10.20.44 76, 85 mm AP test vs. Tiger I plate

Discussions on the vehicles used by the Axis forces. Hosted by Christian Ankerstjerne
User avatar
Mobius
Member
Posts: 577
Joined: 12 Jan 2005 20:45
Location: Glendale, CA

Re: 10.20.44 76, 85 mm AP test vs. Tiger I plate

Post by Mobius » 16 Jan 2020 05:09

Miles Krogfus wrote:
09 Dec 2019 20:37
Russian Firing Table #111 dated 1935 for the 76.2 mm Model 1927 gun mentioned (off topic) in above posts from #15 on gives the same muzzle velocity, down range velocities and times to range ending at 4000 meters as the not dated FT at the flawed site linked for us in post #15. Data in 1935 refers to the BR-350 projectile not the 350 A, thus all the down range data in the undated later FT is wrong (as was the case in other Soviet FT's that I began to report years ago in AFV News articles and later here at AHF). In the future, even when wandering off topic, please supply actual dates of the FT's (and AP projectile production dates) for any FT documents and AP drawings that you post.
It's really hard to see very much error in the firing table flight path of this low velocity shell. Comparing it to the firing table of the German L24 as described in O.B./43/C.V. 20.
75mm v 76.jpg
You do not have the required permissions to view the files attached to this post.

Yoozername
Member
Posts: 2149
Joined: 25 Apr 2006 15:58
Location: Colorado

Re: 10.20.44 76, 85 mm AP test vs. Tiger I plate

Post by Yoozername » 16 Jan 2020 18:39

I do recall an anecdotal account regarding the adapting of the German 7,5 cm projectiles onto the US 75mm guns in North Africa. I believe it was found that the US propellant loads varied and they went about mixing up propellant (perhaps the US and German) and weighed it out more precisely.

Peasant
Member
Posts: 336
Joined: 16 Oct 2018 17:21
Location: Italy

Re: 10.20.44 76, 85 mm AP test vs. Tiger I plate

Post by Peasant » 16 Jan 2020 19:12

Mobius wrote:
15 Jan 2020 20:41
I thought the DeMarre formula was only reliable for incident angles up to only 30°. And, you know that the ballistics of the US table is different than that in the Russian firing table? That may account for some of the difference. The B.C. of the Russian is about 1.87 while US has it as 2.05.
I dont think a difference in the external ballistics would have any effect since they probably recorded striking velocities with a chronograph rather than relying on the accuracy of their calculations.

No, it should work fine as long as you choose an appropriate K constant for that specific obliquity. the 0-30° range is a bit of a special case where it stays pretty much constant, unless you are trying to extrapolate beyond the limits where the shell stays intact/shattered between the reference ballistic limit and the target.

critical mass
Member
Posts: 614
Joined: 13 Jun 2017 14:53
Location: central Europe

Re: 10.20.44 76, 85 mm AP test vs. Tiger I plate

Post by critical mass » 17 Jan 2020 12:06

Mobius wrote:
08 Dec 2019 20:17
That must be the KT-28 /L16.5 gun. I didn't know it fired the BR-350A.
Here is the firing table for the F-34 using the BR-350A. The MV can only be 662 m/s though it's not printed in the table.
Russian 76mm F34 FT.jpg
Notice the BR-350B is lumped in here too. Though it could be a case of cut and paste.
Here there is the ominous BR-350SP mentioned. Its an unfilled (blind) version of the normal APBC-HE shell (APBC-shot, cavity presumably filled up with sand/salt to match the weigth and consequently, no burster effect)). Against thick plate, such shell might have slightly more chance to effect perforation due to the deletion of the HE component of an inferior shell.
The HE component would only be useful, if the projectile could stay intact and protect the cavity during perforation. This, on the other hand, is only feasable against relatively thin and soft armor plate due to the inferior projectile hardness of the soviet wartime ammunition families.
Against thick plates, the cavity may split open, thus allowing premature burst, which will cap penetration of the shell (even a low order burst will degrade the shape of the AP projectile, rendering penetration highly improbable. Sort of self induced (by help of the HE component) full shatter.

Peasant
Member
Posts: 336
Joined: 16 Oct 2018 17:21
Location: Italy

Re: 10.20.44 76, 85 mm AP test vs. Tiger I plate

Post by Peasant » 21 Apr 2020 16:28

I've found the source of the table posted by Miles. It's a 2009 russian book "Танковая мощь СССР часть III Золотой век". Unfortunately no translated version is available atm.
The table is an addendum on one of the last pages and has no other information other than that it comes from a 20th of October 1944 report. :(

Peasant
Member
Posts: 336
Joined: 16 Oct 2018 17:21
Location: Italy

Re: 10.20.44 76, 85 mm AP test vs. Tiger I plate

Post by Peasant » 04 Jun 2020 12:22

Guys, look what I found:
The altered DeMarre formula from 1944, Miles mentioned here returns the (V)elocity for 85mm soviet shell against 82mm/45°target as 734m/s, exactly the value reported in these trials. This suggests that these results were incorporated into the formula(likely) or that the "results" themselves are calculated(less likely).
critical mass wrote:
17 Jan 2020 12:06
Hey, cm, the formula also returns 859m/s as the PSP limit for 82mm/0° which is equivalent to exactly 1000m range for v0=990m/s and using 2nd edition FT for the ZiS-2 gun (which they would've been using at the time). So the reported distances in those Tiger I trials are relative to v0=990m/s after all.

Miles Krogfus
Member
Posts: 450
Joined: 08 May 2015 19:54
Location: San Diego, CA

Re: 10.20.44 76, 85 mm AP test vs. Tiger I plate

Post by Miles Krogfus » 04 Jun 2020 19:50

In my original AFV News article, I first posted projectile K figures and the Russian version of the DeMarre formula, then later in the article I gave my K figures and my modified formula to fit 1944 penetration curves. Here at the AHF when posting a shortened version of this article, so as not to confuse readers, I removed the part that Peasant later quoted.

Return to “The Ron Klages Panzer & other vehicles Section”