Yu guns vs armor tests of 1960s...

[alejandro_]

4 hours ago, Junior FO said:

Instead of opening a new topic I'll add in the results of the 1954 Swiss trials for the 20pdr and US 90mm in here. Incudes various different plate qualities at different angles.

Thank you, those graphs are very interesting and really well presented. Data in one of the graphs is also presented in imperial units (ft/s). It becomes obvious why Western countries moved to 105mm when you look at the results. T-54/55 had 100mm@60°,which is challenging.

[Junior FO]

...

Edited September 23 by Junior FO

[Peasant]

On 8/7/2023 at 12:51 PM, Junior FO said:

Instead of opening a new topic I'll add in the results of the 1954 Swiss trials for the 20pdr and US 90mm in here. Incudes various different plate qualities at different angles.

 

https://ufile.io/5zsm4fbe

 

Durchschlag= penetration

Anschlag=non penetration

neues rohr= new barrel

ausgeschossen= shot out barrel

Wow, amazing info! I'd very much like to discuss this new data, but I dont want to derail this ancient and venerable thread. Would you mind creating a dedicated thread, or should I do it?

[Junior FO]

...

Edited September 23 by Junior FO

[Peasant]

From the "Preliminary Report No.20: Russian T/34" from the brits.

From what I've seen in the documents of the time, the specs for T-34's rolled plates called for Brinell dent diameter of 2,9 - 3,15mm (375 - 444 BHN).

As we can see here, all plates but the glacis meet these specifications.

[DB]

Is the variation across the samples typical for the era?

It's a bit difficult to get a feel for the consistency without knowing how many samples of each plate were measured, and what values a good quality process would yield,. One might assume that the specification range was considered achievable for large scale production, so might be a suitable definition for "good quality".

Presumably the higher hardness for the Russian plate is a design choice, rather than a capability gap.

[sunday]

They could have choose to have a less hard glacis in exchange for more tenacity.

[bojan]

4 hours ago, sunday said:

They could have choose to have a less hard glacis in exchange for more tenacity.

Don't forget that T-34 glacis and upper side hull requirement was protection vs 37-45-47-50mm, and vs those projectile s higher hardness was good thing. Then war started and whole thing just kept staying the same, first not to interrupt production, and second as there was no way to really uparmor T-34 hull and keep it reliable (front wheels were already overloaded in T-34-85 version) there was no point in changing anything about front armor and delaying production..

KV-1s., whose protection scheme was intended vs 75-76mm field guns firing AP, used softer armor plates.

T-34M prototype, whose 60mm@60deg glacis was intended to protect vs 76mm field guns firing AP @ 250m was supposed to have lower hardness armor plate, probably same as KV-1 did.

[sunday]

Dunno, I think the only change needed was a slightly different heat treat of the front glacis armor.

But could be also a failure of quality control.

[bojan]

Also different composition of armor, at least KV-1 used different composition.

QC was all around however, it was noted locally that some WW2 era T-34s were way better made than other. Later, T-34-85M which were acquired in '60s, that passed post-war UKN improvement program were less maintenance intensive to keep in good order than Shermans, while WW2 era T-34-85s were considered more maintenance intensive (I don't have numbers at hand, but If Sherman took X hours,  T-34-85M took 20-30% less time, while WW2 era T-34-85 took about 50-60% more).

Then there was a problem of uneven quality of electrical wiring, but that one plagued Shermans also, through to a lesser degree, and was easier to fix in Sherman due the better "unification of electrical scheme" (whatever was that supposed to mean in the report...).

Then there was a thing, noted with only few* T-34s however that not all parts fitted well (report is incomplete, but it appears that transmission and engine mountings were sort-of non-standard), local estimate was that was due those few tanks being upgraded older tanks (but we know that is false, since no T-34-76 was ever upgraded to T-34-85).

*IIRC 7 of those tanks in 1949, and they were all sent to be used as training tanks until they were no longer operational, after which they were converted to a static training aids.

[sunday]

9 minutes ago, bojan said:

Then there was a problem of uneven quality of electrical wiring, but that one plagued Shermans also, through to a lesser degree, and was easier to fix in Sherman due the better "unification of electrical scheme" (whatever was that supposed to mean in the report...).

I am as much in the dark as you, but perhaps the Sherman used fewer different wire gauges than the T-34s, or the cable harnesses were uniformly laid in the same place in different tanks.

On armor composition, yes, that is a way to change hardness of steel, but heat treating could be used also.

Edited August 18, 2023 by sunday

[DB]

Although I assume it's possible to heat treat the full thickness of plates, I'd assumed that in general it was more a surface treatment - these plates are described as being homogeneous.

Incidentally, I've seen "homogenous" and "homogeneous" used interchangeably and previously assumed that it was an American vs. Real English thing, but apparently not.

https://writingexplained.org/homogenous-vs-homogeneous#:~:text=Is it homogeneous or homogenous,describes similar or uniform characteristics.

[alejandro_]

On 8/18/2023 at 11:58 AM, bojan said:

QC was all around however, it was noted locally that some WW2 era T-34s were way better made than other. Later, T-34-85M which were acquired in '60s, that passed post-war UKN improvement program were less maintenance intensive to keep in good order than Shermans, while WW2 era T-34-85s were considered more maintenance intensive (I don't have numbers at hand, but If Sherman took X hours,  T-34-85M took 20-30% less time, while WW2 era T-34-85 took about 50-60% more).

Very interesting, T-34 quality also varied from one factory to the other. Factory #112 "Krasnoye Sormovo" had reputation for being the worst, and at some point T-34s built in this factory were nicknamed Sormovo;s monsters (or freaks).

Edited August 20, 2023 by alejandro_

[lucklucky]

Any Yugoslav testing of Italian WW2 leftovers like the 90mm gun and the 75mm Obice with solid, EP or EPS rounds?

Edited August 22, 2023 by lucklucky

[bojan]

On 8/22/2023 at 11:57 PM, lucklucky said:

Any Yugoslav testing of Italian WW2 leftovers like the 90mm gun and the 75mm Obice with solid, EP or EPS rounds?

Not that I know, and I doubt it, since main tests were done in the second half of '50s and early-mid '60s and those would be considered of little interest at that moment - Italian 75mm guns of various types were removed from service in the early '50s , declared obsolete sometime before 1958. and fully removed from storage before 1968. - they are not listed in 1968. artillery inventory, and are in "obsolete weapons" category in 1958. one.  Italian 90mm guns were relegated to coastal defense use after early 50s and influx of US 90mm and UK 3.7" AA guns. Those survived until '90s, through they were modified with barrels from US 90mm guns in order to standardize ammo.

 

[lucklucky]

Thanks

[Peasant]

On 12/1/2006 at 2:05 PM, Guest bojan said:

85mm ZiS-S-53 (from T-34/85) firing AP, HVAP and HEAT

Vs Sherman:

 

BR-365 AP penetrates glacis @ 1100m

BR-365P subcaliber penetrates glacis @ 1200m

 

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

 

BR-365 AP penetrates turret @ 1000m

BR-365 AP penetrates turret @ 1250m

 

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

 

Interesting - almost same performances as 75mm PaK save shorter range that BR-365P subcaliber penetrates front turret compared to PzGr.40...

 

BR-367 AP, BR-367P subcaliber and BK-367 were tested also but I have no info about those tests.

I would like to point out that the 85mm AP shell used here is almost certainly the BR-365K. Here is my reasoning:

Quote

S.V. of 1856fps is equivalent to a distance of 1450-1500m for BR-365K shell and ~2600m for the BR-365 blunt shell. Neither of these number match perfectly the data from Yugo trials but one is much closer than the other.

[bojan]

Apparently both BR-365 and BR-365K were in use, despite the fact that early '60s (1962 IIRC) T-34-85 manual note only BR-365. I will try to see if 1969. ammunition inventory listing has 365K, but for some reason that one also does not have some of the ammo that was in use.

[Peasant]

On 9/26/2023 at 6:12 PM, bojan said:

Apparently both BR-365 and BR-365K were in use, despite the fact that early '60s (1962 IIRC) T-34-85 manual note only BR-365. I will try to see if 1969. ammunition inventory listing has 365K, but for some reason that one also does not have some of the ammo that was in use.

I wonder if you have any information that might help me: I have a theory that the BR-365 projectiles were only manufactured during the 1939-1941 time period. As an AA gun's primary role was not anti-tank, they were produced in small quantities just to have a few dozen AP shells per gun for self-defence against heavy tanks (because at the time it was, logically, believed that an 85mm high velocity shell is equally effective against early war tanks with thin armour, regardless of its type AP or HE)

I was able to ascertain that once the war began the production of 85mm AP ammunition was almost entirely halted in favour of 45mm and 76mm AP shells and resumed only in late 1943/ early 1944 when AFVs with guns of this caliber entered widespread service.

So my theory is that the new shells were mostly or entirely the BR-365K model and comprised the entirety of AP ammunition of T-34/85 tanks in 1944-45 (besides APCR).

1) Since neither type of shell could pierce the frontal hull armour of a Panther tank, neither would be favoured.

2) The 80-100mm thick, mostly vertical armour plate on new german tanks, was not face hardened and sharp tipped shells are more effective against it.

3)The shell without a windshield is shorter and therefore easier to load inside a tank.

Unfortunately soviet production numbers for artillery ammunition do not discriminate between specific models, so I dont have a way to prove my theory.

[bojan]

2 hours ago, Peasant said:

....So my theory is that the new shells were mostly or entirely the BR-365K model and comprised the entirety of AP ammunition of T-34/85 tanks in 1944-45 (besides APCR).

BR-365 (not Ks) that were in use in Yugoslavia were all manufactured in 1944-49, but that is based on relatively small sample rounds found in single warehouse in Bosnia. So there was definitely production of original 365 going on in 1944 and later. How much compared to 365K is unfortunately, as you have noted, impossible to find out from sources we have.

Edited September 28, 2023 by bojan

[Peasant]

3 hours ago, bojan said:

BR-365 (not Ks) that were in use in Yugoslavia were all manufactured in 1944-49, but that is based on relatively small sample rounds found in single warehouse in Bosnia. So there was definitely production of original 365 going on in 1944 and later. How much compared to 365K is unfortunately, as you have noted, impossible to find out from sources we have.

Good to know, thanks. Btw, are you sure the shells/projectiles themselves were manufactured in that time period? Because I've seen samples of soviet ammunition/rounds captured in Korea, where a shell manufactured years earlier was assembled into a case years later.

[bojan]

Should be projectiles since ammo must have been reworked at least once by then, and in that case, since primers and propellant was certainly changed date of original manufacture should be one of the projectiles.

Also, another dead end:

On 9/26/2023 at 5:12 PM, bojan said:

Apparently both BR-365 and BR-365K were in use, despite the fact that early '60s (1962 IIRC) T-34-85 manual note only BR-365.  I will try to see if 1969. ammunition inventory listing has 365K...

And drumroll... 1969. ammo inventory has BR-365K and no BR-365. It has every other type of 85mm ammo, including brand new at the time BK-2M and exotics like time fused frag. Now I would really like to see newer T-34-85 manual than 1962., but I have never found one...

Mystery deepens.

Edited September 29, 2023 by bojan