Yu guns vs armor tests of 1960s...

[jwduquette1]

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.

404803[/snapback]

 

Fuze models can be updated as can the geometry of the bursting cavity. Note the change in fuze number even amongst the various hooded BR-365 images I posted. MA-7 and MA-8.

 

Conversely the non-hooded images show MA-5 and MA-8. So I don't think this in and of itself puts a date on the original design of the projectile, nor does it put a ballistic cap on the projectile which is all that is important here.

 

I freely admit that there is something odd here, but this was something I was weirded out by several years ago and ultimately motivated me to track down Arthur Volz and ask him about this. I am obviously not going to convince you of anything here, so you'll have to find your own way to what you think truth might be in this instance.

 

I am going to run with the assumption that the Yugoslavian trials were conducted with what I will call BR-365 APBC-HE -- blunt nose. So when folks see me reference 85mm BR-365 -- I am referring to the 85mm APBC, not 85mm AP.

[jwduquette1]

Regarding your question about 100mm BR-412B, I don't know what the Yugoslavians believed 0-degree penetration to be, however I do have figures for what the East German believed 0-degree penetration to be.

 

Edited December 16, 2006 by jwduquette1

[Mobius]

I freely admit that there is something odd here, but this was something I was weirded out by several years ago and ultimately motivated me to track down Arthur Volz and ask him about this.  I am obviously not going to convince you of anything here, so you'll have to find your own way to what you think truth might be in this instance.  

404817[/snapback]

Not without further information.

But I admit it is wierd. As the 100mm went from olgive shape APHE to APBC, the 122mm went from olgive APHE to APBC. Why was the 85mm round evolution backward?

[Mobius]

Regarding your question about 100mm BR-412B, I don't know what the Yugoslavians believed 0-degree penetration to be, however I do have figures for what the East German believed 0-degree penetration to be.

 

404821[/snapback]

Do you have East German tables of:

 

75mm M40 PaK 40

M39 AP:

 

76mm M1

M79 AP:

 

88mm M43 PaK43

M39 AP:

 

90mm M3A1

T33 AP:

 

?

[jwduquette1]

Not without further information.

But I admit it is wierd.  As the 100mm went from olgive shape APHE to APBC, the 122mm went from olgive APHE to APBC.  Why was the 85mm round evolution backward?

404831[/snapback]

 

I'll admit it is weird that you have this idea that 85mm went from APBC to AP. But as I say, you'll need to find your own way. As for me, I'll run with the assumption that the East Germans could tell the difference between a hooded projectile and an unhooded projectile.

Edited December 16, 2006 by jwduquette1

[jwduquette1]

Do you have East German tables of:

 

75mm M40 PaK 40

M39 AP:

 

76mm M1

M79 AP:

 

88mm M43 PaK43

M39 AP:

 

90mm M3A1

T33 AP:

 

?

404835[/snapback]

 

No. The material I have is only for Soviet Equipment used by the East Germans.

 

Regarding M79, you have Okuns stuff on this projectile. Do you not trust it?

 

I think 30-deg T33 is included in Hunnicutt's material.

 

Here is 0-deg V50 BL(N) for T33:

 

Velocity

2800-fps 6.5" of RHA

2400-fps 5.85"

2000-fps 4.9"

1600-fps 3.65"

1200-fps 2.1"

Edited December 16, 2006 by jwduquette1

[jwduquette1]

if you need associated ranges, vdrop for T33 is a very-very-very mild exponential curve. you can pretty much assume linear between 0-yards and about 4000-yards and be within a percent or two of actual. terminal velocity @ 4000-yards is 1900-fps

Edited December 16, 2006 by jwduquette1

[Mobius]

I'll admit it is weird that you have this idea that 85mm went from APBC to AP.  But as I say, you'll need to find your own way.  As for me, I'll run with the assumption that the East Germans could tell the difference between a hooded projectile and an unhooded projectile.

404836[/snapback]

I don't see where the East German's ability to tell the difference between hooded and unhooded projectile has a bearing on which round came first?

But I do note that if it were an old model round the Soviets produced it as late as 1-45. . And used in the ASU-85. But for their other rounds they discontinued old model rounds. I for one can't explain that

(Maybe some commissar made a political decision not to stop production in his hometown factory.) ;

[Mobius]

Regarding M79, you have Okuns stuff on this projectile.  Do you not trust it?

404838[/snapback]

I have all this data in their home countries tests. I need a Rosetta Stone of common tests to translate it in terms of Yugoslav standards. Edited December 16, 2006 by Mobius

[Guest bojan]

jw. Mobius - 85mm AP round used in Yugoslav tests was definetly BR-365 and it is classed as AP, blunt, with balistic cap, (lit. translation of "pancirni, tupi, sa balistickom kapom").

100mm AP ammo used in tests was BR-412B, also clssed as AP, blunt with balistic cap. (lit. translation of "pancirni, tupi, sa balistickom kapom").

 

IIRC Soviets introduced BR-365K to deal with Tiger's thick vertical armor. Hence sharp nose.

 

85mm caliber was "new" in the time of the WW2 and original ammo developed was APBC.

100mm was a naval design and original BR-412 was a non caped, sharp nosed naval round. Only lated was more-modern BR-412B introduced, and not w/o problems - eg due the 100mm ammo production problems some SU-100 were armed with 85mm guns making a hybrid SU-85M.

[Mobius]

Bojan,

Do you have anything like this:

88mm M43 PaK43

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

M54 subcaliber: 295mm@100m, 270mm@500m, 240mm@1000m, 215mm@1500m, 190mm@2000m

399078[/snapback]

for the 100mm laying around?

[jwduquette1]

jw. Mobius - 85mm AP round used in Yugoslav tests was definetly BR-365 and it is classed as AP, blunt, with balistic cap,  (lit. translation of "pancirni, tupi, sa balistickom kapom").

100mm AP ammo used in tests was BR-412B, also clssed as AP, blunt with balistic cap. (lit. translation of "pancirni, tupi, sa balistickom kapom").

 

IIRC Soviets introduced BR-365K to deal with Tiger's thick vertical armor. Hence sharp nose.

 

85mm caliber was "new" in the time of the WW2 and original ammo developed was APBC.

404899[/snapback]

 

Thanks Bojan. That actually makes a fair bit of sense. Ogival AP will typically perform better against thick slabs of low obliquity armor than blunt nosed AP. Blunt nose should do better against high sloping and low t/d impacts.

Edited December 16, 2006 by jwduquette1

[Guest bojan]

Bojan,

Do you have anything like this:

for the 100mm laying around?

404995[/snapback]

 

Nope.

[jwduquette1]

I'm still curious about how using kinetic energy for any of these shot records posted thus far lead us to a conclusion that the T34/85s glacis is shattering. Or was this just a random drive-by shooting sort of comment?

[Alvaro]

T-54 turret front

200mm cast, curved

 

Range m /theorical pen. mm @0º

PaK43 /600 /220

100mm D10 /500 /162

 

 

T-34 85 turret/mantle

90mm cast, curved

 

Range m /theorical pen. mm @0º

ZIS-3 /250 /81

Pak40 /1000 /105

85mm /1000 / 85

ZIS-2 /600 /103

 

Sherman M4A3 turret/mantle

90mm cast, cuved

 

Range m /theorical pen. mm @0º

ZIS-3 /350 /79

Pak40 /1000 /105

85mm /1000 /85

ZIS-2 /900 /97

 

 

Let’s assume for a while, in order to simplify, that cast curved armor had the same resistance to penetration than flat RHA.

Because target is common, is possible to make some comparisons between these guns and therorical claimed performance: (rounded values)

 

Pak43: -10%

Pak40: -15% (T-34), -15% (Sherman)

100mm D10: +20%

85mm: +5%(T-34, +5% (Sherman)

ZIS-3: +10%(T-34), +12% (Sherman)

ZIS-2: -13% (T-34), -7% (Sherman)

 

If curved cast armour had less resistance than flat RHA, then just add that value to all that percents.

 

So that, what do you think? Can you find a way to explain all this? Perhaps late war German ammunition performed worse than expected? And why Russian ammo were usually understimated?, if they were.

 

Best regards

[Mobius]

Ah, ha. That is why it didn't follow the pattern of the other shells.

 

The UBR-271 is APBC. Blunt nosed with cap. Maybe that is why behaves differently.

 

The UBR-271K is AP solid shot.

http://www.battlefield.ru/index.php?option...emid=65&lang=ru

Edited December 18, 2006 by Mobius

[Kip Swanson]

T33AP penetrates front turret @ 350m

M304 subcalibre penetrates front turret @ 750m

M431 HEAT penetrates front turret

 

T33AP penetrates frontal part of the side of the turret @ 850m

M304 subcalibre penetrates frontal part of the side turret at any practical range

M431 HEAT penetrates frontal part of the side turret

 

All round penetrate rear part of the side turret at any practical range.

389954[/snapback]

 

About a year ago you had posted on the Yahoo Modern Armor Forum that 90mm T33 AP could penetrate The T54's turret front at 450meters. This was followed by a rather lengthy and detailed disscussion on cast armor quality. Now you are saying the T33 could penetrate at only 350m?

[Guest bojan]

About a year ago you had posted on the Yahoo Modern Armor Forum that 90mm T33 AP could penetrate The T54's turret front at 450meters.  This was followed by a rather lengthy and detailed disscussion on cast armor quality.  Now you are saying the T33 could penetrate at only 350m?  

405511[/snapback]

 

That post was from my notes, copied from a document.

This post is from original document.

I made a mistake while copyng it. Sorry for a mistake I made and adding to the confusion...

Edited December 18, 2006 by bojan

[jwduquette1]

About a year ago you had posted on the Yahoo Modern Armor Forum that 90mm T33 AP could penetrate The T54's turret front at 450meters.  This was followed by a rather lengthy and detailed disscussion on cast armor quality.  Now you are saying the T33 could penetrate at only 350m?  

405511[/snapback]

 

I'm sure there is nothing more sinister going here than a transposition error. To put this in perspective, the contrasts in limit velocities for T33 at 350m and 450m is only 20-fps -- ~2725-fps @ 350m and 2705-fps @ 450m. A 20-fps contrast is probably well within the possible statistical error for a set of ballistic trials conducted at either range.

 

I am interested in some of the findings by Alvaro --- particularly the 88mm pak results. Were the M39 AP projectiles German manufactured? You indicated something about the 88mm HVAP round (M54) using an American core. Was M39 manufactured in the US maybe, or Yugoslavia? Or was Yugoslavia not producing large caliber AP at that time?

Edited December 18, 2006 by jwduquette1

[jwduquette1]

One additional question -- a lot of weapons are being fired during these tests. This would entail a fair number of hits on a given vehicle even if the ballisitic limit were being determined with only three or four shots. Do you have any idea how many tanks were actually used as targets during these trials? I would guess that at the time, T54's and T55's as well as M47s were not items you wanted to take out in great quantities and destroy.

[Guest bojan]

...Were the M39 AP projectiles German manufactured?

 

Projectile was. However whole round was not:

Case - original german;

Primer - localy produced copy of the german primer;

Propelant - either US or localy produced licenced version (IIRC reason was that US propelants caused less barrel erosion while retaining same mv);

I am not sure if HE charge in APHE rounds was changed from german to local/US explosives... It was changed in case of HE rounds but not in case of HEAT rounds...

 

You indicated something about the 88mm HVAP round (M54) using an American core.  Was M39 manufactured in the US maybe, or Yugoslavia?

As noted M39 was Yu overhaul of original german PzGr.39.

 

M54 was standard US M304 HVAP (not just core) tuned down for 88mm gun (exactly how it was done I don't know, but I guess that "sabot" part was tuned down, driving bends reinstalled etc.)...

 

Or was Yugoslavia not producing large caliber AP at that time?

405543[/snapback]

 

Localy produced ammo:

76mm ZiS-3: M55 HE, M55 (BR-350B) AP, M74 HEAT

 

76mm M1: M70 HE, M74 HEAT

 

90mm: M71 HE, M74 HEAT

 

85mm ZiS-S-53: M50 (BR-365) AP, M65 (BR-367) AP, M74 HEAT

 

88mm PaK43: M54 HVAP

 

100mm: M65 (BR-412B) AP, M68 (BK-5M) HEAT, M69 HEAT (improved M68)

 

 

Tricky part in determinating if any ammo of US or UK origin was localy produced is that unlike Soviet ammo it newer got local Mxx designation keeping US Mxx or british Mk.xx designations...

 

Anyway interest in full-bore AP ammo was greately reduced after those tests, and some developement was halted as AP in most ocasions failed vs standard treat of the day (T-54/55)... HEAT was seen as universal ammo that could deal with all threats...

[Guest bojan]

Do you have any idea how many tanks were actually used as targets during these trials?...

 

90+ (most probably 95 or 97) T-54A delivered by Soviets.

74 delivered to various units.

11 reserved for training.

So between 10 and 12 available for testing.

 

319 M-47 delivered (

~300 were in service (both active and training) in early '61s.

So ~20 (minus one sent to Soviets) of those to chose. from My guess is that M-47s for testing were choosen among most worn-out examples, like those used for training.

 

T-34 were actual WW2 manufacture, so those were from the original 1944 shipment.

 

599 Shermans delivered.

~500 in service in early '60s.

[jwduquette1]

90+ (most probably 95 or 97) T-54A delivered by Soviets.

74 delivered to various units.

11 reserved for training.

So between 10 and 12 available for testing.

 

319 M-47 delivered (

~300 were in service (both active and training) in early '61s.

So ~20 (minus one sent to Soviets) of those to chose. from My guess is that M-47s for testing were choosen among most worn-out examples, like those used for training.

 

T-34 were actual WW2 manufacture, so those were from the original 1944 shipment.

 

599 Shermans delivered.

~500 in service in early '60s.

405593[/snapback]

 

Thanks. I wanted to make sure they weren't shooting up tanks to this condition and than kidding themselves that they were actually learning something about the armor or projectiles being fired.

 

[Guest bojan]

...I wanted to make sure they weren't shooting up tanks to this condition and than kidding themselves that they were actually learning something about the armor or projectiles being fired...

 

Most probably not. As I have posted previously where plate failed catastroficaly as here it was noted in report (eg T33 AP vs T-34/85) and furter testing was stoped until new target was aquired.

 

I can only confirm that for every weapon vs T-54A glacis, a new plate, manufactured to the specs of T-54A glacis was used - I don't know for the rest of tests but I suspect it was the same...

[jwduquette1]

these are the penetration figures I grabbed from 57mm firing tables and posted several days ago.

 

i added the 57mm penetration figures posted on the RBF web site. RBF site figures are for 90-degree obliquity.

 

http://www.battlefield.ru/index.php?option...=290&Itemid=123

 

not much resemblance between the two sets of figures. not sure what projectiles are being represented by the RBF 57mm figures, but the drop in penetration is considerably more dramatic with range than the firing table data I had posted before.

 

 

 

Most probably not. As I have posted previously where plate failed catastroficaly as here it was noted in report (eg T33 AP vs T-34/85) and furter testing was stoped until new target was aquired.

 

I can only confirm that for every weapon vs T-54A glacis, a new plate, manufactured to the specs of T-54A glacis was used - I don't know for the rest of tests but I suspect it was the same...

405706[/snapback]

 

Thanks. I missed that the first time around. Sounds like the test methodolgy was both careful and methodical. That's good. So we can draw realistic conclusions from the results.

Edited December 18, 2006 by jwduquette1