Yu guns vs armor tests of 1960s...

[jwduquette1]

I'm not looking so much at t/d but at energy. 

Could be a case of shatter gap in reverse.  Where it's the armor that shatters.

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I'm still not sure I am tracking with what it is you are doing, or why you feel like the BR271 tests imply the T34 glacis is doing some sort of reverse shatter gap.

[jwduquette1]

Moreover the kinetic energy levels for BR271 perforating 45mm of armor at 0-degrees is about 0.380MJ. Same projectile perforating 45mm at 60-degrees is about 1.26MJ. Ratio is about 3.31.

 

BR271 perforating 64mm of armor at 0-degrees is about 0.667MJ. At 47-degrees perforating 64mm is about 1.19MJ. Ratio is about 1.79.

 

How does this lead to the conclusion that the T34s glacis is shattering?

[jwduquette1]

Another question for Bojan.

 

With respect to the Yugoslavian 85mm AP trials vs Sherman and T34/85 -- were the tests conducted with BR-365, or BR-365K? The former includes a windscreen according to East German Army range tables for their T34/85s. So the velocity drop for BR-365 is much less than BR-365K. To back out limit velocity I need to know which is the appropriate velocity decay figures to use.

 

85mm BR-365K

 

85mm BR-365

[Guest bojan]

BR-365, APBC-HE-T in full nomenclature...

I am not sure if BR-365K was used at all by Yugoslavia.

[Mobius]

Is the BR-365K APBC or just AP?

The date on the shell seems to say 1-45 for th BR-365K. I wonder why it was produced so late in the war?

[jwduquette1]

BR-365, APBC-HE-T in full nomenclature...

I am not sure if BR-365K was used at all by Yugoslavia.

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Thanks Again Bojan.

[jwduquette1]

Is the BR-365K APBC or just AP?

The date on the shell seems to say 1-45 for th BR-365K.  I wonder why it was produced so late in the war?

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Hey Steve:

 

BR-365K is solid shot -- straight up AP with a base charge. Although you'll note the fragmentation grooves right below the base of the ogive, ala flat nosed APBC. There is no windscreen on 365K. It appears in East German reference materials for their T34/85 well into the 1960's. Perhaps it was being used as a training round. An aside, but 100mm BR-412B was still being used in Iraqi T54/T55s during Desert Storm -- probably OIF as well.

 

BR-365 is capped with a windscreen, although I don't think I have ever seen a reveal of the projectile noses section -- whats the nose look like beneath the windscreen. I assume it is traditional blunt-nose like BR-412B, but I don't know this for certain.

 

Jeff

[jwduquette1]

85mm BR-365K AP

 

[jwduquette1]

This was a source of confusion for me some time back as the projectile shown below was identified in a US Army Foreign Ordnance Manual as BR-365 (no “K”). I enquired with a Dr. Arthur Volz on the subject several years ago. He’s was some sort of expert for the US Army on Soviet Equipment back in the 1960’s and 1970’s. Retired now -- but I have come across his name on various intelligence reports on Soviet armor from this period -- now unclassified. Anyway, he indicated the Foreign Ordnance Manual misidentified the projectile in the attached image, and that it is actually another form of BR-365K.

 

 

Compare this image with that of the East German Army schematic of BR-365 that I posted above. Very different looking nose between the two projectiles.

 

We may have had this discussion on the Yahoo Tankers forum sometime back, but I wanted to address this now as invariably someone will post the Foreign Ordnance Manual image and proclaim Eureka!

[Mobius]

Hey Steve:

 

BR-365K is solid shot -- straight up AP with a base charge.  Although you'll note the fragmentation grooves right below the base of the ogive, ala flat nosed APBC.  There is no windscreen on 365K.  It appears in East German reference materials for their T34/85 well into the 1960's.  Perhaps it was being used as a training round.  An aside, but 100mm BR-412B was still being used in Iraqi T54/T55s during Desert Storm -- probably OIF as well.

 

BR-365 is capped with a windscreen, although I don't think I have ever seen a reveal of the projectile noses section -- whats the nose look like beneath the windscreen.  I assume it is traditional blunt-nose like BR-412B, but I don't know this for certain.

 

Jeff

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I have a print out of an old Russian Battlefield table of these rounds and the BR-365 is listed as (APHE) and the BR-365K as (APBC).

[jwduquette1]

I have a print out of an old Russian Battlefield table of these rounds and the BR-365 is listed as (APHE) and the BR-365K as (APBC).

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Eureka! you found it. Do they still list it that way

 

From Svirin's booklet of Soviet WWII Tank Armament...pretty much copied verbatim by RBF. Looks like what the East German Range tables are calling BR-365. The NVA RTs show BR-365 to be ballistically more efficient -- i.e. much less drag than the BR-365K.

 

From Svirin's booklet -- 85mm BR-365

 

East German Range Tables -- 85mm BR-365

Edited December 15, 2006 by jwduquette1

[Guest bojan]

...An aside, but 100mm BR-412B was still being used in Iraqi T54/T55s during Desert Storm -- probably OIF as well...

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Not just Iraq - Yugoslavia pacticly newer replaced M65 (local BR-412B copy), only in early 1999. M98 APFSDS began replacing it, but replacement is still not complete...

[Guest bojan]

Re: jwduquette1 - Please corect me if I am wrong - looking at your BR-271 penetration table I see that BR-271 in the tests performed poorer then expected?

[jwduquette1]

Re: jwduquette1 - Please corect me if I am wrong - looking at your BR-271 penetration table I see that BR-271 in the tests performed poorer then expected?

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I don't know what you mean. The 0-degrees and 30-degrees penetration curves vs. range are what are often reported for BR-271.

 

The 47-degree data point is pulled directly from the results you posted for the tests vs. the Sherman M4A3E4 test results.

 

The 60-degree data point is pulled directly from the results you posted for the Yugoslavian tests vs. the T34/85.

[jwduquette1]

You mean this figure?

 

[Mobius]

Eureka!  you found it.  Do they still list it that way 

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Yes.

http://web.archive.org/web/20050412075200/....ru/t34_85.html

 

I saw something on a tables at the Russian Battlefiled .

http://www.battlefield.ru/index.php?option...d=149&Itemid=74

Edited December 15, 2006 by Mobius

[jwduquette1]

Yes.

http://web.archive.org/web/20050412075200/....ru/t34_85.html

 

I saw something on a tables at the Russian Battlefiled .

http://www.battlefield.ru/index.php?option...d=149&Itemid=74

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The first URL you posted clearly shows BR-365 being the same capped projectile as what I have already indicated. Look at the bottom of the page. The image is taken directly from Svirin’s work on Soviet Tank Artillery. A ballistic cap makes the projectile “APBC”. BP-365 mit leuchtspur und ballistischer haube.

 

BP-365K is uncapped – no ballistic cap – no windscreen. Mit Leuchtspur und ogivalem Kopf. No cap – therefore AP.

 

Both have bursting charges so you can add an ”HE“ to both if you like.

 

Are you really arguing that BR-365K is capped?

[John_Ford]

Bojan, Was there ever a HEAT round developed for the 88M L56?

[jwduquette1]

Bojan, Was there ever a HEAT round developed for the 88M  L56?

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I'm not Bojan, but a HEAT round was developed for the 88mm Flak18/36/37

 

8,8cm HL.Gr.39

[jwduquette1]

I’m not sure I can make it any clearer than this. These are the images that typically float around for the BR-365 and BR-365K. The image outlined in pink is – at least in my mind -- the logical disconnect.

 

An uncapped projectile is being identified in the old US ARMY manual on of Foreign Ordnance as both BR-365 and BR-365K (these are the two upper left images). But again, in both cases The US Army Ordnance Manual identifies BR-365 AND BR365K as an “uncapped” AP-HE projectile, not APBC-HE.

 

Conversely Svirin and an East German manual on the T34/85 identifies the BR-365 as a capped projectile – APBC-HE. Furthermore the East German manual identified BR-365K as an ogival headed AP-HE projectile – uncapped.

 

One of these identifications seems to me to be incorrect. This is what stimulated me sending a letter to Dr. Arthur Volz.

 

My only reasoning for positive ID of which is which is to determine what set of firing tables to use when determining velocity drop, and therefore limit velocities for the various tests Bojan posted.

 

[Mobius]

The first URL you posted clearly shows BR-365 being the same capped projectile as what I have already indicated.  Look at the bottom of the page.  The image is taken directly from Svirin’s work on Soviet Tank Artillery.  A ballistic cap makes the projectile “APBC”.  BP-365 mit leuchtspur und ballistischer haube. 

 

BP-365K is uncapped – no ballistic cap – no windscreen.  Mit Leuchtspur und ogivalem Kopf.  No cap – therefore AP.

 

Both have bursting charges so you can add an ”HE“ to both if you like.

 

Are you really arguing that BR-365K is capped?

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True enough, but look again at Table 4 on the first URL. It s the BR-365K that is listed as APBC and the BR-365 as the APHE.

[jwduquette1]

True enough,  but look again at Table 4 on the first URL.  It s the BR-365K that is listed as APBC and the BR-365 as the APHE.

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And it has never crossed your mind that it's an error?

 

So your contention is that the Yugoslav tests represent uncapped 85mm AP?

Edited December 15, 2006 by jwduquette1

[Mobius]

So your contention is that the Yugoslav tests represent uncapped 85mm AP?

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No.

But it is a little wierd that they would come out with a less advanced round after they had APBC. Maybe the large charge didn't allow it to penetrate vertical armor as well?

 

My whole concern is finding what the Yugoslav's consider the penetration data of the 100mm APBC @ 0°. That way we can compare the relative value of APBC vs olgive shaped APHE against 60° armor. You know who had 10,000 posts on his theory on this subject over at Yahoo Tankers.

Edited December 15, 2006 by Mobius

[jwduquette1]

No.

But it is a little wierd that they would come out with a less advanced round after they had APBC.  Maybe the large charge didn't allow it to penetrate vertical armor as well?

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Why do you feel like the capped version of the round predates the uncapped? I'm thinking the exact opposite, and that most of the WWII shooting was done with ogival AP -- no cap.

 

My whole concern is finding what the Yugoslav's consider the penetration data of the 100mm APBC @ 0°.   That way we can compare the relative value of APBC vs olgive shaped APHE against 60° armor.  You know who had 10,000 posts on his theory on this subject over at Yahoo Tankers.

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Sure -- I think Lorrin based most of his Soviet APBC slope effects on 122mm BR-471B and cross-checked where possible with limited data from other APBC projectiles. But the BR-471B information is probably the most detailed over a very wide range of obliquities -- the famous AMMRC figure.

 

I don't have a problem with his methodology given the level of information he had at the time. But more information has surfaced on APBC trials such as those conducted with BR-412B by the UK, as well as this material Bojan has posted on BR-365 and BR-412B. Part of the reason I am interested in pinning down exactly what was used by the Yugoslavians in the 85mm shot tests.

 

I'm not arguing for the sake or arguing on this matter. I wanna know if the 85mm trials are APBC or AP. From Bojan's description, I'd have to conclude that the round used is capped and therefore probably blunt nosed APBC. We can argue about "K's" or lack of "K's" later. If there is a reason to think the shot trials were done with straight up AP, than I’m not gonna waste my time with any in-depth assessments of the 85mm trials. But I think the Yugoslav 85mm shot trials are blunt nosed APBC.

 

Anyway, I had looked at BR-412B slope effects sometime ago after obtaining UK trials on the projectile. And I think your suspicions are probably justified. As I recall Slope Effects for BR-412B don’t necessarily correlate well with BR-471B. So there is an opportunity -- what with all this new material -- to take a look at several forms of APBC and see how they correlate with Lorrins original work.

Edited December 16, 2006 by jwduquette1

[Mobius]

Why do you feel like the capped version of the round predates the uncapped?  I'm thinking the exact opposite, and that most of the WWII shooting was done with ogival AP -- no cap. 

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Probably because of the "K". What other ammo type had the earliest verison with a "K"? Then there's the fuse model series, Model 8.