T44 armor trials 1944

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critical mass
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T44 armor trials 1944

Post by critical mass » 01 May 2019 20:58

http://btvt.info/3attackdefensemobility ... 4_1944.htm

Mid 1944 prototype T44 armor trials vs 75mm Pzgr 39/42 & 88mm Pzgr39/43

75mm 42S grade RHA Front glacis penetrated (PSP) to 815 m/s by 88mm and >870m/s to 75mm( not testable due to structural constructive failure of the plate after a couple of 88mm impacts)
75mm 42S grade RHA side plate at 45deg (PSP) to 536-524 m/s by 88mm (nose plate similar)
Cast side turret (psp) to 509m/s by 75mm and 518m/s by 88mm
Cast Turret at 45deg target and 5-20 der constructive angle (psp) to 746m/s by 75mm

Considerable troubles were experienced with the welding under impact.
Despite the high obliquity, the projectiles generally stayed undeformed with or without nose breakage.
The side hull was not perforated by domestic 76mm Br350 from 100m striking at normal (mv 616m/s)

Assessed vulnerability was
To 75mm kwk42:
75mm at 60 deg( glacis or side at acute angle): <700m
75mm at 45deg (nose plate or side at acute angle): 1000m
75mm side at 30 deg target angle: 2100m
Turret at45 deg: 1300m
turret hits within 30deg: 1810m

To88mm kwk43:
75mm at 60 deg (glacis or side plate at acute angle): 2000m
75mm at 45deg (nose plate or oblique side hit): 3500m
any practical range for not acute side Hits
Any practical range for turret hits within 30 deg

I have had it somewhere else but lost the source meantime’s.
Last edited by critical mass on 02 May 2019 19:50, edited 1 time in total.

Yoozername
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Re: T44 armor trials 1944

Post by Yoozername » 02 May 2019 18:16

Nice find. RHA seems to be less protective than the HHA?

critical mass
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Re: T44 armor trials 1944

Post by critical mass » 02 May 2019 19:34

30 and 45 deg figures indicate that HHA (cast) turret armor maybe somewhat better or similar than RHA. There is a certain scatter due to the thickness of the turret varying from 90 to over 105mm, though.Plus, the netto angle is somewhat higher for the turret in all cases.
thats roughly 1.3 cal HHA for the 75mm, so the plate does overmatch the projectile (failure to adiabatic shear is less likely).
notice that the trials are from summer (less brittle tendencies, yet the cast turret exhibits brittle failure types)
generally, both RHA and HHA are somewhat inferior at highly oblique impact.

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Mobius
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Re: T44 armor trials 1944

Post by Mobius » 02 May 2019 21:54

Looks like the Russian now have the MV of the 75mm model 40 as 750 m/s.

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Re: T44 armor trials 1944

Post by Yoozername » 02 May 2019 23:39

The test seems to only mention the German weapons as far as 'Panther' and 88mmL71 I believe. The velocity of the Panther weapon is a little fuzzy with them mentioning it measured 680 M/s (?), possibly a worn weapon and/or a old ammunition exposed to humidity. They also say the 75mm Panther is usually 1000 M/s.
vel.jpg
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Peasant
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Re: T44 armor trials 1944

Post by Peasant » 04 May 2019 13:05

critical mass wrote:
02 May 2019 19:34
30 and 45 deg figures indicate that HHA (cast) turret armor maybe somewhat better or similar than RHA. There is a certain scatter due to the thickness of the turret varying from 90 to over 105mm, though.Plus, the netto angle is somewhat higher for the turret in all cases.
thats roughly 1.3 cal HHA for the 75mm, so the plate does overmatch the projectile (failure to adiabatic shear is less likely).
notice that the trials are from summer (less brittle tendencies, yet the cast turret exhibits brittle failure types)
generally, both RHA and HHA are somewhat inferior at highly oblique impact.
Last time you were saying that cast armour is inferior under oblique impact, now it's the other way around, so which is it?

What "brittle tendencies"? The document explicitly says:
На литой башне первая трещина наметилась после 18 попаданий в башню, сквозная трещина получилась после 23 попаданий. Всего в башню дано 40 попаданий, причем ни на одном из них не образовалось отколов, что свидетельствует о хорошем качестве литья (фото №№ 32 и № 33).
On the cast turret the first crack appeared after 18 hits, a through crack after 23. In all there were 40 hits made and none of them generated spalling,which indicates a good quality casting.
Now, you might be talking about this part:
На всех деталях корпуса наблюдается большое количество окалины, а на литых деталях – также земли.

При снарядных попаданиях окалина и земля отлетают внутрь корпуса и могут привести к ранениям экипажа (фото № 35).
On all parts of the armour there is a large amount of mill scale present and on the cast parts of earth as well.
When a shell is hitting the armour the mill scale and earth fly inside the hull which can lead to injury of the crew.
The only part of that shows signs of brittle fracture is the lower glacis, but the description says it cracked only once along the crack showing a rusted surface, which I take means it appeared before, during the production, not from the ballistic attack.

Image

I see a lot of welds failing in the report but the armour itself seems good.
Yoozername wrote:
02 May 2019 23:39
--- snip ---
I think you meant "860m/s" ?

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Re: T44 armor trials 1944

Post by Yoozername » 04 May 2019 15:17

Yoozername wrote: ↑
02 May 2019 23:39
--- snip --- I think you meant "860m/s" ?
Yes, 860 M/s.

Clearly, they are measuring velocity. The Germans state a nominal 950 M/s in most documents for the Panther. 860 M/s would be ~ 10% less. The Soviets claim a 'normal' velocity of 1000 M/s for the 'Panther' gun.

Measuring velocities, and varying powder charges to simulate velocities, as other nation's did, would not be beyond the Soviets capabilities by summer of 1944.

It is actually a fascinating report. Hits by 88mm high velocity HE rounds seem to be devastating. Whether these are set on super-quick, or delay, might be interesting. I have read of Tiger I crews using this tactic against side armor of enemy tanks. One can imagine what a Soviet 122 HE round could also do.

It would have been interesting if they included the Pak 40, KWK 40, etc. in the study, but it seems they only had one hull. I suppose one can extrapolate from the Panther gun.
The tested T-44 75 mm trophy shots had a reduced speed not exceeding 860 m/sec. Such reduced speed of shells can be caused by application of gunpowder and shells of various parties and years of manufacture.

At subsequent tests of other objects of the same gun shots from other parties received speeds up to 1000 m/sec.

Therefore, the initial speed of 75 mm cannon Tank "Panther" adopted 1000 m/sec. And all distances are determined based on this initial velocity.

The tests were carried out by armour-piercing shells in full combat equipment with the given charges from a distance of 100 m . It should be noted that in a significant percentage of cases German armor-piercing shells are not torn and work like a bolt (Photo № 1).

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Re: T44 armor trials 1944

Post by critical mass » 04 May 2019 15:42

Brittle tendencies are shown in photo#32-33.
impacts #55/57.
These were called satisfactory because the turret did not collapse structurally. Though they are examples of brittle impact behavior.

Structural nonsense was the use of brittle, high hardness plate for mine protective bottom plating- with expectable results...

impact angle on Cast 90-105mm turret was 32.4deg to 35.5deg netto when striking at 30 deg
and 15-20deg when striking perpendicular.
I'd argue that the cast armor therefore was inferior to the RHA on account of its larger thickness (90-110mm as opposed to 75mm).
K=1715 vs pzgr39 at normal nominal
K=2165 vs pzgr39 at30 deg nominal
K=2450 vs pzgr39 at 45 deg nominal

vs 75mm sides:
K=2350 vs pzgr39 at 30 deg
K=3165 vs pzge39 at 45deg

this is also supported by the commissions findings, claiming that the turret is defeated by 75mm kwk42 at all angles at 1300m or closer while the 75mm hull protects at above 1000m with 45 deg target angle.I therefore, have to correct my earlier comment based on single datapoints.
The medium hard 42S is approx as good or even slightly better as german test armor at 30 deg but grossly inferior to it at 60 deg impact. The 75mm sides could be penetrated by 75mm under 600m from extremely acute 60 deg impact, were official german penetration of 75mm was only 60mm at 100m...
Last edited by critical mass on 04 May 2019 16:11, edited 3 times in total.

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Re: T44 armor trials 1944

Post by Yoozername » 04 May 2019 15:46

critical mass wrote:
02 May 2019 19:34
30 and 45 deg figures indicate that HHA (cast) turret armor maybe somewhat better or similar than RHA. There is a certain scatter due to the thickness of the turret varying from 90 to over 105mm, though.Plus, the netto angle is somewhat higher for the turret in all cases.
thats roughly 1.3 cal HHA for the 75mm, so the plate does overmatch the projectile (failure to adiabatic shear is less likely).
notice that the trials are from summer (less brittle tendencies, yet the cast turret exhibits brittle failure types)
generally, both RHA and HHA are somewhat inferior at highly oblique impact.
My thought was actually the glacis. On a T34, the 45mm sloped armor is very hard armor. On the T-44, the 75mm armor is similarly sloped, thicker than a T34, yet is 'RHA' that apparently does not give as much protection as its increased thickness might. The findings seem to conclude it needs at least 90 mm to give protections from the two threats under investigation ('Panther' and 88mm L71 weapons). Would very hard 75mm armor have been better for the glacis?
The upper frontal part of the 75 mm medium hardness armor is tilted at an angle of 60 °, the lower frontal part of the 75 mm high hardness armor is tilted at an angle of 30 °.
The test does not really mention the 'lower frontal part' being tested?

The T-44 design is clearly getting away from many T34 features. Side armor seems to be dropping sloped armor for vertical thicker armor, perhaps in hopes of simplifying mass production. Oblique hits by the threats are tested against it.

While the penetration criteria may be different than the Germans, is anyone else amazed at the ability to hole this armor, given the angles, seems to show?
Last edited by Yoozername on 04 May 2019 16:10, edited 1 time in total.

critical mass
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Re: T44 armor trials 1944

Post by critical mass » 04 May 2019 15:55

Hard armor is inferior in glancing hits to ductile armor, very generally. The problem may have been to make good quality 90mm RHA with the tech at hand. In the early 1950s, this was achieved by making the glacis softer than the side and by putting high% molybdenium to combat temper brittleness in 100mm RHA plate.

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Re: T44 armor trials 1944

Post by Mobius » 04 May 2019 16:03

Doesn't the glacis look like it consists of several thinner panels (maybe ~45mm thick and ~400mm wide) sandwiched between two other panels (about 10-15mm thick)?
If so it would not be well suited to being welded to the lower solid plate.

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Re: T44 armor trials 1944

Post by Yoozername » 04 May 2019 16:16

This view seems to show the glacis plate caved backwards. It seems to be a solid plate? Maybe a seam on the side. Perhaps that guy at 'Archival awareness' can explain how great it is?
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critical mass
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Re: T44 armor trials 1944

Post by critical mass » 04 May 2019 16:18

Glacis was solid 75mm. they required an increase in armor thickness to >90mm all around (turret 130mm minimum), to provide some resistence to 75mm. Dont know if that actually materialized- it would have requiref a heavier vehicle?
Issues were encountered by 88mm HE exploding against cupola and mantlet, taking the ordnance out of seevice

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Re: T44 armor trials 1944

Post by Avalancheon » 07 May 2019 12:31

critical mass wrote:
01 May 2019 20:58
To88mm kwk43:
75mm at 60 deg (glacis or side plate at acute angle): 2000m
75mm at 45deg (nose plate or oblique side hit): 3500m
any practical range for not acute side Hits
Any practical range for turret hits within 30 deg

I have had it somewhere else but lost the source meantime’s.
Fascinating results. That high hardness armor really doesn't fare too well against capped projectiles...

Would the 88mm kwk 43 have been able to deal with the glacis of the IS-2? Specifically, the 1944 model with 100mm armor sloped at 60 degrees?

Its only 25mm thicker than the T-44 glacis, but theres lots of people who assume the IS-2 was immune. (Of course, the turret face was still vulnerable from long range)

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Re: T44 armor trials 1944

Post by critical mass » 07 May 2019 19:56


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