DTD Testing of Panzer III Armour Plate

[critical mass]

The thin armor plate tested on this Pz III had some very curious properties in the ability to damage shells, particularely to regularely succeed in shattering 2pdr capped A.P. down to fairly low velocities. This is a quality, which british FH armor plate lacked, which could shatter uncapped A.P. shot but not capped A.P.
Notice that the armor piercing cap was added in the first place to actually prevent shatter, a rapid, brittle failure mode of the projectile associated with a loss of cavity confinement (compromising filler action, if there would be a filler) and a rapid loss of penetration ability, characterising uncapped A.P. striking surface hardened armor.

Usually, You would have to reckon with large scaling effects when a FH plate succeeds in shattering capped A.P., which may manifest itselfe in different forms, such as inferior resistence against shock attack or overmatching shot or ballistic resistence to shattered, uncapped AP. However, the 31.2mm plate didn´t exhibit any inferiority vs 2pdr A.P. special proof shot either (attempts discontinued after two hits at 20° and 1500fps not producing penetrations (-none and C-scoop), though the 2nd hit caused the plate to crack).

Now, one possible conclusion of that observation points towards the consideration that an earlier presence of 2pdr APCBC in the Middle East and North Africa wouldn´t necesarely have made any difference towards Pz III vulnerability. If You hold the Pz III plate as relevant then the capped 2pdr A.P. would be shattered much like A.P. shot was, at least against this sort of FH armor.
The improved performance of 2pdr capped A.P. was relevant for british FH plate, for which penetration data were tabulated and circulated. I believe everybody thought that 2pdr capped A.P. was the solution against FH plate generally -but against PzIII FH plate, these tabulated data would bear no significance because the projectile failure mode against pzIII FH plate unexpectedly changes from intact back to shattered.

That´s something which was hinted at also in german trials 1939-1942. Simply adding an armor piercing cap doesn´t ensure that the projectile stays intact. Also the projectile body itselfe needs to be able to negotiate the increased triaxial stress levels.

[MarkN]

Since every person who contributes to this forum has known for years that 2 pounder AP was useless against German face hardened armour at a distance over 100 yards, and that 2 pounder APCBC arrived too late for use in the Middle East and North Africa, what on earth are you trying to prove with this?

The point that critical mass is highlighting, albeit not actually making, is the significant potential for poor decision-making in the UK based upon deluded thinking flowing from faulty testing. To what extent did these tests influence the decision to delay the introduction of the 6-pdr, to delay the development of more effective 2-pdr ammunition and so on and on? I wonder whether the original poster has considered this and followed it up with his research. Or whether he was just planning to copy/paste the text into his book giving the impression of 'British efficiency'.

[Don Juan]

I have to say I'm not really willing to go down the rabbit hole of armour testing right at this moment, but the full and final report on this series of tests on the Panzer III was AT 40, issued on 26th June 1942 (AT 37 being merely an interim report).

In its conclusions, AT 40 stated this:

It's notable that the British didn't use face hardened ("cemented") armour in any thickness above 14mm (i.e. for light tanks and armoured cars only), so it is a surprise that they did not consider that the German equivalent was better.

[Don Juan]

The point that critical mass is highlighting, albeit not actually making, is the significant potential for poor decision-making in the UK based upon deluded thinking flowing from faulty testing. To what extent did these tests influence the decision to delay the introduction of the 6-pdr, to delay the development of more effective 2-pdr ammunition and so on and on? I wonder whether the original poster has considered this and followed it up with his research. Or whether he was just planning to copy/paste the text into his book giving the impression of 'British efficiency'.

These tests were conducted long after the fateful decisions had been made, and so were more in the nature of "confirming the bad news".

[critical mass]

I have to say I'm not really willing to go down the rabbit hole of armour testing right at this moment, but the full and final report on this series of tests on the Panzer III was AT 40, issued on 26th June 1942 (AT 37 being merely an interim report).

(...)

It's notable that the British didn't use face hardened ("cemented") armour in any thickness above 14mm (i.e. for light tanks and armoured cars only), so it is a surprise that they did not consider that the German equivalent was better.

Don Juan,
can You provide more information about the final report A.T.40? The quoted part shown in Your memo does state 2pdr, but does not specify whether or not it was fitted with armor piercing cap. As mentioned previously, the ability of the PzIII FH plate to shatter 2pdr capped A.P. comes as a surprise to me, and I study armor and projectile dynamics since a good 18 years now. I happen to know that the british even in 1945 were convinced that capped A.P. would have negated any advantage face hardened armor had over uncapped A.P. and the PzIII FH plate trials with capped A.P. against surface hardened (flame or induction hardened) plate demonstrably falsify this presumption, at least in the context of the 2pdr Hadfield special trial shot used there (best quality shell).
I understand that the british made limited quantities of face hardened (carburized) A.F.V. armor plate in 50mm, 70mm, 4.5" thickness, too, of which I have the physical test reports here. But they didn´t procure a lot of them in the period 1941-1943 because at that time, when the demand was greatest for them, it was sufficiently difficult to obtain the necessary output of homogenious plate.

[MarkN]

The point that critical mass is highlighting, albeit not actually making, is the significant potential for poor decision-making in the UK based upon deluded thinking flowing from faulty testing. To what extent did these tests influence the decision to delay the introduction of the 6-pdr, to delay the development of more effective 2-pdr ammunition and so on and on? I wonder whether the original poster has considered this and followed it up with his research. Or whether he was just planning to copy/paste the text into his book giving the impression of 'British efficiency'.

These tests were conducted long after the fateful decisions had been made, and so were more in the nature of "confirming the bad news".

You are quite right, those particular test were indeed performed after the decisions were made. However, I was considering the 'testing regime' as a whole. In otherwords, to what extent were the decisions to delay entry of the 6-pdr and improved 2-pdr ammunition influenced by earlier flawed testing - or to be more precise flawed analysis and understanding of the results of that testing?

Also, I'm not sure they were "confirming the bad news"; I'd suggest they were doing rather the opposite and sustaining the delusion in certain quarters that it was not all bad news. They were retesting, in mid-1942, the performance of the standard pre-war AP ammunition. Ammunition whose performance was well past its sell-by date on the battlefield as they had been repeatedly informed but refused to accept - because of the flawed testing they were carrying out.

I also suspect this could be part of the reason why the massively inflated claims in early 1941 were readily accepted. AP, being inert, is unlikely to provide confirmation of a 'kill' unless there is a significant secondary event (internal secondary explosion etc etc). If a gunner/donkey walloper is being told by grown ups that all you have to do is 'hit' the enemy and the AP will do the rest unobserved, you can immediately sense a source of overclaiming.

[ClintHardware]

The point that critical mass is highlighting, albeit not actually making, is the significant potential for poor decision-making in the UK based upon deluded thinking flowing from faulty testing. To what extent did these tests influence the decision to delay the introduction of the 6-pdr, to delay the development of more effective 2-pdr ammunition and so on and on? I wonder whether the original poster has considered this and followed it up with his research. Or whether he was just planning to copy/paste the text into his book giving the impression of 'British efficiency'.

These tests were conducted long after the fateful decisions had been made, and so were more in the nature of "confirming the bad news".

You are quite right, those particular test were indeed performed after the decisions were made. However, I was considering the 'testing regime' as a whole. In otherwords, to what extent were the decisions to delay entry of the 6-pdr and improved 2-pdr ammunition influenced by earlier flawed testing - or to be more precise flawed analysis and understanding of the results of that testing?

Also, I'm not sure they were "confirming the bad news"; I'd suggest they were doing rather the opposite and sustaining the delusion in certain quarters that it was not all bad news. They were retesting, in mid-1942, the performance of the standard pre-war AP ammunition. Ammunition whose performance was well past its sell-by date on the battlefield as they had been repeatedly informed but refused to accept - because of the flawed testing they were carrying out.

I also suspect this could be part of the reason why the massively inflated claims in early 1941 were readily accepted. AP, being inert, is unlikely to provide confirmation of a 'kill' unless there is a significant secondary event (internal secondary explosion etc etc). If a gunner/donkey walloper is being told by grown ups that all you have to do is 'hit' the enemy and the AP will do the rest unobserved, you can immediately sense a source of overclaiming.

So you are still not happy with missing columns of numbers even if half of those not subsequently seen in action in early and mid 1941 appear weeks and months later to be lost in Crusader? I am very surprised.

6-Pdr and 2-Pdr comments - yes mostly. Recovery not good enough either.

[Don Juan]

There are certain caveates with thesse DTD trials.

A) The plates tested were face hardened
Rigid FH plates cannot fail by ductile hole formation. They will always fail by plugging / discing, which may be viewed as one of the more brittle types of failure mode. FH plate relies not on it´s own strength but on the ability to shatter the projectile, which the Pz-III plate did just fine, even at the low velocities tested here (1497-1600´s fps). This tends to indicate a good ability of the FH Pz-III plate to damage AP and even capped AP projectiles.

They can fail by cracking too, which is what appears to have happened in this test. As the purpose of the cap on an APC round is to transfer the energy of impact from the tip to the sides of the round, thus preventing shatter, the greater surface stress on FH plate makes cracking more likely than with RHA.

B) the plates were removed from a PzIII hull with help of a cutting torch.
This is a significant information because use of a cutting torch means that the plate is subject to a secondary heat treatment, which includes heating within the heat affected zone and subsequent air-cool.
Surface hardened plates do not behave nicely under reheat-treatment and the aircool is almost set to embrittle the plate by definition. That´s why the use of cutting torches were prohibited for intact armor plate, or the plate had to be discarded.

But surely the gas cutting was no more a secondary heat treatment than the welding of the plates in position in the first place? I would anticipate that the temperature induced by the welding operation was, if anything, even higher than the gas cutting.

[MarkN]

So you are still not happy with missing columns of numbers even if half of those not subsequently seen in action in early and mid 1941 appear weeks and months later to be lost in Crusader? I am very surprised.

I have absolutely no idea what "columns of numbers" you are referring to - thus I hold no position, stance or opinion on them. if, as you claim, they are "missing", it seems I am unlikely ever to do so either. Also not sure what you are getting at with "not subsequently seen ... in early and mid 1941 appear weeks and months later to be lost in Crusader?" Has this got something to do with the standard British staff officer abyssmal admin? Can't find something in June but only admit to it being lost several weeks later hoping somebody else will get the blame. It reminds me of how the RAOC (as they were then) managed to explain the loss and write down of 3 decades worth of lost kit when the Atlantic Conveyer went down. And then there's the infamous "Great Bicester Fire"...

[critical mass]

They can fail by cracking too, which is what appears to have happened in this test. As the purpose of the cap on an APC round is to transfer the energy of impact from the tip to the sides of the round, thus preventing shatter, the greater surface stress on FH plate makes cracking more likely than with RHA.

This is correct. However, the plate can fail by cracking but still do it´s job (to keep the projectile out). The 2pdr AP impacts in this trial scooped off (no penetration), but also, at least once, caused a plate crack. But it´s the 2pdr capped A.P. performance which is so much off the chart.

B) the plates were removed from a PzIII hull with help of a cutting torch.
This is a significant information because use of a cutting torch means that the plate is subject to a secondary heat treatment, which includes heating within the heat affected zone and subsequent air-cool.
Surface hardened plates do not behave nicely under reheat-treatment and the aircool is almost set to embrittle the plate by definition. That´s why the use of cutting torches were prohibited for intact armor plate, or the plate had to be discarded.

But surely the gas cutting was no more a secondary heat treatment than the welding of the plates in position in the first place? I would anticipate that the temperature induced by the welding operation was, if anything, even higher than the gas cutting.

The temperature itselfe is one part of the issue with gas cutting. It´s an important component but not the most important one, the plate gets heated locally. If the temperature increases beyond 120°C it starts to temper (softening) the heat affected zone. But more important is how quickly the heated up section has been cooled down to prevent temper brittleness, which among other things, greatly reduced the local toughness and therefore increases the likelyhood of catastrophic plate failure (cracking, and more severe plate shatter).
Temper brittleness wasn´t yet properly understood in this period. If the plate was allowed to air cool after heat treatment (cutting or welding), You will have to reckon with a very high probability of serious embrittlement of the plate as the temperature slowly walks back through the embrittling temperature range. The effect depends on alloy state, impurities, section thickness and original hardness. Lean alloyed FH plates as manufactured in Germany are particularely problematic in this regard (they have smaller thermal ellbow spaces to prevent embrittling) and are referred to as thermo-mechanically treated armor. It was heat treated, hot rolled, heat treated again, then shaped and sized, then welded in place with another crew following the weld guys with high pressure water jet for rapid cooling of the heat affected zone. This process could be dispensed with by RHA of softer grades but FH was very sensitive, because the softening is occurring at fairly low temperatures here.

[ClintHardware]

I have absolutely no idea what "columns of numbers" you are referring to

Yes it is possible to continue to ignore the missing panzers but then the damaging effect of the 2-Pdr in combat remains hidden and a significant part of the history is lost from sight. A translation of the Werkstat Kompanie report from Kew, which you have not previously given, states that the German figures excluded those damaged in battle in respect of the Panzer III and IV. This may be an original incorrect interpretation but how are we to know for sure? If it is correct it indicates another element in how the Germans were not reporting combat damage alongside mechanical wear and tear in the same report. I do not know why Panzer IIs were excluded from the original remark in brackets.

[MarkN]

have absolutely no idea what "columns of numbers" you are referring to

Yes it is possible to continue to ignore the missing panzers but then the damaging effect of the 2-Pdr in combat remains hidden and a significant part of the history is lost from sight. A translation of the Werkstat Kompanie report from Kew, which you have not previously given, states that the German figures excluded those damaged in battle in respect of the Panzer III and IV. This may be an original incorrect interpretation but how are we to know for sure? If it is correct it indicates another element in how the Germans were not reporting combat damage alongside mechanical wear and tear in the same report. I do not know why Panzer IIs were excluded from the original remark in brackets.

Oh, you're back on that subject again. :roll:

The words of the 'werkstatt' report indicate that it refers to pantsers damaged by the desert - NOT enemy action. We've already had this discussion several times and you've spent far too much time disingenuously reinterpreting the words to suit your agenda to me and other posters. I thus see no point in going over it yet again here. Still, it's good to read you've finally found a copy of the GHQ ME 4-page translation yourself and noticed the pencilled notes they made indicating they understood it too as a report about damage from desert bashing not enemy action. I posted an image of that very section several months back.

Still have no idea what "columns of numbers" you are referring to. It can't be a document you've just found as you claim they're missing!

Given the interesting posts by critical mass above, you may wish to open the blinkers a little as regards to the 'true' performance of the 2-pdr and how the information you posted here https://forum.axishistory.com/viewtopic ... 6&t=202119 was more detrimental to understanding than of tactical use.

[ClintHardware]

A long time ago in a place not far far far away..... you happily disparaged the data you apparently considered inconvenient. No worries.

The version of the Werkstatt report is one you have not given here or perhaps have even discovered at Kew. Never mind. Some claims made on this forum have hoped that there was no combat damage because it is not mentioned in that report.

The 2-Pdr was not as ineffective as you hope and eye witness accounts from the battlefield in early to mid 1941 are such that the 2-Pdr did sufficient damage to cause panzers to no longer take part in the immediate battle. Proving that with analysis of captured panzers was limited at the time. Yes by Crusader and later the situation more limited for success with the 2-Pdr.

In respect of the availability of ammunition types and dates - I provided that data recently which updated anything else on this forum. I checked the forum before placing it. If you had that data you did not openly share it.

In addition your Battleaxe German numbers were and are mostly slightly wrong but only slightly, but repeatedly slightly.

[MarkN]

The version of the Werkstatt report is one you have not given here or perhaps have even discovered at Kew. Never mind. Some claims made on this forum have hoped that there was no combat damage because it is not mentioned in that report.

I have no idea what files and documents you have acquired. Similarly, you have no idea what is in my collection.

This is the image (at least a rehack theroeof) I posted several months back...

Does it have the same information as your copy?

Have you acquired the original German language 10-page report which then gives you a better understanding of its purpose and intention. Hint: it was NOT written by the wersktatt company - although they of course supplied all the data contained therein.

The 2-Pdr was not as ineffective as you hope and eye witness accounts from the battlefield in early to mid 1941 are such that the 2-Pdr did sufficient damage to cause panzers to no longer take part in the immediate battle.

A woeful concoction of words to hide the reality you have no credible evidence to support your fanciful claims and unreliable 'witness' accounts. You have no data how many pantsers broke off engagements through enemy action and how many through mechanical failure. The nature of the AP round, being inert, means that a tank or anti-tank crew firing that round have no idea what damage they have or have not inflicted.

In addition your Battleaxe German numbers were and are mostly slightly wrong but only slightly, but repeatedly slightly.

I have no numbers. I post information from primary sources. If you think those numbers are erroneous, feel free to post up more credible primary data.

[Urmel]

I'm really not so sure what this argument is about any longer.

By 15 November, the Germans had received 93x Panzer II, 183x Panzer III, and 40x Panzer IV. According to CAB146 they fielded the following runners on 14 November: 70x Panzer II (-23), 139x Panzer III (-44) and 35x Panzer IV (-5) for total absence of 72 tanks, broken down in 49x mediums and 23x light tanks. Of which some may or may not have been in short- or long-term repair.

Considering they had been through eight months of ops, with three major battles (1st offensive, Tobruk, BATTLEAXE), and considering the tank losses inflicted on the Imperial forces, I know on which side I would have wanted to be a donkey walloper.