The Russians test the Pak 38 and its PzGr 39

Discussions on the vehicles used by the Axis forces. Hosted by Christian Ankerstjerne
Yoozername
Member
Posts: 1004
Joined: 25 Apr 2006 15:58
Location: Colorado

Re: The Russians test the Pak 38 and its PzGr 39

Postby Yoozername » 08 Sep 2017 20:19

I was mostly pointing out the Soviet test methodology....from the OP

Here are results of the spring 1942 testing of a captured German gun and its AP rounds, firing at 45 MM plate with HB 450+/- 40, as for the T 34 glacis. (A total of six regular APC, APBC and APCR projectiles were tested, I mention two of them).
At 0 degrees total deflection of 45 mm plate: PTP 363 m/s, PSP 415 m/s. 15 degrees 375/465 m/s, 30 deg. 411/539 m/s, 45 degrees 613/770 m/s, 60 deg. 809 m/s PTP no PSP penetration.

User avatar
Mobius
Member
Posts: 159
Joined: 12 Jan 2005 20:45
Location: Glendale, CA

Re: The Russians test the Pak 38 and its PzGr 39

Postby Mobius » 09 Sep 2017 16:56

Here's a Russian document on that subject.
You do not have the required permissions to view the files attached to this post.

User avatar
Christian Ankerstjerne
Forum Staff
Posts: 11003
Joined: 10 Mar 2002 14:07
Location: Denmark

Re: The Russians test the Pak 38 and its PzGr 39

Postby Christian Ankerstjerne » 12 Sep 2017 18:29

Mobius wrote:Why doesn't the table data reflect this penetration plateau? It shows a 67mm penetration instead of the 56mm from the graph.
http://www.panzerworld.com/5-cm-pak-38

Here is a Impact velocity table of the 50mm/L60 APC
50mmL60APC.jpg


Those numbers match the German firing table quite closely:

200 m: 783 m/s
500 m: 707 m/s
1000 m: 591 m/s
1500 m: 491 m/s

The penetration data on my website for the Pzgr. 39 also matches the data in the German firing table.

User avatar
Mobius
Member
Posts: 159
Joined: 12 Jan 2005 20:45
Location: Glendale, CA

Re: The Russians test the Pak 38 and its PzGr 39

Postby Mobius » 12 Sep 2017 20:41

Christian Ankerstjerne wrote:
Mobius wrote:Why doesn't the table data reflect this penetration plateau? It shows a 67mm penetration instead of the 56mm from the graph.
http://www.panzerworld.com/5-cm-pak-38

Here is a Impact velocity table of the 50mm/L60 APC
50mmL60APC.jpg


Those numbers match the German firing table quite closely:

200 m: 783 m/s
500 m: 707 m/s
1000 m: 591 m/s
1500 m: 491 m/s

The penetration data on my website for the Pzgr. 39 also matches the data in the German firing table.


That's little different than the firing table data I have:
50mm/L60 APC
0m: 835 m/s
100m: 809 m/s
500m: 706 m/s
1000m: 590 m/s
1500m: 489 m/s

Could your data be for the Pzgr. 38 AP?

Still I could of done a better job of adjusting the ballistic coefficient until they matched.
should be able to locate on page 89.
http://www.lexpev.nl/downloads/handbuch ... 361945.pdf

User avatar
Christian Ankerstjerne
Forum Staff
Posts: 11003
Joined: 10 Mar 2002 14:07
Location: Denmark

Re: The Russians test the Pak 38 and its PzGr 39

Postby Christian Ankerstjerne » 12 Sep 2017 22:00

It refers specifically to the 5 cm Pzgr and 5 cm Pzgr 39, with a muzzle velocity of 835 m/s, and a weight of 2.06 kg, from the April 1943 version of H. Dv. 119/313.

I would venture to say that the difference is smaller than for what the altitude, temperature, and humidity would account.

User avatar
Mobius
Member
Posts: 159
Joined: 12 Jan 2005 20:45
Location: Glendale, CA

Re: The Russians test the Pak 38 and its PzGr 39

Postby Mobius » 13 Sep 2017 01:16

Christian Ankerstjerne wrote: April 1943 version of H. Dv. 119/313.
.

Which I would take as a primary source.

Miles Krogfus
Member
Posts: 308
Joined: 08 May 2015 19:54
Location: San Diego, CA

Re: The Russians test the Pak 38 and its PzGr 39

Postby Miles Krogfus » 17 Sep 2017 19:35

Here are 3 pages from the DHHV daybook with data from the Metallurgic Quality Control Department. The "Sicher" or 'safe' range of German armor plate of different chemical contents tested by 50 mm AP did not change from 1942 to 1945. The Nov.1942 TL 4033 curve for uncapped AP (not from DHHV) is a draft version with different AP weight and velocity than later shown on German documents. DHHV page 700 has an August 25,1942 test graph, using 50 mm AP. DHHV page 1355 has the April 19,1943 data showing Sicher thickness of plates tested by various mm of all types of AP : plates 7 to 100 mm. thick.
You do not have the required permissions to view the files attached to this post.
Last edited by Miles Krogfus on 18 Sep 2017 08:09, edited 1 time in total.

Miles Krogfus
Member
Posts: 308
Joined: 08 May 2015 19:54
Location: San Diego, CA

Re: The Russians test the Pak 38 and its PzGr 39

Postby Miles Krogfus » 17 Sep 2017 23:07

Two more pages from the April 19,1943 DHHV document:
You do not have the required permissions to view the files attached to this post.

Miles Krogfus
Member
Posts: 308
Joined: 08 May 2015 19:54
Location: San Diego, CA

Re: The Russians test the Pak 38 and its PzGr 39

Postby Miles Krogfus » 19 Sep 2017 00:26

This extract from DHHV page 696 shows the results of the 50 mm uncapped AP firings diplayed on page 700 above. The February 1945 50 mm uncapped AP curve shows that with such 60-110 mm panzer plate as listed on page 696, even with revised chemical contents, there was no late war lessening of penetration resistance allowed producers.
You do not have the required permissions to view the files attached to this post.

User avatar
Mobius
Member
Posts: 159
Joined: 12 Jan 2005 20:45
Location: Glendale, CA

Re: The Russians test the Pak 38 and its PzGr 39

Postby Mobius » 23 Sep 2017 16:28

How are the Germans calculating the energy in these graphs or on tables in http://www.lexpev.nl/downloads/handbuchderflugzeugbordwaffenmunition19361945.pdf?
Shouldn't mkg be joules?

Stiltzkin
Member
Posts: 642
Joined: 11 Apr 2016 12:29
Location: Germany

Re: The Russians test the Pak 38 and its PzGr 39

Postby Stiltzkin » 24 Sep 2017 01:48

How are the Germans calculating the energy in these graphs or on tables in http://www.lexpev.nl/downloads/handbuch ... 361945.pdf?
Shouldn't mkg be joules?

It is in Meterkilogramm , the Energy to raise an object of 1 Kilo weight by 1 meter (1 to 0,102, or 1 J = 1 Kgm²/s²)= 9,81 Nm or 9,81 Joule. Just multiply with 9,81 to get in J.

critical mass
Member
Posts: 87
Joined: 13 Jun 2017 14:53
Location: central Europe

Re: The Russians test the Pak 38 and its PzGr 39

Postby critical mass » 28 Sep 2017 12:50

The charts provided by Miles show service acceptance conditions for armor plate. The test projectile in this case was not the 5.0cm Pzgr but the decapped 5.0cm Pzgr.39 (notice the difference beyond presence / absence of the cap in the differing heat treatments and "welded on tip"!).


Notice that the data in these tables refer to protection limit (Gs), not perforation limit (Gd). Of course, while the AP-maker would be interested to know what kind of penetration could be expected by his product, the armor maker would be interested on what kind of protection his product provides for.
WaPrüf6 issued a number of these "protection limit" graphs, of which I attached one to show the ratio for various calibres in this memo.
The procedure differed from AP-explorative trials in that
[+] velocity was constant (at 100m distance for 2.0cm and up)
[+] the obliquity was started at 60°, 45° or 30°, depending on plate thickness and so much changed in steps of 2.5° each after each set of, say 5 shots, until complete protection was obtained by the plate. Examples of the reults can be viewed in Miles attachments above.
[+] "Ballistic Protection" was obtained when the backside of the plate only showed smooth bulging but no complete cracking through (light shall not pass) a disc/ plug started was ok, but disc/plug ejected was a failure
[+] Plate failure (cracking through, excessive plugging / discing) will reject the plate. Discing itselfe was not considered a problem -unlike US/British practices- when it had the same high critical velocity, but plugs beyond 2 to 2.2 times the attacking calibre diameter indicated shear sensitive problems with the armor and thus might also lead to a poor resistence vs intact, pointed projectiles.

The use of decapped AP for test of homogenious armor was rational for a specific reason. Decapped AP would -at least at high impact velocities- break up or deform on plate impact, creating a blunt nose for penetrating attempt. Such blunt noses will show defects of armor in shear strength more readily than pointed noses because the principle failing of blunt nose penetrators is tied to adiabatic shear failure vs ductile hole formation in case of intact pointed projectiles. Plugs and discs were considerably smaller with capped AP than with uncapped AP. The use of uncapped AP therefore constitutes a more severe test of the armor material in regard to exposure of the materials shear failure.
Notice that this was important for german homogenious armor due to their preference of more harder / more brittle armor plate at the ductile/ brittle first transition. Also, "lean" armor with lower alloying content tended to have significantly narrower bandwidths between the different failure modes than more "fat" armor with higher alloying content, as could be expected.
One of the charts show that against vertical impact (normal to the perpendicular), the limit for protection against 5.0cm decapped Pzgr.39 was about 80mm Wh, while the capped Pzgr39 would be resisted fully only with a 90mm Wh plate. The difference is not only related to the the different failure mechanisms involved in whether or not the plate fails by ductile hole formation or plugging. Also the projectiles behave differently. While the uncapped projectile undergoes nose damage and blunting, the penetration energy is spread out over more initial contact area (less focussed) while the capped AP keeps the nose shape of the Pzgr 39 intact at such impact velocities (ca. 810m/s in this case) and allows penetration at lower residual kinetic energy because it is focussed more. Lower energy penetration of course translates into a thicker plate beeing needed to stop said projectile in the first place.
It appears from the data that only partial nose break up occurs with the two piece 5.0cm Pzgr 39, probably enticed by the welded on tip. The old uncapped, monobloc 5.0cm Pzgr could reliably defeat only ca. 58mm Wh at 30°at 820m/s and hardly more than 60mm at normal due to complete break up at these velocities.
However, at low velocities (below 600m/s), where neither projectile suffers by break up effects, the old, uncapped monobloc design was better because it didn´t waste any weight for the cap.

Notice that cast homogenious armor plate offered ca. 20% LESS resistence vs uncapped 5.0cm Pzgr 39 at normal impact and ca. 40% LESS resistence to it in oblique impact. Therefore 100mm cast armor offer just enough resistence to keep out 5.0 cm Pzgr 39 o.K. (without cap) at normal and 90mm cast at 45° where 80mm RHA and 70mm RHA, respectively, would suffice.
You do not have the required permissions to view the files attached to this post.
Last edited by critical mass on 28 Sep 2017 16:31, edited 2 times in total.

critical mass
Member
Posts: 87
Joined: 13 Jun 2017 14:53
Location: central Europe

Re: The Russians test the Pak 38 and its PzGr 39

Postby critical mass » 28 Sep 2017 12:58

Mobius wrote:Here's a Russian document on that subject.


It´s calculated data, not tested. Therefore, You cannot possibly see differences between 5.0cm Pzgr and 5.0cm Pzgr 39. Both had the same weight and therefore also have the same residual kinetic energy when calculated. The constant De Marre K=2400 used here is describing typical soviet AP vs soviet armor interaction, and has no relevance with how german AP interacts with soviet armor.
I suspect that while the monobloc 5.0cm Pzgr would not be too different (due to projectile break up, at least at close range), the capped 5.0cm two piece Pzgr 39 has be expected to vary significantly from the tabulated data given therein.

critical mass
Member
Posts: 87
Joined: 13 Jun 2017 14:53
Location: central Europe

Re: The Russians test the Pak 38 and its PzGr 39

Postby critical mass » 13 Nov 2017 18:21

It seems to me enlightening to shed some perspective on the soviet firing trials of german 5cm Pzgr referred to by Miles Krogfus.
The soviet research institute and ARTKOM used the De Marre nickel-steel formula to normalize their results. Because both, PSP and PTP have been identified in soviet trials and even plotted for various obliquities, it seems useful to compare their results with german official penetration data compiled by WaPrüf for this projectile. Because the projectile is identic, any variance between the results thus can be narrowed down to armor plate quality differences in resistence and different defintion of penetration.

German G(s) for 5cm Pzgr39 m.K. at 0°: 90mm RHA [100kg/mm²] at 810m/s (protection limit)
De Marre K=2100 for reliable (5/5), protection of plate (no hole through)
German G(d) for 5cm Pzgr39 m.K. at 0°: 90mm RHA [100kg/mm²] at 880m/s (5 consecutive penetrations)
De Marre K=2285 for reliable (5/5), complete and intact penetration at 0° obliquity

German G(s) for 5cm Pzgr39 m.K. at 30°: 60mm RHA [110kg/mm²] at 717m/s (protection limit)
De Marre K=2475 for reliable (5/5), protection of plate (no hole through)
German G(d) for 5cm Pzgr39 m.K. at 30°: 60mm RHA [110kg/mm²] at 780m/s (5 consecutive penetrations)
De Marre K=2695 for reliable (5/5), complete and intact penetration at 30° obliquity

According to Miles, the data for soviet trials vs their own high hardness armor was:

Soviet data for PSP (75%/80% penetration expectation):
0°: K=1752
15°: K=1964
30°: K=2275
45°: K=3250
60°: no PSP

Soviet data for PTP (protective limit of backside damage):
0°: K=1531
15°: K=1583
30°: K=1735
45°: K=2588
60°: K=3415

The differences are so stark, that one might be unable to explain whats going on here. May I ask Mr. Krogfus to check once again whether or not the data are correct? Usually, when I encounter such differences (roughly 1/3 lower effective resistence at normal impact for the soviet 45mm (BHN 316-356) RHA test plate) I suspect the involvement of some form of shatter effects but this has to be excluded here -at least for the 5cm Pzgr- because it is stated explicitely that the Pzgr39 curves are for intact ("heil") projectiles in G(d).
The only tentative interpretation I can come up so far, and that should be treated with due caution (let´s not forget, it´s only a limited sample size here), is that the soviet high hardness test plate gives way to the impact in some sort of catastrophic manner (plate shatter? adiabatic shear failure?) which makes it resist an intact penetrator roughly like a construction grade, mild steel plate, and not at all like armor steel -at least when striking 0° to 30°.
Against broken up penetrators or shattered projectiles, such as the soviet domestic BR240 series, it would gain 1/3 resistence back and behave much like normal armor steel. But if the plate doesn´t succeed in breaking up the shot, that armor won´t protect You.

This interpretation seems to find some confirmation in an apparent reduction of the quality difference between 0° impact and 30° impact. at between 40°- and 50° obliquity, both resistence curves may even fall together, if the extrapolation is to be believed. This is the range of obliquities, where the 5cm Pzgr39 cease to be indestructable and where projectile break up occurs on this projectile, too. Unfortunately, at high obliquity, projectile break up may improve penetration by inhibiting ricochet. Else, it cannot be excluded that the soviet domestic armor works particularely fine at high obliquity, too.
You do not have the required permissions to view the files attached to this post.


Return to “The Ron Klages Panzer & other vehicles Section”

Who is online

Users browsing this forum: apollo111, CommonCrawl [Bot], neicox1204