Shurzen

[chuckfourth]

Hi
Firstly from
http://groups.google.com/group/soc.h...c45cd330025628

"150% was typical for WW2 HC weapons and 250% for (early) 1950s HC weapons -- at that time already called "HEAT" for "High Explosive, Anti-Tank" in US Milspeak, I believe. Modern penetration optimized hollow charge weapons can reach up to ten times (1000%) the warhead diameter, although 7-8 times is a more common figure for weapons in actual service"

This is important because,
http://knygos.sprogmenys.net/knygos-...%20Walters.pdf
or
http://www.scribd.com/doc/6193899/An...Charge-Concept

"Due to the presence of a velocity gradient, the jet will stretch until it fractures into a column of particles. Jet breakup or particulation occurs at the peal penetration. Once the jet has particulated, the individual particles are no longer perfectly aligned and usually result in side wall collisions with the previously formed crater and do not act to increase the penetration depth. ... The standoff is the distance between the front of the shaped charge (the liner base) and the target."

So...
the typical 150-250% (of WH diameter) penetration for WWII munitions is the depth penetrated because any deeper and the jet has dissipated and the hole is getting wider not deeper. So the key issue here is Geometric. It makes very little difference what medium the jet is travelling through, air or metal the Geometry of the jet limits its range/cutting depth to 1.5 to 2.5 cone diameters, this is why schurzen works.

and from
http://en.wikipedia.org/wiki/Shell_(...ank_.28HEAT.29

"A HEAT charge is most effective when detonated at a certain, optimal, distance in front of the target and HEAT shells are usually distinguished by a long, thin nose probe sticking out in front of the rest of the shell and detonating it at the correct distance, e.g., PIAT bomb."

So the following comment is wrong.
"Given that the effect of stand-off was not yet fully understood in those days, it could well be that adding a small spacing could in fact increase the effect of an enemy HEAT shell by inadvertently optimising the stand-off for the round"

PIAT at a 3-1/4 (9.53cm) cone diameter and at the best penetration of 2.5 cone diameters can reach out/cut to a depth of 9,1/2 inches (24cm) Max.

The paraphrased results posted by Claus show that PIAT can cross 15 (38cm) inches and still penetrate a 32 cm armour plates 50% of the time (3 out of 6 attempts).
This would indicate to me that that 38 cm is the maximum air space PIAT can cross and still hole a pz 3/4 side armour. As the Lower Hulls and Turrets of shurtzen clad vehicles are much further away than that the only possible vulnerable parts are the upper hulls. A small to neglible target on pz IV but larger on stug. I'll have a look to see exacly what the distances are.
The tests also show that 51cm (20 inches) air gap defeats PIAT.
Also though the armour may be penetrated the effect (size of hole) may be neglible.

In any case the British test results seem odd to me, either they are using a precision made munition of perhaps the munition conatained a test type of explosive unable to be produced in Britian or too expensive or difficult to mass produce, hence never reaching the troops.

Claus please note the use of Quotes I am supplying the other authors coments, not my interpretation of what they have said.

Best Regards Chuck.