Possible Revisions to German Penetration

[rexford]

Comments raised on the CMBB forum resulted in re-examination of penetration data for early war 37mm, 50mm and 75mm German armor piercing ammo, which appear to match up better against expected results against T34 and KV tanks:

37mm L45 AP

48mm at 100m

45mm at 250m

39mm at 500m

34mm at 750m

30mm at 1000m

Data developed by converting 30° figures in Jentz Panzertruppen to 0° using slope multipliers and armor hardness effects. Projectile metal in 37mm AP appears to be very inferior to 75L43 APCBC. Turret front successes against T34 will be severely reduced.

50mm L42 APC

75mm at 0m

71mm at 100m

66mm at 250m

58mm at 500m

45mm at 1000m

Data lowered to be more consistent with American and British estimates. KV-1 75mm armor vulnerability reduced significantly.

50mm L60 APC

99mm at 0m

94mm at 100m

88mm at 250m

77mm at 500m

59mm at 1000m

Data lowered to be more consistent with American and British estimates and German tests against KV-1 75mm/30° during spring 1942 (round succeeded at 100m and failed at 200m).

75mm L24 APCBC

50mm at 100m

49mm at 250m

47mm at 500m

46mm at 750m

44mm at 1000m

Following changes follow from analysis of data in Jentz Dreaded Threat and American/British data on Flak ammo:

88mm L56 Flak (up to spring 1942)

123mm at 100m

121mm at 250m

116mm at 500m

112mm at 750m

108mm at 1000m

Early war large HE burster capacity ammo

88mm L56 Flak (spring 1942 and beyond)

149mm at 100m

145mm at 250m

139mm at 500m

133mm at 750m

127mm at 1000m

Later war large capacity HE burster ammo

My thanks to Amedeo Matteucci and the others who brought many surprising combat results to my attention.

[TSword]

Great !

I knew (quietly) something is wrong with the 37 mm..

The Question is when will we get the fixed ones ??!!

Please take it into Patch 1.01 if possible.

Greets

Daniel

[aka_tom_w]

Hi Rexford

How does that data compare or relate to the penetration calculations in CMBB that are now have the fidelity to determine partial penetrations?

:confused:

Would those figures you gave lead to 100% certainty of complete penetration?? Or would those values represent some occasions when there would only be a partial penetration at those threshold values?

-tom w

[Thin Red Line]

Is it an official announcement ?

[aka_tom_w]

Originally posted by Thin Red Line:

Is it an official announcement ?

I think it is just another "unofficial" thread about penetration values. However that said anyting Rexford posts usually sounds somewhat "official"

(in good humour there Rex )

-tom w

[Amedeo]

So Rexford, what are your 'practical' suggestions to BFC? That is, what variables already built in the game engine should be 'activated' to obtain more realistic results?

If I got it right:

- assume substandard manufacture for 37mm rounds

- assume large HE burster penetration penalities for almost all German AP/APC rounds early in the war

BTW what about the availability of APC rounds for the short 50mm and APCBC rounds for the short 75mm in 1941?

Regards,

Amedeo

[Bastables]

I suggest looking for old posts on the 3,7cm. BTS feels that Jentz figures are off where as Hogg's ones correlate very well to the figures in game.

[rexford]

German armor acceptance curves show that a 55mm plate at vertical was expected to stop 37mm AP hits at 100m without any through-the-plate cracking.

That being the case, do you trust 0m/0° penetration of 68mm or 50mm for 37mm AP?

[Bastables]

Steve on the power of the 3,7cm gun earlier

So yes I do trust it since it correlates with Hogg's figures and the figures presented in your book.

*sigh* here we go again with people not understanding what published figures mean and how CM really works. I don't even want to remember how much time we spent trying to explain this for CMBO, but I guess to some degree it will have to be done again

First, as many people have noted the initial reaction to "how is this possible" is just that... a reaction. There are several factors that were initially not taken into account, such as the close range, the flaws with this particular type of T-34, the increase in a turret hit if hull down, the relative weakness of side armor, and that luck is very important. One thing not mentioned is that the German gunners are Vets. That means a lot.

Another factor not mentioned is that the guns tend not to survive the encounter, even if they do toast a couple of T-34s. When the average German Infantry Division only had a handful of AT guns to draw from, this kind of tradeoff was totally unacceptable and would have disasterous consequences in subsequent battles.

Now back to the technical discussion. This is from Charles:

We don't use tabular data of course because of all their inherent problems, but just as a quick reality-check comparison our PaK 36 has the following AP penetration stats:

100m, 0 degrees: 62mm

100m, 30 degrees: 51mm

Hogg's _German Artillery of World War Two_ gives the following penetration stats:

100m, 0 degrees: 65mm

100m, 30 degrees: 50mm

How much closer should we be?

And as for the shell not losing enough punch over distance, this is nonsense. We have the 2000m penetration figure (at 0 degrees) pegged at a mere 25mm. That's a 60% reduction from 100m to 2000m.

My guess is that some posters are checking our data against the table in the back of Chamberlain/Doyle/Jentz' Encyclopedia of German Tanks of World War Two. While that is an excellent book, that penetration table has quite a number of oddities and likely errors. It's a prime example of why we don't use tabular data in CM.

--------

The conclusion here is that CMBB's data is correct. If it looks wrong to you, question your understanding of ballistics and how CMBB works first before claiming to know if it is working correctly or not.

[ October 22, 2002, 08:25 PM: Message edited by: Bastables ]

[John D Salt]

Originally posted by Bastables:

Steve on the power of the 3,7cm gun earlier

Now back to the technical discussion. This is from Charles:

We don't use tabular data of course because of all their inherent problems, but just as a quick reality-check comparison our PaK 36 has the following AP penetration stats:

100m, 0 degrees: 62mm

100m, 30 degrees: 51mm

Hogg's _German Artillery of World War Two_ gives the following penetration stats:

100m, 0 degrees: 65mm

100m, 30 degrees: 50mm

How much closer should we be?

[snips throughout]

CM:BB gives the PaK 36 an expected penetration figure of 42mm at 500m at 30 degrees.

Let us compare these with the figures found in the literature:

38mm is given by Chamberlain & Gander and Playfair, both for a range of 400 yards. This seems consistent with the figure of:

36mm, far the most popular answer, given by Bidwell, Hoffschmidt & Tantum, von Senger und Etterlin and Pemberton for 500 yards, and by Hogg in two separate publications, and by Quarrie for 500 metres.

35mm is given by Ogorkiewicz for 500 yds; this was read from a graph, and so might equally well be another vote for 36mm.

There is then a bit of a jump to lower figures favoured by other sources:

30mm is given in the Bovington booklet Fire & Movement for 500 yards.

29mm is given in Chamberlain, Doyle & Jentz, Jentz' "Panzertruppen" for 500 metres, and by and Woodman for 500 yards.

28mm is given by Messenger and John Ellis.

It seems that we have about ten sources (although it;s not always possible to tell who's copying who without attribution) favouring a figure close to 36mm, and about half as many favouring one of about 29mm.

That is a big enough gap to make me think that these are not referring to the same thing, and that one or more of the projectile design, armour type or penetration criterion is different between the two cases. Shoots against FH or MQ armour, for example, could easily account for 5-7mm difference in penetration performance.

The CM:BB figure, however, is as much again above the higher of the two documented figures.

I would favour reducing the penetration performance of the PaK 36 slightly more than Rexford has suggested, to be consistent with the widely-agreed 36mm figure.

6mmm might not sound like much of a difference, but with such a puny gun as the PaK 36 that difference over-states its penetrative power relative to the two figures found in the literature by 17% of the higher figure, and 40% of the lower.

All the best,

John.

[Grisha]

Well, Bastables, I will say that CMBB comes as close as you're going to get with a simulation that can be handled, CPU-wise, by a PC.

Regarding German veteran gunners, you've doubtlessly heard about the Bix encounter with a KV-1, right? He had the wherewithal to finally put a cap in the barrel as the turret started coming their way, but even a vet gunner like Bix was unable to penetrate the KV's side armor from a distance of, what, 30m? That thing must've looked like the broadside of a barn at that range. Wasn't he in a PzIIIH? And, this doesn't necessarily mean that CMBB's penetration properties are in error. It could also be the cannon round is simulated as tougher than it actually was at that time, which is rexford's argument.

[Andrew H.]

Originally posted by John D Salt:

I would favour reducing the penetration performance of the PaK 36 slightly more than Rexford has suggested, to be consistent with the widely-agreed 36mm figure.

6mmm might not sound like much of a difference, but with such a puny gun as the PaK 36 that difference over-states its penetrative power relative to the two figures found in the literature by 17% of the higher figure, and 40% of the lower.

All the best,

John.

Hmm...I notice that v. Senger and Etterlin give the 37mm gun a penetration of 43mm @ 30 degrees for PzGr 40 (i.e., the tungsten round). I don't know enough about metal to know if there is an error there, but it is interesting how close CMBB's number is to the PzGr. 40 number. Moreover, when you consider that the range v. Senger and Etterlin use (for whatever reason) is 457 meters, 42 mm at 500 meters might be dead on.

[Bastables]

Originally posted by Grisha:

Well, Bastables, I will say that CMBB comes as close as you're going to get with a simulation that can be handled, CPU-wise, by a PC.

Regarding German veteran gunners, you've doubtlessly heard about the Bix encounter with a KV-1, right? He had the wherewithal to finally put a cap in the barrel as the turret started coming their way, but even a vet gunner like Bix was unable to penetrate the KV's side armor from a distance of, what, 30m? That thing must've looked like the broadside of a barn at that range. Wasn't he in a PzIIIH? And, this doesn't necessarily mean that CMBB's penetration properties are in error. It could also be the cannon round is simulated as tougher than it actually was at that time, which is rexford's argument.

What are you talking about? The 1940 KV-1 has a side armour basis of 75mm at 0deg the penetration of the 5cm Kw.K L/42 is 73mm at 0deg at 100 metres in game with what I assume is the Pzgr APC. How does this contradict vet gunner Bix account? At 30 metres in game you need a hit angle of 0 degs to gain a partial penetration on KV 1940 75mm side armour. A real departure in emulating reality

[Grisha]

Originally posted by Bastables:

What are you talking about? The 1940 KV-1 has a side armour basis of 75mm at 0deg the penetration of the 5cm Kw.K L/42 is 73mm at 0deg at 100 metres in game with what I assume is the Pzgr APC. How does this contradict vet gunner Bix account? At 30 metres in game you need a hit angle of 0 degs to gain a partial penetration on KV 1940 75mm side armour. A real departure in emulating reality

You're right, Bastables, my apologies for bringing up this episode when it has absolutely nothing to do with the T-34 discrepency. I'd best stay out of these tactical/technical discussions, and stick to the more familiar grounds of the operational level.

[Amedeo]

Gentlemen,

In my humble opinion the point is: since CMBB has not a set of values hard coded into the game to handle penetration but, correctly, models the results with some mathematical equations that take into account things like terminal velocity, angle of impact, calibre, type of round, thickness of armour plate, hardness, HE filler size, projectile quality etc. etc. the point is simply to see whether there is the possibility that some of the input values that are feed into this 'number crunching' machine are to be revised.

It's not simply a matter simply of saying that Jentz quote those figures but Hogg states that etc. etc. (while this is quite interesting and may help in 'debugging', if fact I myself posted a lot of data of this kind), after all this is not some other game in which you can simply edit the penetration value of the so and so gun.

What I want you to note is that perhaps there are some data that was not taken into account for some weapon systems: namely the presence of larger HE fillers in 37mm and 50mm AP rounds and the unavailability of APC projectiles for the short 50mm in 1941. And possibly there's also the issue regarding the poor quality of 37mm AP rounds.

Please consider that all those factors (type of round, e.g. AP, APC etc., size of HE filler, quality of the metal) are already taken into account by the engine for those weapon system for wich sufficient information was available. Thus before intoducing subjective variables and multipliers I think that it would be essential to risolve first those issues.

Regards to all,

Amedeo

Probably this alone would

[rexford]

The 30 degree penetration table in Jentz Panzertruppen and Encycl. of German Tanks has 20mm AP defeating 20mm at 100m. British collection of German data has 0 degree estimate of about 45mm at 100m, which does not match up with 20mm at 30 degrees.

So table data at 30 degrees does seem deflated.

Amedeo Matteucci brought up Russian account where 20mm penetrates 45mm vertical on T34, and 37mm penetrates 45mm/40 degrees on T34, at close range.

Table data for both guns would not support either result.

German armor acceptance table from BIOS report shows that 42mm plate was expected to resist 37mm AP hits at 100m and 30 degrees without allowing a through-the-plate crack. I wonder if that is the origin of a 42mm penetration figure at 100m and 30 degrees.

Armor acceptance tables are NOT penetration performance, they are based on the "sicher" criteria where armor had to avoid see-through cracks in order to be accepted.

If 42mm of German armor plate does not crack on the inside at 100m and 30 degrees, clean penetration performance of 37mm AP is going to be quite a bit lower.

We have never found any German penetration figures against face-hardened armor, they tested armor that was going to be face-hardened while it was still homogeneous when it came to ammo firing trials.

I have data from 1942 German trials against face-hardened and T34 armor with 37mm AP (40mm to 53mm plate), 37mm gun could not penetrate 40mm of face-hardened plate at 100m and 0°.

37mm AP has an HE burster that is 1.9% of total weight, which is high. 75mm APCBC has 0.2%.

There is evidence which suggests that early war German ammo was inferior to 1942 stuff. There is a possibility that 37mm AP was improved after 1941 along with 20mm AP when they just didn't cut it anymore. Germans attempted to improve 50mm performance at 45 degrees during late 1942 through 1943 by changing composition and other factors. Tests did not show a change.

Fact remains that German 37mm AP at 100m was not expected to cause a crack clear through a good quality 42mm thick German plate at 30 degrees, so is it likely that it would completely penetrate more than 40mm at that range. Jentz figure of 35mm complete penetration at 100m and 30 degrees is consistent with the German armor acceptance curves.

[Bastables]

Originally posted by Amedeo:

Gentlemen,

Please consider that all those factors (type of round, e.g. AP, APC etc., size of HE filler, quality of the metal) are already taken into account by the engine for those weapon system for wich sufficient information was available. Thus before intoducing subjective variables and multipliers I think that it would be essential to risolve first those issues.

Regards to all,

Amedeo

Probably this alone would

But DAK had already received Pzgr 39 (APCBC for 5cm guns) by June 41 because they were using them in firing tests versus captured British tanks. I don't see how the units in Russia would have a lower priority.

42mm armour. Which German tank had a 42mm armour basis?

[ October 23, 2002, 06:17 AM: Message edited by: Bastables ]

[Amedeo]

Originally posted by Bastables:

</font><blockquote>quote:</font><hr />Originally posted by Amedeo:

[qb]Gentlemen,

Please consider that all those factors (type of round, e.g. AP, APC etc., size of HE filler, quality of the metal) are already taken into account by the engine for those weapon system for wich sufficient information was available. Thus before intoducing subjective variables and multipliers I think that it would be essential to risolve first those issues.

Regards to all,

Amedeo

Probably this alone would

But DAK had already received Pzgr 39 (APCBC for 5cm guns) by June 41 because they were using them in firing tests versus captured British tanks. I don't see how the units in Russia would have a lower priority.

QB]</font>

[Bastables]

Pzgr 39 is what is known in Commonwealth military designations as APCBC. Both the L/42 and PaK/KwK 38 fired the same shell but with differing cases. In June 41 DAK was shooting the Pzgr 39 out of 5cm L/42 and PaK 38 guns at British Infantry Mk.IIs

[ October 23, 2002, 06:28 AM: Message edited by: Bastables ]

[Amedeo]

Originally posted by Bastables:

Pzgr 39 is what is known in Commonwealth military designations as APCBC. Both the L/42 and PaK/KwK 38 fired the same shell but with differing cases. In June 41 DAK was shooting the Pzgr 39 out of 5cm L/42 and PaK 38 guns at British Infantry Mk.IIs

Yep. I was confusing myself over another 'hybrid' APC-APCBC designation, that is "K. Gr. rot Pz.". BTW at least in CMBB the short 75mm shouldn't be allowed to fire APCBC rounds but only this very particular (and less effective) round.

Returning to the DAK 50mm guns issue, the information you have, states that APCBC rounds were available only for tests or were commonly issued to units for field use?

Regards,

Amedeo

[John D Salt]

Originally posted by Amedeo:

Gentlemen,

In my humble opinion the point is: since CMBB has not a set of values hard coded into the game to handle penetration but, correctly, models the results with some mathematical equations that take into account things like terminal velocity, angle of impact, calibre, type of round, thickness of armour plate, hardness, HE filler size, projectile quality etc. etc. the point is simply to see whether there is the possibility that some of the input values that are feed into this 'number crunching' machine are to be revised.

It's not simply a matter simply of saying that Jentz quote those figures but Hogg states that [snips]

Has the algorithm used to calculate penetration on CM been published anywhere? I haven't seen it, and without having done so cannot really comment on how its input values might be twiddled to produce what I would consider a more satisfactory penetration performance for the PaK 36.

All the best,

John.

[Amedeo]

Originally posted by John D Salt:

Has the algorithm used to calculate penetration on CM been published anywhere? I haven't seen it, and without having done so cannot really comment on how its input values might be twiddled to produce what I would consider a more satisfactory penetration performance for the PaK 36.

All the best,

John.

John,

my point was that I'd consider unfair to arbitrarly tweak the inputs only to come up with a preconceived result. I think: let's assume that the engine works, but let's also be sure to feed it all the correct input data. Maybe this would suffice.

Regards,

Amedeo

[Mark Gallear]

I have copied this lot down and will get back to you - on it. (More for people to understand what the figures will mean in game terms rather than to say hey I have seen these figures which are better).

Got to warn you that I have issues with accuracy, number of hits it is taking to range in to a target and rate of fire. Although not that bad as to be unbelievably possible in most circumstances. These for Regular crews in the game appear to be more like very experienced test crews firing at paper targets on a firing range which have perfect weather conditions and are as flat as pancake - rather than pretty average crews that facing people trying to kill them possibly with bigger and better guns and are hiding behind better armour. With all the vagaries of terrain, etc which the game maps do model well. If you cannot see the shot fall - you have to fire again until you can. Maybe obvious for an 85/88mm gun but the little guns? The limit to this falls off long before the theoretical range of the best WW2 guns.

[Bastables]

Originally posted by Amedeo:

Why would DAK receive only enough Pzgr 39 for carrying out firing tests? They received Pzgr 39 for wide issue while the Infantry Mk II still caused a great deal of fear. The field tests were to prove to DAK Panzer crews that the front 75/70mm armour basis was defeat able with the new ammunition at 200metres.

[Amedeo]

Originally posted by Bastables:

Why would DAK receive only enough Pzgr 39 for carrying out firing tests? They received Pzgr 39 for wide issue while the Infantry Mk II still caused a great deal of fear. The field tests were to prove to DAK Panzer crews that the front 75/70mm armour basis was defeat able with the new ammunition at 200metres.