DTD Testing of Panzer III Armour Plate

[MarkN]

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.

Indeed.

Getting back to the 2-pdr story, during COMPASS, 2-pdr AP and APHE had proven effective against Italian armour. Operational experience being confirmed by 2RTR testing post Beda Fomm. So, until March 1941, nothing for anybody to get agitated about anywhere.

During April 1941, 2ArmdDiv's experiences were short-lived and hardly indicative given the lack of engagements. 5RTR had just one encounter which resulted in a significant overclaim. Little info comes from the ATk sub-units attached. Nothing of note from 2-pdr units and sub-units in 9AusDiv or 3IndBde to offer meanigful insight. The battles around Tobruk provided some excellent evidence, but the exact details are obscured.

During May 1941, Op BREVITY resulted in major overclaims, as it did again in June 1941 during Op Battleaxe. However, it was during these events that some started to question the (eyewitness) claims as the Germans always kept coming back with more pantsers than they were supposed to have. Moreover, some (eyewitnesses) were beginning to seriously question the effectiveness of 2-pdr AP and APHE. This timeframe dovetails neatly with a greater majority of pantsers being uparmoured. Remember, Pz.Regt.5 had some uparmoured mediums but not all; Pz.Regt.8 supposedly were all uparmoured - at least according to Jentz who studied it with an obsession.

[Urmel]

Indeed. And suddently after CRUSADER all the lessons-learned reports go 'our tanks are outgunned'.

[ClintHardware]

The 2-Pdr was outgunned in North Africa against the Panzer III and IVs from the first combats (31st March 1941) in terms of kinetic energy and therefore reach and damage at the target. No argument there.

Indirect arguments that it produced no battlefield damage of significance which you both seem to be re-stating obliquely here are not correct or reliable. Yes the chances of producing significant damage diminished as German armour increased.

I did not seek to bring this into this topic. I responded to Mark's comments. The data I have presented in the past five years has been modified by your inputs but has not been overturned by contemporary data or information or any of your responses on any of the topics on this forum.

Yes do carry on with the point of this topic.

[MarkN]

The 2-Pdr was outgunned in North Africa against the Panzer III and IVs from the first combats (31st March 1941) in terms of kinetic energy and therefore reach and damage at the target. No argument there.

The issue at hand is the British delusion in some quarters as to the effectiveness of the 2-pdr against German armor. A delusion brought on, in part, by the abysmal conclusions and advice generated after testing in the UK. The 7ArmdDiv summary of April 1941 being a perfect example of that delusion and the abysmal advice being disseminated. The consequence of all that was (a) being outgunned and (b) denial there was a issue then (c) inaction that prolonged the problem.

[Don Juan]

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.

Well, according to AT 37 there were five rounds fired during this test. The target consisted of the three Pz.III front hull plates still welded together - the glacis plate, the front nose plate, and the lower nose plate. The rounds were directed at the front nose plate at 20 deg.

Round 1 (AP) only hit the edge of the front nose plate, causing negligible damage by chipping. In essence, this round missed. (1502 fps)

Round 2 (AP) shattered on impact on the front nose plate, braking the plate in two longitudinally and causing three other severe cracks. (1497 fps)

At this point, the lower half of the broken plate was separated and used as the target. The attack was switched to APC as it was felt that further AP attack would only further shatter the plates.

Round 3 (APC) This holed the plate, with part of the shot lodging in the plate and generating a deep impression. It was assumed by the testers that the rest of the shot passed though the plate. (1502 fps)

Round 4 (APC) This struck only 3" from Round 3, and holed the plate cleanly, and caused the cracks already established to yield, breaking up the plate. (1496 fps)

With the shattering of the lower half of the original plate, the top half was then employed as the target.

Round 5 (APC) Shot shattered. Plate broke into four pieces. (1634 fps)

I have to say that this looks to me to have been a reasonably successful trial. It shows that either 2 pounder AP or APC could shatter the plate, and that 2 pounder APC could penetrate the plate. I suspect if more AP rounds had been fired they would also have penetrated the plate. It should be borne in mind that the APC rounds used in this test would not have been dedicated APC projectiles (as at this time no such design existed), but would most likely have been the standard AP round with an improvised cap.

One interesting but overlooked aspect is that I have seen British assessments that indicate the 30mm frontal armour of the earlier Panzer III's was NOT face hardened, so as well as the later increase in armour thickness, it may have been the case that at some point the Germans changed the armour specification for the Ausf. F and G. Maybe during the changeover between the F and G?

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.

Well, the plate employed in this trial was 24" wide, and apart from Round 1, they hit towards the centre of the plate, so I' would think it likely that these would have been outside the heat affected zones from the gas cutting. With regard to the shaping and the sizing of the plate, I would presume that the carburising was undertaken on standard large plates, which were then cut down to produce the much smaller plates that would be used to build up the tank hulls. Due to the thickness of these plates (30mm+) I assume that these would have been gas cut, with the dressing of the edges of the plate for welding being undertaken by grinding. If I'm correct, then the plates would have been subjected to two secondary heating operations and one cold working operation prior to the British ever getting their hands on them.

[ClintHardware]

I fully accept the limitations of 2-Pdr AP-Shot and the lack of alternatives other than a residual amount of 2-Pdr APHE apparently still available up to July 1941 with at least one unit according to war diaries I have examined.

An extreme test of 2-Pdr AP-Shot in terms of its place in changing history would be: Replace each 2-Pdr gun with a Boys Anti-Tank Rifle and re-run the combats from the 31st March 1941 into June 1942 or until Rommel takes the Delta. During this test keep to the same numbers of 25-Pdrs, 18-Pdrs, 60-Pdrs, 4.5-inch Howitzers, 37mm Bofors and 40mm Bofors and RAF RAAF and SAAF numbers then available but field them as you require to attempt to stop Panzer Regiments 5 and later 8 from outflanking and forcing the surrender of British and Commonwealth units.

How many days would Rommel need to reach the Delta without the presence of 2-Pdr AP-Shot? It would still take 10 to reach the edge of Tobruk unless he chose to take longer to reduce wear and tear but how many beyond Tobruk?

For those concerned with classifying as Delusional the remarkable eye witnesses of events they were not present to witness for themselves - the available test to us today is the SCWVNT test (Subsequent Contact With Visible Numbers Test). In respect of Battleaxe the actions on the 18th and 19th June are of use. For some, I am an utter SCWVNT, but accept already that one of the limitations of the test is fuel supply and another must be wear and tear.

[MarkN]

For those concerned with classifying as Delusional ...

In respect of the performance of of 2-pdr AP and APHE in 1941, the delusion was held by those writing up fictional weapon performance reports. In fact, delusional is not the right word, it should be deceitful.

4. Penetration – 2 Pdr A/Tk & Tk guns.
All German tank front armour, ... is penetrated by the 2 pdr gun at ranges varying from 1000 yds to 200 yds, according to armour thickness.

Were the tests conducted against German pantser armour or British manufactured stand-ins?

To be more accurate and truthful, the report should have been worded something like this...

We have no idea how the 2-pdr performs against German pantser armor as we don't have any genuine German pantser armor to test it against. However, having tested the gun against British manufactured plate metal the following data explains how successful you will be if you fire against yourselves.
PS. We've invented 3 German tanks just to show how smart we are.

Nobody in Cairo managed to pick up the obvious flaws in the report. Nobody at 7 ArmdDiv did either. Or if they did, they did not have the gumption to question it!

[ClintHardware]

By 17th April they were still guessing with very little evidence to do better. In terms of deceit it would be counter-productive very rapidly and would start to see crews baling out before being hit at increasing rates. What was the rate of such bale outs? These would definitely indicate hopelessness amongst the crews.

Stuart Hamilton's troop in 8th RTR using Valentines worked out two tactics they put into use several times: 1) reverse into a firing position and use the rear sloped armour and engine to hopefully absorb or deflect the punishment coming at them, plus it gave a faster means of withdrawal, and 2) Hamilton could hold three 2 Pdr rounds at the same time and he and his gunner would load and fire without orders to rapidly pepper a selected panzer to knock it out or cause its kommandeur to changes his intentions. The basis of this being that three rapid impacts would scare the panzer crew. These methods worked at least once but required a lot of hope.

[critical mass]

Round 2 (AP) shattered on impact on the front nose plate, braking the plate in two longitudinally and causing three other severe cracks. (1497 fps)

At this point, the lower half of the broken plate was separated and used as the target. The attack was switched to APC as it was felt that further AP attack would only further shatter the plates.

Yes, but no part of the projectile did penetrate and there was no plugging or hole formation, just the cracks noticed. The penetration code was "C". None of the uncapped AP hits managed to penetrated the 31.2mm plate at 20° and ~1500fps. That´s a good performance considering that uncapped 2pdr AP was expected (80% probability to succeed) to penetrate 27.7 and 32.6mm british FH armor at 1250yd and 1000yd, respectively, when tilted 30° (not 20°).

I have to say that this looks to me to have been a reasonably successful trial. It shows that either 2 pounder AP or APC could shatter the plate, and that 2 pounder APC could penetrate the plate.

One might agree with this view, or stress it as barely when compared with what the british credited the gun for. One partial penetration at 20° and a successful one but too close to the first hit. Further, a failure with projectile shatter at 30° at 1634fps, or about 1000yd. 2pdr A.P.C.B.C. were expected to penetrate FH plate at 30° and 1000yd which are 2/3 thicker than this plate. The only thing which really stands out in advantage to the 2pdr is consecutive plate break up.

Well, the plate employed in this trial was 24" wide, and apart from Round 1, they hit towards the centre of the plate, so I' would think it likely that these would have been outside the heat affected zones from the gas cutting. With regard to the shaping and the sizing of the plate, I would presume that the carburising was undertaken on standard large plates, which were then cut down to produce the much smaller plates that would be used to build up the tank hulls. Due to the thickness of these plates (30mm+) I assume that these would have been gas cut, with the dressing of the edges of the plate for welding being undertaken by grinding. If I'm correct, then the plates would have been subjected to two secondary heating operations and one cold working operation prior to the British ever getting their hands on them.

Carburizing was done according to the specifications. The carburizing itselfe was followed by a temper with one or more rapid cooling and heating phases, usually timed to the next second. After the desired crystal structure had been fixed with the heat treatments and to guarantee the plate doesn´t suffer too much reheating afterwards, the plate was fitted with lead seals to check for and exclude subsequent thermal exposures. That´s why rapid cooling after welding and installation was important, too.
There is a difference here between RHA and FH plate. The RHA plate has a lower BHN hardness, so subsequent temper embrittling happens, in case the plate is heated up to just below the critical point and then allowed to slowly cool through the embrittling range. For low BHN, the required temperatures for german alloy compositions were fairly high. FH plate, on the other hand, had differentially high BHN sections, some of which are more easily affected due to the lower tempering heat correlating with higher BHN. These sections, if embrittled can act as triaxial stress risers, through which cracks can form rapidly.

[Don Juan]

Yes, but no part of the projectile did penetrate and there was no plugging or hole formation, just the cracks noticed. The penetration code was "C". None of the uncapped AP hits managed to penetrated the 31.2mm plate at 20° and ~1500fps. That´s a good performance considering that uncapped 2pdr AP was expected (80% probability to succeed) to penetrate 27.7 and 32.6mm british FH armor at 1250yd and 1000yd, respectively, when tilted 30° (not 20°).

As only one AP round hit the plate properly, we're judging by a single example, and so you could cite a 100% failure. That said, if you are cracking a plate right through, this means that you are in the ball park of a penetration. i.e. an internal crack at 1000 yards would normally mean holing the plate at approx. 950 yards, and obtaining a clean penetration at 900 yards. This is readily observable for RHA plates, where you can keep firing at them from varying distances. The problem with testing FHA plates, as this trial attests, is that their tendency to shatter makes it difficult to assess the full performance of the plate.

One might agree with this view, or stress it as barely when compared with what the british credited the gun for. One partial penetration at 20° and a successful one but too close to the first hit. Further, a failure with projectile shatter at 30° at 1634fps, or about 1000yd. 2pdr A.P.C.B.C. were expected to penetrate FH plate at 30° and 1000yd which are 2/3 thicker than this plate. The only thing which really stands out in advantage to the 2pdr is consecutive plate break up.

Well, I don't know from the penetration table that you posted what initial MV was assumed - by Oct 42 the initial MV of the 2 pounder had been increased from 2600-2650 fps to 2800-2850 fps. Also, the ballistic cap on the APCBC would have allowed it to maintain its velocity for longer than the APC. It is certainly interesting that the third APC round failed to penetrate, but as the plate was being broken into smaller and smaller pieces, its support was having to be improvised, so I don't know if the lack of rigidity of the plate was having an influence.

The actual production 2 pounder APCBC round was tested against a captured Panzer III Ausf J in February 1943, this confirming that the 52mm FHA nose plate was vulnerable at 500 yards at normal (i.e. at 20 deg.), while the 31mm FHA side superstructure plate was vulnerable at 2000 yards at 30 deg. and 1000 yards at 40 deg. This was with the APCBC with a standard charge (i.e. 2600-2650 fps). These trials are described in Armour Trial Report AT 113 of 10th May 1943.

Carburizing was done according to the specifications. The carburizing itselfe was followed by a temper with one or more rapid cooling and heating phases, usually timed to the next second. After the desired crystal structure had been fixed with the heat treatments and to guarantee the plate doesn´t suffer too much reheating afterwards, the plate was fitted with lead seals to check for and exclude subsequent thermal exposures. That´s why rapid cooling after welding and installation was important, too.

So are you suggesting here that the plates were cut to size for fitting on the tank prior to carburization?

[MarkN]

By 17th April they were still guessing with very little evidence to do better.

So they made it up and mislead the front-line troops to the extent of inventing 3 types of pantser that didn't exist.

[ClintHardware]

Not quite. By the 17th April 1941 the contemporary 7th Armoured Division evidence shows that they didn't even know enough about German types of AFVs to be able to lie about them. A serious military intelligence failure. How did information not seep out before 1/9/1939 sufficiently to equip them with accurate AFV identifications even if not armour and armament data? Perhaps the intelligence was known but not disseminated.

Your anti-British stance is always useful.

[MarkN]

Not quite. By the 17th April 1941 the contemporary 7th Armoured Division evidence shows that they didn't even know enough about German types of AFVs to be able to lie about them. A serious military intelligence failure. How did information not seep out before 1/9/1939 sufficiently to equip them with accurate AFV identifications even if not armour and armament data? Perhaps the intelligence was known but not disseminated.

With this response I see that you still haven't managed to understand the 17April 1941 intsumm and its implications...

The testing was done in the UK. Thus, in para 4. Penetration – 2 Pdr A/Tk & Tk guns., the core advice, that 2-pdr penetrates X, Y and Z, is advice/information sent out from the UK to GHQ ME. Whether it was the UK or GHQ ME who chose the deceitful words "German tank front armour...is penetrated by the 2 pdr gun at ranges varying from 1000 yds to 200 yds" - who knows.

On the otherhand, it would certainly have been GHQ ME who added paragraph 5 explaining which German pantser types had been identified in theatre.

It is NOT HQ 7ArmdDiv inventing tanks, nor even GHQ ME. It is somebody back in the UK. GHQ ME has correctly identified the German pantsers in theatre.

[valentine III]

Church has it's doctors. I am not one of them. On the 17 april 1941 7th Armoured div. had not had any direct contact with german panzers. Probably the first german tanks in NA destroyed and "captured" by british hands were the ones from the failed german attack on Tobruk on the 13-14 April. They had belonged to 5th Panzer regiment and were not up-armoured, so vulnerable to 2pdr ammo.

[Urmel]

Solid point. And I seriously doubt they captured another one to analyse until at least Sommernachtstraum in mid-September, after May 1941.