7,5 cm Kwk/StuK/Pak 40 Firing Table Data

[Michael Kenny]

Diversion: The above has been photo-shopped by adding the two tanks in background. They were all merged into one photo to make it look more impressive.

[Stiltzkin]

Here is the translation of the JS2 part:

Fremde Heere Ost (IId)

Notes

Observations on a new heavy tank, possibly “Joseph Stalin”

Examination of a recovered tank, possibly of the type “Joseph Stalin” on the 9.5. in Tlumaczyk (H Gr Northern Ukraine) revealed the following:

The weight of the tank is approx. 55t.

Dimensions (check document):

Length:
Width:
Height:
Tank width:
Ground clearance:

Armour protection:
Gun mantlet:
Turret:
Turret ceiling:
Front glacis:
Side:
Rear:
Chassis top:
Belly plate:
fore
aft

Armament: a 122mm Kwk/43 – D 25 with a muzzle break.
Barrel length: 5230mm (muzzle break excluded)
Caliber: L43

Optics (observation): (to the extent that was possible to determine from the burned out wreck):

3 drivers optics (mirrors), drivers front
1 in the turret on the right side of the gun.
1 in the commanders cupola.
1 tele sight on the left side of the gun
6 observation slits in the commanders cupola

3 MG 7,62 mm DT namely:

1 MG right of the driver
1 MG in the turret next to the gun
1 MG in the turret pointed backwards

Ammunition composition could not be determined because of the interiors destruction.

Engine: 520 PS, 12 cylinder diesel, same as in the SPG “SU-152”

The tank was taken out by a 8,8cm Pak 43/1 (Hornet) by a clean penetration through the strongest part of the gun mantlet from a distance of 2600m.
Two shots from the Tiger from a distance of 1200m on the frontal, flat part of the bow bounced off. One shot of the Tiger penetrated the turret side (from 200m).

A “Joseph Stalin” tank which was engaged and destroyed by AOK 8 at the beginning of May was hit by a Panzer IV from 500m away, in the turret and another shot went into the tank hatch. Both resulted in a clean penetration, the tank burned out.

The captured tank is transported to the trial area in Kummersdorf and stands for disposal for Wa A / Wa Prüf 6.

[critical mass]

Pz IVl ´s 75mm Pzgr 39 penetration at 500m was rated 91mm RHA @ 30°.
The hatch was sloped back 30° matching the reference specifications. It´s thickness varied between 100mm Cast to 120mm Cast, depending on where it impacted. According to modern military standarts, cast armor is about 15% less effective ballistically, by ww2 germany considered the difference almost identically to be 14%. It is therefore believable, that the turret was penetrated frontally by PzIVl.

[Mobius]

Pz IVl ´s 75mm Pzgr 39 penetration at 500m was rated 91mm RHA @ 30°.
The hatch was sloped back 30° matching the reference specifications.

That's a hatch? Somebody gets in and out of the tank through that little opening?

[Michael Kenny]

Looks like a penetration on turret side (lower) below but other than that can't see any other obvious holes.

khhhummers0001.jpg (46.98 KiB) Viewed 1543 times

[Miles Krogfus]

The "Fahrerlucke" is the "driver's gap," an opening to look though to guide his driving, not any type of escape hatch.

[critical mass]

Interesting that the german interpretation of soviet ballistic calculations for the gun relate to De Marre K=2400 againt face hardened KC (navy type, KC cementated) armor, not against homogenious tank armor. De Marre originally was devised to calculate homogenious nickel-steel armor and only later was adopted for face hardened armor (which it was ill suited for due to the different mechnics of petalling and plugging failures). These calculated data may differ from actual penetration. However, because russian AP defeated armor in principle by shear failure, rather than the resistence to plastic deformation, and because shear failure was also the dominant failure mechanism for face hardened armor, the error does not need to be very large.

[Mobius]

Nathan Okun's HCWCALC STS Armor Penetration Calculation Program calculates the penetration of class 'B' armor by various pointed projectiles.
http://navweaps.com/index_nathan/index_nathan.php
I haven't looked at the code yet but some ppl want me to convert it to a windows program.

[critical mass]

Mobius,

I happen to know Nathan. Am contributing to some of his work. My suggestion is to wait for such an undertaking. M79APCLC, Facehd, HCWCALC and other programs are still "work in progress".

His programs run under emulated DOS environment. Once You download free emulators like "DOSBOX", You can play around with them under any operating system...

[Mobius]

About 10 years ago I combined Facehard 5.4 with a ballistics program to fire various shells at all possible ranges to make firing tables. But FH had been updated many times since then. Right now I'm using the latest FH to update that program so a team ( making a game I guess) can use it. I didn't like M79APCLC very much because it couldn't even simulate M79 penetration tables. Hopefully HCWCALC does better.
If he is still tweaking it he should make input via text data tables and not hard code data or it won't be stable for another 10 years.

download available:
http://panzer-war.com/Naab/NAaB.html

[Yoozername]

The early IS-2 would have had it's 'center of mass' aim-point, from the front, have its "Fahrerlucke", turret ring, mantlet, shot trap and gun barrel fairly close to each other. For a gunner that had its range, these target areas might have all been in the dispersion area. Clearly, the later versions viewed the driver's vision device to be a vulnerable area.

[critical mass]

About 10 years ago I combined Facehard 5.4 with a ballistics program to fire various shells at all possible ranges to make firing tables. But FH had been updated many times since then. Right now I'm using the latest FH to update that program so a team ( making a game I guess) can use it. I didn't like M79APCLC very much because it couldn't even simulate M79 penetration tables. Hopefully HCWCALC does better.
If he is still tweaking it he should make input via text data tables and not hard code data or it won't be stable for another 10 years.

download available:
http://panzer-war.com/Naab/NAaB.html

Didn´t knew, You were the one behind NAaB, Mobius. Unfortunately, as with all closed form equitations, they give You a result instead of a probability range. This encourages people, who are less familar with terminal ballistics to take these results as gospel. I spent so much time together with Bill Jurens in the old navweaps forum to make people aware that NAaB does not replace primary sources and improper use can easily lead to misleading results. For some projectiles and armor the database was just too thin and for others it was in error. I believe some data still are in error. Finally, in some cases, the whole logic of the penetration algorythm had to be changed (nose shatter only effects, to name one).
Some of the material, I shared publicly back then in the day directly lead to further code changes of the Facehd series, the last major updates (7.0-7.4 series, 7.5 now in preperation) made by Nathan were a direct response to the thus exposed range of errors present in the handling of face hardened armor. So Your work in turn was not in vain, it helped progressing new data, much like a feedback catalysator.

[critical mass]

The early IS-2 would have had it's 'center of mass' aim-point, from the front, have its "Fahrerlucke", turret ring, mantlet, shot trap and gun barrel fairly close to each other. For a gunner that had its range, these target areas might have all been in the dispersion area. Clearly, the later versions viewed the driver's vision device to be a vulnerable area.

The whole centre frontal aspect of early IS-2- with exception of the flat glacis, was vulnerable to 7.5cm L/43, -L/46 and -L/48. Turret front, mantlet, -cheeks, frontal 30° sloped area, nose plate. The area of the drivers hatch plate "Fahrerluke" is among the strongest ones here due to slope and thickness.
However, once You deviate from the centreline, the probability increases that You frontally hit one of the declined side armor of either turret or upper hull, which will be at such acute angle to provide immunity from 75mm guns and 88mm KWK36. Kind of a "protected something at the expanse of everything" rational.

[Thoddy]

hope the links are visible

From Bericht 166 der Lilienthalgesellschaft: Die Vorgänge beim Beschuß von Panzerplatten, 1943 GkDos
Durchschlagleistung for the "Heilbleiben" criterion (projectile 100% trough plate projectile condition fit to burst; 3/3 100% percent success criterion)



from same document
comparative performance of the older 7,5 cm K.Gr.rot Pz. and 7,5 cm Pz Gr 39 at 60 degrees Auftreffwinkel = 30 degrees obliquity

[Kawinksy]

That would indicate the diagrams in a "Panzerbeschuss-Tafel" were for 60° deflection.

Sorry to pick that up again, but I found another confirmation on that thesis.

It looks like that all figures in those "Panzerbeschuss-Tafel" [anti-tank pamphlets], were apparently done (either calculated or trialed) at 60° degrees (unless otherwise noted, then at 90°) as suggested by the manual H. Dv. 469 / 3a "Panzerabwehr aller Waffen" (link) on how to perform anti-tank trials.

(I posted an excerpt in this topic: viewtopic.php?f=47&t=225047&start=30)