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

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Sheldrake
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Re: 75 mm Kwk/StuK/Pak 40 Firing Table Data

Post by Sheldrake » 14 Nov 2016 22:47

Yoozername wrote: Muzzle velocity seems to be affected by temps more so than any other parameter. Anyone know if the Brits did likewise? That is, make tropical ammunition???
I am not aware that the British manufactured "tropical ammunition."

The ambient temperature does have an effect on MV as warmed propellant generates a bit more oomph. It is one reason why ammunition should be stored in a shelter and not left lying in the sun.

Firing characteristics also change as the gun barrel and breech warm after repeated firing. There is something called the "Cold gun effect" with the first round being outside the norm.

High rates of fire can heat the gun far hotter than even a tropical sun. So hot that the round can eventually "cook off." This happened to at least one battery in 51st Highland Division that were left loaded at the end of the fireplan for Op BAYTOWN, the invasion of Italy across the straits of Messina. It was night. The assault troops were ashore and the sea was full of boats. The guns were allowed to burst.

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Re: 75 mm Kwk/StuK/Pak 40 Firing Table Data

Post by Mobius » 20 Dec 2016 19:51

Here's an interesting find.
http://tankarchives.blogspot.com/2016/1 ... ables.html
Shows vulnerable locations 2/1942.
Plus per the early HEAT thread the HL/B was available 2/1942.

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Re: 75 mm Kwk/StuK/Pak 40 Firing Table Data

Post by Yoozername » 24 Dec 2016 20:42

Can anyone identify the notes/translation language? Is it Finnish? Possibly captured by the Soviets?

Interesting that Pzgr 40 is only meant for the KV tanks (extra armored). The T34 can be handled by the Pzgr 39 and HL/B rounds. This is a very early document, Feb 42, which is interesting. The KV tanks sloped upper hull seems proof in all cases, is that 75mm or 90mm? Looks like turret shots on KVs would be the most profitable...

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Re: 75 mm Kwk/StuK/Pak 40 Firing Table Data

Post by Yoozername » 25 Dec 2016 03:49

An interesting German document from July 1943

Image

Image

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Re: 75 mm Kwk/StuK/Pak 40 Firing Table Data

Post by Yoozername » 25 Dec 2016 04:17

Merry Christmas....I think you might like seeing where he gets his stuff and make your own decisions...

http://wwii.germandocsinrussia.org/ru/n ... rid/zoom/1

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Re: 75 mm Kwk/StuK/Pak 40 Firing Table Data

Post by Mobius » 26 Dec 2016 17:42

And it has the infamous 770 m/s. This may mess up Christian's Pak 40 ammo evolution timeline.

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Re: 75 mm Kwk/StuK/Pak 40 Firing Table Data

Post by Yoozername » 26 Dec 2016 19:22

Yes, it is a interesting point. The L43, which includes the early long barreled StuGs, has the progressive twist called out also (6 deg to 9 deg). i believe that document also calls out what 'L43' means, that is the length of the end of the barrel to the inside face of the breech. It also calls out the rifled length, which is really the most important length since the driving band engages it and that is the 'travel' inside the tube. Roughly 'L33' might describe that.

It is interesting to compare all the German suggested data on the link I just posted. Check out the 5cm L60...The front sloped armor of the T34 seems 'immune'. One would certainly aim at the turret and at close range...Note that 'HK" (Pzgr 40) does not offer much improvement at all against the T34.

http://wwii.germandocsinrussia.org/ru/n ... ect/zoom/9

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Re: 75 mm Kwk/StuK/Pak 40 Firing Table Data

Post by Yoozername » 26 Dec 2016 19:43

Mobius wrote:And it has the infamous 770 m/s. This may mess up Christian's Pak 40 ammo evolution timeline.
That document is for July 1943. At that time, the L43 had been discontinued in the Panzer IV and had been replaced with the L48 version. Of course, they were certainly fighting side by side and sharing the same ammunition. The StuGs had replaced the L43 earlier with the L48. As you know, the early L48s had the progressive twist and were quickly replaced with the constant rifling (7 deg). The Pak 40, which is said to be somewhat common with the L43 barrel, kept its progressive twist for the war.

In any case, if the KWK 40 (L43) could attain a muzzle velocity of 770 M/s, then the Pak 40, which had more powder(2,7 Kg vs. 2.5 Kg) would certainly be higher. The L46 designation for the Pak 40 means that the distance between the back of the breech is 75mmx3=225mm longer. I will check back to the PC thread at Matrix, but the actual travel of the projectiles in the Pak 40 and KWK 40 (L43) might be the same.

@Mobius...have you updated your Pak 40 page?

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Re: 75 mm Kwk/StuK/Pak 40 Firing Table Data

Post by Mobius » 26 Dec 2016 20:07

Yoozername wrote:
Mobius wrote:And it has the infamous 770 m/s. This may mess up Christian's Pak 40 ammo evolution timeline.
@Mobius...have you updated your Pak 40 page?
No. I'm waiting for Christian to release his KwK/Pak 40 V0 timeline graphic. I was going to borrow from that.

The above document is a German document. So the 770 m/s is not just a Russian/US rumor.

This is going to make the gun tables in Panzer Command difficult to model.

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Re: 75 mm Kwk/StuK/Pak 40 Firing Table Data

Post by Kawinksy » 26 Dec 2016 22:40

Not wanted to disrupt the conversation, but I recently stumbled over an interesting report about the "Panzerbeschuss-Tafel" which I'd like to share:

From the Generalinspekteur der Panzertruppen, Heinz Guderian, Mitteilung Nr. 6, 15.09.1944 :

[....]

The perception in the troops concerning the information on the "Panzerschschuss-Tafel" was found very unfavourable regarding to Russian tanks, as it seems that Russian armor quality had deteriorated considerably. It has to taken notice:

It is correct that on occasions a tank can be destroyed at far greater distance than indicated in the "Panzerbeschuss-Tafel". This is not due to the supposed deterioration of armor quality present at enemy tanks, but rather due to a particularly favorable angle of attack, the data in the "Panzerbschuss-Tafel" apart from considering the tanks sloped armor, is also based on a sideward angle of 60° degrees.

In addition, the data in question always refer to the most heavily armored types of the model. The T-34 for example, is based on the latest of the 7 construction models with reinforced armor, as specified with "verstaerkt" in the "Panzerabschuss-Tafel".

It can be said, that when the leaflet for anti-tank combat ("Panzerbeschuss-Tafel") is carefully followed, a success in any case is assured.

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Re: 75 mm Kwk/StuK/Pak 40 Firing Table Data

Post by Mobius » 27 Dec 2016 05:09

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

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Re: 75 mm Kwk/StuK/Pak 40 Firing Table Data

Post by Yoozername » 27 Dec 2016 08:52

It was probably the standard. or others, 30 degrees, obliuity?

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Re: 75 mm Kwk/StuK/Pak 40 Firing Table Data

Post by Kawinksy » 27 Dec 2016 14:43

Mobius wrote:That would indicate the diagrams in a "Panzerbeschuss-Tafel" were for 60° deflection.
Yes, that's what the source is suggesting. Though I might have mistranslated it, but I highly doubt so:

"Das liegt aber nicht an der angeblichen Verschlechterung des beim Feind vorhandenen Panzermaterials, sondern an einen besonders günstigen Aufschlagwinkel, denn den Angaben in der Panzerbeschuss-Tafel ist neben Plattenneigung noch ein Seitenwinkel von jeweils 60° zugrunde gelegt."

It is interesting to note that the Panther Fibel also mention: "The firing range is always given at a sideward angle of 60°" and "The specification for 60° is the most favorable, as it gives an average value that fits the shooting from 8 different directions." Though not sure if it's related, but it certainly gives some annotations how one have to interpret the leaflet for anti-tank combat.

However, the document "Auszug aus Panzerbekämpfung aller Waffen - Richtilinien und Mittelung Nr. 1-6" can be found on germandocsinrussia.com.
Link: http://wwii.germandocsinrussia.org/de/n ... ect/zoom/7

With the aforementioned quote on page 29 (paper 23). Overall, it contains training instructions, guidance in tank warfare/ in close combat (Panzerschreck, T-Mines, Magnetic Mines) etc.

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Re: 75 mm Kwk/StuK/Pak 40 Firing Table Data

Post by Mobius » 27 Dec 2016 15:26

I wonder if the Russians used the information in captured Panzerbeschuss-Tafels to generate tables (below link) like that outlined in red. Rather than testing themselves.

http://3.bp.blogspot.com/-u9VFDPfmDeA/U ... 00/pen.jpg

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Re: 75 mm Kwk/StuK/Pak 40 Firing Table Data

Post by Kawinksy » 27 Dec 2016 16:40

Mobius wrote:I wonder if the Russians used the information in captured Panzerbeschuss-Tafels to generate tables (below link) like that outlined in red. Rather than testing themselves.
I highly doubt so, as that penetration table is entirely based on calculations done with the DeMarre formula, factor K=2400.

Link: http://i.imgur.com/Vn8ENDi.jpg

Source is: ЦАМО РФ 81-12038-303, ЦАМО РФ 38-11369-250, red marked: "Расчетная при к=2400"

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