RGAE-8752-7-038 "Investigation of the armour of German tanks" Oct. 1945

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Peasant
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RGAE-8752-7-038 "Investigation of the armour of German tanks" Oct. 1945

Post by Peasant » 11 Mar 2023 16:41

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From my analysis of this data, I believe the penetration of the soviet 45mm gun can be described using DeMarre coefficient of 2648 (point of 50% probability). For the 76mm one, the K coefficient would be 2317. For the 85mm blunt tipped shell the K seems to be ~2400.

Using this data I've compiled these penetration tables against german RHA using modified DeMarre equation:

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45mm L/66 ATG should be able to perforate the Panther's lower side at up to 1100m at 0° (600m for the L/46 gun) and the rear armor at up to 850m (350m for the L/46 gun). viewtopic.php?p=2355589#p2355589

I remind you that Pz.III and IV had face hardened armour at the front and these values are not directly applicable to them.

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We can see that this gun will halfway reliably perforate the Tiger I upper side (82mm/0°) only from 100m. Lower side, where it's not protected by the running gear, can be pierced from up to 750mm at 30° angle.

One thing to note: by now it's clear, beyond any reasonable doubt, that the soviet blunt tipped shell are less affected by slope of the armour, at least between 0 and 30° and the T/D ratios investigated here.

The slope multiplier is only ~1,1 as opposed to the commonly accepted value of 1,23 for sharp tipped shells.

I wonder, if perhaps the sharp tipped shells would be less affected by slope as well when striking under such conditions where their nose shatters, as for example against face hardened armor.

Too bad that currently I have little testing data to tell one way or another.

Excel spreadsheet: https://mega.nz/file/CbRTEBiL#KT8eo9Ndd ... 4IIi2tRdKU

the report itself (in russian): https://mega.nz/folder/fLRmmSiD#ZrnkDPzyMthz7RmA7VfN-Q

critical mass
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Re: RGAE-8752-7-038 "Investigation of the armour of German tanks" Oct. 1945

Post by critical mass » 13 Mar 2023 09:42

Generally, a De Marre K>2300 implies a poor quality of the attacking projectile. Nose shatter or nose break up does contribute to these results. I also assume that Your assumption is likely to be re-confirmed with sources. Sharp tipped shells which shatter against a plate behave like broken ones unless the projectile overmatches the plate so severely, that the sharp tip does stay intact (i.e. against half calibre or very soft armor plate). On the other hand, broken up projectiles induce very severe plugging forces against the plate. Against such projectiles, the plate cannot fail by ductile hole formation and has to fail by more brittle forms of failure such as either plugging / discing or (against a blunt nose shaped, yet intact projectile), shearing out a small plug. The armor shown in post #1 in this thread responded in a very ductile form.

For comparison, intact projectiles generally range between K~1600 (against a softer plate) to K~2000 (against a harder plate)

Peasant
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Re: RGAE-8752-7-038 "Investigation of the armour of German tanks" Oct. 1945

Post by Peasant » 13 Mar 2023 16:07

I will translate the detailed account of testing carried out of one of the plates:

Plate No.2: Lower nose of "Panther" No.1.
Thickness: 60mm
BHN: 311 - 321

76mm shell, schematic 2-09038.
Obliquity: 0°

Shot No.1:
Propellant load (g): 800
Measured Velocity (m/s): 521,6 [Distance: ~1150m]
Result: "Hole. Entry size 80x80mm, exit: 80x80mm. The shell's nose was eroded up to the 1-st localizer groove."

Shot No.2:
Propellant load (g): 730
Measured Velocity (m/s): 476,8 [Distance: ~1600m]
Result: "Dent 15mm deep, partially filled with pieces of the shell stuck inside. A 17mm smooth bulge at the rear. The shell's nose was eroded up to the 1-st localizer groove."

Shot No.3:
Propellant load (g): 765
Measured Velocity (m/s): 493,2 [Distance: ~1450m]
Result: "Dent 25mm deep. A 20mm bulge on the rear with a crack 100mm long. The shell's nose was eroded up to the 1-st localizer groove."

Obliquity: 30°
Shot No.4:
Propellant load (g): 800
Measured Velocity (m/s): 519,6 [Distance: ~1200m]
Result: "Dent 30mm deep. A 20mm bulge on the rear. The shell's nose was eroded up to the 1-st localizer groove."

Shot No.5:
Propellant load (g): 920
Measured Velocity (m/s): 577,2 [Distance: ~650m]
Result: "Dent 50mm deep. A 30mm cracked bulge on the rear. The shell's nose was eroded up to the 1-st localizer groove."

Shot No.6:
Propellant load (g): 865
Measured Velocity (m/s): 566,0 [Distance: ~750m]
Result: "Hole, entry 50x50mm, exit 70x55mm. The shell's nose was eroded up to the 1-st localizer groove."

Obliquity: 45°

Shot No.7:
Propellant load (g): 1080
Measured Velocity (m/s): 651,6 [Distance: ~50m]
Result: "Disregard, the shot hit the hole from the first shot. The shell's nose was eroded up to the 1-st localizer groove."

Shot No.8:
Propellant load (g): 1020
Measured Velocity (m/s): 644,0 [Distance: ~100m]
Result: "Hole, entry 100x80mm, exit 100x80mm. The shell's nose was eroded up to the 1-st localizer groove."

Shot No.9:
Propellant load (g): 990
Measured Velocity (m/s): 623,2 [Distance: ~250m]
Result: "Dent 30mm deep. A 20mm bulge on the rear. The shell's nose was eroded up to the 1-st localizer groove."

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Peasant
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Re: RGAE-8752-7-038 "Investigation of the armour of German tanks" Oct. 1945

Post by Peasant » 14 Mar 2023 20:00

Here is the comparison of results from the 85mm blunt and sharp nosed soviet shot. The NPL formula for british uncapped shot gives the W/R limit for 83mm/45° as 757 - 784 m/s (depending on the plate's hardness).

It is interesting to note that although the blunt shell managed to perforate the armour, it then failed twice at higher velocities. Perhaps some kind of shatter gap effect is taking place.

Closer examination of shot No.12 photo seems to show a perforation, although we cant be sure because the other side was not photographed for some reason.

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dgfred
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Re: RGAE-8752-7-038 "Investigation of the armour of German tanks" Oct. 1945

Post by dgfred » 14 Mar 2023 21:27

Very good stuff. Thanks.

Peasant
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Re: RGAE-8752-7-038 "Investigation of the armour of German tanks" Oct. 1945

Post by Peasant » 24 Mar 2023 14:02

An in-depth review of the results obtained with the 76mm gun against a thicker plate.

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Photo No.25:

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Another target:

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Photos No.28 and 29:

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critical mass
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Re: RGAE-8752-7-038 "Investigation of the armour of German tanks" Oct. 1945

Post by critical mass » 27 Mar 2023 14:29

It seems to me a lot of the variance in penetration is due to the inherent variance in shell quality (i.e. ability to resist shatter and stop erosion. It would be nice to see the projectile remains for further clarification.

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Re: RGAE-8752-7-038 "Investigation of the armour of German tanks" Oct. 1945

Post by Carl Schwamberger » 27 Mar 2023 15:07

critical mass wrote:
27 Mar 2023 14:29
It seems to me a lot of the variance in penetration is due to the inherent variance in shell quality ...

There was a issue with a number of AP ammunition types. ie: the development of the US 76.2mm tank cannon was slowed by failures in projectile development. The converse is variable quality in armor as built. ie: There seems to have been a large difference or variation in the quality of the T34 turret resistance between those initially built in early 1941 & those after june 1941. Similarly US examinations of German tank armor note flaws in armored components and variable resistance between the same section from different vehicles. There are similar findings in the armor of US tanks. manufacturing flaws would lead to failures not predicted by the penetration tables & tests.

Testing protocols throw another difficult variable into the mix. I've seen some evidence French tests of AP ammunition vs tank armor was better planned or designed than British or German tests of the 1930s.

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Re: RGAE-8752-7-038 "Investigation of the armour of German tanks" Oct. 1945

Post by Peasant » 27 Mar 2023 16:01

critical mass wrote:
27 Mar 2023 14:29
It seems to me a lot of the variance in penetration is due to the inherent variance in shell quality (i.e. ability to resist shatter and stop erosion. It would be nice to see the projectile remains for further clarification.
I have this: 100mm blunt tipped shells after impacting a 120mm thick plate at various angles. Notice how the nose is sheared along the planes of maximum shear stress at ~45°.

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Another bit of data on 45mm shells:

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This is the plate No.1

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Re: RGAE-8752-7-038 "Investigation of the armour of German tanks" Oct. 1945

Post by Peasant » 30 Mar 2023 17:54

Warning: extreme tank gore, not for the faint of heart. :D

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Table for converting the s.v. to distance for the sharp tipped shell.

Excel sheet updated with this new information.

Apparently plates that broke into pieces were not photographed, so these are the only pictures we have.

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MFW after typing all this by hand.

A few words about these results: the brittle damage produced in the armour plate is a product of two things: the level of inherent toughness/brittleness in the specific plate and the conditions of attack it is subjected to. Attack by matching/overmatching AP shells at 0° slope are more likely to cause brittle damage then glancing hits at 45° and over. Also, a blunt tip of the shell enhances the shock imparted to the target, whether the tip was originally blunt or it was originally sharp and shattered on impact, leaving a blunted tip.

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