The Russians test the Pak 38 and its PzGr 39

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Miles Krogfus
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The Russians test the Pak 38 and its PzGr 39

Postby Miles Krogfus » 08 Jun 2015 05:26

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.
The 0fficial German 30 degree deflection figure against 45 mm HB 316-356 with "Clean" perforation (GD) at 554 m/s.
British Ordnance Board firing test curves: critical velocity (CV = the 3 highest partial perforations with no projectile completely through, or 50% chance): 0 degrees deflection CV 469 m/s, 30 degrees CV 527 m/s.
The difference between CV partial pen. and WR complete is a smaller percent than the velocity from PTP and PSP, and I ESTIMATE the following WR PzGr 39 figures (based on various British AP study papers concerning CV, WR etc.): O degrees WR 496 m/s, 30 deg. WR 558 m/s.
The Russians also tested their 45 mm BR 240 APBC versus 45 mm plate: 0 degrees deflection 695 PTP, 716 PSP.
March 1942 DHHV figures for the 2 piece PzGr 39: Cap .30+ Cr of RC 42, nose .85-.95 Cr RC 59-67, body .30+ Cr RC 27 at base to 52 near weld.
Americans checked hardness for 50 mm PzGr.39 and BR 240: 5 PzGr. 39 projectiles had an average RC 61.6 nose, and center line to weld RC 60.4.
A pre-war BR 240 with nose RC 45, center line of nose to HE cavity RC 45 (no effort was made to vary the hardness of the APBC from nose to base). An improved BR 240 produced in 1942 with more distance from nose to HE cavity: nose RC 50.3, center line nose to HE cavity RC 49.6. Again no effort was made to vary RC through the whole projectile, unlike German PzGr.
Last edited by Miles Krogfus on 09 Jun 2015 02:57, edited 1 time in total.

Yoozername
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Re: The Russians test the Pak 50 and its PzGr 39

Postby Yoozername » 08 Jun 2015 06:07

Do you have a date for the test? Which 50mm AP round was it?

I am sorry, this seems interesting, but these posts seem like data-dumps.

Edit: You mean PAK 38? Not PAK 50?

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

Postby Miles Krogfus » 09 Jun 2015 03:06

There was only one 50 mm Pzgr 39 projectile, labeled for example in the firing table H Div. 119/313 of April 1943 as 5 cm Panzergranatpatrone 38 Pak 38 and 5 cm Panzergranatpatrone KwK 39. See Zeichnung #13 D 1124. The 1942 Russian test drawing illustrates this projectile only half cutaway, and its appearance shows the excellent job they did in measuring and illustrating it. Both projectiles are marked in these drawings as 2.06 Kg, and Germans in their FT, and the Russians for testing it, with a 835 m/s muzzle velocity. I have revised my post to address your questions.

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

Postby Yoozername » 09 Jun 2015 05:23

Miles Krogfus wrote: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).


I believe they had AP, APC and APCBC. There is no APBC. There are also versions with welded and solid bodies.

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

Postby Yoozername » 09 Jun 2015 17:06

This data is from a post here...
viewtopic.php?f=47&p=1930920&t=213801


It is a snapshot of armor piercing availability for the Germans (in thousands) 1 November 1942

50 mm

L42
Sprgr Patr 38 (5 cm Kw K): 1975.4
Pzgr Patr (5 cm Kw K) and Pzgr Patr 39 (5 cm Kw K): 1950.1
Pzgr Patr 40 (5 cm Kw K): 416.3

KWK L60
Sprgr Patr 38 (5 cm Kw K 39 L/60): 835.2
Pzgr Patr 39 (5 cm Kw K 39 L/60): 960.7
Pzgr Patr 40 (5 cm Kw K 39 L/60): 58.4

PAK 38 L60
5 cm Sprgr Patr 38 (Pak 38): 1093.7
5 cm Pzgr Patr (Pak 38) and 5 cm Pzgr Patr 39 (Pak 38): 1627.3
5 cm Pzgr Patr 40 (Pak 38): 383.4
5 cm Stielgr 42: 0

The L42 tank weapon and PAK 38 are firing a mix of PzGr and PzGr 39, while the KWK L60 seems to fire PzGr 39 primarily (antitank).

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

Postby Miles Krogfus » 09 Jun 2015 20:33

The carbon content for The 50 mm Pzgr.39 is C not Cr as I mistyped. The Pak 38 used the Pzgr 39 projectile and the earlier one listed just as AP Pzgr. In the February 2,1944 Allgemein zu beachtende Vorschriften bei der Munitionslaborierung on list D400 Nr 0530 here is Pzgr 39: 5 cm Pzgr Patr 39 Pak 38, 5 cm Pzgr 39 FES, 5 cm Pzgr 39 (Ub) FES. The first two projectiles with the same dimensions, weight and MV, the third for practice shooting. The German and Russian projectiles tested were as I list, the 50 mm Pzgr 39 being APC. The APBC is Russian . . .

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

Postby Yoozername » 11 Jun 2015 19:33


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

Postby critical mass » 04 Sep 2017 18:54

Miles Krogfus wrote: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.
The 0fficial German 30 degree deflection figure against 45 mm HB 316-356 with "Clean" perforation (GD) at 554 m/s.


Interesting. German G(D) is confirmed to be 554m/s @ 30° for 45mm (110-125kg/mm^2 tensile strength) according to official penetration curves for Pzgr 39. That´s roughly inline with the soviet data for PSP (539m/s), considering that PSP [four out of five] is a slightly lower standart of penetration than G(D)[five out of five]. However, what IS amazing is that the soviet armor had a subtantially lower PTP limit than german G(S). The latter was at 92% velocity of G(D) which in this case allows for G(S) = 510m/s, roughly 100m/s higher velocity than the soviet PTP of 411m/s, interesting.

The older, uncapped AP (5cm Pzgr. Gg) was slightly better under these specific conditions: 45mm (110-125 kg/mm^2 tensile strength) RHA at 30° would be defeated reliably at 500m/s. This is understood to be correct, because the old 50mm Pzgr lacked a cap and was sufficiently strong to survive such low impact velocities. Until the velocity of break up (starting at 550m/s), the uncapped 50mm Pzgr was better than the capped one, and then plateaued off so that at 650m/s the Pzgr 39 overtakes it in performance.

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

Postby Yoozername » 07 Sep 2017 17:43

Do you know the ranges that correspond to that data? Perhaps Mobius might know. At a muzzle velocity of 835 M/s, those velocities might be achieved at 900-1000 meters?

The shorter KWK L42 weapon seems to use both types of ammunition for quite awhile, as did the Pak 38. I do not think the Panzer III KWK L60 had both types since it was only brought online in Spring of 1942. Perhaps the shorter L42 could achieve similar results at 500-600 meters?

FWIW

PENETRATION DATA
Type shell Range Angle Compact Penetration
AP shell 250 yds 30° homog 60 mm (2.36")



AP shell 1,300 yds Normal Same 60 mm (2.36")

Unconfirmed on AP 40 330 yds 20° Same 90 mm (3.54")
440 yds 20° Same 64 mm (2.54")
NOTE.—The above tests were fired with a limited supply of ammunition and the results probably represent underestimates.

http://www.lonesentry.com/articles/50mm/
Last edited by Yoozername on 07 Sep 2017 19:05, edited 1 time in total.

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

Postby critical mass » 07 Sep 2017 18:27

The composite APC-HE 5.0cm Pzgr39 was a dedicated, higher velocity projectile. It´s velocity where projectile break up occured at 30° impact is >900m/s and thus, greatly superior to the old Pzgr Gg. There is very little gain in penetration of the 5.0cm Pzgr Gg from 600m/s to 800m/s due to the projectile break up. Increasing the velocity doesn´t translate into better performance (compare graph in attachment for older series AP performances).
I have no firing table velocities for the variou 50mm guns at hand.

Only under conditions when both projectiles stay intact, does the old uncapped Pzgr have superior penetration. That´s correct because the AP-cap does not add penetration, it gets destroyed in the initial impact leaving the bare projectile. Therefore, the APC projectile looses a bit of it´s mass for penetration compared to the AP.
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Re: The Russians test the Pak 38 and its PzGr 39

Postby Mobius » 07 Sep 2017 19:52

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

Postby Yoozername » 07 Sep 2017 20:18

Good point.

Also, HB 450 is like 155 Kg/mm^2? That is very hard homogenous armor. Could an uncapped projectile have issues even at lower velocities?

Another graph, A. BB.10 shows the same relationship for the 50mm but extends the Pzgr 39 linearly to 800 M/s or so. Penetration would be around 75mm @ 30 degrees.

Again, the Germans did initially use welded penetrators but switched to one part penetrators after mastering the hardness gradient. There is even a Pzgr 42 'on the books' that is a APCBC-HE. I believe it is heavier and might have a lower velocity. But it would sustain it's velocity longer.

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

Postby critical mass » 08 Sep 2017 15:43

Also, HB 450 is like 155 Kg/mm^2? That is very hard homogenous armor. Could an uncapped projectile have issues even at lower velocities?


In principle yes, but not in this case. High hardness homogenious armor plate was made only in small section thicknesses (5mm to 15mm), used mostly on various armoured personal carriers. It was not intended to be shellproof but effective instead against rifle calibre impact, which it could destroy owing to the superior hardness. Before ww2, plate for these applications were even harder, ca. 550BHN but problems with welding and ballistic resistence (too hard led to frequent shear failures against capped shot) led to reduced hardness beeing applied after 1940.

Against such thin plating, 50mm AP would significantly overmatch the armor and defeat it by attacking it´s shear strength. The hardness would be insufficient in combination with too thin thickness to create sufficient stress to also destroy 50mm AP bullets.

Why doesn't the table data reflect this penetration plateau? It shows a 67mm penetration instead of the 56mm from the graph.


That´s a secondary source. I gave a primary source, a graph attached to an article written 1943 by the prooving ground guys who conducted the ttrials which led to these penetration curves. Originally classified SECRET.
According to Your velocity data and actual penetration curves for both projectiles, below ca. 800-1000m the 5.0cm Pzgr39 was better, while above ca. 1000m the 5.0cm Pzgr was superior in penetration, when fired by 50mm KWK39 L/60. More significantly, the 5.0cm Pzgr could not be expected to penetrate thick armor close due to break up, while the 5.0cm Pzgr 39 did exactly that, which came in handy against KV1 and T34.
Tabulated data indicating otherwise are in error.

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

Postby Yoozername » 08 Sep 2017 17:06

2. The armor components of the T-34 tank, with the exception of
the bow casting which was unheat-treated, were heat-treated to very high
hardnesses (430-500 Brinell), probably in an attempt to secure maximum
resistance to penetration by certain classes of armor-piercing projectiles
even at the expense of structural integrity under ballistic attack.
The armor components of the KV-1 heavy tank were heat-treated to hard- !
nesses more nearly approaching American practice (280-320 Brinell).


http://www.dtic.mil/dtic/tr/fulltext/u2/011426.pdf

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

Postby critical mass » 08 Sep 2017 17:49

Yoozername,

thanks for pointing it out. That´s not german RHA armor, detailed by in german penetration graphs.
This high hardness armor would be very effective vs 5.0cm uncapped Pzgr*, breaking it up indeed at lower velocities -and more completely- than those encountered in the german graphs. However, this armor would be considerably less effective vs APC projectiles which couldn´t be broken up -such as capped 5.0cm Pzgr39- because it relies on projectile break up effects for resistence. Therfore it has high resistence to plastic deformation but also low resistence to shear failure. Shear failure, however, is a lower energy penetration event than ductile hole formation**

*) meaning penetration of 5.0cm Pzgr (AP-HE) would be lower than that given in penetration graphs
**) meaning penetration of 5.0 cm Pzgr 39 (APC-HE) would be higher than that given in penetration graphs


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