German HEAT shell Gr. 38 HL/C

[Mobius]

Hey Steve:

 

I have some test data on at least one of these grenade types -- Information from penetration trials conducted by the British in 1944'ish. Captured material. However, it's buried in the morass that I call my computer room. I'll try to dig it up this weekend and post the results here.

Jeff

I'd love to see it, Jeff.

[gewing]

Could be. The early US bazooka rockets started with mild steel liners, but switched to aluminum liners at some point in the war -- 1944 or some such thing. There is a write-up about in in the Green Books -- "Planning Munitions for War" I think.

 

 

 

Would copper liners have added any significant amount to the penetration of the Bazooka?

[JWB]

Would copper liners have added any significant amount to the penetration of the Bazooka?

It did a quite a bit. > http://www.inert-ord.net/atrkts/bazoo/

[jwduquette1]

My bad. Sorry. The bazooka rocket was upgraded from a steel cone liner to a copper cone liner.

 

[jwduquette1]

Ok, this one was buried deep in the morass and took a bit of effort to find its hiding place. Some day I'll get organized.

 

It's WO 194/6696 Dated July 20th, 1944. “Enemy Munitions. German. 30mm Rifle anti-tank hollow charge grenade. Trial Report.”

 

These appear to have been all dynamic tests. Moreover the grenades were actually shot at the test plates rather than statically detonated against plates at design stand-off. The penetration\perforation information is therefore I suppose much more valuable to your sort of application -- simulation & game design.

 

The target plates were I.T.80 armor steel.

 

The German 30mm A/T Rifle Grenade cone diameter is indicated as 35mm. From the firing trials, the British figured critical thickness to be about 90mm at 0-degrees and about 75mm at 30-degree.

 

Of interest is that they also conducted side-by-sides with American built M.9A1 A/T Rifle Grenade. Cone diameter is indicated as 40mm. The M9A1 did 100m @ 0-degrees and 90mm @ 30-degrees.

 

Regards

Jeff

Edited April 29, 2007 by jwduquette1

[Mobius]

The target plates were I.T.80 armor steel.

 

The German 30mm A/T Rifle Grenade cone diameter is indicated as 35mm. From the firing trials, the British figured critical thickness to be about 90mm at 0-degrees and about 75mm at 30-degree.

That little 30mm grenade penetrated 90mm?! How can it produce a cone of 35mm?

[jwduquette1]

Just a bit more context on the German gewehrpanzergrante30. Below is a set of tables that summarize the British firing trial test results. In all cases, the behind armor fragmentation effects were much greater in the 0-degree perforations than the 30-degree perforations.

 

 

Below is a sectional of the projectile. The stand-off is a bit less than one CD. Approximately 0.8 to 0.85CD. I’d guess with crush-up the stand-off is further reduced by perhaps 10% for 0-degree obliquity hits.

 

[jwduquette1]

That little 30mm grenade penetrated 90mm?!

 

Apparently.

 

How can it produce a cone of 35mm?

 

I don't understand your second question.

[jwduquette1]

Never mind -- I see what you are trying to say. Dunno for certain. The report says the projectiles tested had 35mm dia cones. But the report refers to the projectiles as 30mm rifle grenades. My guess is that they were actually testing gewehrpanzergranate 40. The gewehrpanzergranate 40 has about the same projectile base diameter as the gewehrpanzer granate 30. The 40 is however larger toward the head\nose of the projectile to accomodate the larger cone.

 

Edited April 29, 2007 by jwduquette1

[Mobius]

Never mind -- I see what you are trying to say. Dunno for certain. The report says the projectiles tested had 35mm dia cones. But the report refers to the projectiles as 30mm rifle grenades. My guess is that they were actually testing gewehrpanzergranate 40. The gewehrpanzergranate 40 has about the same projectile base diameter as the gewehrpanzer granate 30. The 40 is however larger toward the head\nose of the projectile to accomodate the larger cone.

 

Right the weight is completely different than the normal 30mm. The 30mm had 44-46 gms of explosive. The 30mm in the test had 125 gms. The Konigsgrenade.

[jwduquette1]

Agree with your grenade selection for the British tests.

 

I suppose one thing I sort of keep in the back of my head is lower levels of behind armor effects of these small cone diameter shaped charges. While they may be rated at 90 or 100mm of perforation and thus on the surface seem to be about as effective as a big caliber shaped charge – one with lower penetration as a result of spin and angular velocity of the jet – the bigger caliber cones invariably create bigger, sloppier craters. Greater behind armor fragmentation for the larger cone diameters and thus a greater P(k) probability for the seemingly same level of perforation.

 

P(k) for hollow charges used be described as function of the amount of over penetration by the projectile. This becomes a bit more complex as one starts to consider the differences between differing cone materials. Moreover Copper cones penetrate more armor than aluminum, but aluminum and mild steel cones are nastier in behind armor effects. Pyrophoric effects for aluminum and increased fragmentation for both steel cones and aluminum cones.

 

In other words, perforation in and of itself does not equate to 100% P(k). A figure of 60mm of over-penetration used to be thrown around in various ABL studies as the level of over-penetration required for a reasonable probability of a K-Kill. This was a fast and loose rule of thumb before the days of spall liners and could vary between about 25mm to about 75mm of over penetration. Obviously other variables come into play such as hit location, diameter of cone, cone material, stand-off, etc. The smaller the cone diameter and the greater the stand-off, the greater the amount of over-penetration required for effective behind armor fragmentation.

 

The long and short being if it were me, I would tend to run perforation levels on the low\conservative side. Or; develop a simple probability algorithm for determining P(k), or P(m), or P(f) based upon over-penetration. Or; if you wanna get fancy, vary the probability of effect – be it P(k), P(f) or P(m) -- based upon the actual hit location; the magnitude of over-penetration. And if you wanna get really fancy throw in a smattering of initial cone diameter, stand-off and cone material into your probability of effect algorithm.

[jwduquette1]

This is more related to the first page of this thread. Below is a photo scanned from Col. James Mrazek’s book: “The Fall of Eben Emael”. Mrazek commanded a US Army glider infantry battalion during WWII.

 

It’s an observation cupola on casemate-19, Eben Emael. Six inch thick steel. The ventilation hole on top was created by a German 110-pound hollow charge.

 

There’s sort of a generic cupola sketch in the book showing these things to be hemispherical in shape. If it was originally rounded, than the shaped charge has really flattened the top of this thing.

 

[gewing]

Just a bit more context on the German gewehrpanzergrante30. Below is a set of tables that summarize the British firing trial test results. In all cases, the behind armor fragmentation effects were much greater in the 0-degree perforations than the 30-degree perforations.

 

 

Below is a sectional of the projectile. The stand-off is a bit less than one CD. Approximately 0.8 to 0.85CD. I’d guess with crush-up the stand-off is further reduced by perhaps 10% for 0-degree obliquity hits.

 

 

 

 

I have been trying to find a copy of teh brassey's guide to Shaped charges etc. So far even Interlibrary loan has failed, and at last search I couldn't even find a used copy. Assuming, of course, that I could afford it.

 

Relative to stand off distance, are EFP warheads more tolerant of it? Specifically in terms of do they need much to achieve effect?

 

 

Oh, and if anyone happens to spot a copy of it, let me know, please

[jwduquette1]

All shaped charge projectiles that employ metallic liners form slugs. With more “conventional” shaped charge weapons the slug is located at the tail end of the jet. But in fact the majority of the liner material ends up in the slug. The slug may or may not contribute to either perforation capability or behind armor effectiveness of a “conventional” shaped charge projectile – dependent on a variety or things.

 

EFP is of course also a shaped charge. EFP effectiveness is focused upon the proper formation and action of the slug. Call it what you like – formed projectile – forged projectile, blah blah blah. It’s a slug.

 

Shaped charges that rely less on slug action and more on jet action typically have narrower cone angles (hemispheres aside for the moment). Shaped charges that rely less on jet action and more on slug action have much wider cone angles – much flatter cones.

 

As to your question, it would seem intuitive to me at least, that the slug has to be formed properly in order to optimize it’s perforation characteristics. If you study flash radiograph imaging of the projectile\slug formation from an EFP warhead you see that it is a very broad\wide projectile during the early stages of its formation. As the slug formation event progresses the liner material squeezes in upon itself -- slug diameter becomes progressively smaller and smaller (but obviously it doesn’t narrow down to the sorts of diameters one would associated with a shaped charge jet). What if you place a target at varying stand-off distances away from the shaped charge cone? It would seem evident that the slugs perforation capability would be very limited during the initial portion of slug formation. Moreover, early on in the projectile formation, the energy of impact would be spread over a very wide area. But as the slug folds in on itself the energy becomes focused into a progressively smaller and smaller projectile diameter. So yes – I think stand-off for EFPs is crucial. Lets hold mass and velocity constant for a second -- do we think a pancake moving at 2 to 3Km/s would be more effective in perforating armor; or do we think a narrow slug moving at 2 or 3Km/s would be more effective at perforating armor?

 

P.S. Never heard of Brassey's book on shaped charges. I know they had approached Manfred Held about preparing a work on shaped charges and reactive armor, but it was never published. This according to an email inquiry I sent to Held several years back.

[Mobius]

This is more related to the first page of this thread. Below is a photo scanned from Col. James Mrazek’s book: “The Fall of Eben Emael”. Mrazek commanded a US Army glider infantry battalion during WWII.

 

It’s an observation cupola on casemate-19, Eben Emael. Six inch thick steel. The ventilation hole on top was created by a German 110-pound hollow charge.

 

There’s sort of a generic cupola sketch in the book showing these things to be hemispherical in shape. If it was originally rounded, than the shaped charge has really flattened the top of this thing.

 

Remind me hits from our Maverick missles.

[gewing]

All shaped charge projectiles that employ metallic liners form slugs. With more “conventional” shaped charge weapons the slug is located at the tail end of the jet. But in fact the majority of the liner material ends up in the slug. The slug may or may not contribute to either perforation capability or behind armor effectiveness of a “conventional” shaped charge projectile – dependent on a variety or things.

 

EFP is of course also a shaped charge. EFP effectiveness is focused upon the proper formation and action of the slug. Call it what you like – formed projectile – forged projectile, blah blah blah. It’s a slug.

 

Shaped charges that rely less on slug action and more on jet action typically have narrower cone angles (hemispheres aside for the moment). Shaped charges that rely less on jet action and more on slug action have much wider cone angles – much flatter cones.

 

As to your question, it would seem intuitive to me at least, that the slug has to be formed properly in order to optimize it’s perforation characteristics. If you study flash radiograph imaging of the projectile\slug formation from an EFP warhead you see that it is a very broad\wide projectile during the early stages of its formation. As the slug formation event progresses the liner material squeezes in upon itself -- slug diameter becomes progressively smaller and smaller (but obviously it doesn’t narrow down to the sorts of diameters one would associated with a shaped charge jet). What if you place a target at varying stand-off distances away from the shaped charge cone? It would seem evident that the slugs perforation capability would be very limited during the initial portion of slug formation. Moreover, early on in the projectile formation, the energy of impact would be spread over a very wide area. But as the slug folds in on itself the energy becomes focused into a progressively smaller and smaller projectile diameter. So yes – I think stand-off for EFPs is crucial. Lets hold mass and velocity constant for a second -- do we think a pancake moving at 2 to 3Km/s would be more effective in perforating armor; or do we think a narrow slug moving at 2 or 3Km/s would be more effective at perforating armor?

 

P.S. Never heard of Brassey's book on shaped charges. I know they had approached Manfred Held about preparing a work on shaped charges and reactive armor, but it was never published. This according to an email inquiry I sent to Held several years back.

 

 

 

Well, here is the reply I missed! SHITE!

 

 

 

I realize that it is going to need some standoff distance, but I was wondering if it needed as much as a conventional "jet" shaped charge. I was thinking that it doesn't "stretch" as much, so it might work better with short standoff distances, say 1-3 diameters.

 

Years ago I saw a picture, iirc in "military Technology" that showed the effects of a conventional shaped charge at various standoff distances on the same thickness of target, iirc.

 

As I recall, though it didn't penetrate anywhere near as far at 1-2 diameters, the diameter of the hole was relatively large, and it looked as if there might have been multiple perforations if the target was thin enough.

 

I just tried a quick google and couldn't find it, so I will look again in a little while.

Edited May 13, 2007 by gewing