Bullets Flying

In relation to an ongoing conversation (here) about whether or not a bullet fired up into the air can kill or maim you, we have this editorial concerning an actual (possible) case:

Too many guns. How many is too much? Well, we might start with the nameless half-wit somewhere in Ruskin last weekend who thought it would be fun to shoot off some celebratory gunfire on New Year’s Eve.

A 12-year-old boy, Diego Duran, was on the bloody receiving end of all the revelry. Duran, a popular student at Beth Shields Middle School, was simply trying to enjoy the New Year’s fireworks with his family until the errant bullet struck the top of his head.

The devastating shot could have come from as far as several miles away. The goober shooter might not even know what he or she did. But the Duran family sure knows.

The editorial does not say, but the young boy was critically wounded. At the moment of impact, he issued blood from his nose and eyes.

My argument about guns in the air is that if you actually shoot a bullet up in the air, mostly straight, it will probably slow, stop, and drop at terminal velocity. But much shooting into the air achieves a ballistic trajectory so the bullet continues moving and spinning at all times. Since it starts out much faster than the speed of sound, by the time it gets a mile or two away it can still be quite fatal. Thus, snipers.

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31 Responses to Bullets Flying

  1. Chris P says:

    well yeah, when it comes back down to earth a bullet will be travelling at (almost) the same speed it was when it left the gun. So it’s just a matter of being that unlucky person to be standing in the wrong spot.

  2. Greg Laden says:

    Chris, no it won’t. If the bullet goes truly “up” to the point where it loses all of it’s forward momentum, then falls back down, it will accelerate to terminal velocity, which is prob. about 100 mph.

    The bullets that were “shot into the air” and then penetrate, seriously wound, or kill people were not “shot into the air” they were “shot into the people”

    Like a sniper would do if shooting long distance … elevate the barrel, adjust for wind, lead the target if it is moving. All that must be done if you are beyond point blank range (by definition).

  3. Matt Penfold says:

    Chris, no it won’t. If the bullet goes truly “up” to the point where it loses all of it’s forward momentum, then falls back down, it will accelerate to terminal velocity, which is prob. about 100 mph.

    Would it be that slow ? Humans, without a parachute can get upto 120 mph. A lot would depend on the extent to which the bullet was tumbling I suppose.

  4. gddiver says:

    IIRC Myth Busters had a segment on this one. Again allowing for faulty memory they were never able to actually measure the velocity of a bullet fired straight up. They did a wind tunnel measurement and determined a relatively low terminal velocity. Keep in mind that the muzzle velocity of a high powered rifle is usually about 3000 feet per second or 2000 mph so a terminal velocity of 200 mph is relatively slow.

  5. felicis says:

    Why guess – we can look to the internet and find the wikipedia article on terminal velocity:

    In this case, the terminal velocity increases to about 320 km/h (200 mph or 90 m/s),[2] which is almost the terminal velocity of the Peregrine Falcon diving down on its prey.[3] The same terminal velocity is reached for a typical .30-06 bullet dropping downwards—when it is returning to earth having been fired upwards, or dropped from a tower—according to a 1920 U.S. Army Ordnance study.[Emphasis mine]

    While 295 ft/s is far slower than the 30-06 travels even at long range (>500 yd), it can still pose a significant danger (clearly). And – regardless of how dangerous it might be, to fire a rifle (or any firearm) without having an actual target in site violates basic safety principles. whoever shot that bullet is in the wrong.

  6. Greg Laden says:

    Matt: “Would it be that slow ? Humans, without a parachute can get upto 120 mph” Head down, but otherwise humans are much slower.

    There is probably some kind of size effect. A piece of lead sixty or seventy microns wide will float around in the sky for a month. A piece of lead 30 cm across will fall like a lead baloon. Explain that!

    gddiver: My “guess” is from memory of the Myth Busters figuring that out. They were unable to grapple with the problem directly because you can’t easily shoot a bullet at an oblique angle from a rifle and then measure it’s falling velocity because it will be very far away and very small.

    felicis: The 1920 army ordinance study is widely regarded as flawed.

    Until some actual evidence comes along to change my mind, and that is quite possible, I’m thinking a bullet-drop is the same as a penny-drop (but maybe a bit faster) and that bullets seriously injuring people are not bullets “fired into the air” that then come down later, but rather, bullets fired at a ballistic angle that simply find a target while still going vast enough to do some serious damage.

    Like in that move.

  7. Greg Laden says:

    OK, I’m looking at the terminal velocities for humans and they seem to be faster than I was thinking.

  8. Jim T says:

    The myth busters determined if shot straight up bullet tumbles on the way down

    45deg angle allowed spin of rifle bullet to maintain high velocity

  9. DVMKurmes says:

    Adam Savage discussed the bullet drop show at TAM 8 or 9, and I remember him saying it was nearly impossible to fire a bullet straight up and have it fall back at terminal velocity. They almost always took a ballistic trajectory and came down fast enough (probably still with some spin and falling point first, the most aerodynamic attitude) to be very dangerous. Just for comparison purposes, a relatively light (52 grain) .22 bullet fired at 3000fps muzzle velocity has dropped about 600 inches from level at 1000yards, but is still traveling 857fps and has 85 foot pounds of force. (ballistic information taken from Hornaday handbook)
    I don’t know how close to vertical a bullet has to be to fall back at terminal velocity, but it is possible that even a light bullet can still maintain enough velocity, even when fired at a relatively steep angle to be deadly if it hits someone, especially in the head.

  10. Dorid says:

    http://www.koat.com/news/30113175/detail.html This happened near me. This New Year they’ve run frequent video of the little girl.

  11. Greg Laden says:

    I know about that discussion, but I’m still not convinced that this is understood. The comparison you gave of a bullet fired at level is an interesting data point but does not address the question. The Myth Busters were faced with a situation where they could not replicate a vertical shot and still measure it, and they were being shown evidence that bullets “fired into the air” had come down and killed/wounded people. SOme of that evidence, however, may be exaggerated … this is a little culty … there are people who really need these bullets to be deadly for some reason and there is even evidence that some of the data is fabricated, such as hospital data from one source that defines a “bullet fired into the air” on the basis of the wound it makes, not the way the bullet was fired.

    There is an angle above which, if you fire a bullet, it will slow down, stop, and become a dropped bullet. I doubt that this angle is so accuse (with respect to at theoretical ray extending out form the gravitational center of the earth) that it can’t be replicated by a gun in a vice. However, a bullet fired ad a fairly oblique angle may well retain a lot of velocity for a long distance. The girl who was killed by the Amish guy cleaning his musket was two miles away. I imagine that barrel was angled up quite a ways!

    It is interesting that one piece of evidence proffered for the deadliness of bullets “fired into the air” is a handful of cases where someone was shot, often with a bullet from a gun that no one can identify the location of (and thus, we can’t say that we would see it as “fired into the air” if we actually saw it happen), but in the mean time, every single time someone gets married in Yemen or Saudi or a dozen other countries, several hundred rounds are fired into the air and people pretty much live.

    So far I regard this question as in the realm of cultural pheonemena until the proper set of experiments can be deviced.

    One other small item: If you shot a rifle into, say, a treeline and found out later that some kid had his brains scrambled by your bullet, you would probably claim that you had fired the gun “harmlessly into the air” when what you really did was shot somebody who was to far away for you to see.

  12. felicis says:

    Greg – are you arguing that my estimate is too fast or too slow? Another site calculated the terminal velocity of a 150gr .300 caliber bullet to be 320 fps (a bit higher, but not a lot). And ‘widely regarded to be flawed’ begs a citation – or at least an explanation in what way it was flawed.

    Unless the terminal velocity is significantly lower than 300 fps, the bullet retains enough energy to cause serious injury – if the velocity is higher, that only makes the risk worse. As a side note – the energy calculated was 30 ft-lbs, which is a lot less than being hit by being shot at directly, but still enough to cause serious injury. We can also not that people do occasionally get hit by (small) meteors – and generally live to tell the tale. So we should not expect extremely high velocities.

    The terminal velocity is not so much determined by the mass, but the drag coefficient (which combines mass and cross-sectional area) and the density of the medium through which it travels. If fired so that the bullet will travel over a mile, I would call that ‘in the air’ and the end result would be a bullet falling nearly straight downward at the end of its trajectory with terminal velocity.

  13. Greg Laden says:

    It’s high. Google that army source, you’ll see it cited and discussed here and there.

    If the terminal velocity of a bullet was 200 mph, that would be a dangerous nastly thing. But there would not be dead bodies laying around after the Iraqui wedding. There woudl be some dinged windshields.

    If the TV is 300 mph and we want to believe that this would penetrate human skulls, etc., then we still have the problem that there are not very many dead bodies left after the wedding.

  14. Greg Laden says:

    This is especially interesting:

    “The mortality rate among those struck by falling bullets is about 32%, compared with about 2% to 6% normally associated with gunshot wounds.[5] The higher mortality is related to the higher incidence of head wounds from falling bullets.”

    (from the source above)

    Meanwhile, from the same source, paired uncritically with the above data:

    ” In the U.S. Commonwealth of Puerto Rico, about two people die and about 25 more are injured each year from celebratory gunfire on New Year’s Eve, the CDC says.”

    Yeah, it’s cultural.

  15. DVMKurmes says:

    I wonder what the angle is at which a bullet will be going at “only” terminal velocity versus a ballistic trajectory that results in a higher velocity at ground level. It would appear that deaths and injuries are fairly common in the middle east as well, and that terminal velocity of 200fps or higher is enough to penetrate skulls and other parts of the body.
    http://ats.ctsnetjournals.org/cgi/content/full/83/1/283

    I would not be surprised if heavy clothing (jackets, hats, etc.) is enough to prevent a more serious injury at relatively low velocities such as the 2-300 fps we are talking about, and it may just be more likely that a randomly fired bullet will hit an inanimate object most of the time, which does not make shooting into the air a good idea.

  16. Greg Laden says:

    Allah is wise. He commands that we wear hats.

  17. tielserrath says:

    This is something I’ve been curious about, so I asked a colleague, a surgeon who had relocated from Iraq.

    He said they often saw significant scalp wounds from falling bullets, some skull fractures and concussion, and the occasional death.

    The wounds are different from falling as opposed to ‘trajectory’ bullets, mainly because of the loss of spin, so they could tell them apart.

  18. Azkyroth says:

    There is probably some kind of size effect. A piece of lead sixty or seventy microns wide will float around in the sky for a month. A piece of lead 30 cm across will fall like a lead baloon. Explain that!

    Square/cube law.

  19. jamessweet says:

    He said they often saw significant scalp wounds from falling bullets, some skull fractures and concussion, and the occasional death.

    The wounds are different from falling as opposed to ‘trajectory’ bullets, mainly because of the loss of spin, so they could tell them apart.

    Now that I believe.

    A bullet falling at terminal velocity is probably not going to kill you, but it is probably going to fuck you up. And it just might kill you.

    Think about getting punched really hard in the head, hard enough to give you a concussion. You probably won’t die — you just might, but probably not — but you’ll definitely land in the hospital.

  20. Greg Laden says:

    I think it is interesting and a testament to the whimpiness of modern culture that no one has yet cited being whacked in the face by a piece of gravel thrown up by a truck going the other direction while you are driving at speed on the roof of some vehicle or another…. the kind of gravel hit that would ding a windshield.

    Why do you think people are wearing goggles and leather hats in all those old photographs!?!? Steampunk wasn’t just a fashion statement!

  21. Scotlyn says:

    In Europe we’ve got the kind of gun laws Americans wouldn’t put up with. Even so, our farm gate boasts a random bullet hole – the product of a most definitely careless and mis-aimed, but legal, hunter’s rifle shot from the game preserve across the valley.

    I’ve reared my kids and hundreds of animals here over the years. Despite the random bullet hole mentioned, I believe they’re a lot safer, on their behalf, than I would if I had stayed in the US.

  22. @ 18 DVMKurmes:

    The angle at which the bullet will ‘only’ be at terminal velocity depends on how much of the initial ballistic energy needs to be lost for you to consider it negligible. The velocity imparted to the bullet along the lateral direction (rusty physics- should be the dot product of [sine of the angle from the vertical]and [magnitude of muzzle velocity]?) is not reduced by gravity and only faces air resistance. If I’m doing it right (I’m probably not), around 5-6 degrees off the vertical leaves you with 10% of the original muzzle velocity, assuming negligible air (a bad assumption in a terminal velocity problem). Then you make a right triangle with that number as the lateral edge and the terminal velocity as the vertical edge and solve to get your final velocity. The central question is what to reasonably call ‘small’ compared to terminal velocity.

  23. Greg Laden says:

    It seems to me that one can calculate velocity at apogee (maybe you just did that?). If velocity at apoge is less than terminal velocity for that bullet, then the bullet won’t speed up any more than terminal velocity. If it is greater, it still may slow down to terminal velocity.

    For a given bullet fired from a given rifle, the angle at which velocity at apogee is terminal velocity or slower is the angle at which one is “shooting a bullet into the air” instead of “shooting the bullet at an unknown distant target”

    (with that grey area in between we can ignore for now)

    What I question is that this angle is exactly 90 degrees. That’s a gut feeling, but a strong one!

    Aside from that I think we have a LOT of problems with terminal velocity. I don’t see any cited sources that do anything other than citing other sources, thumsucks, or poorly documented emperical tests done so long ago I don’t see how they apply in that bullets have changed so much.

    Which brings up a whole bunch of questions. Aren’t some bullets designed to flatten out on firing, others not? Rifle bullets spin in a way to even flight. Does that influence the configuration of a falling bullet? TV is a function of density, size, shape, attitude, and rotation. All these things can vary a LOT from bullet to bullet, firing to firing.

    The idea that TV can be between 200 and 500 mph could be reasonable (those are the cited numbers) but given that the emperical and theoretical basis for this is all over the place, I don’t think this is a range of possibilities as much as it is a range of guesses.

  24. F says:

    Thing is, in many cases, the “horizontal” vector component for bullet velocity isn’t going to disappear. No one celebrates with firing their weapon into the air with a vice and a plumb bob.

  25. Greg Laden says:

    F: A bullet going zero speed can’t accelerate beyond terminal velocity and takes a certain amount of time to do so. A bullet “dropped” with, say, 10% terminal velocity will not accelratre to 110% of terminal velocity and then slow down … it simply reaches terminal velocity sooner. Right?

  26. F: A bullet going zero speed can’t accelerate beyond terminal velocity and takes a certain amount of time to do so. A bullet “dropped” with, say, 10% terminal velocity will not accelratre to 110% of terminal velocity and then slow down … it simply reaches terminal velocity sooner. Right?

    False. Ish. If the 10% is in the vertical direction, you are correct. If not, we need to consider the vertical and horizontal vector components independently. (Consider- a bullet “dropped” out of a gun at many times terminal velocity in the lateral direction still accelerates downward due to gravity.) Terminal velocity is the vertical speed at which the net force of gravity and air resistance along the vertical axis is 0. This condition does not cause the bullet to lose or gain horizontal momentum.

  27. sandra says:

    I can’t believe this…it’s insane! you people have lost the point trying to prove each other wrong. Celebratory gunfire is dangerous and illegal.

    Even children are taught to not throw rocks when people are around. It’s common sense you do not shoot a firearm up in the air because this can kill anyone within at least a mile away. There are people out there unless you are in the desert. This has happened more often than you might know. You could have been the victim as well.

    Saying Diego Duran was in the wrong place at the wrong time is really something I don’t get. It’s like you are saying the shooter was ok, it’s the boy who was in the way? I think the shooter was in the wrong place at the wrong time. There is no good place or time for this act of stupidity and selfishness. What an extraordinary lack of common sense!

  28. Greg Laden says:

    A young girl was shot here a day or two ago, a few miles from my house. No gunshot was heard, the wound was not criticle, probably a .22 cal rifle. Seems like a shot in the air situation.