Yu guns vs armor tests of 1960s...

[Mobius]

For 5 cm cored projectiles, see pages 17 and 18 of this PDF. PzGr. 40 was arrowhead APCR, Pzgr. 40/1 was fully-body APCR, although much different than US designs.

 

Thanks, for that. I saw the 5cm pzgr 42 mentioned in the BIOS report but never saw it in any US document on captured German ammo. Also, new to me that they put caps on the 37mm, 47mm AP. Now, trying to find the ballistic coefficient of these gives me a hobby.

 

The core of the 5cm APCR 40 looks the same as the 40/1. Seems to enclose the sides better so less drag. And the added magnesium alloy windscreen to flash when a hit is scored to better tell if the round hits.

Edited April 9, 2013 by Mobius

[bojan]

I didn't know the 8.8cm PzGr. was APCBC either.

It was, with pretty large HE cavity.

[Marek Tucan]

Knew about HE cavity, but somehow I thought it was APC based on descriptions.

[Mobius]

It's hard to tell if that 50mm APC pzgr 39 with the tapered cap is ballistically better or worse than the AP with the ogive shape. The US 37mm with the full diameter cap is definitely worse than the ogive 37mm.

[Peasant]

Dont hold it against me if I revive this old thread, as I have some interesting info to add:

As you can see, the frontal armour of a T-54/55 is much stronger than the commonly quoted figure of "200mm". This explains why the german Kwk43 and the US 90mm HVAP shells had trouble defeating this target.

Edited November 15, 2022 by Peasant

[bojan]

Feel free to add, it is a purpose of forum after all, adding each other's knowledge together

[FinStabilized]

Is there any offical documentation for these tests? I appreciate the posting but these have been on the internet now for well over a decade but I have not every been able to find any proof of their existence. I have never seen another historian quote from them, or seen any pictures of the documents. 

Edited November 28, 2022 by FinStabilized

[bojan]

As described previously those are taken from a notebook of a person involved in those. There must be full official copy somewhere in some archives*. For that to surface someone would have to do some real deep digging, which costs time and money. And people** willing to sacrifice both for what is really a fringe interest.

*Provided it was not in some "lost part" (1990s wars  made a mark even on the archives, as some things were lost or stayed in other republics, lost as "non-perspective archives etc"...), but there should be multiple copies so quite likely it has survived.

**There is single historian that has bothered to write about armor and armor development in Serbia and used archives. And while he knows a thing or two about tanks (he was a tanker in the army during conscription) , his books are general history, and don't go too deep in technical things.

Edited November 28, 2022 by bojan

[FinStabilized]

Who was the person who was involved in the tests? How was the notebook obtained? This leaves many questions about how much the information in these tests can be relied on. Is the person who owned the notebook still around to elaborate etc? 

Are there any other sources that corroborate that these tests even took place? 

I am not trying to be unreasonably skeptical here and I am assuming everyone is acting in good faith, but I do not think we should take these at face value unless we have the original documents. The devil is in the details of things like this. There could be tons of information in the original documents that completely changes our understanding of them etc. Even small omissions or mis-rememberings could have rather large ramifications. 

Do we have pictures of the notebook? 

Note: I just now found the part mentioning the original source. So this is based on information from unnamed persons and documents which apparently are not officially declassifed. That is not much to go on. 

Edited November 28, 2022 by FinStabilized

[bojan]

6 hours ago, FinStabilized said:

...That is not much to go on. 

Agree. That is what I had, if you don't believe it - it is your choice.

PS. What country are you from? Because you might not understand how archives bureaucracy works in Serbia and in what kind of mess is in the archives. Or even understand how many people might be  really interested in that topic (very, very few).

 

Edited November 28, 2022 by bojan

[FinStabilized]

On 11/28/2022 at 6:33 AM, bojan said:

Agree. That is what I had, if you don't believe it - it is your choice.

PS. What country are you from? Because you might not understand how archives bureaucracy works in Serbia and in what kind of mess is in the archives. Or even understand how many people might be  really interested in that topic (very, very few).

 

Oh I am not expecting anything out of anyone. I know little of Serbia and I do not have really any expectations regarding anyones desire or ability to find these documents etc. 

My only concern was trying to find out why everyone on the internet is taking them at face value when there is very little to go on. I see them quoted every so often as if they are established historical record. 

[alejandro_]

I am not sure of where to put this link, but this thread is suitable because it deals with 100 mm D-10 and 88 mm KwK 43

http://www.tankarchives.ca/2022/11/100-mm-d-10-vs-88-mm-kwk-43.html

[bojan]

6 hours ago, FinStabilized said:

...My only concern was trying to find out why everyone on the internet is taking them at face value when there is very little to go on. I see them quoted every so often as if they are established historical record. 

That is their problem. But those do compare well with other tidbits of info we got since then from Soviet and other archives. So there is that.

[DB]

Not sure why this is any different to using any other source of data with caveats regarding its provenance. What people who don't understand what the caveats mean do with the data is their problem, shirley? It's easy enough to point out that the notebook is not likely to be part of the official record (mind you, if mine was full of performance data, it would be.)

[bojan]

Reason why I never wanted to publish more is potential (unlikely, but still potential) problem for a person who has generously provided those. I am pretty sure that somewhere in archives is much more detailed report than "reader's digest" in the notebook. But I could not find it with time I had at one moment, so someone else would have to try to do that.

I have asked @FinStabilized does he have a knowledge of Serbia and horrible state of archives there for a reason. Let's illustrate problem:

This a picture of the Yugoslav testing of the RPG-16 in the 1976.

I actually went to archives in the hopes of finding anything about that*. I had year when tests were done, as told by a guy handling RPG-16 on the pic. I had at least one person's name. Just to make sure, I have checked whole decade.

Nothing. Either never declassified, or lost in the chaos of '90s or thrown as a junk in the "reforms" of the 2000s, or somewhere else, or... you get it.

*For a book on Yugoslav infantry armament development 1945-1992. Which is also encountering increasing number of problems of the same nature, horrid archives.

 

[FinStabilized]

On 11/30/2022 at 7:06 AM, bojan said:

That is their problem. But those do compare well with other tidbits of info we got since then from Soviet and other archives. So there is that.

Which Soviet data? Because I actually find it very hard to make sense of many of the results in these tests. 

 

One that is mentioned is the m47. Things penetrate according to the tests that simply don't make sense. Low hardness and cast armor doesn't explain it. The protection values for the glacis should be far far in excess of any margin for error on something like the pak43 being able to penetrate it. The difference in limit velocity between 200-350bhn is very small, and the largest differences are only seen when the armor is significantly overmatched. 

 

 

[Peasant]

3 hours ago, FinStabilized said:

Which Soviet data? Because I actually find it very hard to make sense of many of the results in these tests. 

 

One that is mentioned is the m47. Things penetrate according to the tests that simply don't make sense. Low hardness and cast armor doesn't explain it. The protection values for the glacis should be far far in excess of any margin for error on something like the pak43 being able to penetrate it. The difference in limit velocity between 200-350bhn is very small, and the largest differences are only seen when the armor is significantly overmatched. 

The 88mm Kwk 43 was able to defeat the ufp of the late JS-2 model with the same 100mm cast at 60° at close range. Granted, that was high hardness cast armour, which would be a bit worse under these conditions, but it shows that it would be close call for M47s ufp.

Its quite possible that this particular M47 tank had somewhat below average armour quality which mightve been enough to tip the balance just enough to let the Kwk 43 penetrate.

Edited December 3, 2022 by Peasant

[bojan]

M47 used for tests was one damaged in fire, but as only only engine compartment and part of the crew compartment were damaged by fire it was considered fit to be used for tests since front part did not burn out.

Maybe there was some degradation of glacis armor, maybe there was not.

Edited December 3, 2022 by bojan

[FinStabilized]

15 hours ago, Peasant said:

The 88mm Kwk 43 was able to defeat the ufp of the late JS-2 model with the same 100mm cast at 60° at close range. Granted, that was high hardness cast armour, which would be a bit worse under these conditions, but it shows that it would be close call for M47s ufp.

Its quite possible that this particular M47 tank had somewhat below average armour quality which mightve been enough to tip the balance just enough to let the Kwk 43 penetrate.

This? Because it hit at a weld joint and that explains the results. As you can see none of the other hits penetrated. 

[Peasant]

On 12/4/2022 at 1:34 AM, FinStabilized said:

This? Because it hit at a weld joint and that explains the results. As you can see none of the other hits penetrated. 

As you can see from the presence of a weld joint, this is a variant of JS-2 nose made from RHA plates 90mm thick. 

[FinStabilized]

1 hour ago, Peasant said:

As you can see from the presence of a weld joint, this is a variant of JS-2 nose made from RHA plates 90mm thick. 

Alright, so if it cannot penetrate 90mm at 60 degrees, how is it going to go through 100mm or more? 

What seems more likely to me is that:

-the details of the tests in the notebook are not entirely accurate. Unfortunatley we dont have the actual documentation to tell for certain. 

-the details are lacking and there are special reasons for the success. This seems highly likely. How many M-47s did the Yugoslavian goverment want to use to test these guns? Was the tank already heavily shot up? Did more than one tank get used? Were all of the hits fair hits? For example a low velocity penetration near another penetration or perhaps near the mg port could explain a scewed 50% probability. The hit on the above IS2 demonstrates precisely why we should take the results here with a large grain of salt. 4 hits bounced off and then one makes it through due to where it hit, etc. 

I find anything along these lines more likely than the 88mm KwK43 penetrating enormously more armor than other data and ballistic science would suggest is possible. 

Edited December 5, 2022 by FinStabilized

[bojan]

Track down of M47s in Yugoslavia indicate there were two M47s in "fully non-operational" (not fit even for repairs) in early '60s, one partially burned and other with damaged and deformed turret ring in army inventory. By mid-60s army inventory was  IIRC reduced by two tanks, indicating that most probably those two tanks were written off after being used for tests.

Problem is that you are taking those tests ultimately theoretically, while those were done with quite a practical purpose - in order to write new manuals for various AT weapons, since there was a long standing complaint that existing ones are obsolete.

Like in 1965. manual for M47 in which following sentence "Use only HEAT ammo for a frontal engagement of newer models of foreign tanks" was added. Or removal of obsolete weapons like PaK40 from service by mid-60s. Or increasing amount of HEAT ammo for M47s (including "panic buying" in Germany and elsewhere), introduction of HEAT ammo for every caliber (76mm, 85mm, 90mm, 100mm). Or removal of muzzle breaks from M36s in order to enable use of HEAT ammo (and removal of HVAP from ammo load as HVAP was forbidden to be fired w/o muzzle break...)...

There are also two ways to approach "guns vs armor" tests, one is "gun biased" other is "armor biased". In first one you have more relaxed standard to what is a penetration, since you are testing performances of armor in "real" situations where all sorts of "unfair" hits will happen*. Second one is where you are testing what is an absolutely guaranteed performances of  a certain gun. Those two approaches will give different results, since they are testing two different things. And yet neither is "incorrect".

*You are complaining about that above, but if tank is hit in combat in that spot it will penetrate. Hence glacis is vulnerable to that gun, even if you consider that "not fair". Or you could explain to a dead crew that no, their tank was not really vulnerable to that, it is unfair hit and should have been discarded.

[FinStabilized]

30 minutes ago, bojan said:

Track down of M47s in Yugoslavia indicate there were two M47s in "fully non-operational" (not fit even for repairs) in early '60s, one partially burned and other with damaged and deformed turret ring in army inventory. By mid-60s army inventory was  IIRC reduced by two tanks, indicating that most probably those two tanks were written off after being used for tests.

Very interesting, thanks for digging that up. 

30 minutes ago, bojan said:

Problem is that you are taking those tests ultimately theoretically, while those were done with quite a practical purpose - in order to write new manuals for various AT weapons, since there was a long standing complaint that existing ones are obsolete.

Like in 1965. manual for M47 in which following sentence "Use only HEAT ammo for a frontal engagement of newer models of foreign tanks" was added. Or removal of obsolete weapons like PaK40 from service by mid-60s. Or increasing amount of HEAT ammo for M47s (including "panic buying" in Germany and elsewhere), introduction of HEAT ammo for every caliber (76mm, 85mm, 90mm, 100mm). Or removal of muzzle breaks from M36s in order to enable use of HEAT ammo (and removal of HVAP from ammo load as HVAP was forbidden to be fired w/o muzzle break...)...

There are also two ways to approach "guns vs armor" tests, one is "gun biased" other is "armor biased". In first one you have more relaxed standard to what is a penetration, since you are testing performances of armor in "real" situations where all sorts of "unfair" hits will happen*. Second one is where you are testing what is an absolutely guaranteed performances of  a certain gun. Those two approaches will give different results, since they are testing two different things. And yet neither is "incorrect".

*You are complaining about that above, but if tank is hit in combat in that spot it will penetrate. Hence glacis is vulnerable to that gun, even if you consider that "not fair". Or you could explain to a dead crew that no, their tank was not really vulnerable to that, it is unfair hit and should have been discarded.

On the contrary, I am more concerned with how theoretically other people are taking them. As you say, multiple hits is a real combat situation (as well as opposite), but the problem I see is that it seems as everyone in this thread as well as the other communities I have seen quote these tests, are taking them as face value indications of in-vaccuum performance and not as you indicated here. For example, the PDF that can be found of these calls them the "rosetta stone" of gun performance because it ostensably solves inconsistencies between various nations gun testing methods etc. Except it could not do that, especially given the lack of verification and detail we have. Gun test data and field testing we have is the better baseline. While combat is a different thing entirely, the baseline still serves to inform. For example, if the IS2 test used the single penetrating hit as the lower limit velocity and published that result, it would give an impression of the combat performance of the tank that is not accurate. The fact that we know the tank was penetrated at the weld seam is indicatcative of both the point your making and the point I am making. Is2s in combat could be penetrated through said seam, but we would be wrong to reduce the general effectivenss of the glacis plate compared to the predictated performance we might assume from ballistic science and testing because that generlization is still entirely valid based on the other 4 hits on that armor (non of which made it through, exactly like we would expect). 

So I entirely agree that neither is incorrect, but it I think its important to discuss which is which in this regard, especially since we lack important details.

[bojan]

People tend to like absolutes and ignore "grey zones", news at 11.

[Junior FO]

...

Edited September 23, 2024 by Junior FO