Yu guns vs armor tests of 1960s...

[alejandro_]

Bojan

 

I assume the angle was 0° and the ballistic criterion 50%. Is there any data for the 85mm S-53 gun?

 

Thanks again for that excellent data.

[Guest bojan]

Bojan

 

I assume the angle was 0° and the ballistic criterion 50%.

 

Yes.

 

Is there any data for the 85mm S-53 gun?

 

I don't have them...

[jwduquette1]

Thanks Bojan -- great stuff. This should make the site archives -- if such a thing exists here on TankNet.

 

One last question -- probably a long shot, but what the heck, I suppose it doesn't hurt to ask -- while I have firing tables for many of these projectiles you have described, were impact velocities for any of the tests recorded within the test report\reports? I know you said earlier the guns employed were reasonably new, but still it is always interesting to see limit velocities if they are available.

[Alvaro]

Extraordinary post, Bojan. Thanks.

[Guest bojan]

...One last question -- probably a long shot, but what the heck, I suppose it doesn't hurt to ask -- while I have firing tables for many of these projectiles you have described, were impact velocities for any of the tests recorded within the test report\reports?...

 

Reports I quoted had two part - one was more scientific and most probably included impact velocities, and one "practical" that I have posted. Unfortunetly I have no access to the first part...

[jwduquette1]

Reports I quoted had two part - one was more scientific and most probably included impact velocities, and one "practical" that I have posted. Unfortunetly I have no access to the first part...

399221[/snapback]

 

I suppose it never hurts to ask.

[Mobius]

It is great to see the different guns all tested with a common method and armor type. And real tests not solely based on calculations.

[Przezdzieblo]

Great posts and data.

 

T-34 hull was said to be 350 BHN, rolled plates of T-54A around 290 BHN. What might be the reasons of using softer steel? Economic (too expensive or too hard to made?)? Performance (290 BHN just made it`s job?)?

What were, generally, war experiences with hard steel plates in T-34, was it good enough or tend to crack while hit (too hard then and too britle?)?

Edited December 3, 2006 by Przezdzieblo

[Guest bojan]

...

T-34 hull was said to be 350 BHN, rolled plates of T-54A around 290 BHN. What might be the reasons of using softer steel? Economic (too expensive or too hard to made?)? Performance (290 BHN just made it`s job?)?

 

It apears that 350 BHN steel was just too hard and brittle for stand-alone plates.

 

What were, generally, war experiences with hard steel plates in T-34, was it good enough or tend to crack while hit (too hard then and too britle?)?

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As you may notice only T-34 glacis and side turret cracked "catastrofic armor filure" when hit repetably 90mm T33 AP and HESH rounds... So it apears that 350BHN was way too brittle to handle overmatching rounds.

290BHN rolled armor on T-54 was of good quality and did not crack even when hit repetably, but than again it was not overmatched 2:1 (that would require one of those all poverfull 8" guns )...

Edited December 3, 2006 by bojan

[Paul Lakowski]

It apears that 350 BHN steel was just too hard and brittle for stand-alone plates.

As you may notice only T-34 glacis and side turret cracked "catastrofic armor filure" when hit repetably 90mm T33 AP and HESH rounds... So it apears that 350BHN was way too brittle to handle overmatching rounds.

290BHN rolled armor on T-54 was of good quality and did not crack even when hit repetably, but than again it was not overmatched 2:1 (that would require one of those all poverfull 8" guns )...

399736[/snapback]

 

 

Yes as I recall the very hard plates did alright as long as the attacking projectiles were narrower than the plate thickness. If the t/d overmatched the plate then the tendancy was to shatter, so in that case more ductile plates were prefered over harder plates. The hole point behind the duel hardness plates and triple hardness plates was to try to marry the advantage of the shattering effect of very hard plates with the ductility of the medium hardness plates to get the best of both worlds.

[jwduquette1]

Yes as I recall the very hard plates did alright as long as the attacking projectiles were narrower than the plate thickness.

399763[/snapback]

 

Exactly. I think the original design criteria were something like immunity to either 37mm or 45mm AP (can't recall which) at all ranges, and immunity to 76mm AP at ranges in excess of 1000m. I presume this latter criteria would have been keyed to velocities achievable by Soviet 76mm guns at the time of the original design work.

 

High Hardness, highly sloping armor enhances ricochet potential and increase resistance to high t/d impacts. In essence, I have never really bought into the idea that the T34's armor was somehow inferior because it was high hardness. I think it's a bit more complex than this. I think there was very good reasoning for the high hardness armor at the time of the original design – the design is pre-Barbarossa. And it is not as if the Soviet were incapable of producing RHA at hardness levels that would be more typical of say British or American materials. For example the KV-1's design -- much boxier -- lower sloping armor – it relied upon much softer armor.

 

I think there was a method to the madness, and in the first year of the war the T34's armor performed well and as expected by its designers – i.e. it did pretty well against German 37mm AP and 50mm AP. We can reopen all the talk about turret ring hits and glacis hatch hits and spalling armor -- blah blah blah -- no tank is invulnerable everywhere.

 

Obviously as the war progressed and larger caliber, faster projectiles began being employed by the Germans, the armor on the T34/76 was not up to the task. However, the T34/76 was never designed to take hits from high velocity 88mm guns or high velocity 75mm guns. But as things played out, it would not have mattered much if the armor was high-hardness or homogeneous with lower hardness levels. High velocity 75mm AP and 88mm AP were going to penetrate regardless.

 

Regards

JD

Edited December 4, 2006 by jwduquette1

[Przezdzieblo]

I see, thanks bojan, Paul and Jeff.

 

One more question - HEAT hits that were not fuzed can be considered as glanced off, ricochets, right? Is there any other data (or rather an idea - coz probably bojan shared with all his great data) how many KE rounds that did "not penetrate", were ricochets, how many penetrated armour without perforation, and how many perforated with too less mass of projectile, to be registered?

Edited December 4, 2006 by Przezdzieblo

[Guest bojan]

...how many KE rounds that did "not penetrate", were ricochets, how many penetrated armour without perforation, and how many perforated with too less mass of projectile, to be registered?...

399997[/snapback]

 

Only thing I have is that in case of T-54A glacis vs 90mm T33 AP fired from 90mm M36 gun (M-47 Patton) all rounds ricosheted.

[Alvaro]

Reported hardness of 350 BHN for T-34 85 is not too much for Russian T-34 standards. That hardness level even fails into German early war specifications for 30-50mm test plate thickness: 323-368 BHN.

 

It is also possible that during late war T-34 armor reduced its hardness level, I don't know. Anyway, both 90mm cast mantles of Sherman and T-34 were penetrated at the same distance with PaK40 AP ammo, 1000m in these tests. And here hardness difference is very big. I suppose that high hardness armor, because it required lower tempering temperature, was easier or faster to produce. And softer armour was less prone to spalling. And perhaps also requeriments of aleations of strategic metals were different. What I mean is that the thinking behind of armour characterists was not only based upon prenetration resistance and other factors may had a place here.

 

Best regards.

[Guest bojan]

... both 90mm cast mantles of Sherman and T-34 were penetrated at the same distance with PaK40 AP ammo, 1000m in these tests...

400124[/snapback]

 

However renges were drasticly different in case of 57mm ZiS-2... Don't have an exact ranges but Sherman mantle was claimed to be penetrated at much greater range then T-34 mantle was penetrated. So it apears that high hardness armor worked well vs smaller non-caped AP rounds (57mm BR-271), but did not make a diferance vs larger capped AP rounds (PzGr.39).......

Edited December 5, 2006 by bojan

[jwduquette1]

Reported hardness of 350 BHN for T-34 85 is not too much for Russian T-34 standards. That hardness level even fails into German early war specifications for 30-50mm test plate thickness: 323-368 BHN.

 

It is also possible that during late war T-34 armor reduced its hardness level, I don't know. Anyway, both 90mm cast mantles of Sherman and T-34 were penetrated at the same distance with PaK40 AP ammo, 1000m in these tests. And here hardness difference is very big. I suppose that high hardness armor, because it required lower tempering temperature, was easier or faster to produce. And softer armour was less prone to spalling. And perhaps also requeriments of aleations of strategic metals were different. What I mean is that the thinking behind of armour characterists was not only based upon prenetration resistance and other factors may had a place here.

 

Best regards.

400124[/snapback]

 

Hi Alvaro:

 

Your argument would suggest that T34's produced before the war -- and before all of the motivating factors you are suggesting have had a chance to come into play into both design and manufacturing -- would have been produced of steel at hardness levels more akin to US and British Steel. I have not seen any evidence of this as yet. Have you? Was the armor steel on pre-war T34's being produced at much lower hardness levels – like in the 240 to 270BHN range? If the answer is yes, than I would tend to agree with your argument about extraneous factors driving the sort of armor being employed on the T34. If the answer is no, than I see no reason why we should think that the choice of hardness was not based upon ballistics and the protection criteria established for the original design – i.e. immunity to 37mm/45mm projectiles at all ranges. Again, high hardness provides a ballistic advantage against high t/d impacts. It promotes ricochet when used in combination with high obliquity plate layout. Why shouldn’t I believe that Russian designers were specifically taking advantage of these aspects of high hardness armor given the protection criteria required of the design?

 

Based upon my own research it seems clear to me that as obliquity increases, the optimum plate hardness which provides the most efficient ballistic qualities also increase. Again this is specific to higher t/d ratio impacts. t/d of say 1 or 1.1 to say 1.4. Schematically, it looks something like what I have portrayed below. Boxier designs – ala -- the KV-1 should be utilizing lower hardness armor. Highly sloping designs -- ala T34 -- in which the anticipated attacking caliber envelopes a certain range of t/d, should be utilizing higher hardness armor.

 

I don’t doubt that armor plate quality declined as the war progressed, but this is a different issue.

 

Best Regards

Jeff

 

Edited December 5, 2006 by jwduquette1

[Alvaro]

Hi Jeff:

 

Yes, I agree that T-34 was designed from the beginning to withstand 37mm guns at any range and 76mm at 1000m. But also, it was designed from the beginning to be cheap and easy to manufacture tank in large numbers, as during its desing phase in Russian the war was considered inminent.

 

High hardness plates were well studied before the war. And I am nearly sure that the relation between tempering temperature, hardness, ballistic limit and protection limit was not a secret for WWII designers of any power.

 

If T-34 armor was a bit less hard it would be at least so resistant to 37mm guns, as less prone to spalling. Memories of T-34 tankers also talk about the spalling of their armour. So it must be any design reason to make it very hard.

 

KW tanks were not designed by the same team and followed a different path. They begun with thick plates at moderate hardness, classical style, but later, the following design, IS tanks went to thick plates but very high hardness. Why? After the war this practice was abandoned, it seems.

 

Russian tanks designers worked in competitive teams of several projects al the same time. At the end, the best will be selected for production in a comunist state. So their points of view surely were different than the others. They had to make tanks that were easy to be produced with limited technology, in big numbers and at the same time perform well. In that situation some have to be sacrified to succeed.

 

Best regards

Alvaro

Edited December 5, 2006 by Alvaro

[jwduquette1]

Hi Jeff:

 

High hardness plates were well studied before the war. And I am nearly sure that the relation between tempering temperature, hardness, ballistic limit and protection limit was not a secret for WWII designers of any power.

400549[/snapback]

 

Hi Alvaro:

 

I disagree with the above -- at least from the perspective of high hardness + high obliquity. Sure optimized hardness levels were developed in the United States, Germany, and the UK – presumably the USSR as well. But it was not being done from the perspective of highly sloping armor tests – not pre-war anyway. Most tanks in the initial portion of the WWII were rather boxy designs in which low hardness rolled armor or face hardened armors would out-perform high hardness armor.

 

Prior to WWI (World War One), and well into WWI Armor and armor piercing projectiles -- naval armor and naval projectiles as there were no tanks running around until mid to late war -- were typically tested at 0-degree obliquity. Effects of slope were generally extrapolated. No one was anticipating the sorts of engagement ranges that would occur at Falklands, Dogger Bank and Jutland. Shoots were originally anticipated to be in the 10000-yrd to 12000yard range where impacts would typically be occurring on vertical surfaces at relatively low obliquities. So there was not much motivation to test either plates or projectiles at even moderate obliquity level. After Jutland and the poor performance of shell fire against heavy cemented armor (belts, barbettes, turret facial armor etc), folks began looking at obliquity effects a little harder. People wanted to determine how projectiles and bursting charges were actually performing against moderately sloping armor. Armor and projectiles began being routinely tested at both 0-degrees and 30-degrees.

 

Prior to WWII there was really very little precedent as far as what would work best for tank armor and what would prove to be important and what would prove to be evolutionary dead ends. There were some minor lessons learned in the Spanish Civil War. But this event had minimal importance relative to where tanks and projectiles were to progress by the end of WWII. Only in the latter parts of WWII and post WWII do you begin to see more and more testing being “routinely†conducted at obliquities in excess of 30-degrees. At least in the United States and Great Britain and presumably German if the Panther is any indication.

 

On the other hand the highly sloping armor on the T34 implies the Soviets had a bit of a jump as far as understanding in the effects of very highly sloping armor on AP projectiles. And again the average AP calibers most typical of this time were much smaller caliber than they would become by the end of the war. Optimization based upon present and near future ballistic threats.

 

If T-34 armor was a bit less hard it would be at least so resistant to 37mm guns, as less prone to spalling. Memories of T-34 tankers also talk about the spalling of their armour. So it must be any design reason to make it very hard.

400549[/snapback]

 

Again – optimal performance is keyed to t/d, obliquity, plate hardness as well as the anticipated ballistic threat. If I had a crystal ball I could foresee all possible threats in the future and design accordingly. But they didn’t teach us clairvoyance in Engineering School. I’m guessing it wasn’t in Soviet school curriculums either. Arm chair quarterbacking is a bit of a snooze. You can’t arbitrarily separate one parameter from another and expect the same performance level. Any armor will spall – High Hardness or not. Laminations and inclusions created during the rolling process. In fact many modern tank and PC designs now include spall liners. So yeah, as I already said, I can lay my hands on a story or two in which a T34 crew mentions spalling. I can lay my hands on a story or two about turret ring hits, etc. But does this establish precedent or tell us what the norm is? I think the effectiveness of the T34’s design and its armor is played out in the rush on the part of the Germans to start fielding higher velocity and larger caliber guns on their main battle tanks after Barbarossa. After which it wouldn’t have mattered if the plates were BHN200 or BHN350.

 

KW tanks were not designed by the same team and followed a different path. They begun with thick plates at moderate hardness, classical style, but later, the following design, IS tanks went to thick plates but very high hardness. Why? After the war this practice was abandoned, it seems.

400549[/snapback]

 

KV-1s were designed to meet a different set of threats, as were the IS tanks. Again you can’t arbitrailly separate the how’s and whys of the design philosophy. By the time of the IS tanks we may very well be looking at very poor manufacturing quality – and wasn’t this thing made of high hard cast armor. Cast armor is ballistically inferior to RHA. By dragging IS tanks into the fray you’re jumping the gun again and playing arm-chair quarterback.

 

You need to put yourself in the shoes of what was known during the design period encompassing the original T34 – pre-Barbarossa. What was the vehicle expected to do; what ballistic threats were anticipated within the design at the time of the design – not what some vehicle four years into the future was doing. Again the T34 performed remarkably well during the first year of the war against German 37mm and 50mm AP. It was designed to do this, so the design – to include the high hardness armor – was a great success.

 

As to High-Hardness armor being some sort of an evolutionary dead end – I again disagree. It is quite often utilized these days, albeit it in thinner plates with expectations of resisting small arms delivered AP up thru medium caliber AP – 20mm to 35mm stuff.

 

Russian tanks designers worked in competitive teams of several projects al the same time. At the end, the best will be selected for production in a comunist state. So their points of view surely were different than the others. They had to make tanks that were easy to be produced with limited technology, in big numbers and at the same time perform well. In that situation some have to be sacrified to succeed.

400549[/snapback]

 

I was born and raised an American capitalist dog, and damn proud of it. Competition in design work, manufacturing work, construction work etc etc etc is ingrained in my culture. In my mind it’s a very good and healthy thing. Efficiency in design and the manufacturing process are of course all pluses. But efficiency in design and efficiency in the manufacturing process are not in and of themselves indications of a poorly made end product. So if the Russians had competing design teams – more power to um’. They’ll turn themselves into capitalists yet. Competition tends to optimize results – not always – but most of the time. I mean you can’t please all of the people all of the time.

 

Very few can convince me, alas. I don't mean to say I'm being obstinate here – but I’m being obstinate here. I have looked at the problem, mapped out a fairly huge amount ballistic data from the period, and made up my mind. If you have done the same and drawn a different conclusion, so be it. Unless you have something new to offer other than rehashing what’s already been mulled over and argued over at length on the old Yahoo Forum, than all we will succeed in doing here is irritating each other At this point I’ll drop it, as I think the best we can do now is agree to disagree.

 

I yield the floor to you – I promise not to rebut your final say on the matter.

 

Best Regards

Jeff

Edited December 6, 2006 by jwduquette1

[Alvaro]

Hi Jeff:

 

I don’t see any reason for irritation here . I do not pretend to convince anybody. I am just trying to share my opinions. Perhaps my English is not good, but please, do not answer to what I didn’t mean. I never defended, and neither do it now, hypothesis of flawed T-34 armor plates, turret ring hits, etc. T-34 was a success, no doubt about this. And not only was well designed from the classic firepower/protection/mobility triangle, but also from a strategic point of view of easy mass production in a country with quite less industrial power than Germany, for example.

 

Prior WWII, France was a leader in armor technology and research, which was halted during German occupation, of course. So it is reasonable to think that technical publications of French Army just after the war reveal just their knowledge in 1940. They knew what happens when armour hardness was increased up to very high hardness levels. They knew that the perforation limit had two maximum levels for a given plate/projectile. One in the range of, let’s say, normal hardness and the other in the range of very high hardness. Between them there was a drop in the perforation limit. What I say is that French knew that very high hardness armor had similar perforation limit than normal hardness armour.

Also they knew that the protection limit of the armour, where there is no internal damage from projectile/spalling, was optimum in the normal hardness range. But when the hardness was progressively increased, the protection limit decreased also progressively, without any improvement in the very high hardness range.

So, it is possible that Russian designers also know this in 1940 and chose high hardness armour because was easier to produce for them, with the only drawback of more spalling, and the same perforation limit as normal hardness armour.

Or perhaps you are right, and high hardness armour at high angles of attack was even better that normal hardness armour. If so, then why to make the whole turret and hull sides also of high hardness armor? They were not very much sloped…

 

Best regards

Alvaro

Edited December 6, 2006 by Alvaro

[Guest bojan]

...If so, then why to make the  whole turret and hull sides also of high hardness armor? They were not very much sloped…

400763[/snapback]

 

Upper side hull was sloped at 45deg - reasonable slope to give good protection.

Side turret armor was actualy part of the FRONT turret protection - when you look at T-34 model 1940 or 1941 front turret much of visible armor are actualy side turret plates... Same aproach was used with King Tiger, M-47 and M-60...

Also one of the most important aspect of protection to the Soviets was at 30-45deg from the straight-on (they found out that majority of the hits are from those angles) - in that case hard turret and hull side armor makes lot of sense...

[jwduquette1]

Hey Alvaro:

 

I don't suppose you have had any contact with Miles K. over the last year or two. I thought he was going to further develop his work with the ARTKOM Equation. However, I've seen nothing new from him in AFV News for some time now.

 

Best Regards

Jeff

Edited December 6, 2006 by jwduquette1

[Alvaro]

I don't suppose you have had any contact with Miles K. over the last year or two.

 

Jeff, I didn't have contact with him and I don't know whether he will publish the book he said he was preparing.

 

Best regards

Alvaro

[Guest bojan]

Good news - results of 57mm ZiS-2 vss Sherman and T-34 found...

Post tomorrow, with some very interesting data...

Edited December 10, 2006 by bojan

[Guest bojan]

57mm ZiS-2 firing AP and HVAP

 

Vs M4A3E4 Sherman:

 

BR-271 AP penetrates glacis @ 900m

BR-271P subcaliber penetrates glacis @ 1100m

 

Both rounds penetrate side hull at any efective range...

 

BR-271 AP penetrates front turret @ 900m

BR-271P subcaliber penetrates front turret @ 1100m

 

Both rounds penetrate side turret at any efective range

 

Vs T-34/85

 

BR-271 AP penetrates glacis @ 700m

BR-271P subcaliber penetrates glacis @ 1100m

 

BR-271 AP penetrates upper side hull @ 1500m

BR-271P subcaliber penetrates upper side hull @ 1750m

 

Both rounds penetrate lower side hull at any efective range...

 

BR-271 AP penetrates turret front turret @ 600m

BR-271P subcaliber penetrates turret @ 1000m

 

BR-271 AP penetrates side turret @ 1500m

BR-271P subcaliber penetrates side turret @ 1750m

 

Note parts in ittalic and note that PaK 40 had almost same performances vs both T-34/85 and Sherman turret front and glacis. So it definetly apears that T-34/85 hard armor worked better vs smaller caliber projectiles.

[jwduquette1]

More excellent material Bojan. Thanks yet again for taking the time to post this stuff.

 

Jeff