what happens to bullets that you fire up in the air?

[OulOat]

Originally posted by: Heisenberg

Originally posted by: OulOat
Army studied this. Falling bullets will not kill anyone. Why? Air resistance. Bullets going up experience it, same for when it come down. However, the most important fact to note is that when bullets fall, they fall with the flat edge down (center of mass is there). Thus, it is not aerodynamic at all. Plus, if a falling bullet does hit you, the blunt edge will make the contact, thus causing less damage than if point made contact (distribution of force).

On the same note, planes have been shot down due to random firings. The most recent one was last year during a wedding in ?Turkey? (some European country)

Do you have a link to the study, or at least something that refers to it? I'd be interested to know what the terminal velocity (and Cd) of a bullet flat-side down is. If that's true, the howstuffworks.com link above is wrong also.

Read tcsenter's post in rh71's link. The article I read was actually in a miltary magazine in AROTC lounge, so I can't produce a link. However, tcsenter got most of it.

 

[OulOat]

Originally posted by: 0roo0roo

Originally posted by: OulOat
Army studied this. Falling bullets will not kill anyone. Why? Air resistance. Bullets going up experience it, same for when it come down. However, the most important fact to note is that when bullets fall, they fall with the flat edge down (center of mass is there). Thus, it is not aerodynamic at all. Plus, if a falling bullet does hit you, the blunt edge will make the contact, thus causing less damage than if point made contact (distribution of force).

On the same note, planes have been shot down due to random firings. The most recent one was last year during a wedding in ?Turkey? (some European country)

its fast enough to go through your skull. perhaps they mean it won't kill outright you if it just hits you elsewhere.

No, not if you fire it straight up. If it was fire at a 45degree angle, then yes.

 

on a related note, i've heard that if you fire two guns (same calibur, same everything), one straight up into the air, one level with the ground, they'll land at the same time

i don't see how it's possible though :\

 

[Gurck]

I fondly recall reading about a falling bullet killing someone at a KKK rally (need I mention that's also where it was fired from?). Terminal velocity for skydivers is what, about 180mph? A bullet going 180mph to the head would probably be enough to kill, though I'd imagine one might fall faster than that.

 

[sciencewhiz]

Originally posted by: OulOat
Army studied this. Falling bullets will not kill anyone. Why? Air resistance. Bullets going up experience it, same for when it come down.

My physics professor's daughter used several methods to veryify that bullets don't come down fast enough to kill someone for a science fair. She won the local and regional competitions, no idea how she did at state.

Two of the methos she used was dropping the bullet through a deep pool, getting the terminal velocity in that, and then using the differences in drag in water and in air, calculating the terminal velocity in air. She also hung a bullet off of the wing of her father's airplane, and measured the angle that the cord made with vertical, to get the drag, from which the terminal velocity could be calculated. She had another method also that I don't remember. The results weren't real close (one was 50% more then the other), however, all of them were close to an order of magnitude smaller then what was necessary to kill.

 

[Heisenberg]

Originally posted by: jntdesign
on a related note, i've heard that if you fire two guns (same calibur, same everything), one straight up into the air, one level with the ground, they'll land at the same time

i don't see how it's possible though :\

They won't. If you fire a bullet perfectly horizontally, and drop one from the same height as the one fired, they will hit the ground at the same time. It comes from independence of velocity vectors in orthogonal directions (here horizontally and vertically).

 

[Eli]

quoted from tcsenter's post.

This wouldn't be the first time "How Stuff Works" has sacrificed technical veracity for simplicity of explanation. Ok, its time to put this one to bed.

The US Military studied this exhaustively decades ago and found that a falling small arms bullet will not have enough force to do any serious penetrating injury to all but perhaps a small child or infant. Further, most bullets will in fact fall point-up provided that they are allowed to fall far enough in order to stabilize that way.

From Hatcher's Notebook by the late Major General Julian S. Hatcher, U.S. Army, a renowned authority on military firearms and legendary Army ordinance officer:

----- Begin Excerpts -----

"Among the many experiments carried out at Miami and Daytona, was this same one of vertical firing. It was desired to find out how fast a bullet returned to earth and how dangerous such a bullet would be if it struck a soldier after dropping from a great height. Many interesting things were learned from this test, and they are given in detail in the "Official Report of Vertical Time Flight for Small Arms Ammunition," in the files of the Ordnance Department. Much of the information given below is from that source.

"At Miami the firing was done from a platform built in the shal- low water of a protected inlet, where water was often calm. A frame was built to hold a machine gun tripod so that the barrel pointed vertically. Instruments were provided to check the angle of the barrel, and the tripod controls permitted any necessary changes in the barrel inclination to be made with ease and preci- sion.

"Out of more than 500 shots fired after adjusting the gun--only four shots hit the platform. One of the shots was a service 30.06, 150 grain flat based bullet, which came down base first...it left a mark about 1/16 inch deep in the soft pine board.

"Two more bullets struck in a pail of water and left only a perceptible dent in the bottom of the pail. One struck the edge of the thwart (seat across a boat, used by an oarsman) in the boat, and left a shallow indent...The last two bullets were 175 grain boat-tailed.

"It was concluded from these tests that the return velocity was about 300 feet per second. With the 150 grain bullet, this corresponds to an energy of 30 foot pounds. Previously, the army had decided that on the average, an energy of 60 foot pounds is required to produce a disabling wound. Thus, service bullets returning from extreme heights cannot be considered lethal by this standard.

"Most .30 caliber bullets seem to attain this final velocity, and it doesn't make any difference how far they fall. Even if a bullet was fired downward from a very high plane, it would still reach the ground at the same velocity. That is because the resistance increases very rapidly with increases in air speed. If the air resists the motion of the bullet a certain amount at 300 feet per second, it will resist three times as much at 600 feet per second and nearly nine times as much at 1000 feet per second.

"A 150 grain bullet weights .021 pounds, and when, in falling, it reaches a velocity where the air resistance balances the weight, the velocity of the fall will no longer increase.

"For a .30 caliber bullet of standard experimental shape, having a pointed nose of two caliber radius, the air resistance on the nose at 2700 fps. would be about 2.3 pounds; at 2000 fps. 1.5 pounds; at 1500 fps. .89 pounds; at 1000 fps. .17 pounds; at 500 fps. .04 pounds; at 350 fps. .025 pounds; at 320 fps. .021 pounds, balancing the weight of the bullet and stopping any further increase in velocity in the case of a falling bullet."

---- End Excerpts ----

In Europe during and after WWII there dozens of seperate reports from servicemen and locals concerning hundreds of anti-aircraft rounds being found stuck point-up in tarred roof-tops. Contrary to intuition and conventional thought, bullets will actually fall point-up and rear-down. Why?

A couple of factors contribute to this:

The point of the bullet will easily 'plane' through air resistance, causing the leading edge of the bullet to react more chaoticly to air resistance. Without any rotational force (spin) to resist that planing, the bullet will begin to tumble and roll. Eventually, provided that the bullet falls far enough, it can actually stabilize with the point-up and the blunt edge down because A. its heavier on that end and B. the blunt edge provides a more uniform surface upon which air resistance will act and promote stabilization.

Arrows don't do this because the tip is almost always the heavier end and the fletching of the arrow creates not only drag but keeps the arrow spinning a certain rate as long as its falling.

 

[OulOat]

Originally posted by: Gurck
I fondly recall reading about a falling bullet killing someone at a KKK rally (need I mention that's also where it was fired from?). Terminal velocity for skydivers is what, about 180mph? A bullet going 180mph to the head would probably be enough to kill, though I'd imagine one might fall faster than that.

So when was the last time you heard people dying directly from hail?

 

Originally posted by: Heisenberg

Originally posted by: jntdesign
on a related note, i've heard that if you fire two guns (same calibur, same everything), one straight up into the air, one level with the ground, they'll land at the same time

i don't see how it's possible though :\

They won't. If you fire a bullet perfectly horizontally, and drop one from the same height as the one fired, they will hit the ground at the same time. It comes from independence of velocity vectors in orthogonal directions (here horizontally and vertically).

ahhh, thats right
my memory must have altered it (damn beer)

 

[OulOat]

Originally posted by: jntdesign

Originally posted by: Heisenberg

Originally posted by: jntdesign
on a related note, i've heard that if you fire two guns (same calibur, same everything), one straight up into the air, one level with the ground, they'll land at the same time

i don't see how it's possible though :\

They won't. If you fire a bullet perfectly horizontally, and drop one from the same height as the one fired, they will hit the ground at the same time. It comes from independence of velocity vectors in orthogonal directions (here horizontally and vertically).

ahhh, thats right
my memory must have altered it (damn beer)

Actually, that is, once again, ignoring air resistance. If air resistance was taken into account, the fired bullet would hit first. The dropped bullet would almost immediately change to the stable position with flat end down. The fired bullet would have a spin for a while, thus it would be in a more aerodynamic position. Of course, over time, it would end up in the same position as the dropped bullet, but it would a have that little head start.

 

[Gurck]

Originally posted by: OulOat

Originally posted by: Gurck
I fondly recall reading about a falling bullet killing someone at a KKK rally (need I mention that's also where it was fired from?). Terminal velocity for skydivers is what, about 180mph? A bullet going 180mph to the head would probably be enough to kill, though I'd imagine one might fall faster than that.

So when was the last time you heard people dying directly from hail?

Last I checked lead was heavier than water. After reading Eli's post though, I'm guessing I probably read it from a "National Enquirer" type source, but who knows; someone could be looking up and have it hit them in the eye which might be a bit more serious than hitting them in the skull and cause / lead to death.

 

It would come back down at terminal velocity.

 

[DaiShan]

Originally posted by: Eli
How would it come back down at the speed it went up?

When you fire a bullet from a gun, it basically immediately begins slowing down due to air resistance. It has much more energy imparted on it than a bullet would gain while falling.

A falling bullet would reach an equlibrim between speed and air resistance. It is still going to be enough to kill you if it hits you in the top of your head, but it isn't going to be traveling at the same speed that it left the gun.

Please correct me if I'm wrong.

Edit: I realize that the more energy that is imparted on the bullet, the higher it will go, and theoretically in a perfect atmosphere it would keep building that energy back the further it fell, but there are restrictions/limitations somewhere, I am almost positive...

There is less of an effect of wind resistance on a bullet than on a person for example. We all know that when people go skydiving they reach a certain speed and can't go any faster (something aroudn 200mph iirc) well a bullet has air resistance working on it as well, but it isn't as pronounced because it is more "aerodynamic"

/edit maybe I'm wrong, thats just what I've always heard.

 

[klah]

http://www.newscientist.com/lastword/article.jsp?id=lw142

Different bullet types behave in different ways. A .22LR bullet reaches a maximum altitude of 1179 metres and a terminal velocity of either 60 metres per second or 43 metres per second depending upon whether the bullet falls base first or tumbles. A .44 magnum bullet will reach an altitude of 1377 metres and a terminal velocity of 76 metres per second falling base first. A .30-06 bullet will reach an altitude of 3080 metres with a terminal velocity of 99 metres per second.

According to tests undertaken by Browning at the beginning of the century and recently by L .C. Haag, the bullet velocity required for skin penetration is between 45 and 60 metres per second which is within the velocity range of falling bullets.

On the other hand, pennies dropped from tall buildings are harmless.

 

[sygyzy]

BadDad!

 

[spanky]

i heard the government puts giant magnets that levitate in amongst the clouds that just gobble up all bullets fired into the air.

 

[Harvey]

Physics happens. If you're dumb enough to shoot blindly into the air, I hope you are the only one in range of the falling bullet.

Hmmm.... That suggests a good way to defeat the Iraquis trying to kill our guys. They seem to enjoy shooting their weapons into the air to celebrate or protest almost anything. Just corral them into a big arena, give everyone a gun, and tell them anything that would make them shoot into the air to celebrate... and DUCK!

 

[DrPizza]

Originally posted by: OulOat

Originally posted by: jntdesign

Originally posted by: Heisenberg

Originally posted by: jntdesign
on a related note, i've heard that if you fire two guns (same calibur, same everything), one straight up into the air, one level with the ground, they'll land at the same time

i don't see how it's possible though :\

They won't. If you fire a bullet perfectly horizontally, and drop one from the same height as the one fired, they will hit the ground at the same time. It comes from independence of velocity vectors in orthogonal directions (here horizontally and vertically).

ahhh, thats right
my memory must have altered it (damn beer)

Actually, that is, once again, ignoring air resistance. If air resistance was taken into account, the fired bullet would hit first. The dropped bullet would almost immediately change to the stable position with flat end down. The fired bullet would have a spin for a while, thus it would be in a more aerodynamic position. Of course, over time, it would end up in the same position as the dropped bullet, but it would a have that little head start.

Actually, ignoring air resistance, the dropped bullet will hit the ground before a bullet fired horizontally. Why? Because the earth is round(ish). Furthermore, if there were no air resistance and no hills/mountains/bulges/houses/billboards, etc to get in the way, you could conceivably fire a bullet fast enough to get it to orbit the earth at an altitude of 3 feet. If the earth were flat though, they'd hit the ground at exactly the same time. I demonstrate this in physics class with a device that shoots a marble and drops a marble simultaneously.

Also, as stated above, the terminal velocity is far less than the muzzle velocity. But, it left me wondering... could bullets be redesigned with dimples (like golf balls) to decrease the drag?

 

[MainFramed]

what goes up, must come down

 

[Viper GTS]

http://www.cnn.com/2003/US/South/11/24/klan.initiation.ap/

Viper GTS

 

[Gurck]

Originally posted by: Viper GTS
http://www.cnn.com/2003/US/South/11/24/klan.initiation.ap/

Viper GTS

Well, I was half-right. Thanks for the link.

 

[Wag]

An angel collects them.