What’s happening here?

Pond, James Pond · February 6, 2019, 01:48 PM

I’ve seen enough ballistic gel videos in slo-mo to know that this is not normal.

What is the explosion after the bullets exist.

Any thoughts as to the cause?

mehavey · February 6, 2019, 05:40 PM

You're going to have to find a new link.
Reddit thinks (whateveritis) should be "CENSORED - CENSORED - CENSORED"

Pond, James Pond · February 6, 2019, 05:50 PM

OK. I'll try but basically it's a 7 sec slo mo vid of a HV bullet hit what looks to be 18" of ballistic gel.

It does a straight pass-through length-wise and as the bullet tumbles out of the other end, there is a flash in the temporary cavity which is clearly a small explosion to the point that when the cavity collapses again, grey smoke is expelled from the entry point!

**JohnKSa** · February 7, 2019, 12:50 AM

I've seen that in a few gel videos.

When the gelatin collapses, the air inside the cavity is compressed extremely rapidly. When you very rapidly compress air in the presence of anything that is remotely flammable, the heat generated can rise to the point of causing the air/fuel mixture to burn.

Here's a good example of it:

https://www.youtube.com/watch?v=fX4ODh1g4eM

F. Guffey · February 16, 2019, 01:57 PM

Quote:

When you very rapidly compress air in the presence of anything that is remotely flammable,

Things have changed, there was a time when atmosphere was compressed moisture became visible. Some of the most interesting effects I have seen came off the end of propellers in what looked like a screw effect on humid days.

F. Guffey

F. Guffey · February 16, 2019, 02:00 PM

And then there was one of the most interesting pictures ever taken; it took years to be appreciated in the gun world but it won a prize in the world of art.

F. Guffey

481 · February 20, 2019, 11:29 AM

Since Clear Ballistics Gelatin has a large percentage of paraffinic oil (which is quite flammable) within its composition this sort of thing is hardly remarkable. Rapidly compress a volatile, flammable vapor and you get adiabatic compression ignition (aka: dieseling). Pretty cool to watch though...

pwc · February 20, 2019, 11:57 AM

If this is caused by the diesel effect, yhen why hasn't it been seen, over the years, before in other slo- mo vids? What is the particular "fuel mixture" cause with this bullet caliber / rifle, hel composition, weather condition that would cause that? Surely, one of the bullet / powder mfgrs could find out.

481 · February 20, 2019, 01:32 PM

Quote:

Originally Posted by pwc

If this is caused by the diesel effect, yhen why hasn't it been seen, over the years, before in other slo- mo vids? What is the particular "fuel mixture" cause with this bullet caliber / rifle, hel composition, weather condition that would cause that? Surely, one of the bullet / powder mfgrs could find out.

It has been documented for quite some time, numerous videos exist dating back 5, 6, 7 or more years. A little google-fu turns up lots of videos like this one:

https://www.youtube.com/watch?time_c...&v=LhBBCOIjkiM

The fuel mixture is the paraffinic oil vapor that arises under the reduced vapor pressure and atmospheric O2 produced by the bullet's entry into the test medium, compression (thanks to the ideal gas law) increases pressure as the temporary cavity collapses and by extension of that law temperature increases proportionally causing auto-ignition to occur.

Nanuk · February 20, 2019, 02:55 PM

And here I thought it was the mini nuke effect of the 10mm I keep hearing about.

F. Guffey · February 26, 2019, 05:30 PM

In the mid 50s there were 500 cubic inch inline 6 cylinder engines that had a hemispherical piston design. It seemed it escaped the notice of most mechanics but the exhaust manifold was mounted on one side of the engine and the Intake manifold was installed on the other.

I understand none of this means nothing to reloaders but the mechanics rebuilt one of engines and then decided it did not need all of that plumbing so they left it off

Then came the time for the road test; they had to take the truck off the highway because it would quit running after a few miles. It bothered me to see that magnificent old truck confined to the yard for moving equipment locally.

F. Guffey

reynolds357 · August 18, 2020, 12:37 PM

Quote:

Originally Posted by F. Guffey

Things have changed, there was a time when atmosphere was compressed moisture became visible. Some of the most interesting effects I have seen came off the end of propellers in what looked like a screw effect on humid days.

F. Guffey

What changed? Laws of physics?

reynolds357 · August 18, 2020, 12:40 PM

Quote:

Originally Posted by F. Guffey

In the mid 50s there were 500 cubic inch inline 6 cylinder engines that had a hemispherical piston design. It seemed it escaped the notice of most mechanics but the exhaust manifold was mounted on one side of the engine and the Intake manifold was installed on the other.

I understand none of this means nothing to reloaders but the mechanics rebuilt one of engines and then decided it did not need all of that plumbing so they left it off

Then came the time for the road test; they had to take the truck off the highway because it would quit running after a few miles. It bothered me to see that magnificent old truck confined to the yard for moving equipment locally.

F. Guffey

Amazing it ran at all with the intake manifold left off.

Ricklin · August 23, 2020, 11:24 AM

Some things NEVER change. We learn and understand more about them, they do not change.

February 6, 2019, 01:48 PM	#1
Pond, James Pond Senior Member Join Date: July 12, 2011 Location: Top of the Baltic stack Posts: 6,079	What’s happening here? I’ve seen enough ballistic gel videos in slo-mo to know that this is not normal. What is the explosion after the bullets exist. Any thoughts as to the cause? __________________ When the right to effective self-defence is denied, that right to self-defence which remains is essentially symbolic. Freedom: Please enjoy responsibly.

February 6, 2019, 05:50 PM	#3
Pond, James Pond Senior Member Join Date: July 12, 2011 Location: Top of the Baltic stack Posts: 6,079	OK. I'll try but basically it's a 7 sec slo mo vid of a HV bullet hit what looks to be 18" of ballistic gel. It does a straight pass-through length-wise and as the bullet tumbles out of the other end, there is a flash in the temporary cavity which is clearly a small explosion to the point that when the cavity collapses again, grey smoke is expelled from the entry point! __________________ When the right to effective self-defence is denied, that right to self-defence which remains is essentially symbolic. Freedom: Please enjoy responsibly.

February 7, 2019, 12:50 AM	#4
JohnKSa Staff Join Date: February 12, 2001 Location: DFW Area Posts: 24,579	I've seen that in a few gel videos. When the gelatin collapses, the air inside the cavity is compressed extremely rapidly. When you very rapidly compress air in the presence of anything that is remotely flammable, the heat generated can rise to the point of causing the air/fuel mixture to burn. Here's a good example of it: https://www.youtube.com/watch?v=fX4ODh1g4eM __________________ Do you know about the TEXAS State Rifle Association?

February 20, 2019, 11:29 AM	#7
481 Senior Member Join Date: April 18, 2011 Posts: 540	Since Clear Ballistics Gelatin has a large percentage of paraffinic oil (which is quite flammable) within its composition this sort of thing is hardly remarkable. Rapidly compress a volatile, flammable vapor and you get adiabatic compression ignition (aka: dieseling). Pretty cool to watch though... __________________ QUANTITATIVE AMMUNITION SELECTION

February 20, 2019, 02:55 PM	#10
Nanuk Senior Member Join Date: January 2, 2005 Location: Where the deer and the antelope roam. Posts: 3,082	And here I thought it was the mini nuke effect of the 10mm I keep hearing about. __________________ Retired Law Enforcement U. S. Army Veteran Armorer My rifle and pistol are tools, I am the weapon.

February 6, 2019, 05:40 PM	#2
mehavey Senior Member Join Date: June 17, 2010 Location: Virginia Posts: 6,631	You're going to have to find a new link. Reddit thinks (whateveritis) should be "CENSORED - CENSORED - CENSORED"

February 16, 2019, 02:00 PM	#6
F. Guffey Senior Member Join Date: July 18, 2008 Posts: 7,249	And then there was one of the most interesting pictures ever taken; it took years to be appreciated in the gun world but it won a prize in the world of art. F. Guffey

February 20, 2019, 11:57 AM	#8
pwc Senior Member Join Date: March 21, 2018 Location: AZ Posts: 236	If this is caused by the diesel effect, yhen why hasn't it been seen, over the years, before in other slo- mo vids? What is the particular "fuel mixture" cause with this bullet caliber / rifle, hel composition, weather condition that would cause that? Surely, one of the bullet / powder mfgrs could find out.

February 26, 2019, 05:30 PM	#11
F. Guffey Senior Member Join Date: July 18, 2008 Posts: 7,249	In the mid 50s there were 500 cubic inch inline 6 cylinder engines that had a hemispherical piston design. It seemed it escaped the notice of most mechanics but the exhaust manifold was mounted on one side of the engine and the Intake manifold was installed on the other. I understand none of this means nothing to reloaders but the mechanics rebuilt one of engines and then decided it did not need all of that plumbing so they left it off Then came the time for the road test; they had to take the truck off the highway because it would quit running after a few miles. It bothered me to see that magnificent old truck confined to the yard for moving equipment locally. F. Guffey Last edited by F. Guffey; February 27, 2019 at 12:32 PM.

August 23, 2020, 11:24 AM	#14
Ricklin Senior Member Join Date: February 22, 2008 Location: SW Washington state Posts: 1,834	The laws of physics are inviolate Some things NEVER change. We learn and understand more about them, they do not change. __________________ ricklin Freedom is not free

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search