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(ID : 0028815) Wrong Penetraiton Values of the KwK/Pak 44 128L/55

So Greetings this Bug Report is about the Penetration Values of the KwK/Pak 44 128L/55 (used by Jagdtiger and Maus)!

 

To but it bluntly the 128mmL/55 is underperforming.

I know that for the ingame Penetration Values from WW2 Ballistics: Armor and Gunnery where used.

[spoiler]4wtpd6gr.png[/spoiler]

 

So now to the point why those ingame are underperforming!

The MV is listed ingame for both AP rounds at 930m/s.[spoiler]hcvusber.png

dtkwtwu7.png[/spoiler]

They first testet it with the light charge(used by the Flak 40) and they got 845m/s that was changed when the KwK/Pak 44 was going in Production to 930m/s (heavy charge) for TD duty.

The Flak 40(used by Sturer Emil)  produced 880m/s(thanks to the longer barrel).

So now why are they under performing?

They are underperforming because even if the stat cards of the Ammo rightly says 930m/s the penetration Value is the same given by 845m/s.

here[spoiler]h9xzompq.png[/spoiler] From Armor and Gunnery changed from feet to m/s .

1. 880m/s

2. 860m/s

3. 845m/s

 

So after that and knowingly that they should have 930m/s .

I used Demarre with the given values(seen in the spoiler^) (Weight of the Rounds i got from http://www.file-upload.net/download-10590118/geschossringbuch.pdf.html)

 the APC (Pzgr.)   [spoiler]3ln9b5st.png[/spoiler]

Values i got are (in yards)

               0°

100y     305.14mm

250y     292.16mm

500y     271.5 mm

750y     252.12mm

1000y   234.81mm

 

 

 

the APCBC (Pzgr.43)    [spoiler]8yma6hm3.png[/spoiler]

 

Values i got are (in yards)

 

               0°

100y     306.14mm

250y     300.41mm

500y     290.09mm

750y     280.92mm

1000y   271.74mm

 

So i hope that the Penetration Values can be changed in the coming  Patches.  :salute:

 

Btw the weight of both Rounds is wrong in the Statcards Pzgr. should have 26.35kg and Pzgr.43 should have 28.3kg u can see that under the Ammo drawings.

 

 

(Posted )

Missing :
-two historically valid documents for each claim
-.clog
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Hello JG27_Iluminas,

 

As stated in the Data and Performance Errors guidelines,  "for claims about historical inaccuracies with vehicles in-game, it is required that two historically valid documents are provided supporting any and all claims".

 

I'm going to need two documents to back up your claims regarding the shells penetrations and shells weights.

 

Meanwhile, i'm going to look at my own sources and read WW2 Ballistics: Armor and Gunnery again to see what i can find to make the report move forward.

 

Thanks :salute:

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ok for what do u need a second source?

for the penetration it will be hard to get one because most where testet against an 30° angle and not 0°

thats why i used WW2 Ballistic: Armor and Gunnery and used the demarre equation on theyr 0° angle penetration stats

 

 

 

or do u need 1 about the velocity?

 

for the second

[spoiler]

here would be an Ballistic Table from Steel_AP_and_Theory_of_Penetration_1946

plate to pen at 60° angle(also noted in the right bottom corner) and the velocity for the shell is given (920m/s) for the 128mm

2wwiiytz.jpg

[/spoiler]

i also read somewhere in armor and gunnery about 920m/s i will try to find it

 

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OK i found more sources suggesting that the 128mm AT rounds had an MV of 920m/s i will later make another pen table like in my first post with 920m/s as MV.

but first to the sources

from (KAMPFPANZER MAUS Der überschwere Panzer Porsche Typ 205 - Michael Fröhlich - Motorbuch

Verlag" 1. Auflage 2013) is this text [spoiler]citdrjrr.jpg[/spoiler]
note the highlighted part it says: The FullCalliberTankGrenade 12,8-cm-Pzgr.43 had the loading L/4.4 an weight of 28.3 kg and  first an MV of 940m/s later reduced to 925m/s (could be because of barrel wear or somthing like that)
so next as i said i looked through WW2 Ballistic:Armor and Gunnery and found this[spoiler]qlqo9xno.png[/spoiler]
note the highlighted part
they get for 920m/s 298mm pen using demarre
and the second part says that there are several sources that state an MV of "920"m/s
 
now to the Penetration Table using 920m/s as MV
for demarre i use again this[spoiler]
h9xzompq.png
[/spoiler]
Pzgr. (APC-HE-T)
Values i got are (in yards)

               0°

100y     300.6 mm

250y     287.30mm

500y     267.08mm

750y     247.93mm

1000y   230.90mm

 

now the Pzgr.43 (APCBC-HE-T)

Values i got are (in yards)

 

               0°

100y     301.46mm

250y     295.81mm

500y     285.65mm

750y     276.62mm

1000y   276.58mm

 

 

so i hope this clears some things up and we will see changes soon™ ;)s

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Hello JG27_Iluminas,

Thanks for your hard work, the issue have been forwarded to the developpers for review, ID : [background=#d8d8d8]0028815[/background]
 
This thread will remain unlocked for one week (7 days) so that anyone with additional information\evidence\examples will have a place to post.  It will also serve as a place where the developers may post questions for you to answer so please keep up to date here. Please note, only posts relevant to the topic will be approved, all others will remain hidden.
 
Thanks for your report.

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Some sources of data that may be useful:

 

This one shows a penetration/velocity curve for the 26.35 kg PzGr. APC shell; at 60 degrees from horizontal (which is 30 degrees from vertical).

[spoiler]

wAib3nD.png

[/spoiler]

At 930 m/s, the curve for the 12.8cm is a bit over 230mm, I estimate around 235mm.

 

Running that through the APC/APCBC sloped armor equations from WWII Ballistics: Armor and Gunnery, by L. Bird and R. Livingston, produces 0 degree penetration of 310mm.

 

 

Next, a German data chart for the 12.8cm L/55 PaK 80, which was the towed AT gun version, and had identical performance.

[spoiler]

JBNV192.jpg

[/spoiler]

Notably, it says 950 m/s velocity for PzGr, and lists the 28.3 kg weight for PzGr.43 shells.

 

Hard to say if the MV was actually 950 or 930 m/s though; really need more primary sources saying one or the other.

 

 

 

Then there's this penetration chart:

[spoiler]

deh4g2F.png

[/spoiler]

These penetration figures are a fair bit lower than expected for a 920 m/s velocity at 0 degrees from vertical. It is likely this is penetration testing done to stricter criteria than the US Navy 50% probability of penetration criteria, which would lower penetration results.

This is another source that corroborates the 28.3 kg shell weight and 920 m/s or higher muzzle velocity for the PzGr. 43 shell though.

(Posted )

Could you provide the documents titles / author?
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Interesting documents, thanks.

 

Could you provide the documents titles / author?

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Interesting documents, thanks.

 

Could you provide the documents titles / author?

 

Well, they were documents I'd encountered online and downloaded to my computer, but I failed to make note of where the documents were sourced from when I DLed them.

 

The first is from "Vorgänge beim Beschuß von Panzerplatten Bericht 166 Lilienthalgesellschaft 1943 (Operations in the bombardment of armor plates)"

The second is some sort of official German technical data sheet from WW2.

The third I have no idea where it is from, sorry.

Edited by SunsetShimmers
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The second is a WW2 German data sheet giving a basic overview of any item in question, they did these for just about everything.

 

 

There was a book published with the ones found for armor and guns in the 70's

 

 

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

 

http://www.scribd.com/doc/230234125/Dokumentation-W-127-Datenblatter-Fur-Heeres-Waffen-Fahrzeuge-Gerat

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