Flaws in Russian WW II BR 471 Velocities

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Miles Krogfus
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Flaws in Russian WW II BR 471 Velocities

Post by Miles Krogfus » 03 Jun 2015 02:40

WW II Russian firing tests published incorrect information on various AP and APBC projectiles. For example, the 122 mm BR 471. A late 1944 firing test against a Tiger II listed the BR 471 and the BR 471B as having the same velocities at range, as at 2500 meters, 653 m/s for the BR 471 and 653.6 m/s for the BR 471B. Also the BR 471: 759.3 m/s 700m, BR 471B 771.1 m/s at 500, 641.9 m/s at 2700 m, 602.3 m/s at 3400 m. A 1944 #144 T
Firing Table gave the BR 471 with a 800 m/s muzzle velocity the same speeds per range as the 122 HE also with 800 m/s mv. Thus the BR 471 was incorrectly assumed to have these figures: 794 m/s at 100 meters, 770 m/s at 500 m, 741 m/s at 1000 m, 712 m/s at 1500 m, 684 m/s at 2000 m, 656 m/s at 2500 m, 629 m/s at 3000 m.
A 1969 Russian FT #144 T corrects confusions. Its figures for the 800 m/s mv BR 471 are: 200 m 770 m/s, 500 m 733 m/s,1000 m 670 m/s, 1500 m 612 m/s, 2000 m 558 m/s, 2500 m 509 m/s, 3000 m 464 m/s.
Thus the ranges that this AP could supposedly penetrate WW II Panzers during firing tests are incorrect. Likewise for the BR 471B, that was not used in WW II combats because of the assumed performance of the BR 471. It has the actual speeds at the above ranges (in meters per second): 779, 756, 718, 681, 646, 611, and 579 m/s at 3000 m.

Contender
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Re: Flaws in Russian WW II BR 471 Velocities

Post by Contender » 17 Jun 2015 06:32

The DDR document has it slower than that:

BR-471 (122mm L/43 D-25T)
200m:756 m/s
500m: 715 m/s
1000m: 655 m/s

Your numbers seem to fit the AT piece:
BR-471 (A-19 122mm L/46)
200m: 776 m/s
500m: 738 m/s
1000m: 676 m/s

Miles Krogfus
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Re: Flaws in Russian WW II BR 471 Velocities

Post by Miles Krogfus » 20 Jun 2015 23:35

I used these Russian firing tables: the 1938 edition for the #144 1931 Corps Cannon 1931, the 1944 2nd edition #144 T Supplemented, for the Model 1943 (A-19 S) and 1944 !22 SU (D 25 S), and JS II Tank gun Model 1943 (D 25), and the 1969 #144 T (D 25 T) for my post. Could you post the muzzle velocity and velocities at 1500, 2000, 2500 and 3000 meters for the DDR firing table of the A-19?

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Re: Flaws in Russian WW II BR 471 Velocities

Post by Contender » 21 Jun 2015 11:07

Sure
A-19:
1500m: 617 m/s
2000m: 561 m/s
2500m: 509 m/s
3000m: 461 m/s

Miles Krogfus
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Re: Flaws in Russian WW II BR 471 Velocities

Post by Miles Krogfus » 27 Jun 2015 02:31

The 1969 corrected muzzle velocity of the D-25 T gun was 795 m/s with a 5933 mm long barrel (L 48.33). The D-25 barrel was 5840 mm (L48) and the 1931 and 1931/37 models of the A-19 field artillery 5650 MM (L 46.3). Without a muzzle break as a field gun, the A-19 barrel was shorter, but had more muzzle velocity than all JS 122 mm tank guns with their muzzle brakes. Lacking its muzzle break, the D 25 barrel measured 5240 mm (L 43).

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Mobius
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Re: Flaws in Russian WW II BR 471 Velocities

Post by Mobius » 07 Sep 2016 14:57

Miles Krogfus wrote:WW II Russian firing tests published incorrect information on various AP and APBC projectiles. For example, the 122 mm BR 471. A late 1944 firing test against a Tiger II listed the BR 471 and the BR 471B as having the same velocities at range, as at 2500 meters, 653 m/s for the BR 471 and 653.6 m/s for the BR 471B. Also the BR 471: 759.3 m/s 700m, BR 471B 771.1 m/s at 500, 641.9 m/s at 2700 m, 602.3 m/s at 3400 m. A 1944 #144 T
Firing Table gave the BR 471 with a 800 m/s muzzle velocity the same speeds per range as the 122 HE also with 800 m/s mv. Thus the BR 471 was incorrectly assumed to have these figures: 794 m/s at 100 meters, 770 m/s at 500 m, 741 m/s at 1000 m, 712 m/s at 1500 m, 684 m/s at 2000 m, 656 m/s at 2500 m, 629 m/s at 3000 m..
To visualize the differences between the WWII error ballistics and the correct ballistics I produced the following graph.
The table at the right of the graph is from the WWII BR-471 data above using the G1 Gâvre drag table with a ballistic coefficient of 4.778 at an elevation of 615 ft.
You do not have the required permissions to view the files attached to this post.

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Mobius
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Re: Flaws in Russian WW II BR 471 Velocities

Post by Mobius » 07 Sep 2016 17:59

Miles Krogfus wrote:Likewise for the BR 471B, that was not used in WW II combats because of the assumed performance of the BR 471. It has the actual speeds at the above ranges (in meters per second): 779, 756, 718, 681, 646, 611, and 579 m/s at 3000 m.
I do have some problems with above BR-471B Firing table numbers.
The above data also works for the BR-471B when the MV=795 m/s.
From Archive Awareness
Image
So can't be 718 m/s with both MV. Can it?

Then the DDR tables which also appear to be pretty authentic have a bit of a problem. Or at least one of the tables has a problem.
While the BR-471B the MV=781 m/s, the Impact vel. @3000m = 584 m/s. It only takes a 781m/s BR-471B shell 4.2 seconds to go 3,000m while a 795m/s shell of the same type 4.4 seconds.

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