Fly320s
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42?
What's the temperature of a fired bullet?
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Heat Transfer Porn!
dwhitlat's analysis above is pretty good. I'm actually a bit jealous, since I used to know how to figure that kind of thing out. Alas, much of Heat & Mass Transfer has left me.
The link below is to a PDF of the IR imaging article that might have been referenced above. A couple differences from dwhitlat's calcs:
What's interesting is that the IR image has been processed to account for differences in emissivity, or (I think) how easily a given region radiates heat. Their analysis indicates frictional heating where the bullet contacts the rifling lands, and aerodynamic heating at the bullet tip (as well as reflection from the heat of the muzzle flash at the bullet's base).
So, what do we need to solve this problem conclusively? (I'm just guessing, but it's kind of neat to pretend I still remember this stuff):
Figure all that, and you could probably get a good approximation of the temp (both surface and core) at the instant before impact.
I agree, though, that it would take less time, and be a lot more fun, just to shoot it and see.
Any other ideas?
http://www.indigosystems.com/PDF/articles/AdvImg3-04.pdf
dwhitlat's analysis above is pretty good. I'm actually a bit jealous, since I used to know how to figure that kind of thing out. Alas, much of Heat & Mass Transfer has left me.
The link below is to a PDF of the IR imaging article that might have been referenced above. A couple differences from dwhitlat's calcs:
- The bullet is a .30 cal boat-tail (assume FMJ)
- The images are taken soon after the bullet leaves the muzzle
What's interesting is that the IR image has been processed to account for differences in emissivity, or (I think) how easily a given region radiates heat. Their analysis indicates frictional heating where the bullet contacts the rifling lands, and aerodynamic heating at the bullet tip (as well as reflection from the heat of the muzzle flash at the bullet's base).
So, what do we need to solve this problem conclusively? (I'm just guessing, but it's kind of neat to pretend I still remember this stuff):
- Heat transfer coefficient of the air (fairly easy to get)
- Heat transfer coefficient and thickness of the copper jacket (again, easy)
- Heat transfer coefficient and thickness of lead core to center (easy)
- Coefficient of friction between bullet and rifling (not so easy?)
- Initial bullet temp (assume this from the IR analysis?)
- Travel time (say on a 100 m range?)
- Effects of aerodynamic heating (maybe where dwhitla's calcs come in?)
Figure all that, and you could probably get a good approximation of the temp (both surface and core) at the instant before impact.
I agree, though, that it would take less time, and be a lot more fun, just to shoot it and see.
Any other ideas?
http://www.indigosystems.com/PDF/articles/AdvImg3-04.pdf
MT GUNNY
Member
I dont know how
But i do know a 22 round is hot enough to singe dried wood (causing a little smoke) at 25 yards even
after walking the distance to the target after the shot.
But i do know a 22 round is hot enough to singe dried wood (causing a little smoke) at 25 yards even
after walking the distance to the target after the shot.
bogie
Member
The problem is that the bullets don't stay still long enough to insert the thermometer.
While in the Army we fired the m-16 at plastic-fibreglass silhouette targets and the holes left in the target were melted around the edge and had shrunk in size so as to appear about .17 cal not .223. These were at 600 yards.
Bullets had to be hot to do that.
$.02
Vern
Bullets had to be hot to do that.
$.02
Vern
DMK
Member
I've never seen any burn marks on paper target.
DMK
I believe you will find that plastic will melt at a much lower temperature that target paper will burn.
Try warming a nail on the kitchen stove (not cherry red, just hot) and then placing it on a plastic milk jug and heating it again and placing it on a target paper.
I think you will find that the jug will melt before the paper will show signs of burning. Obviously if you heat the nail cherry red both the paper will burn/scorch and the plastic will melt.
Also you could try pushing a heated nail thru the jug and removing it rapidly taking note of how thw plastic deforms during the experiment.
Actually sounds like a project for the box of truth. Might be kind of fun. On a warm day that is, right now the temperature here is at zero degrees and that would not help the experiment.
Vern
I believe you will find that plastic will melt at a much lower temperature that target paper will burn.
Try warming a nail on the kitchen stove (not cherry red, just hot) and then placing it on a plastic milk jug and heating it again and placing it on a target paper.
I think you will find that the jug will melt before the paper will show signs of burning. Obviously if you heat the nail cherry red both the paper will burn/scorch and the plastic will melt.
Also you could try pushing a heated nail thru the jug and removing it rapidly taking note of how thw plastic deforms during the experiment.
Actually sounds like a project for the box of truth. Might be kind of fun. On a warm day that is, right now the temperature here is at zero degrees and that would not help the experiment.
Vern
Anna's Dad
Member
Fly320s said:
That may be wasted on most of the readers, but I laughed out loud.
Anna's Dad
Member
DMK said:
Myself, having little knowledge of the physics involved but a much greater knowledge of science fiction (in the particular instance, Ray Bradbury) will conclude that they are cooler than 451 degrees fahrenheit.
Ryder
Member
I doubt they get as hot as that ejected case that landed in my shirt pocket the other day. Even if they were it couldn't cauterize a wound considering I fished it out with my bare fingers.
Fired bullets that fall onto ice do not melt into the surface enough to be evident. I've even picked them up off the top of packed snow. The same can not be said for ejected cases. Those will melt into a frozen surface enough to be evident.
Ever seen bubbling coming off a bullet after it was fired into water? I haven't. If it exceeded 212° F by very much it would cause boiling.
Fired bullets that fall onto ice do not melt into the surface enough to be evident. I've even picked them up off the top of packed snow. The same can not be said for ejected cases. Those will melt into a frozen surface enough to be evident.
Ever seen bubbling coming off a bullet after it was fired into water? I haven't. If it exceeded 212° F by very much it would cause boiling.
Barrelmaker
Member
Quote:
Originally Posted by Fly320s
Quote:
What's the temperature of a fired bullet?
42?
That may be wasted on most of the readers, but I laughed out loud.
Ok clue us in.
Originally Posted by Fly320s
Quote:
What's the temperature of a fired bullet?
42?
That may be wasted on most of the readers, but I laughed out loud.
Ok clue us in.
carebear
Member
pistolman1974
Member
Hot as hell!....In Centigrade
Geronimo45
Member
Lemme take a wild guess: Three hundred and twelve degrees fahrenheit, on average, for rifle and pistol bullets.
Lesser heat for lesser bullets + lesser velocities.
Magnums can get very warm, though.
I discovered all this while doing my nightly Ninjitsu meditations. Debunk at your own peril. *prepares to launch throwing stars*
Lesser heat for lesser bullets + lesser velocities.
Magnums can get very warm, though.
I discovered all this while doing my nightly Ninjitsu meditations. Debunk at your own peril. *prepares to launch throwing stars*
I recommend "Gunshot Wounds" by Vincent J. M. Di Maio
Page 85 and 92
The bottom line is that bullets don't even get hot enough to be sterilized after firing. Bacteria placed on the bullet before firing can be cultured from the retrieved bullet. This has been known for a long time:
Von Beck, B. Cited by La Garde, L. A. Can a septic bullet infect a gunshot wound? N.Y. Med. J. 56: 458-464, 1892
Thoresby, F. P. and Darlow, H. M. The mechanisms of primary infection of bullet wounds Br. J. Surg. 54: 359-361, 1967
Page 85 and 92
The bottom line is that bullets don't even get hot enough to be sterilized after firing. Bacteria placed on the bullet before firing can be cultured from the retrieved bullet. This has been known for a long time:
Von Beck, B. Cited by La Garde, L. A. Can a septic bullet infect a gunshot wound? N.Y. Med. J. 56: 458-464, 1892
Thoresby, F. P. and Darlow, H. M. The mechanisms of primary infection of bullet wounds Br. J. Surg. 54: 359-361, 1967
Stainless Chili
Member
I'm surprised no one answered the easiest of your questions
The melting point of lead ... (327.46°C, 621.43°F)
I always thought it was 550°, but that might have been 50/50 lead/tin solder.
The melting point of lead ... (327.46°C, 621.43°F)
I always thought it was 550°, but that might have been 50/50 lead/tin solder.
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