- May 9, 2004
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If you fired a bullet into the sky
- Thread starter StrangerGuy
- Start date
spherrod
Diamond Member
Sphexi
Diamond Member
- Feb 22, 2005
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Q. What happens when a bullet is fired straight up?
A. A lot of shooters have wondered what happens when a bullet is fired vertically. Popular lore includes such mis-ideas as the bullet burns up falling back down, it comes down at the same velocity as its original muzzle velocity, and probably one that says it disappears in a time warp.
The two best references on the subject are "Hatcher's Notebook", (by Julian S. Hatcher, 3rd edition, June 1962, Stackpole Books, ISBN: 0811707954) which includes a chapter on bullets fired vertically, and an article titled "Terminal Velocity and Penetration Studies," by Lucien C. Haag, which appeared in Vol 2, No. 1 of Wound Ballistics Review. This information is excerpted from both.
First, it must be understood that recovering vertically fired bullets is difficult because wind causes them to drift from the expected vertical line. (This probably accounts for many of the myths.)
Hatcher's tests indicated that on the average, vertically fired rifle bullets reach about 9000 feet in altitude (slowed from their muzzle velocity by air drag and gravity to zero velocity), taking about 20 seconds to reach maximum height. Then, pulled by gravity, and slowed by air drag they take about 40 or so seconds to return. Bullets fired vertically come back base first. Why? Read on!
Hatcher describes one experiment with the 150gr M2 Ball bullet fired vertically. When it came back from vertical (round trip time was about 42.9 seconds) it left only a 1/16 inch dent in a soft pine board that it happened to hit. (Not exactly what it would do at 2700f/s, eh?) Based upon this and similar tests Hatcher concluded that the impact velocity was about 300 f/s, which from additional testing appears to be the terminal velocity (the maximum free fall velocity which is limited by air drag on the body in question) of that bullet falling from any height in the atmosphere. (If I remember correctly from my limited parachuting experience the terminal velocity of a falling person is somewhere around 130 mph or about 200 f/s.)
What does not substantially change, even at extreme range, is the rotational speed of the bullet that was imparted by the rifling (around 300k rpm) since the effect of air drag on the rotational velocity in negligible. Thus the gyroscopic action, once the projectile is stabilized, tends to keep the bullet oriented in the same direction, thus the base first (well ok, original position trailing end) return. It is interesting that this was not commonly known until just before WWII. The British had lots of dud antiaircraft rounds that all came back base down, or more correctly oriented to the same elevation as shot from the gun. BTW, this is what raises hob with traditional long range small arms ballistics. With lots of elevation on the bore (past 2,000+ or so yards) at the far end the bullet is actually falling sideways and all frontal air drag algorithms are out the window.
Interestingly, Hatcher describes an experiment that shows the gyroscopic stability at work. They loaded the 150gr M2 flat based bullet backwards and found that the round trip time was a bit shorter (about 30.4 seconds) due to the bullet being "streamlined (point down) on the return trip. The drag on the upward trip was not as greatly effected due to the high muzzle velocity. No estimated impact velocity was given but it would have been somewhat higher due to the lower air drag on the bullet since it was coming down point first.
The Haag article used a ballistics computation program to calculate vertically fired bullet performance and came up with results comparable with Hatcher's work. Using bullets ranging from the .22 rim fire to the 180gr .30 caliber spitzer in the .30-06 the time of flight (up & back) ranged from a low of 25 seconds for the .25ACP to a long of 77 seconds for the M193 ball. Maximum altitudes ranged from a low of 2288 feet for the .25ACP to a high of 10,103 feet for the 180gr .30-06. Terminal velocities ranged from 134 f/s for a tumbling .22 Short to a high of 323 f/s for the 180gr .30-06.
Haag calculated the performance of the .30cal 150gr M2 ball round fired by Hatcher as a maximum altitude of 9330 feet and a round trip time of 57 seconds which is, for all intents and purposes, the same as Hatcher's observations.
As a point of interest a velocity of about between 160 and 200 f/s (±) is needed to penetrate skin. However, one could still be seriously injured if struck by a falling bullet.
Those interested in learning more about vertically fired bullets may want to obtain a copies of Hatcher's Notebook and the Haag article.
A. A lot of shooters have wondered what happens when a bullet is fired vertically. Popular lore includes such mis-ideas as the bullet burns up falling back down, it comes down at the same velocity as its original muzzle velocity, and probably one that says it disappears in a time warp.
The two best references on the subject are "Hatcher's Notebook", (by Julian S. Hatcher, 3rd edition, June 1962, Stackpole Books, ISBN: 0811707954) which includes a chapter on bullets fired vertically, and an article titled "Terminal Velocity and Penetration Studies," by Lucien C. Haag, which appeared in Vol 2, No. 1 of Wound Ballistics Review. This information is excerpted from both.
First, it must be understood that recovering vertically fired bullets is difficult because wind causes them to drift from the expected vertical line. (This probably accounts for many of the myths.)
Hatcher's tests indicated that on the average, vertically fired rifle bullets reach about 9000 feet in altitude (slowed from their muzzle velocity by air drag and gravity to zero velocity), taking about 20 seconds to reach maximum height. Then, pulled by gravity, and slowed by air drag they take about 40 or so seconds to return. Bullets fired vertically come back base first. Why? Read on!
Hatcher describes one experiment with the 150gr M2 Ball bullet fired vertically. When it came back from vertical (round trip time was about 42.9 seconds) it left only a 1/16 inch dent in a soft pine board that it happened to hit. (Not exactly what it would do at 2700f/s, eh?) Based upon this and similar tests Hatcher concluded that the impact velocity was about 300 f/s, which from additional testing appears to be the terminal velocity (the maximum free fall velocity which is limited by air drag on the body in question) of that bullet falling from any height in the atmosphere. (If I remember correctly from my limited parachuting experience the terminal velocity of a falling person is somewhere around 130 mph or about 200 f/s.)
What does not substantially change, even at extreme range, is the rotational speed of the bullet that was imparted by the rifling (around 300k rpm) since the effect of air drag on the rotational velocity in negligible. Thus the gyroscopic action, once the projectile is stabilized, tends to keep the bullet oriented in the same direction, thus the base first (well ok, original position trailing end) return. It is interesting that this was not commonly known until just before WWII. The British had lots of dud antiaircraft rounds that all came back base down, or more correctly oriented to the same elevation as shot from the gun. BTW, this is what raises hob with traditional long range small arms ballistics. With lots of elevation on the bore (past 2,000+ or so yards) at the far end the bullet is actually falling sideways and all frontal air drag algorithms are out the window.
Interestingly, Hatcher describes an experiment that shows the gyroscopic stability at work. They loaded the 150gr M2 flat based bullet backwards and found that the round trip time was a bit shorter (about 30.4 seconds) due to the bullet being "streamlined (point down) on the return trip. The drag on the upward trip was not as greatly effected due to the high muzzle velocity. No estimated impact velocity was given but it would have been somewhat higher due to the lower air drag on the bullet since it was coming down point first.
The Haag article used a ballistics computation program to calculate vertically fired bullet performance and came up with results comparable with Hatcher's work. Using bullets ranging from the .22 rim fire to the 180gr .30 caliber spitzer in the .30-06 the time of flight (up & back) ranged from a low of 25 seconds for the .25ACP to a long of 77 seconds for the M193 ball. Maximum altitudes ranged from a low of 2288 feet for the .25ACP to a high of 10,103 feet for the 180gr .30-06. Terminal velocities ranged from 134 f/s for a tumbling .22 Short to a high of 323 f/s for the 180gr .30-06.
Haag calculated the performance of the .30cal 150gr M2 ball round fired by Hatcher as a maximum altitude of 9330 feet and a round trip time of 57 seconds which is, for all intents and purposes, the same as Hatcher's observations.
As a point of interest a velocity of about between 160 and 200 f/s (±) is needed to penetrate skin. However, one could still be seriously injured if struck by a falling bullet.
Those interested in learning more about vertically fired bullets may want to obtain a copies of Hatcher's Notebook and the Haag article.
I remember in the 90's, there were articles meantoning Iraq's celebrating something by firing into the sky with guns. Repeatedly. The bullets coming back down injured or killed a lot of people.
obviously it magically dissappears.
WTF do you think happens? It goes up, and then comes back down. Bullets do not have enough energy for escape velocity.
Read the bolded area... doesnt that seem like bad science? If the bullet falling point first experiences much less friction, then one being fired backwards would have much more friction on the way up, making it not go nearly as high, and shortening the distance it has to fall.
Less friction up, more friction down, 43 seconds of travel time
More friction up, less friction down, 30 seconds travel time.
From their math the first example would have taken 14 seconds up and 28 seconds down ~
In the second example the bullet would be receiving more friction, not go as high, and slow down quicker, so its safe to say that the time to reach max height would be less than 14... and the distance needed to fall being less should be less than 28 seconds to fall.
If they are trying to say there is 100% more friction falling flat end first, then it would take 10 seconds to go up, and 20 seconds to fall down. So really the reason for the less "travel time" wouldnt be that the bullet is falling MUCH MUCH faster, but that it is slowing down MUCH quicker and not getting as high.
Otherwise, if they said firing it backwards was negligible, the bullet would reach the maximum height in 14 seconds, and fall back down 16 seconds, and be nearly the same speed as muzzle velocity (which even with a streamlined point is just unrealistic)
OrganizedChaos
Diamond Member
- Apr 21, 2002
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OrganizedChaos
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- Apr 21, 2002
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also depends on where you live, if you happen to be a celebrating Iraqi and live near an FOB you may be surprised to find that more will come down than you remember shooting up.
spherrod
Diamond Member
DrPizza
Administrator Elite Member Goat Whisperer
For what it's worth, that entire article quoted above sounds pretty much like, bullsh!t. I sincerely doubt the source of that cut and paste (no link?) is not very credible.
If you're looking for more credible information, try googling. The correct answer (if I recall correctly from prior reading) is that many bullets will tumble on the way down; most have a tendency to fall base first. I'll search for a moment or two for credible sources. (Coming from me should be credible enough) ;P
That statement alone is more than enough to make me think these "scientists" didn't have a clue what the heck they were doing, although I can see how someone naive would believe that the bullet would maintain it's orientation (point up or point down) the entire flight. How exactly did they conclude the bullet remained point down? And, why didn't they conclude that the round trip was shorter, simply because there was more drag on the bullet on the way up (thus, it didn't go up as high)?
If you're looking for more credible information, try googling. The correct answer (if I recall correctly from prior reading) is that many bullets will tumble on the way down; most have a tendency to fall base first. I'll search for a moment or two for credible sources. (Coming from me should be credible enough) ;P
rh71
No Lifer
- Aug 28, 2001
- 52,844
- 1,049
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almost 3 years ago for me...
http://forums.anandtech.com/messageview...hreadid=1023589&enterthread=y&arctab=y
JulesMaximus
No Lifer
- Jul 3, 2003
- 74,581
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Birds snatch the bullets out of the air and use them line their nests with lead so that Superman won't be able to see them.
They pierce the atmosphere, make holes in the ozone layer, causing the earth to flatulently pollute space with all the greenhouse gases we humans have diligently collected and stored...and the escaping gas causes the earth to fly around like a balloon untied, messing up all celestial bodies orbits. Eventually even our oxygen will escape, and all life on earth will simply evaporate and explode due to the vacuum of space. Thats why everybody around the world needs to do this too, at the same time, to counteract just one side of the world causing earth to lose its orbit and sputter off aimlesly into space.
Also due to the earths rapid rotation, the bullest fired in Iraq actuually land in the middle of kansas. Fotunately the shooters there havent figured out that using less powder would allow the bullets to fall in DC. Please dont tell them...
actually the hatcher report is accurate science, and does a good job explaining fluid dynamics and physics involved in spinning projectile trajectories. Simply due to the muzzle velocity and energy given by firing, a bullet going "backwards" is less acted on by aerodynamics, until the much slower return drop. (well, relatively slower than the upward portion, but certainly faster in freefall point down).
Also due to the earths rapid rotation, the bullest fired in Iraq actuually land in the middle of kansas. Fotunately the shooters there havent figured out that using less powder would allow the bullets to fall in DC. Please dont tell them...
actually the hatcher report is accurate science, and does a good job explaining fluid dynamics and physics involved in spinning projectile trajectories. Simply due to the muzzle velocity and energy given by firing, a bullet going "backwards" is less acted on by aerodynamics, until the much slower return drop. (well, relatively slower than the upward portion, but certainly faster in freefall point down).
I've heard a while back that many folks in LA like to make their own firework in the 4th of July, firing their guns.
"What goes up must come down [unless it escapes earth's gravity, which a bullet wouldn't be ableto do]"?
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