Monday, 9 January 2017

Comparative Penetration

"Conclusions

1. As a result of trials of D-25 (122 mm) and D-10 (100 mm) tank guns, the following penetration ranges against the upper front plate of the Panther tank were established:

Gun
Shell
Distance of complete penetration
122 mm D-25
Armour piercing
2000
100 mm D-10
Armour piercing
1200
German 88 mm gun (Ferdinand SPG)
Armour piercing
600
German 75 mm gun (Panther tank)
Armour piercing
No penetration
Notes:
  1. The distance of complete penetration listed for the D-25 is not the maximum distance, as trials over a larger distance were not performed.
  2. The armour piercing shell of the German 88 mm gun (Ferdinand) does not penetrate the upper front plate of the Panther tank: the impact forms a breach and the shell ricochets.
  3. The distance of complete penetration listed for the D-10 is not the maximum distance, the maximum is 1300-1400 meters.
2. The armour piercing shell of the D-25 gun (122 mm) can penetrate an 85 mm thick armour plate at 55 degrees (upper front plate of a Panther tank) from 700 meters further away than the D-10.

3. The penetration of the armour piercing shell of the D-10 gun can be increased to penetrate from 1500-1600 meters (when firing at a Panther's upper front plate) if the muzzle velocity and shell quality are increased.

4. The practical rate of aimed fire of the D-25 obtained during trials (2.5 RPM) is insufficient and is limited by the amount of time it takes to reload the gun with the two piece shell.
The practical rate of fire of the D-10 gun (7.5 RPM) is good due to the one piece shell.

5. When firing at ranges up to 1500 meters with the D-25 and D-10, fire correction is complicated by the amount of gases emitted when firing."

24 comments:

  1. I'm confused. The distance of complete penetration for the 8.8cm is 600 meters, but the shell ricocheted?

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    1. The shell hit the sloped armour and ricocheted. The impact was hard enough to knock a hole in the armour, but the shell itself did not end up inside the tank, and thus detonation from the round didn't destroy any mechanisms or kill any crewmen. This isn't unique to this gun and tank, I've seen similar scenarios happen before.

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  2. I wonder what the angle of fall of the D-25 shell is at 2000m.

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    1. 1.2 degrees http://tankarchives.blogspot.ca/2013/08/d-25t-artillery-tables.html

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    2. Thanks, it appears that angle of fall did not contribute too much to this long range hit of sloped armor.

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  3. The datum for D-25 (2,000 meters) has been discussed ad nauseam in many forums, claiming that the Panther should have had defective armour plate for the round to penetrate from 2,000 meters.

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    1. Then again given what state the German industry and resources were in "defective" was pretty much the norm anyway...

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    2. Those sneaky Soviets, using special super-Panthers for testing German guns, but defective Panthers for testing their own! :)

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  4. "(Ferdinand) does not penetrated"
    Main verb tense bro.

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  5. Which projectiles were used? 100mm BP-412 or BP-412B? 122mm BP-471 or BP-471B? The terminal velocities differ significantly between those shells. Also what exactly was used as defintion of penetration? hole made? 50% of mass behind plate? 20%? 80%?
    Whether or not the plate might have been defective depends on the conditions. The performance obtained is not incredible per se.

    However, the notion that "improve in projectile quality" helps penetration at 55° obliquity demonstrates a rather poor knowledge of the armor penetration mechanics from the authors of this report. Break up actually improves penetration in this case because break up changes the headform so that ricochetting is inhibted. It´s better to have some part of the projectile penetrating than nothing at all. Compare the superior quality 88mm Pgr 39 which ricochettes off. though to be fair, break up would not have helped the 88mm nearly as much due to the smaller calibre and resultant smaller body weight. More useful against highly oblique armor would have been the 88mm Pzgr.45.

    The aspect which does improve with higher quality ammunition is penetration under conditions where break up does not occur. And the realm of those conditions where the projectile stays intact is widened in terms of velocity and obliquity. F.e. the 88mm Pzgr.39 will reliably penetrate 200mm armor sloped 30° from the normal or 240mm RHA vertical close to the muzzle that neither the 100mm and 122mm will be able to penetrate with their respective ww2 AP. I have a couple of test records with randomly selected 88mm Pzgr 39 service AP ammunition which penetrated 305mm RHA at 30° and 1280m/s striking velocity in experimental trials at the Army prooving ground in Unterlüss. A penetrative performance which was unobtainable for any soviet tank gun with ww2 AP ammunition, regardless of how much velocity You give those projectiles.

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    1. The US did some post war tests of the 88mm/L71.

      3000+ muzzle velocity projectile integrity testing.

      8" (203mm) @ 0°:Two complete (NBL) penetrations with projectile passing through plate. 3124mv and 3257 mv.(550y/90y) Two ABL penetrations. Projectiles Intact. 3001 mv 3038 mv. (990y/860y)

      3 7/16" (87mm) @ 55°: Two complete penetrations. both projectiles fractured. Projectile fragments passing through plate.

      The British did 17 pdr tests on the Panther and found that it would penetrate the glacis up to 900 yards.

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    2. During WWII the Russians incorrectly calculated the velocities in their firing tables. They also assumed the BR-471 and BR-471B had the same ballistics. In fact they assumed velocity of the BR-471/BR-471B at 2000m was that for 1300-1400m for the BR-471B and 900m for BR-471.

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    3. Hello Mobius. How did you reach this conclusion?

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  6. I am not convinced that we can presume that the Panther glacis used in the test was inferior in regard to quality.

    It resisted complete Pzgr.39 penetration with 80/85mm @ 55° and 600m.
    IS3 prototype cast turret armor of somehow thicker, 90/100mm thickness was perforated by 88m Pzgr.39 at 59.2° resolved netto obliquity and velocities correponding to 1000m range.

    Nothing here indicates poor performance of the Panther glacis. It´s figure of merit compared to soviet cast armor is more than 30% more resistent for each mm thickness, factoring in obliquity and velocity differences, too.

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    1. I agree, there isn’t any evidence that the Panther’s armor was compromised. British tests show the glacis hardness was around 272 BHN.

      The Pzgr 39 did not do as well against highly sloped armor than it did to vertical armor. The larger caliber Russian shells did better vs. sloped armor and not as well against vertical armor.

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  7. Of course, once projectile break up occurs, all projectiles behave similarely poor, irregardless of their headshape, cap, or hardness contour. The differences are only related to if & when exactly break up occurs.

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  8. Do German guns have any advantage to Russian guns? It seems they have less penetration, accuracy, caliber, and rate of fire etc. Was there perhaps better economics?

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    1. Hardly. Even the British were leagues ahead of the Germans (and Continentals in general) when it came to economic mass production; the US and Soviets, being by necessity used to designing and planning for production runs on massive scales, were in a different league entirely. (And yes, many German tanks were rather undergunned for their size.)

      Reminder that by the late war the Soviets were cramming a gun for most practical intents and purposes equivalent to the Tiger's 88L56 into the T-34 without any real problems with either ergonomics or production rates.

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  9. They do:

    A) Due to the less blunt nose shape and the hardened nose, Pzg 39 AP had substantially more penetration under conditions where the projectile stays intact
    B) a superior envelope of conditions where the projectile stays intact in terms of cal/thickness, velocity and obliquity
    C) a significantly higher accuracy (german data give deviations in rectangles matching the radii while the soviets give deviations in circles of diameters, big difference when You consider that a radius is only half as large as a diameter
    D) they carry a tiny (Pzgr 39) or small (Pzgr rot) burster charge with a reliable delay fuze causing explodion behind target plate.
    Russian projectiles did not explode behind target plate when tested but loaded AP detonated on plate or (if the plate was thin enough) while penetrating
    D) smaller claibre guns typically had a higher rate of fire
    E) russian guns used a more energetic propellant, causing more gas exposure and flash. German propellant was flashless, and firing guns were consequently more difficult to spot than large cal russian guns with smokeless (but not flashless) powder.
    F) Russian projectiles were uncapped and always had the disadvantage of insufficient strength of the projectile body, causing low order deflagrations of the fillerdue to break up striking even at normal if the plate was more than 1 cal strong.
    G) Russian (typically larger) projectiles were heavier and only a smaller quantity could be carried compared to german

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    1. I agree with most of your points except ‘C’. The Russian oval deviation system is more realistic than the German rectangular deviation system. In that it assumes the x and y deviations are independent variables. Which infers there is a square root of 2 (when x=y) deviation along the 45° diagonal. That is implausible. For example if they were to rotate their gun (or target) 45° would there be a square root of 2 times deviation along one of the axis? I doubt it.

      A) As the war progressed German AP caps became more blunt and harder. Thus in this way mimicking the advantages the blunt nosed Russian projectiles had vs. highly sloped armor.

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    2. Not sure what's supposed to be the point of (the second) D) since for the most part the two sides used *extremely* similar calibres - 50/45 mm, 75/76 mm, 88/85 mm, 128/122 mm... the Germans never actually used 10.5 cm guns in AFVs in any larger numbers but those'd have been firmly in the same size class as the Soviet 100 mm as far as shells went, obviously.

      Ofc as mentioned earlier the Soviets cheerfully put big guns into even medium tanks while the Germans, well, didn't so yeah.

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