Shurzen

[cbo]

Originally Posted by Imp

The only other thing I will add is while it may have been origionaly designed to stop ATR the Germans would have realised just as the allies did the benefits against HEAT

So far, no evidence have surfaced suggesting that the Germans ever considered Schürzen as anti-HEAT shields.

However, I think you are right that the Germans knew that they would some effect. About a year before they employed Schürzen, they tried firing HEAT at the spaced armour on the front of the Panzer IV. Basically 20mm thick plates spaced a short distance from the front turret and superstructure similar to what you see on many Panzer IIIs. They were originally designed to damage enemy AP rounds before they hit the main armour, particularily be de-capping capped rounds.
Anyway, the result was that the spaced plate would indeed stop a gun-fired HEAT round from damaging the main armour, but it would destroy or remove the spaced plates in the process. So just like the British found with thin skirting plates, it was a one-shot protection.

I would venture a guess, that the Germans probably knew that Schürzen would have some effect on HEAT weapons, but that they probably drew the conclusion that

- Against gun-fired HEAT, it was a one-shot protection
- Against un-spun HEAT rounds, they were only effective up to a point. British tests showed that Panzerschreck and Panzerfaust were both capable of penetrating the skirting plate, breach any meaningfull air-gap and still penetrate 70-100mm on the other side. As we have already seen, the German Schürzen setup barely protected against the PIAT and could probably be defeated by anything bigger.

Had the US fielded the 3,5" bazooka in WWII, no one would probably bothered considering the Schürzen as anti-HEAT shields anyway

cbo

[Mobhack]

Originally Posted by cbo

So far, no evidence have surfaced suggesting that the Germans ever considered Schürzen as anti-HEAT shields.

However, I think you are right that the Germans knew that they would some effect. About a year before they employed Schürzen, they tried firing HEAT at the spaced armour on the front of the Panzer IV. Basically 20mm thick plates spaced a short distance from the front turret and superstructure similar to what you see on many Panzer IIIs. They were originally designed to damage enemy AP rounds before they hit the main armour, particularily be de-capping capped rounds.
Anyway, the result was that the spaced plate would indeed stop a gun-fired HEAT round from damaging the main armour, but it would destroy or remove the spaced plates in the process. So just like the British found with thin skirting plates, it was a one-shot protection.

I would venture a guess, that the Germans probably knew that Schürzen would have some effect on HEAT weapons, but that they probably drew the conclusion that

- Against gun-fired HEAT, it was a one-shot protection
- Against un-spun HEAT rounds, they were only effective up to a point. British tests showed that Panzerschreck and Panzerfaust were both capable of penetrating the skirting plate, breach any meaningfull air-gap and still penetrate 70-100mm on the other side. As we have already seen, the German Schürzen setup barely protected against the PIAT and could probably be defeated by anything bigger.

Had the US fielded the 3,5" bazooka in WWII, no one would probably bothered considering the Schürzen as anti-HEAT shields anyway

cbo

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 !

Cheers
Andy

[Imp]

Cbo
Slightly off topic but as you seem to know quite a bit why did the PzMkIV recieve minimal improvements to its turret armour. Was this due to the fact that the long barrel 75 was a tight squeeze meaning the glacis could not be improved, in other words the turret was at its design limits or maximum weight for traverse possibly?

Late war it was not a great tank to have on the defence either dug in or on a hill due to the comparativly weak turret.

[chuckfourth]

Hi
Well I guess someone better put the con argument for AT shurzen heres what John D Salt has to say at
http://groups.google.com/group/sci.m...tary.moderated

"1. There is no need to hang the outer plates at such a distance
from the main armour (with the attendant difficulty of having
them knocked off) unless one wants to increae stand-off distance;

and

2. There were no 14.5mm ATRs or anything comparable on the
Western or Italian fronts, yet German AFVs continued to wear
Shurzen there.

It also seems to me that, whereas an outer plate struck at an
angle might succeed in reducing the penetration of a 14.5mm APCR
round, it would make little difference with a normal impact. The
performance of the 14.5mm against the 30mm side armour of the Pz
III or Pz IV is so marginal that I would have thought it would
mostly fail at any great angle anyway. While not disputing that
Shurzen might indeed reduce the effect of 14.5mm (though, as
mentioned in another post of mine, it might not), it beggars
belief that anyone would put such engineering effort into a
counter to such a marginal threat when there are plenty of other
things to worry about.

Finally, I have yet to hear any basis for the statement that
Schurzen were intended to protect against 14.5mm apart from a
misreading of a single Spielberger book, which is nicely
contradicted by the same author in a companion volume. Does
anyone have any evidence they can point to of Pz IIIs and IVs
going down like flies to 14.5mm ATR teams, at any time in the
war? I'd be fascinated to hear about them. "

Makes sense to me.

Im sure that plenty of bazooka and PIAT rounds got fired at shurtzen in the brocage etc, now if these weapons could penetrate the plate and the armour behind dont you think the germans might have changed the configuration slightly? or just left them off?
Best Regards Chuck.

[chuckfourth]

Hi Claus
I think this is a copy of the new British test results we are talking about?

http://home19.inet.tele.dk/cbo/div/heat/wo194-755.htm

I notice one odd thing here.
In this Forum you says this
"PIAT could, on a good day, in fact penetrate a 6mm plate, reach across 50cm of space (that's about 20") and still penetrate a 32mm armour plate"
However the test results say that the space was 38cm.
Have you made a mistake here Claus?
Best Regards Chuck.

[DRG]

Chucky...... did you notice anything at all familar about that website's URL ??? Perhaps the "DK" and "CBO" is a hint

Don

[cbo]

Originally Posted by chuckfourth

Hi Claus
I think this is a copy of the new British test results we are talking about?

http://home19.inet.tele.dk/cbo/div/heat/wo194-755.htm

I notice one odd thing here.
In this Forum you says this
"PIAT could, on a good day, in fact penetrate a 6mm plate, reach across 50cm of space (that's about 20") and still penetrate a 32mm armour plate"
However the test results say that the space was 38cm.
Have you made a mistake here Claus?

Of course not

As Don points out, this is actually a compilation made by me with the data from one of the tests. There are two additional tests that I found.

But why dont you try taking a look at the figures in 194/755, for starters:

You argued previously, that Schürzen were about 15" from the hull of the Panzer IV - i.e. 38cm. If you look at PIAT shots 3-5 fired at target 5-6, they actually penetrated the 6mm skirting plate, breached the 38cm of space and just managed to make a hole in the 32mm armour plate. Shot #6 just made a bulge. The report concluded that this was probably a critical target for the PIAT, i.e. the target where some hits would fail and other succed in penetration (IIRC 50/50).

In another test, the 6mm skirt was penetrated, 48cm of space crossed and the 32mm armour just penetrated while the third hit nearly made it through. Again showing that the PIAT could do the job, but with very little damage behind the main armour.

While the sample is small, one could draw several tentative conclusions from these tests. One being that there were considerable variation in the performance of individual PIAT rounds, another that spacing between plates might not have mattered that much, at least not until you reached distances which were impractical on tanks anyway.

As for John Salts comments, I suggest you read through the entire thread and the other threads on that page. Then it will become pretty obvious what the point of Schürzen was. Hint: It wasn't to stop HEAT.

But if you want to believe that they were, I'm not going to try to persuade you otherwise.

Claus B

[chuckfourth]

Hi Claus
In your paraphrased document
http://home19.inet.tele.dk/cbo/div/heat/wo194-755.htm
you say this
"PIAT with improved filling"
So do you have a service entry date for the -new- improved pait round? did it even get used during WWII?
Best Regards Chuck.

[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.

[cbo]

I find it highly amusing that you are willing to believe all sorts of speculative arithmatic and undocumented opinion you find on the internet over actual test results from WWII using the weapons and armour of the day.

And that you conviniently pick whatever results fit your prejudice and ignore the rest

You posts has a hamster in a wheel quality to them: Never going anywhere, but kinda cute to watch in small doeses

With regards to how much WWII HEAT could penetrate measured in terms of cone diameter, it is simply bollocks to state that:

"150% was typical for WW2 HC weapons"

WWII HEAT was a lot of different things and developed a lot during the war. May I remind you that German gun-fired 75mm HEAT went from something like 0.5 cone diameters penetration to about 1.5 cone diameters?

Or that the Panzerfaust penetrated about 1.8 cone diameters, the Panzerschreck about 2.3 cone diameters or the 3kg Hafthohladung about 1.2 cone diameters?

The actual figures might differ depending on which source you use for penetration data, but they are still all over the place.

Real life just isnt as simple as some people seem to think.

Originally Posted by chuckfourth

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.

Your calculations might improve if you tried to understand the terms you are using.

First of all, I'm unaware of the arithmatic which translates 3 1/4 inch to 9.53 centimeters? May I suggest that you meant 3 1/2 inch corresponding with ~89mm?

Secondly, it is the warhead of the PIAT that was about 90mm in diameter. But warhead diameter is not cone diameter.....

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.

It is rather amusing you keep repeating this old wives tale, as I debunked it thorougly on the old SPWWII forum back in 2005.
But OK, lets debunk it again.

Panzerschreck penetrates about 160mm of steel armour - figures differ, but lets run with this one. With a cone diameter of 70mm, that is 2.3 cone diameters.

So according to the impaccable chuckalogic, the "jet" would move about 175mm through any type of material, even air, after which it would fizzle out, expanding sideways rather than forward.

When the British fired captured Panzerschrecks at their skirting armour test target, it managed 6mm of steel plate, 380mm of air and 100mm of armour plate. Hmmm, that is 6.9 cone diameters....

The US Army experimented with plastic armour panels using HCR2, a mix of quartz gravel, asphalt and wood flour boxed in by aluminium plates. They fired Panzerschrecks at these panels mounted on a Sherman, resulting in penetration of 25mm aluminium, 250mm of HRC, another 25mm of aluminium and still penetrated the 38mm side hull of the Sherman. That is 4.8 cone diameters.

As for the improved filling in the PIAT used for the tests in 194/755, it was 50/50 RDX and TNT. I'm not aware that either type was in short supply during the war and in any case, it only improved the performance of the PIAT by about 12%. Other tests were performed with the standard explosive and performance was, if anything, better. That probably had more to do with individual variations in the rounds than the different fillings, though.

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).

If you actually read the data, it might improve you interpretations. Of the 6 rounds fired, two were detonated while static in front of the target. Four where fired from the launcher.

The reason why they tried firing the rounds instead of simply detonating them, was because experienced had shown that HEAT rounds generally performed better when fired from the launcher.

So the real deal here is that 3 out of 4 rounds penetrated the target when fired from the launcher.

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.

Gee - that is exactly what the British concluded on the test described in 194/755. As I said previously.

However, in another test, one round actually breached the 50cm gap and still penetrated the 32mm of armour on the other side while two other rounds failed to breach a gap of only 38cm. Which again shows that the difference in performance of individual rounds was considerable. Still, it would be a reasonable bet to conclude that the 38cm gap was about critical for the PIAT round.

The tests also show that 51cm (20 inches) air gap defeats PIAT.

No they dont. 194/755 shows that 6mm of skirting plate + 51cm of air gap + 50mm of armour defeats PIAT.

Now, I'm sure you will continue this thread or revive the issue endlessly, but I'm leaving the field now.

Don and Andy has the data, know what to do with it and how to use it to improve the game and that is what's important.

I dont think our continued headbutting is going to change anything

cbo