a lady that said a bullet had come through her ceiling fan.

Before I arrived, I was thinking part of her ceiling fan had just come off and she had mistaken it for a bullet. When I got there, sure enough there was a .308 round laying on the carpet in the kids upstairs play room. The caller advised she had just put the kids to bed and heard a loud bang and observed the round come through the ceiling next to the fan.

The round came all the way through the roof and penetrated the ceiling of a second floor room and finally stopped when it hit the carpet. I have no doubt that would have killed someone had it struck them in the head.

I also believe that it would be very difficult to fire a round straight up to where it is "free falling". That round is coming down on a trajectory even if it is a very steep one its arcing over at the top not just stopping and free falling back to earth.
Kevin

Muff Brother #4041
Team Dirty Sanchez #467

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most high powered rifle round and hand gun rounds used today will simple shred apart on impact with water a test i have done my self. better to use a balistic jell if you want an intact bullet, not positive of the reason for the bullet shredding a part with contact to water but if you take glass and heat it up and then dip it in water it will shatter as well so it might have something to do with the heat generated on firing as for the rest of the things though the experiment done on tv might have flaws check out mythbuster on dsc ch i belive they did exp. on both the peeny from the top of the empire stat building and verticaly fired shots both experiment faild to prove that either would be fatal. as a amature comp shooter shooting a rifle perfectly straight up while holding it would be almost unbearable and extremly painfull to do recoil would most likely put your ass on the ground to. hand gun more easily done but the recoil might have an effect as well.
light travels faster than sound, that's why some people appear to be bright until you hear them speak

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shooting a rifle perfectly straight up..

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Perhaps Dr. Kallend could answer, but I don't think it's POSSIBLE to shoot a projectile STRAIGHT up...what with the planet spinning and all!

I know you can't draw a PERFECT circle unless you're at one of the poles.;)










~ If you choke a Smurf, what color does it turn? ~

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as a amature comp shooter shooting a rifle perfectly straight up while holding it would be almost unbearable and extremly painfull to do recoil would most likely put your ass on the ground to. hand gun more easily done but the recoil might have an effect as well.



Shooting a rifle straight-up will produce no more recoil than shooting it in any other orientation. You could simply hold it out in front of you with both hands and pull the trigger. No big deal.

airtwardo:
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I don't think it's POSSIBLE to shoot a projectile STRAIGHT up...what with the planet spinning and all!



The trajectory doesn't have to be perfectly straight up in order to produce freefalling bullets. An angle of, say, 45-degrees would produce a ballistic trajectory in which some of the horizontal velocity would be retained. But if you are, say, just 10-degrees off vertical, there's going to be almost zero horizontal velocity, and a true freefalling bullet.

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I just watched Episode 50 of Mythbusters the other night, and they did some experiments on this very issue :D.

They fired freefalling bullets at freefall speeds at a pigs head, and it bounced off (but would definitely have hurt). Basically, if it's fired at a shallow enough angle that it keeps spinning, it'll keep its ballistic trajectory and go much faster; it can kill then (they interviewed an LA doctor who has X-rays). But if it really goes straight up, where it's just freefalling down (like John's experiment), then it just keeps tumbling, and ends up going about 100 mph.

Wind tunnels, desert firings, pig heads -- it was a great show :ph34r:. Not to mention the vodka myths they busted. They're my new heroes :D

John, I think you oughta email them.

Wendy W.


__________________________________

I saw the same show and what was amazing was, the bullets, after being shot straight up, were only about 2" into the ground and on their side. I also saw the show where, high-speed bullets were fired into a swimming pool and the bullets shattered on impact with the water. Thus, saying the idea of 'hiding' under water from gun shots would save someone from being injured 'plausable'.


Chuck

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shooting a rifle perfectly straight up..

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Perhaps Dr. Kallend could answer, but I don't think it's POSSIBLE to shoot a projectile STRAIGHT up...what with the planet spinning and all!

I know you can't draw a PERFECT circle unless you're at one of the poles.;)



You can fire it straight up anywhere. The issue is will the bullet come back down to the same spot on account of the Coriolis effect!

I once did a consulting job for the US Navy, which had a test range for it's big guns where the shell (without HE filling) was fired straight up. The test gun was in the center of a large sandy area, and when the shell came back it buried itself in the sand, and they dug it out and downloaded the ballistic profile from an onboard computer. The shells never hit the gun!

Perhaps you should only fiire your gun straight up when at the pole.
...

The only sure way to survive a canopy collision is not to have one.

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