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View Full Version : What happens when a bullet is fired straight up? (Good Article)



Ata
05-08-2009, 05:54 PM
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.

Abu Al Hawl
05-08-2009, 06:14 PM
Ata, good info for thsoe who fire aerial

KageFox
05-08-2009, 06:49 PM
Good info... though a little confusing. Am I right in interpreting that greater the muzzle velocity, longer the round trip time, and subsequently, greater impact velocity?

In simple terms, when you throw up something it has to come down, and God have mercy on those on whom the thrown object lands :lol:

Skeeter60
05-08-2009, 07:37 PM
Mr Ata has provided excellent information. I just want to add a little to it.
When the bullet reaches the max height on firing vertically up wards it starts its downward travel from zero velocity and as gravity takes over it starts to accelerate but air resistance does not allow it to reach higher velocities, also the bullet is only rotating as long as it is moving forward so it is unstable ; but there are cases where a bullet stabilised point forward and reached velocities of 600 ft and can cause grievious hurt

Omer571
05-08-2009, 07:44 PM
Great article by Ata. This question always got me thinking. Btw the little physics that i remember taught me that a free falling body accelerates at 9.8 m/s2. Perhaps its the air drag that doesn't let it accelerate beyond terminal velocity. Perhaps a physicist could explain beter....:cool:

Rizshu
05-08-2009, 07:53 PM
let's say the police officer shot a 9 mm bullet into the air.

let's say the bullets mass was 147 grains = 9.51 grams
and it's velocity out of the barrel was 1000 ft / s = 305 m/s
and it's diameter was 0.355 in = 0.00902 m

now, let's calculate it's terminal velocity....

Vt = ?(2mg / ?ACd)

where m = mass of bullet = 9.51 grams
g = acceleration due to gravity = 9.8 m/s
? = density of air = 1200 g/m
A = cross sectional area of bullet = 3.14 x (.00902 m ) / 4 = 6.39 x 10^-5 m
Cd = drag coefficient of bullet = 0.295

so Vt =

?(2 x (9.51 g) x (9.8 m/s) / [ (1200 g/m) x (6.39 x 10^-5 m ) x .295)

= ?(2 x (9.51 g) x (9.8 m/s) / [ (1200 g/m) x (6.39 x 10^-5 m ) x .295)

= 90.8 m/s

so if the bullet was fired straight up, it would leave the gun at 305 m/s, would rise to a height, then stop, then fall back to the earth. it's max velocity when it reaches the earth would be 90.8 m/s. It will still have about 1/3 of it's initial kinetic energy and will still be very dangerous.

Enigmatic Desires
05-08-2009, 08:26 PM
Without the complicated maths.. I can say it can be very dangerous... there is a hole in the Dicky of my brother's car were a 22 penetrated like a hot knife through butter.. almost ewnt though an through. an its an old car.. of 88 vintage.. in htose days they ued fairly think metel...

if a simple 22 can do that to a car. what can a .30 do to a child's soft head...

The answers sadly are too common place in hte hospitals of the country.. an yet people don't learn..

Striker1
06-08-2009, 01:01 PM
Its 2 pm and I can already hear people aerial firing. With it being a shab-e-barat... tonight... the crazy bunch of people are active again...

My friends do avoid aerial firing in cities and town tonight as well on the 14th of August eve. MODERATORs!

How about a New Thread on Aerial Firing?

-S

Khalidsh
06-08-2009, 03:37 PM
Guys .... even if one wants to avoid the articles and the mathematics as given above, just imagine you are travelling at 30kms per hour on a bike or a car and you hit something solid!

Ata
06-08-2009, 04:39 PM
I posted this article just to behave reasonable and responsible when you have Gun. On winning of 20 20 world cup everyone in my area fired but I did not fired a single shot because I don't want to hurt anyone.

If you have licensed arm that doesn't mean you have license to kill.

Thanks all for participating

Fahim
06-08-2009, 07:37 PM
Very well said ata.. it really is dangerous and still in Pakistan it looks like a very common thing.. Specialy on 14th of August or som other event every1 just start ariel firing.. hope and pray every1 learn from the mishaps and be responsible..

Omer571
06-08-2009, 08:04 PM
Thanks to rizshu to the interesting detail and to Ata for starting this thread.
Though, some contribution from Abbas or other moderators would be more than welcome.
Regards

Ka_Khan
06-08-2009, 11:34 PM
My friends do avoid aerial firing in cities and town tonight as well on the 14th of August eve. MODERATORs!
How about a New Thread on Aerial Firing?
-S
@Striker1 we have a complete thread on Aerial Firing,the link is : http://www.pakguns.com/forum/viewtopic.php?id=904

@Ata very interesting Thread.

What about the pellets of 12 bore?They dont have the same velocity as they are lighter.Comments..?

Enigmatic Desires
16-08-2009, 02:46 AM
My friends do avoid aerial firing in cities and town tonight as well on the 14th of August eve. MODERATORs!
How about a New Thread on Aerial Firing?
-S
@Striker1 we have a complete thread on Aerial Firing,the link is : http://www.pakguns.com/forum/viewtopic.php?id=904

@Ata very interesting Thread.

What about the pellets of 12 bore?They dont have the same velocity as they are lighter.Comments..?


yes I was thinking hte same thing. spacialy using the smallest birshots available.. can the tiny pellets do any harm ?

KageFox
16-08-2009, 08:13 AM
The shotgun pellets are small, but have a greater probability of hitting someone, simply due to their larger number. Though I too wonder about the kind of damage they can do...

Btw, a BB fired from a range of around 30-40 yards, from a low-powered, spring BB gun, is enough to bust the windshield of a car on a hot day. My uncle learnt that the hard way (after he discharged his BB gun from his apartment, believing that the BB was too weak to do anything :D)

Skeeter60
17-08-2009, 02:27 PM
Bird shot can be very dangerous, even if fired vertically upwards, the terminal velocity (on return) will be some thing between 130 to 150 miles per hour or about 220 ft/sec this is the velocity of # 6 shot will have when shot directly at about 80 yds or so, it can seriously injure an adult in the face or eyes and will be fatal for children.

Shot heavier than #4 and larger will be extremely dangerous at any angle. The practice of aerial firing is idiotic and criminal.

Safe Hunting/shooting

A R K TAREEN
17-08-2009, 03:53 PM
Ata,
Interesting and informative article gentleman. It is our duty being a gun enthusiast as well as a responsible citizen, to educate our friends those who ever ready for Aerial Firing.
This article is a good effort in this regard.
Take care gentleman.
With Best Regards.

Zahid Hussain
29-10-2009, 11:11 PM
Well if you want to shoot in the air shotgun blanks are great.But try to avoid this kind of activity because your celebration might end up in someone else's tragedy.My 3 year old neighbour was killed instantly when a .30 bullet hit him in the head.I suggest using fire works they are dangerous too but less than bullets.

KageFox
29-10-2009, 11:51 PM
How about we do nothing which endangers other (read: innocent) lives...

Shahzeb
15-08-2010, 09:33 PM
good article

Gilani
17-08-2010, 02:25 AM
A very good article followed by an interesting discussion. Thanks for sharing Ata brother :)

Amjad Ali
17-08-2010, 02:51 PM
thanks for shairing these useful informations

StevenCline
05-09-2010, 07:49 AM
Well done, Ata. Great find and thanks for posting.

A.Abbas
05-09-2010, 11:56 PM
Nice article ata bahi, thanks for sharing.

mhrehman
06-09-2010, 02:14 AM
nice share thanks

wadood
09-08-2011, 11:24 PM
[QUOTE=Rizshu;41200]let's say the police officer shot a 9 mm bullet into the air.

let's say the bullets mass was 147 grains = 9.51 grams
and it's velocity out of the barrel was 1000 ft / s = 305 m/s
and it's diameter was 0.355 in = 0.00902 m

now, let's calculate it's terminal velocity....

Vt = ?(2mg / ?ACd)

where m = mass of bullet = 9.51 grams
g = acceleration due to gravity = 9.8 m/s
? = density of air = 1200 g/m
A = cross sectional area of bullet = 3.14 x (.00902 m ) / 4 = 6.39 x 10^-5 m
Cd = drag coefficient of bullet = 0.295

so Vt =

?(2 x (9.51 g) x (9.8 m/s) / [ (1200 g/m) x (6.39 x 10^-5 m ) x .295)

= ?(2 x (9.51 g) x (9.8 m/s) / [ (1200 g/m) x (6.39 x 10^-5 m ) x .295)

= 90.8 m/s

so if the bullet was fired straight up, it would leave the gun at 305 m/s, would rise to a height, then stop, then fall back to the earth. it's max velocity when it reaches the earth would be 90.8 m/s. It will still have about 1/3 of it's initial kinetic energy and will still be very dangerous.[/Q


You Are a mathemesian!

Furrukh
10-08-2011, 12:16 AM
[QUOTE=Rizshu;41200]let's say the police officer shot a 9 mm bullet into the air.

let's say the bullets mass was 147 grains = 9.51 grams
and it's velocity out of the barrel was 1000 ft / s = 305 m/s
and it's diameter was 0.355 in = 0.00902 m

now, let's calculate it's terminal velocity....

Vt = ?(2mg / ?ACd)

where m = mass of bullet = 9.51 grams
g = acceleration due to gravity = 9.8 m/s
? = density of air = 1200 g/m
A = cross sectional area of bullet = 3.14 x (.00902 m ) / 4 = 6.39 x 10^-5 m
Cd = drag coefficient of bullet = 0.295

so Vt =

?(2 x (9.51 g) x (9.8 m/s) / [ (1200 g/m) x (6.39 x 10^-5 m ) x .295)

= ?(2 x (9.51 g) x (9.8 m/s) / [ (1200 g/m) x (6.39 x 10^-5 m ) x .295)

= 90.8 m/s

so if the bullet was fired straight up, it would leave the gun at 305 m/s, would rise to a height, then stop, then fall back to the earth. it's max velocity when it reaches the earth would be 90.8 m/s. It will still have about 1/3 of it's initial kinetic energy and will still be very dangerous.[/Q


You Are a mathemesian!

WTF Mr. Multan ! a mathematician and a gunner at the same time ? You are a geek brother !!!

wadood
10-08-2011, 12:33 AM
[QUOTE=wadood;205467]

WTF Mr. Multan ! a mathematician and a gunner at the same time ? You are a geek brother !!!




Farrukh bro its Orignally posted by Rizshu Bro! i'm very weak in Mathematics!

Furrukh
10-08-2011, 10:38 PM
lolz @Wadood

shakeel
13-08-2011, 04:04 PM
Can any one tell me where I can find a private firing range in Karachi, so that I can learn and practice few shots... if any one knows any institution kindly mail me the address of location of it.

Thanks,

Furrukh
13-08-2011, 06:05 PM
Can any one tell me where I can find a private firing range in Karachi, so that I can learn and practice few shots... if any one knows any institution kindly mail me the address of location of it.

Thanks,

Welcome aboard Shakeel. PNS Karsaz on Karsaz Road