Smoothbore & Hesh Rounds

[JWB]

Its not so much that it doesn't apply so much as its simply not representative or accurate for condensed phase stuff. 

 

I would say that solid and liquid detonations are outside of what CJ theory can generally model/predict.

 

It certainly makes too many assumptions which don't account for any of the physics going on within the actual detonation front (cellular structure, etc).

 

Its a good approximation model that works well for gas phase stuff and nothing more IMO

328278[/snapback]

But is all of that about deflagration of HESH projectiles at excessive impact velocities?

[DB]

I just can't see the basic assumptions of a steady, 1-d det wave applying in the case of a HESH round "cooking off" from frictional heating at excessive impact vels (assuming that is the mechanism which causes it it go before the fuse fires)

328374[/snapback]

Whilst JWB's discussion of the mechanisms possibly causing deflagration in IMs is important, I don't believe that it has been proven here that that any of these is the mechanism that actually limits HESH round impact velocity.

 

What it does do is establish that there is likely to be *an* upper limit to the impact velocity. Whether frictional heating or void compression is the effect that establishes the actual upper limit isn't clear.

 

You are assuming that deflagration is caused by pre-ignition via one of the described heating mechanisms, you have not demonstrated that this is the case, although it seems plausible.

 

David

[DB]

What I was more or less saying before was simply that CJ theory isn't applicable here, not actually trying to demonstrate anything.

328487[/snapback]

Seeing as I'd not actually heard of "CJ Theory" before, anything you were likely to say about it wasn't going to make me comment

 

OTOH, if the theory was developed to explain gas phase reactions, then stating that it doesn't apply well to liquid or solid phase reactions seems to make sense to me.

 

David

[JWB]

CJ> http://www.llnl.gov/str/Simpson99.html

[arcweasel]

I have framentation ratios for several explosives. What do you want?

BTW TM9-1300-214 has A3 being 150% greater than TNT.

327906[/snapback]

 

All of them .

 

What I am going to want to do is try to calibrate my model to real world projectiles and bombs and for that I need to account for the explosive type on the number of fragments generated.

 

No hurry though if its a bunch of work.

 

Thanks,

 

Jay

[JWB]

All of them .

 

What I am going to want to do is try to calibrate my model to real world projectiles and bombs and for that I need to account for the explosive type on the number of fragments generated. 

 

No hurry though if its a bunch of work.

 

Thanks,

 

Jay

329220[/snapback]

It's late, try here for some help.> http://www.tpub.com/content/explosives/

[EasyE]

What is the suspected effect of a 120mm hesh round hitting some K5 ERA or other recent ERA designs? Would the blocks be ripped off or damaged beyond use over a wide area?

[Ssnake]

Probably, but since modern KE penetrators seem to be quite capable of going through K-5 ERA at pretty much all relevant engagement ranges "softening up" armor with HESH prior to firing KE doesn't sound particularly intriguing.

[Kip Swanson]

Probably, but since modern KE penetrators seem to be quite capable of going through K-5 ERA at pretty much all relevant engagement ranges "softening up" armor with HESH prior to firing KE doesn't sound particularly intriguing.

329453[/snapback]

 

That’s an interesting statement. What exactly was the reason for developing K5 than? I think must people here have assumed that heavy ERA is very effective at reducing LRP penetration.

[Guest pfcem]

That’s an interesting statement.  What exactly was the reason for developing K5 than?  I think must people here have assumed that heavy ERA is very effective at reducing LRP penetration.

329648[/snapback]

K5 was developed to increase the KE protection of Soviet MBTs.

 

It would be fair to assume that it is quite effective against 1980's penetrators (such as the M829) but many 1990's penetrators (M829A1 & M829A2) are likely to have been designed not only for greater penetration but greater resistance to K5.

 

Now, of coarse, the US has the M829A3 which should be even more resistant to K5 (& the like) ERA.

 

General consensus is that K5 adds ~200-250mm RHAe vs KE penetrators. But (purely speculation on my part) 1990's penetrators may reduce that to say ~150-200mm RHAe & the M829A3 may reduce it further to just 100-150mm RHAe.

 

Russia (& Ukraine) have developed new heeavy ERA that should be more effective than K5.

[EasyE]

Probably, but since modern KE penetrators seem to be quite capable of going through K-5 ERA at pretty much all relevant engagement ranges "softening up" armor with HESH prior to firing KE doesn't sound particularly intriguing.

329453[/snapback]

 

I'll take your word that DM-53/63 M829A2-M829A3 etc will probably defeat K5 consistently and the tanks behind them, and that it is probably a bad tactic to fire a HESH first.

 

Newer ERA maybe not. But if a round was fired for whatever reason can we assume that a good portion of the frontal arc would be left vulnerable. It seems to make sense that a good strike by a hesh would render even newer systems like NOZH much less effective.. But I could be wrong.

[Richard Young]

My understanding is that the Birtish kept a rifled barrel for the Challenger II due to being able to fire Hesh rounds

 

I was talking to someone about shotguns and he said he shot rifled slugs out of a smoothbore shotgun.

 

Could something like that be done with Hesh rounds?

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The "rifling" on non-sabot shotgun slugs is NOT there to impart spin, nor do I think it does to any signifigant degree. The "rifling" is on the slug to allow the slug to pass through shotgun barrels with "choke", by swaging down when entering the reduced bore diameter of the choke. Otherwise, pressure would spike, and quite possibly the barrel would burst. Shotgun slugs, (again with the exception of sabotted slugs), don't need to spin, anyway: they have a solid head and hollow base, and are therefore stabilized aerodynamically via the "rock in a sock" method. Sabot shotgun slugs must typically be fired from special rifled shotgun barrels in order to stabilize: interestingly, some specialized shotguns have "rifling" that has NO twist: such barrels are intended to reduce shot pattern size by PREVENTING unwanted inducement of spin to the shot cup and wadding. hope this helps....

 

Rich

Edited June 15, 2006 by Richard Young