KillaKiwi

FWD: Feb/28/2018 [1.73.5.32] Wrong performance of the APCBC shell of the KwK L/68

The APCBC shell for the 10.5cm Tiger II is currently not performing as it should.

Spoiler

20171212173859_1.thumb.jpg.ec672d3e92239

Issues:

  1. The ABCBC shell is labeled PzGr. 39 but there was no PzGr. 39 developed for any 10/10.5cm weapon system.
  2. The shell is severely lacking in penetration. Currently the the round has just slightly more penetration than the Russian 100mm APCBC despite being fired at much higher velocity.

 

Source:

Geschoßringbuch, Band II, Juli 1939.

https://de.scribd.com/document/169335753/D460-1-bis-D460-2-Geschossringbuch-Band-I-III

D 435-1 - Handbuch - Die Munition der deutschen Geschütze und Werfer

https://de.scribd.com/doc/179240499/D-435-1-Handbuch-Die-Munition-der-deutschen-Geschutze-und-Werfer-28-12-1940

Dokumentation W 127: Datenblätter für Heeres-Waffen, Fahrzeuge, Gerät:

https://de.scribd.com/doc/230234125/Dokumentation-W-127-Datenblatter-fur-Heeres-Waffen-Fahrzeuge-Gerat

DIE VORGÄNGE BEIM BESCHUß VON PANZERPLATTEN, Lilienthalgesellschaft für Luftfahrtforschung 166 (Berlin 1943):

https://www.dropbox.com/s/mzkvkd8wc64c3w8/Vorg--nge-beim-Beschu---von-Panzerplatten-Bericht-166-Lilienthalgesellschaft-1943.pdf?dl=0

PDF Page 111:

Einige praktische Erfahrungen im Panzerplattenbeschuß bei der Entwicklung von Panzergranten über 3,7cm beim Heer.

 

Both the first and second source list a number of 10/10.5cm shells but a PzGr. 39 is never mentioned. The only 10cm APCBC round is the 10cm PzGr. Rot.

Geschoßringbuch page 150 and 151:

Spoiler

10cmPzGrRot.thumb.png.fee34fc42b51526cc1

 

The third source shows that a Flak 38 firing this 10cm PzGr. Rot/Flak penetrates 190mm of armor at 100m and 60° from the horizontal with a velocity of 860m/s.

Spoiler

25-c1fdb25c0a.jpg

 

This matches the fourth source. PDF Page 114, fig. 10 shows the penetration capability of this round with different velocitys.

With 860m/s the graph shows about 190mm of penetration:

Spoiler

10cmPzGrRot_penetration.png.db73f37290db

However it also shows that with 950m/s the shell is able to penetrate 240mm of armor against a plate 60° from the horizontal which is already much higher then what we have in the game.

In the game the shell has a muzzle velocity of 1005m/s which would lead to even higher penetration. However, since this KwK L/68 gun never existed and its not clear if the 10cm PzGr. Rot could even withstand impacts at that velocity its probably best to just change the velocity of that shell to 950m/s and give it the penetration of 240mm at 100m at 30° from the horizontal.

 

Solution:

  1. Change the APCBC shell description from PzGr. 39 to PzGr. Rot
  2. Reduce the velocity to 950m/s
  3. Increase the penetration of the shell to 240mm at 100m and 60° from the vertical.
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Some more info on the 105mm Pzgr Rot for the 105mm flak 38/39.  Kiwi is right though, there was no actual Pzgr 39 developed for the 105mm German guns. 

5a306786ea914_105mmPzgrRotDiag.thumb.jpg5a30678a10967_105mmPzgrRotDesc.jpg.61c77

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Alternatively the pentration could be calculated using the formular provided by WW2 Ballistics:

Spoiler

Penetration_Estimation.thumb.png.c0e3153

For the 105mm shell we'll use a similiar ballistic factor as comparable shells, 1300 (as the Russian 100mm APBC).

Considering the v0 velocity of 1005m/s the shell will have a velocity of about 860m/s at 1700m.

Since the 10cm FlaK 38 is suppose to have 190mm penetration with a velocity of 860m/s we can calculate the point blank penetration for KwK L/68 using the balistic factor.

Using the formular the penetration table would look like this:

237mm at 0m

233mm at 100m

222mm at 500m

208mm at 1000m

195mm at 1500m

183mm at 2000m

 

This actually matches the De Marre estimation:

Spoiler

105mmPzGr_penetration_de_marre.png.f3f99

 

All values are 60° from the horizontal. Since those values are already stupidly high I will refrain from converting them to US 50% critiera.

Edited by KillaKiwi
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Hello


Thank you for your interest and help improving the game.  

 

Your information has been forwarded to the developers for their consideration.  

 

This thread will remain unlocked for one week (7 days) so that anyone with additional information\evidence\examples will have a place to post.  
After this time the report will remain active but will be archived.

 

It will also serve as a place where the developers will post questions for you to answer so please keep up to date here.

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