Did the US test the 88/L71?

[L.V.]

And rounds for the 128mm AT gun in the Jagd Tiger were not specifically manufactured for AT use?

 

As you know, the AP shells of the Krupp 12,8 cm Pak 80/44 were manufactured for AT use. However, the 12,8 cm Pak was a completely different gun than the 12,8 cm Flak 40 which was a Rheinmetall design intended as a pure AA gun. It's like the 8,8 cm L/56s and 8,8 cm L/71s or 74s -- same bore diameter but different weapons with non-interchangeable ammunition.

[C.G.Erickson]

As you know, the AP shells of the Krupp 12,8 cm Pak 80/44 were manufactured for AT use. However, the 12,8 cm Pak was a completely different gun than the 12,8 cm Flak 40 which was a Rheinmetall design intended as a pure AA gun. It's like the 8,8 cm L/56s and 8,8 cm L/71s or 74s -- same bore diameter but different weapons with non-interchangeable ammunition.

So what were the AT rounds issued to the 128AA Towers?

 

DOH...88 L36 was different thatn 88 L71...

[DKTanker]

They look at projectile integrity at velocity. They fire the projectile at as high of velocity as possible to check shatter tendencies.( Results of this testing discredits shatter gap theories as results show obliquity of strike is the deciding factor...but that is a topic for another thread.)

 

C.G.

I see you've had a discussion or two with Loren.

[Mobius]

So where are you finding your RESEARCH? Why are you posting false assumptions if your original query has nothing to do with plate quality during testing....Just another War Gamer....

I don't make this stuff up. I just find it.

http://www.stormingmedia.us/25/2584/A258459.html

 

Maybe they are building a storage bin with the armor plate.

[Mobius]

I see you've had a discussion or two with Loren.

Well, that bring up what started me looking into this. Lorrin used Mark Diehl's data in articles he did on German guns for AFV G2 magazine. In fact some of the gun penetration in Bird & Livingstons book match Diehl's data spot on. Diehl's data was supposedly from Aberdeen.

In trying to confirm this data I found sources of it in old books on German tank and gun data published by WE, inc on Aberdeen data. Unfortunately where Diehl has the ranges listed as meters the exact same penetration numbers in the Aberdeen book data is in yards.

Thus Lorrin's data would be off by the ratio of yards to meters.

That is one reason I'm trying to find the true nature of the data. Maybe the old book data is wrong and Diehl and Lorrin is correct.

Edited April 19, 2009 by Mobius

[EchoFiveMike]

The question, if you can excuse me, is how many T-33 projectiles were fired in actual combat situations through the T-15E2 Gun....IIRC, just one instance against unidentified targets.

C.G.

 

Well, that was actually a T15 base model with the one piece ammo, the E2 was the two piece ammo version later canceled in favor of the T54 gun using a short fat one piece round which itself was canceled in favor of doing nothing (ballistically) until the M41 gun was fielded which ran at higher pressure.

 

All of which is academic, all I care about is if the projectile hits the target, does the target get penetrated and crew die? Out in real life, not on some test range. The 76mm was evidence how that went wrong. S/F.....Ken M

[CaptLuke]

So what were the AT rounds issued to the 128AA Towers?

 

DOH...88 L36 was different thatn 88 L71...

 

Hogg's "German Artillery of World War II" says this about ammunition available for the 12.8cm Flak 40:

 

12.8 cm Pzgr Patr Flak 40:

Complete round 42.5kg

Projectile 26.5kg capped piercing shell with a base fuze and 670 gram bursting charge.

 

Hogg says: "The purpose of these rounds is somewhat puzzling; it was extremely unlikely that any one of these guns would ever be called on to shoot as anti-tank guns and it must be assumed that these shells were issued as part of a general policy to provide every weapon with an armor-defeating round, irrespective of the likelihood of it ever being used. Specimens seen have been dated 1942 and 1944 and there is the possibility that they were originally produced for the self propelled 12.8cm K40 and then refitted to the 12.8cm Flak cases to use them up."

 

Interestingly enough Flak 40 HE projectiles were also issued for the 12.8cm K44 (projectile only, not the full round) though they were not the standard round.

Edited April 19, 2009 by CaptLuke

[CaptLuke]

. . . If desperation is the motivation than why not try the 3.7-inch HAA gun? . . . Yes it's big -- just like the Flak 88mm was big -- just like the Soviet 85mm HAA was big.

 

The 3.7" AA was almost as heavy as the German 12.8cm K44 gun, which itself was a little difficult to take seriously as a pure anti-tank gun and which was arguably a field gun with AT capability.

 

IIRC the British did develop the 3.7" into a purpose built 32lbr anti-tank gun which was still rejected as way too big and heavy. Then they went down the recoilless rifle road via the Burney guns in order to get something reasonably portable.

[Przezdzieblo]

Tests proove otherwise.

 

Then what was ballistic limit of 90 mm AP-T T33 against 80 mm plate at 55 degrees obliquity? And of what criteria?

[L.V.]

So what were the AT rounds issued to the 128AA Towers?

 

The rounds were called 12,8 cm Panzergranatpatrone.

 

 

DOH...88 L36 was different thatn 88 L71...

 

Well, yeah. Is there something odd about it?

[C.G.Erickson]

I just found this pdf on the 90mm. Nothing like yet on the 88mm/L71.

http://cgsc.leavenworth.army.mil/carl/docr.../projectile.pdf

 

Also one reason the US Aberdeen is using the German tests.

 

Actually, I ran across the very document you are alluding to at the National Archives.IIRC. The two steel manufacturers listed were rejected because of the testing of their steel. This was very very early in Aberdeen History. As they were looking for armor plate for their testing program. Result was that other steel manufacturers were used. I never even copied it as I saw no use for the document. Not relevant to testing done.

 

C.G.

[Mobius]

Actually, I ran across the very document you are alluding to at the National Archives.IIRC. The two steel manufacturers listed were rejected because of the testing of their steel. This was very very early in Aberdeen History. As they were looking for armor plate for their testing program. Result was that other steel manufacturers were used. I never even copied it as I saw no use for the document. Not relevant to testing done.

C.G.

Well it doesn't say when the evaluations took place nor what this did to any tests. If you Google the Great Lakes steel and Aberdeen you will find other similar memos bitching these guys off as having supplied poor armor.

[Mobius]

Then what was ballistic limit of 90 mm AP-T T33 against 80 mm plate at 55 degrees obliquity? And of what criteria?

I don't know what the actual Army or Naval limit. But using Nathan Okun's ballistic formula the NBL calculates at 2755. (Provided I typed it in correctly.)

 

[Edit] Obviously this doesn't match the tests in the pdf which is 2663 at 500yds.

Edited April 19, 2009 by Mobius

[C.G.Erickson]

Then what was ballistic limit of 90 mm AP-T T33 against 80 mm plate at 55 degrees obliquity? And of what criteria?

T33 projectile against all targets 6"@30, 8"@0, 3"@ 55...shattered every single time. MV 3124 to 3244. No penetrations.

 

Now dont jump to conclusions. These were tests with what you could call the first batch of T-33 rounds. This is why you test them.

[Mobius]

T33 projectile against all targets 6"@30, 8"@0, 3"@ 55...shattered every single time. MV 3124 to 3244. No penetrations.

 

Now dont jump to conclusions. These were tests with what you could call the first batch of T-33 rounds. This is why you test them.

 

Speaking of fracturing I just found this pdf with something like that happening to the 90mm on thin skirting.

http://stinet.dtic.mil/cgi-bin/GetTRDoc?AD...oc=GetTRDoc.pdf

Edited April 19, 2009 by Mobius

[Przezdzieblo]

C.G.Erickson,

no conclusions, no problem

 

But information that you were talking about early T33 is, erm, important. In document link by Mobius it could be found quite different data.

90 mm AP-T T33 vs 6" at @30 degrees obliquity - PBL 2590 m/s, which means complete penetration (protection criteria) occurs at 2900 yards (I guess then it was mv=3000 fps variant of T33, not mv=2800 fps mentioned by this document --> http://cgsc.leavenworth.army.mil/carl/docr.../projectile.pdf ).

 

Now questions (still no conclusions ):

- are those results "all right" - in term of source, methodology, propagada-free?

- how those results match with your data of "early" T33?

- if those results are "all right", could it mean that penetration of Panther glacis by T33 was possible at 1100 yards/1000 meters - like wrote Mr. Hunnicutt in his Pershing?

[C.G.Erickson]

C.G.Erickson,

no conclusions, no problem

 

But information that you were talking about early T33 is, erm, important. In document link by Mobius it could be found quite different data.

90 mm AP-T T33 vs 6" at @30 degrees obliquity - PBL 2590 m/s, which means complete penetration (protection criteria) occurs at 2900 yards (I guess then it was mv=3000 fps variant of T33, not mv=2800 fps mentioned by this document --> http://cgsc.leavenworth.army.mil/carl/docr.../projectile.pdf ).

 

Now questions (still no conclusions ):

- are those results "all right" - in term of source, methodology, propagada-free?

- how those results match with your data of "early" T33?

- if those results are "all right", could it mean that penetration of Panther glacis by T33 was possible at 1100 yards/1000 meters - like wrote Mr. Hunnicutt in his Pershing?

Prz

 

I should have made myself clearer in the T-33 post. That 3000 + muzzle velocity was for projectile integrity testing.

 

Compare it to the 88 projectiles for 3000 + velocities vs targets.

8" @ 0:Two complete penetrations with projectile passing through plate. 3124mv and 3257 mv. Two ABL penetrations. All Projectiles Intact. 3001 mv 3038 mv.

 

6 1/16" @ 30:Two complete penetrations, projectile through plate. All Projectiles intact 3008 mv 2971 mv

 

5 1/8" @45: One complete penetration, projectile through plate. Projectile fractured. One projectile shattered. 3288 mv 3211 mv

 

3 7/16" @ 55: Two complete penetrations. both projectiles fractured. Projectile fragments passing through plate. One partial penetration projectile fractured. 3334 mv on two penetrations. 3310 mv on 21/2 deep partial.

Edited April 20, 2009 by C.G.Erickson

[Mobius]

Compare it to the 88 projectiles for 3000 + velocities vs targets.

8" @ 0:Two complete penetrations with projectile passing through plate. 3124mv and 3257 mv. Two ABL penetrations. All Projectiles Intact. 3001 mv 3038 mv.

Interesting.

If my ballistic calculations are close 3001fs =range of 1218yd, 3038fs=range of 960yd. (203.2mm)

This a little bit resolves out close to the Yugo table data that Bojan submitted but didn't match the Yugo test results.

 

88mm M43 PaK43

M39 AP: 240mm@100m, 225@500m, 200mm@1000m, 175mm@1500m, 165mm@2000m

If it was ABL based criteria instead of the 50/50 mass behind armor Yugo criteria of a penentration it would explain the difference.

Edited April 20, 2009 by Mobius

[C.G.Erickson]

Interesting.

If my ballistic calculations are close 3001fs =range of 1218yd, 3038fs=range of 960yd. (203.2mm)

This a little bit resolves out close to the Yugo table data that Bojan submitted but didn't match the Yugo test results.

If it was ABL based criteria instead of the 50/50 mass behind armor Yugo criteria of a penentration it would explain the difference.

Uhhhh

 

I think I see some confusion, The figures I mentioned above are TEST VELOCITIES, not SERVICE VELOCITIES. TEST VELOCITIES above and beyond the normal combat velocities fired in battle. Subtract between 200 to 300 fps for normal velocities fired from a cannon in combat use. For the T-33 projectile. They fired it at German Velocities to test projectile integrity.

 

The L/71 German velocities were normal combat velocities. For 39-1 Old type...3200fps. For 39/43 New model..the same. For 40/43....3705 fps.which was not tested.

Edited April 20, 2009 by C.G.Erickson

[Mobius]

The L/71 German velocities were normal combat velocities. For 39-1 Old type...3200fps. For 39/43 New model..the same. For 40/43....3705 fps.which was not tested.

Err, 3200? I was using 3280 as my muzzle velocity.

[FkDahl]

The figures I mentioned above are TEST VELOCITIES, not SERVICE VELOCITIES. TEST VELOCITIES above and beyond the normal combat velocities fired in battle. Subtract between 200 to 300 fps for normal velocities fired from a cannon in combat use. For the T-33 projectile. They fired it at German Velocities to test projectile integrity.

 

This makes me wonder about service velocity vs test velocity, or rather how "hot" the loading was for guns and howitzers vs the structural ability of the guns to withstand the pressures involved, on a single and on a repeated basis. How large was the margin of safety in the design of guns? Was it different from country to country (in a WW2 setting), and was there a certain kind of gun more prone to accidents? Getting even more off topic (but this IS TankNet after all) I wonder about the evolution of peak chamber pressures in history through today...

[C.G.Erickson]

Interesting.

If my ballistic calculations are close 3001fs =range of 1218yd, 3038fs=range of 960yd. (203.2mm)

This a little bit resolves out close to the Yugo table data that Bojan submitted but didn't match the Yugo test results.

If it was ABL based criteria instead of the 50/50 mass behind armor Yugo criteria of a penentration it would explain the difference.

Mobius

 

Aberdeen penetration was for the majority of the projectile passing through plate for Naval limit.. What % more than 50% who knows. They differentiated between the two, Army and Navy.

 

Do you have the US TM 1907 ballistic study?

 

C.G.

[Mobius]

Mobius

 

Aberdeen penetration was for the majority of the projectile passing through plate for Naval limit.. What % more than 50% who knows. They differentiated between the two, Army and Navy.

 

Do you have the US TM 1907 ballistic study?

 

C.G.

Two of them. yes.

 

I just reread the part the tells of complete penetration of intact projectile. Then I have no explanation of some differences.

Edited April 20, 2009 by Mobius

[jwduquette1]

PBL also began creeping into Aberdeen testing regime during this same period. PBL was already being utilized for testing aircraft armors at this point in time.

 

ABL was invariably associated with plate capability. COnversely NBL was typically utilzed in testing projectile capability.

Edited April 20, 2009 by jwduquette1

[Mobius]

Cary, you mentioned the tests of 39-1 and 39/43. Was there any differences?