The Russians test the Pak 38 and its PzGr 39

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

Post by Peasant » 08 Dec 2020 14:19

I feel like we are missing a part of the picture by evaluating performance of the soviet domestic armour tested in these trials using only one metric: the limit velocity at fixed obliquity. The germans themselves thought that another variable: the critical angle for protection/perforation, can be as important, if not more, than critical velocity as a judge of plate protective quality.

Here I'm comparing the estimated minimum obliquity vs perforation for shells of the same mass and caliber as the german 5cm and 3.7cm AP using formula created by the UK NPL from testing british domestic shot vs plate. It can be found here.

As you can see, the critical obliquity for 35mm HHA is 35-50° compared to the expected 40-45(?)° vs MQ RHA, overall neither is clearly superior.
Against 45mm of HHA its 20-37,5° vs 30-40° expected against MQ RHA, here the HHA is better.

45mm plates made from HHA seems to be strictly worse at resisting oblique impact from 50mm AP shells, not only by PSP angles, but I would immagine that the PTP angles are bigger than they would've been against MQ RHA as well.

60mm plates made for this test seems to be roughly on par with good quality british RHA when under attack from 37 and 50mm german AP shells.
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Peasant
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Re: The Russians test the Pak 38 and its PzGr 39

Post by Peasant » 25 Jul 2021 12:57

critical mass wrote:
04 Apr 2020 11:17
it has just occurred to me that the 5cm Pzgr.39 might experience shatter when impacting against soviet high hardness armour at high velocities, much above the ballistic limit. Maybe not against a vertical 45mm thick plate but against one at low to intermediate obliquity(20-40°). At this t/d ratio (0,9) the nose shatter probably wont prevent the perforation, but will likely prevent it penetrating in condition fit to burst. What do you think?

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

Post by Peasant » 03 Aug 2021 11:11

I've assembled in one chart my estimates on the performance of soviet HH-RHA vs tungsten carbide cores based on the data obtained in testing by the soviets (TsAMO 38_11355_817).

Image

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

Post by critical mass » 25 Aug 2021 12:59

Peasant wrote:
25 Jul 2021 12:57
critical mass wrote:
04 Apr 2020 11:17
it has just occurred to me that the 5cm Pzgr.39 might experience shatter when impacting against soviet high hardness armour at high velocities, much above the ballistic limit. Maybe not against a vertical 45mm thick plate but against one at low to intermediate obliquity(20-40°). At this t/d ratio (0,9) the nose shatter probably wont prevent the perforation, but will likely prevent it penetrating in condition fit to burst. What do you think?
This is quiete possible, at least for thick sections of HHA like 75mm turret side wall elements, where the scaling effects associated with HHA works to the plates advantage over the 50mm projectile.

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

Post by Peasant » 17 Sep 2021 12:08

critical mass wrote:
26 Nov 2019 22:48
The UK NPL formula output also indicates the presence of a scaling effect, albeit one dependent on the exact T/D ratio of the plate/penetrator.
My interpretation of this is that this effect arises mostly from interaction between the shell and the front/rear face of the plate as the change is smaller across different scales for high T/D ratios.

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

Post by critical mass » 18 Sep 2021 09:42

Just to add a caveate: This scaling effect is dependent upon obliquity, too. Normal impact scaling is positive at normal and negative at high obliquity.

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