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


Peasant

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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 2640. For the 76mm one, the K coefficient would be 2300. For the 85mm blunt tipped shell the K is ~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 1200m at 0° (700m for the L/46 gun) and the rear armor at up to 950m (450m for the L/46 gun). https://forum.axishistory.com/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 200m. Lower side, where it's not protected by the running gear, can be pierced from up to 600mm at 30° angle.

British testing seems to agree with this data, giving the W/R for 75mm/0° RHA of 2000fps(610m/s).

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The 85mm BR-365 shell would be able to perforate the Tiger II superstructure side at +-30° from within ~1200m. Although I believe these shells were much rarer than the BR-365K ones, as I haven't seen them captured in T-34/85 in N.Korea nor fired during those famous testing in Yugoslavia.

 

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 45° and the T/D ratios investigated here.

The slope multiplier between 0° and 30°  is only ~1,1 as opposed to the commonly accepted value of ~1,23 for sharp tipped shells. Though this trend doesn't continue past ~45° and at higher angles these shells start to loose their penetration faster.

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/eSwwyKQD#57WrHmHs91-Brdhc607upVaSksWhvkuTsTslAq6JPQg

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

Edited by Peasant
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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."

Something I've noticed: whoever complied the table of ballistic limits didn't average the velocities of the highest partial penetration and the lowest complete penetration to obtain the 50% limit, but just took the lowest velocity where penetration occurred as the ballistic limit.

Which is not too dissimilar to how the Germans did it, although they used 5 rather than 1 shot. 

Using only 1 shot is liable to muddy the results because of possible outliers in the data. 

RGAE-8752-7-038-p-27-B-cr3.jpg

RGAE-8752-7-038-p-27-B-cr4.jpg

 

Edited by Peasant
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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 here.

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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  • 2 weeks later...

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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Edit: It can be argued that the hit No.6 was too close to the previous hit No.4 and should be disregarded in this analysis, but I've opted to consider it in my estimates anyway.

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Explanation for the letters:

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The following is copied verbatim from Appendix F to PRO document WO 194/662, “Report on firing trials held at Inchterf range, 01/01/1942 - 31/12/1942”:

"PENETRATION CODE USED IN FIRING TRIAL REPORTS

A. = Slight or no impression.

B. = Deep impression.

C. = Deep impression and bulge at back.

D. = Deep impression and bulge at back and crack.

E. = Deep impression with flake off back of plate, or with bulge and crack sufficient to see daylight through the plate (after removal of shot if necessary) or with any portion of the projectile protruding through or visible from the back of the plate.

P. = Pinhole penetration.

R. = Penetration; core or shot not clean through the plate.

W. = Penetration; core or shot clean through.

(L)= Core or shot lodged in the plate.

Note :- (L) can qualify any letter of the code from B to R, and is used as in the following examples.

D(L) = Deep impression and bulge at back and crack. Core in plate.

P(L) – Pinhole penetration. Core in plate.

The C/D Limit is the average of four or more velocities within a range of 70 f.s. half of which give a “D” or worse damage and half of which give a “C” or less damage. It shall not be considered valid if such average exceeds any “D” by more than 35 f.s.

The Ballistic Limit is the average of four or more velocities within 70 f.s., half of which give “E”s or worse damage and half “D”s or less damage. It shall not be considered valid if such average exceeds any “E” by more than 35 f.s.

The W/R Limit is the average of four or more velocities within 70 f.s., half of which give “W”s and half “R”s or less damage. It shall not be considered valid if such average exceeds any “W” by more than 35 f.s.

“C” Angle Immunity is the smallest angle at which the projectile at the velocity specified causes only “C” damage. The velocity specified for 2-Pr. is that obtained by full service charge at 100 yards.

NOTE It will be noted from these definitions that it is possible for any of the above limits to coincide with any of the others and this is quite common in attack at angle."

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This is the plate No.1 

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

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Table for converting the striking velocity into distance for the sharp tipped shell.

The Excel sheet in the top post has been 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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  • 4 months later...
  • 1 month later...

I would like to direct attention to an often overlooked fact that WW2 soviet sharp nosed AP projectiles are not analogous in performance to sharp nosed projectiles of other nations and can either perform better or worse under certain conditions of attack, as these US tests with projectiles with reduced nose hardness show.

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Source: https://apps.dtic.mil/sti/tr/pdf/AD0035972.pdf

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  • 7 months later...
Posted (edited)

On topic of soviet guns vs German armour:

You can use this graph next time a discussion about "T-34/85 vs Tiger" comes up.

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Edited by Peasant
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At 800m/s, the accuracy probably isnt too great though. Thats only about 150m/s more than a modern British Hesh shell, and thats only advocated for static targets beyond 1500 metres.

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Posted (edited)
2 hours ago, Peasant said:

On topic of soviet guns vs German armour:

You can use this graph next time a discussion about "T-34/85 vs Tiger" comes up.

Where does this come from? Looks suspect, 30 deg data is ok, but 90 doesnt match any known sources, also not battlefield experience.

EDIT: yep, this graph is definitely wrong. 30 degrees data is for BR-365K AP, but 90 degrees is for BR-365 APBC.

 

Edited by old_goat
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So in both cases worse figure was picked, since BR-365K had more vertical penetration and BR-365 handled slopes better.

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2 hours ago, old_goat said:

Where does this come from? Looks suspect, 30 deg data is ok, but 90 doesnt match any known sources, also not battlefield experience.

EDIT: yep, this graph is definitely wrong. 30 degrees data is for BR-365K AP, but 90 degrees is for BR-365 APBC

Your face looks suspect, bro.

Aleksandr Volgin in his article on Warspot has given more details about this test:

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85-мм остроголовый бронебойный снаряд, выпущенный из орудия С-53 с дистанции 2000 метров, уверенно пробивал бортовую 82-мм броню. С дистанции 2500 метров снаряды оставляли глубокие вмятины, при этом с тыльной стороны образовывались выпучины с надрывом. Поражение при курсовом угле цели 60° было признано возможным до дистанции 700–900 метров. Предельная дистанция пробития верхнего лобового листа корпуса была определена в 700 метров, пи этом пробитие вызвало откол брони с тыльной стороны размерами 270×140 мм.

Translation:

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85-mm sharp tipped shell fired from the S-53 gun reliably penetrated the 82-mm thick side armour at 2000m distance. From 2500m shells left only dents with cracked bulges on the back of the plate. With an extra 30° side angle the penetrations were obtained at distances up to 700-900m. Upper limit for the distance at which the upper frontal hull armour could be pierced was determined to be 700m, this perforation caused a piece of the armour 270x140mm big to detach from the rear face of the plate.

A few photos:

035-d6d481dcfe6c12ccb08beda9c5210564.jpg

more information on this topic in thread here: https://forum.axishistory.com/viewtopic.php?p=2298146#p2298146

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1 hour ago, Peasant said:

Your face looks suspect, bro.

Aleksandr Volgin in his article on Warspot has given more details about this test:

Translation:

A few photos:

035-d6d481dcfe6c12ccb08beda9c5210564.jpg

more information on this topic in thread here: https://forum.axishistory.com/viewtopic.php?p=2298146#p2298146

I still think this is mixed up. 

Look at this.

30 deg data almost perfectly matching BR-365K. 0 deg also almost perfectly matching BR-365. Other sources also confirm this.

Also, just think about it. BR-365K was a plain AP shell, without ballistic cap. It lost velocity at a much higher rate than the BR-365 APBC.

german+table.jpg

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Posted (edited)

More information to add:

In Sept 1942 ballistic trials of captured Wehrmacht tanks the soviet 45mm Mod.1937 ATG managed to perforate the solid 50mm thick frontal armour of a Pz.IV tank in 1 out of 2 hits from 50m (photo No.64, indicated with "1"), but not with 3 hits from 100m (photo No.65, hits 1 - 3).

The combined angle was 20° to the side + 14° slope of the armour itself, resulting in 24° combined obliquity. This confirms the estimates I've made previously from ballistic testing of Panther side armour with this gun.

It is interesting that this gun was able to perforate the armour at all, as this vehicle was supposed to be carrying face hardened armour at the front. Too bad there were no hardness measurements taken from this vehicle's armor, unlike for the Stug III, which was in fact assembled with face hardened 50mm plates at the front.

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Edited by Peasant
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Posted (edited)

I have seen this table so many times, how did I miss this before?

Check this out:

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Look at the 76.2mm gun, it has listed a projectile 14.33lb. That's 6.5kg. It's not a german APCBC, it's a captured russian BR-350B shell! And it's penetration is pretty low. In fact, it's DeMarre K coefficient is 2250! Almost the same (2300) as what I found in my analysis here. This table tells us it should penetrate only 85mm/0° at 100yards (for m.v. of 2149fps/655m/s).

This is not just a case of them using penetration data provided to them by soviets, as it is compiled using K coefficient = 2400. And other full-caliber AP shells have K coefficients significantly lower than this, between 1850-1950.

Edited by Peasant
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  • 1 month later...
Posted (edited)
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It is worth to point out that the presence of a fully fibrous fracture (good toughness of metal) seems to be directly related to the amount of nickel % in the chemical analysis of a given plate.

 

Edit: Updated and re-ordered tables:

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Edited by Peasant
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