British Penetration Stats for German Guns

[rexford]

Following up on an earlier thread regarding the German penetration data in CMAK, British Ordnance Board curves present the following figures for German guns and ammo against vertical plate (British muzzle velocities adjusted to agree with German figures: British had 2300 fps for 75L43 APCBC, two velocities other than 3280 fps for 88L71 APCBC and 2700 fps for 50L50 APC):

50L42 APC (2240 fps muzzle velocity)

100m 72mm

500m 58mm

1000m 43mm

1500m 33mm

50L60 APC (2739 fps muzzle velocity)

100m 97mm

500m 78mm

1000m 59mm

1500m 45mm

75L43 APCBC (2427 fps muzzle velocity)

100m 133mm

500m 118mm

1000m 102mm

1500m 89mm

75L46 APCBC (2600 fps muzzle velocity)

100m 145mm

500m 131mm

1000m 115mm

1500m 101mm

75L48 APCBC (2460 fps muzzle velocity)

100m 136mm

500m 121mm

1000m 105mm

1500m 91mm

75L70 APCBC (3067 fps muzzle velocity)

100m 184mm

500m 166mm

1000m 146mm

1500m 128mm

88L56 APCBC (small HE burster and 2558 fps muzzle velocity)

100m 153mm

500m 141mm

1000m 127mm

1500m 1144mm

88L56 Flak 36 APCBC (large HE burster and 2600 fps muzzle velocity))

100m 140mm

500m 130mm

1000m 118mm

1500m 107mm

Note: Data in Thomas Jentz' DREADED THREAT suggests that early war 88mm Flak ammo penetrated less than the above figures, and data presented by Chamberlain suggests an 810 m/s (2657 fps) muzzle velocity for Flak 18 APCBC based on comparion with Tiger 88mm small burster APCBC at 780 m/s.

88L71 APCBC (small HE burster and 3280 fps muzzle velocity)

100m 216mm

500m 200mm

1000m 182mm

1500m 166mm

The British curves also seem to underestimate German velocities at range, which could lead to lower than actual penetration figures. We used the German velocity-range data to prepare the following estimates which use the British 0m penetration data:

75L46 APCBC

100m 146mm

500m 133mm

1000m 119mm

1500m 106mm

75L43 APCBC

100m 136mm

500m 121mm

1000m 108mm

1500m 96mm

75L48 APCBC

100m 135mm

500m 123mm

1000m 110mm

1500m 98mm

75L70 APCBC

100m 185mm

500m 169mm

1000m 150mm

1500m 134mm

88L56 APCBC (tank gun ammo with small HE burster)

100m 153mm

500m 143mm

1000m 131mm

1500m 120mm

88L71 APCBC

100m 217mm

500m 208mm

1000m 191mm

1500m 178mm

[ March 09, 2004, 10:23 AM: Message edited by: rexford ]

[rexford]

The German penetration estimates in our book for vertical plate are between the two sets presented in the previous post for some guns and above both sets for 88mm APCBC:

75L43 APCBC

100m 133mm

500m 121mm

1000m 107mm

75L48 APCBC

100m 135mm

500m 123mm

1000m 109mm

75L46 APCBC

100m 146mm

500m 133mm

1000m 118mm

75L70 APCBC

100m 185mm

500m 168mm

1000m 149mm

88L56 APCBC (tank gun)

100m 162mm

500m 151mm

1000m 138mm

88L71 APCBC

100m 232mm

500m 219mm

1000m 204mm

We compared our figures to estimates made by the German penetration equations and the results seemed close to our estimates.

[K_Tiger]

Hi Lorrin,

isnt it be more helpfull, if we would know the brinnell hardness of the testing Plates? The differences for the 88/L56 Tank gun are astonishing high....maybe they used different Plates, maybe also in the size?

Wasnt there a thread before, with the meaning, a targeting Plate from lets say 2x2 meters is in the center less ressistant than a 50x50cm one?

If i understand it right, you suggest, the German testings are more right than the english ones...?

I dont know the circumstances both or other countries conduct her tests, but doesnt they whereupon respect also weather/wind conditions? A strong head wind will blow off your estimatings especialy on longer ranges.

Whats with barrel wearing...maybe the Brits used strong weared barrels and the german new ones...as to say.." fresh from the Factory"? Does this made differences too?

Maybe you can lighten this up...

Greetings

Toni

[Abteilung]

One question: Were all figures based upon unified penetration criteria? Semantics wise, I do seem to remember perforation and penetration having disparate definitions in British tests.

[John D Salt]

Originally posted by Abteilung:

One question: Were all figures based upon unified penetration criteria? Semantics wise, I do seem to remember perforation and penetration having disparate definitions in British tests.

Ho, penetration criteria, is it?

I believe that the usual British penetration proof criterion early in the war was to have the complete projectile length pass through the target plate on 80% of proof shots fired. Later, some tables give the "critical thickness" of armour, that is, the one for which a shot win and a plate win are equally likely.

The following is copied verbatim from Appendix F to PRO document WO 194/662, “Report on firing trials held at Inchterf range, 01/01/1942 - 31/12/1942”:

"PENETRATION CODE USED IN FIRING TRIAL REPORTS

A. = Slight or no impression.

B. = Deep impression.

C. = Deep impression and bulge at back.

D. = Deep impression and bulge at back and crack.

E. = Deep impression with flake off back of plate, or with bulge and crack sufficient to see daylight through the plate (after removal of shot if necessary) or with any portion of the projectile protruding through or visible from the back of the plate.

P. = Pinhole penetration.

R. = Penetration; core or shot not clean through the plate.

W. = Penetration; core or shot clean through.

(L)= Core or shot lodged in the plate.

Note :- (L) can qualify any letter of the code from B to R, and is used as in the following examples.

D(L) = Deep impression and bulge at back and crack. Core in plate.

P(L) – Pinhole penetration. Core in plate.

The C/D Limit is the average of four or more velocities within a range of 70 f.s. half of which give a “D” or worse damage and half of which give a “C” or less damage. It shall not be considered valid if such average exceeds any “D” by more than 35 f.s.

The Ballistic Limit is the average of four or more velocities within 70 f.s., half of which give “E”s or worse damage and half “D”s or less damage. It shall not be considered valid if such average exceeds any “E” by more than 35 f.s.

The W/R Limit is the average of four or more velocities within 70 f.s., half of which give “W”s and half “R”s or less damage. It shall not be considered valid if such average exceeds any “W” by more than 35 f.s.

“C” Angle Immunity is the smallest angle at which the projectile at the velocity specified causes only “C” damage. The velocity specified for 2-Pr. is that obtained by full service charge at 100 yards.

NOTE It will be noted from these definitions that it is possible for any of the above limits to coincide with any of the others and this is quite common in attack at angle."

All the best,

John.

[Abteilung]

Outstanding ! Thank you very much John. I had never been privy to that document and had always wondered if there was more to it than most secondary references allude to: Which amounted to a brief description of the "80% rule". Excellent information.

What would be of great interest to me now is the corresponding German criteria. I have rexford's book at home, and also some publishings from Jentz, however, if you've the time and documentation it would be very much appreciated.

[John D Salt]

Originally posted by Abteilung:

[snips]

What would be of great interest to me now is the corresponding German criteria. I have rexford's book at home, and also some publishings from Jentz, however, if you've the time and documentation it would be very much appreciated.

Sadly, that post pretty much exhausts my information on penetration criteria -- none of the documents I've yet found in the PRO make any observations on foreign penetration criteria, except the often-seen warning that figures from Russian official sources are usually more conservative than would be the case if they were calculated British style.

All the best,

John.

[Rausch]

Perhaps I can add some helpfull comments.

"I believe that the usual British penetration proof criterion early in the war was to have the complete projectile length pass through the target plate on 80% of proof shots fired."

Maybe I understand Jentz wrong, but he tells that at least for the 2-pdr the criterium was that not the full projectile, but only at least 20% of the projectile had to penetrate in 80% of the hits.

German had a more stringent definition:

5 to 10 (depending on calibre) consecutive shots had to penetrate the plate with 100% of the projectile, without any failure was permitted.

There were two different 8.8 cm APHE rounds.

The early design of the 8.8 cm Pzgr with a weight of 9.5 kg and the 8.8 cm Pzgr. 39 with a weight of 10.2 kg. the later round was fired by the 8.8 cm Flak 18/36/37 and the 8.8 cm Kw.K 36.

While the 8.8 cm Pzgr. 39 had less explosive filling, it was more potent than that of the old round, since a new explosive mixture with Hexogen was used.

The German penetration data are for an impact angle of 30° (English notation):

8.8 cm Pzgr.: 98 mm on 100 m and 78 mm on 1500 m.

8.8 cm Pzgr. with v0 = 780 m/s: 120 mm on 100 m and 91 mm on 1500 m.

8.8 cm Pzgr. with v0 = 800 m/s: 128 mm on 100 m distance and 97 mm on 1500 m distance.

In 1942 a muzzle velocity of 780 m/s was told for the 8.8 cm Kw.K.36, 800 m/s for the 8.8 cm Flak.

In 1944 the "Geschoßblätter"-collection of the OKW listed both guns with 800 m/s.

That's about the same what the Krupp penetration tests from 1942-1944 told, since both guns had a range of muzzle velocities between 780 m/s and 815 m/s.

A last remark on the 5 cm ammo.

The cap of the 5 cm Kw.K. and 5 cm Kw.K. 39 5 cm Pzgr.39 ammo is listed as ballistic cap in German sources like the original ammo service manuals, the ballistic manuals and the writings of the "boss" of the German tank development department from 1935-1945, Mr. Rau.

[Abteilung]

Tag Michael!

Good to see you in the CM forums.

Hows the website coming along?

I seem to recall the British criteria for the 2pdr in Jentz's TCNA being as you described, albeit the book is still packed in a box somewhere at the house. I just recently moved, so in the next few days I'm sure to run into it and rexford's book in case you haven't the time between now and then.

[Dinsdale]

Maybe I understand Jentz wrong, but he tells that at least for the 2-pdr the criterium was that not the full projectile, but only at least 20% of the projectile had to penetrate in 80% of the hits.

That was what I recall from pre-1942 testing as well.

German had a more stringent definition:

5 to 10 (depending on calibre) consecutive shots had to penetrate the plate with 100% of the projectile, without any failure was permitted.

The german criteria while tougher is not THAT much tougher. Many works on the shelf equate the delta to about 10-15% depending on attack conditions, projectile mass vs armor type, and host of other factors.

--Derek Ward

Gives a quick way to get approximate values.

Hey there Ireg, we'll keep it more civil here ok?

[ March 12, 2004, 04:24 PM: Message edited by: Dinsdale ]

[rexford]

The British data I posted was based on the Critical Velocity for 50% success with German production ammo, where half the hits meet the penetration criteria and half don't.

Plate hardness differences would not amount to much.

There have been many discussions on the web regarding what it means when one penetration test requires that 80% of a round make it fully through the plate, another uses 100%, and still another uses 51%.

There is, according to our readings of American discussions on penetration success criteria, very little difference between requiring that 51%, 80% or 100% of a round make it completely through.

The criteria which requires that a certain percentage make it through the plate is put into the guidelines to eliminate the result where the round sticks in the plate but the nose breaks off and goes completely through. By requiring that a certain percentage of the ammo make it through you rule out partial penetrations where only a small bit of the round (nose) passes the plate.

If at least 51% of a round makes it through the plate chances are a much higher percentage succeeds in most cases.

German test data actually required that the best quality round penetrate the plate five times in a row in a condition where the HE was capable of detonating properly. When you see that the Tiger 88mm Pzgr 39 penetrates 120mm at 30 degrees and 100m, that means that the best quality 88mm ammo penetrates 120mm/30 degree five times in a row at the velocity associated with 100m.

To convert the 120mm/30 degrees for Tiger best quality 88mm apcbc to 50% success with production ammo, one decreases the penetration to convert to production ammo and then increases the result because five consecutive successes would be against less armor than a 1-in-2 success rate.

[Abteilung]

Excellent info Rexford, thank you. I do have a question regarding the following passage in your post:

To convert the 120mm/30 degrees for Tiger best quality 88mm apcbc to 50% success with production ammo, one decreases the penetration to convert to production ammo and then increases the result because five consecutive successes would be against less armor than a 1-in-2 success rate

Question: What is meant by less armor?

Also:

German test data actually required that the best quality round penetrate the plate five times in a row in a condition where the HE was capable of detonating properly. When you see that the Tiger 88mm Pzgr 39 penetrates 120mm at 30 degrees and 100m, that means that the best quality 88mm ammo penetrates 120mm/30 degree five times in a row at the velocity associated with 100m.

Dovetails quite nicely with the info Herr Rausch posted:

5 to 10 (depending on calibre) consecutive shots had to penetrate the plate with 100% of the projectile, without any failure was permitted.

Although Michael sounds to be a bit more certain that 100% of the projectile was required to pass through the plate, Rexford indicates it needed to be in a condition to detonate properly. I would assume they are saying the same thing, however, my assumptions are rarely correct