T-34s driver hatch is back being way to effective

[Henge11220]

It’s your interpretation, it’s pretty funny to first say “normal obliquity” then write NBL, but I’ll humor it.

As the British penetration formula illustrates, the bad hardenability of British armor pretty much negates any benefit of hardness at any angle. While the resistance coefficient for a specified hardness barely changes at the normal.

So, despite the desert heat making every plate fail in a more ductile way, Matilda’s just crack open on clean penetrations.

Soviet’s noticed that the Churchill III breaks apart when hits well under the limit hit the glacis. Maybe this is part of the reason.

[FlipAllTheTables]

@Henge11220

It’s your interpretation, it’s pretty funny to first say “normal obliquity” then write NBL, but I’ll humor it.

The document is quite literally saying that column (8) is the ballistic limit at normal impact. This is not an “interpretation”, the document is stating it. Every column with ballistic limits says “B.L.”, column 8 adds “at N. B.L.” for “at normal, ballistic limit”. Notice how there is a large gap between the N and the BL, almost as if it is not “at NBL”, but rather “at N, BL”. It saying “proof of plate” also correlates to all the other mentions of how “proof plates” were shot at 0 degrees.

Just 2 sections later (section 7) they even specify what the “ballistic limit” is and why they were using it, which is why I’ve been saying it is army ballistic limit because the definition they use is what the US army ballistic limit is.

… and it seemed that the most satisfactory basis of assessment was the ballistic limit. The point at which daylight could be seen through the plate was perfectly definitive, no fragment trap was required, and the differences between the ballistic limit and W/R limit sufficiently small to make conclusions drawn from the ballistic limit to be valid for the W/R limit.

They never specify what “NBL” is, and I’m almost completely certain that the British never used NBL in their own documents, because they have their equivalent, simply called “critical velocity”, which is actually something that is shown on the penetration graphs for the 2 pr. and 6 pr. AP and APCBC shots, specifically saying that the ballistic limit is approximately 40 ft/s below the critical velocity (mind you, that’s 12 m/s, not the 50 you calculated way earlier, but who am I to actually read the document).

March 1944 British Tank School Definition of CV.
British penetration was based on The Critical Velocity (CV) - an average velocity at which a 50% projectile success rate occurs. A projectile success being an impact velocity at which at least 20% of the projectile (or the less subjective “significant proportion of the projectile nose”) passes completely through the plate (as a “free missile”.).

So in their own documents they would’ve never written “N.B.L.”, they would’ve written “C.V.” when
refering to a limit where the round phyisically passes through the plate.

You are the only person that has been doing “interpretations” this entire time. You state something, and every single time I actually look at images you provide, or God forbid I manage to find the actual source of your claims, you are either lying or misenterpreting something that is explained in the document itself (which is probably still just lying).

[Henge11220]

I calculated this section of text?

1800 fps penetration of joint is roughly 50mm (2.84 kg) of resistance at 30 degrees for K2000.

I think you’re not grasping something basic here, even if you add a few % it still performs like garbage.

And using the mount diagram instead of the armor diagram to prove the armor is thicker, when testing gives it resistance ~2/3rds of the thickness you indicated is pretty interesting.

Next, you argued “well there’s holes in the face”.
They didn’t determine the strength of the face by shooting the weakzones or 6 pdr would pen the turret at 1800 f/s velocity.

[FlipAllTheTables]

I found some extra images of this tank, since you have oh so selectively shown only the ones you wanted.

I noticed that on the first image you showed, in the other topic, there are numbers that mark the different hits, however there is one number that is written differently from all the others.

That, right there, is the measured thickness of the plate. And you see these numbers all over the tank. In fact here is it on the front plate where you can see the little “inch” symbols more clearly.

Since it is a 3 piece casting, they seem to have plastered 2’’ on each piece, with the 45 degree angle right next, and you can just about make out the 2 on the main plate, although the angle isn’t visible anymore due to the hit. These numbers are actually painted on the tank, not written with chalk, which makes them extremely easy to identify, because they look visibly different, like they have actually been typed into the tank.

Then I wondered… could I find these markings for the turret front?
And that I did.

Proudly to the top right of the machinegun port, 3.0’'.

So like I said.

You state something, and every single time I actually look at images you provide, or God forbid I manage to find the actual source of your claims, you are either lying or misenterpreting something that is explained in the document itself (which is probably still just lying).

[Henge11220]

Painting on rated thickness doesn’t disprove the previous posting.
Either the face is performing so badly a 6 pdr can pen ~90 LOS at 1860 f/s or the armor is thinner.
I said explicitly I think it’s not possible for it to perform this badly. And when we referred to armor diagram you agreed. You disagreed because of the mounting diagram. I didn’t agree.

The reason I don’t agree is because the test didn’t change. In reply, you keep insisting IT.80 is very good.

Input Q=2.84, V = 567 (1860 f/s), D = 57, A=30, coefficient of resistance is ~1530 for a partial penetration, base stuck in plate. Target is Sherman turret.
I didn’t reject NBL, nor was I the first to read it as naval limit, but it doesn’t matter. Resistance to penetration, converted from Army to full penetration (x1.06) is still under K1800, which is still noticeably better than achievable in WT.

Cast equivalence isn’t often even a comparison between the same hardness of armor, for instance some of the Germans data for slope vs cast equivalence is based on a resistance coefficient of >2400 for the 50mm AP proof shell. Which you might notice, isn’t exactly likely.

You didn’t pay attention to any of this.

[FlipAllTheTables]

@Henge11220

And when we referred to armor diagram you agreed.

Lie, I stated “clearly there’s something wrong.”, talking about the difference in armor that was shown in that full hull + turret diagram by comparison to what was stated in actual documents. Never did I say I agreed with the diagram, and in fact every other blueprint you posted disagrees with that diagram, which you seemingly have decided to ignore, even going as far as to say those blueprints are from 1943, when they clearly state 1942.

Additionally, you still haven’t said where you got that full hull + turret diagram from, or even the name of the document, or even how to find it, despite me asking.

@Henge11220

The reason I don’t agree is because the test didn’t change. In reply, you keep insisting IT.80 is very good.

Lie.

I said I.T.80D is not the same as cast and that the document was stating an equivalent, not actual thickness. You then started saying that the difference wouldn’t be great, when my response to that was “you don’t know that, neither do I”. I never stated how “good” the I.T.80D standard was, the person that started talking about the quality was you, and you continuously made assumptions and errors trying to prove that I.T.80D is garbage, by not reading documents properly, and then me having to actually find the document you’re talking about rather than you providing it first. Like how you stated it didn’t protect against the 15 mm BESA, when the hits done with the BESA are especitly stated to have been at 0 degrees.

[Henge11220]

Now on IT.80

If it’s read as just, normal angle, ballistic limit, the coefficient K is better than listed by about 100. The hardness barely changes the coefficient of resistance by army limit.

The 2nd diagram with marked 3" thickness is from 1943 collection and has the MG mount splash cover on the M34 mount, there is two collections. You can find easily yourself. One is a drive link.

Yes, you said it’s not the same as cast, document is stating equivalent not actual thickness. I’m saying the difference is too big to be plausible. You said I don’t. Now I’m showing you IT.80 coefficient of resistance is ~1680 by Army Limit, and <1800 for a full pass through. Either number torpedoes your theory.

It’s certainly open to interpretation, what I meant by properly is that an Army limit coefficient 2000 when the Finns reported a 12.7 HMG can hardly kill a T-26 ‘isn’t exactly a marvel’. The lower alloy steel used by both US and UK manufacturers has mediocre performance against 0.50 cal even at the normal.

Well unless like KillaKiwi you argue every shot missed from 30 meters without looking at the above table

Like against 2 pdr AP, it can’t achieve resistance proportional to difference in hardness despite massively “overmatching” it in thickness.

(Yes I know the angle is different. K ranges from 1895 at 255 bhn to 2000-2055 at 311 at the normal, while German 50mm armor drowns the 2 pdr.)

[Pecanin]

Get real people ,Russian steel is not like your pansy western steel

inch of western steel is just that …one inch
one inch of russian steel equals 6 inches of your woke western steel.

[Henge11220]

First the point of comparison is German armor significantly outperforming British armor, and second Russian steel is typically the higher alloy steel. Third, they could make comparable armor if they had set aside the alloys, they simply chose not to.

[FlipAllTheTables]

@Henge11220

while German 50mm armor drowns the 2 pdr.)

African Pz.Kpfw.III

Study of Pz.Kpfw.III armour continued until December of 1941. The quality was generally similar to that of British I.T.80 steel, but some samples were considerably worse. For instance, the 15 mm BESA could not score complete penetrations against one 31.5 mm thick hatch door at even 100 yards (91 m) but incomplete penetrations were scored from as far as 430 yards (393 m). Three other 31.2 mm thick plates could be penetrated fully at 150 yards (137 m). The 16 mm thick engine compartment roof could be penetrated at an angle of 35 degrees with a rifle bullet from 35 yards (32 m) and a Boys rifle from 100 yards.

The armour could not withstand trials against more serious weapons. Two hits from 2-pounder AP shot at a velocity corresponding to a range of 1100 yards shattered a 31.2 mm thick plate installed at an angle of 20 degrees in two pieces. The larger piece was reinstalled and fired at with APC shot at the same velocity. The first shot penetrated the plate, the second shattered it again. The upper portion was placed at a 30 degree angle, but another APC shot shattered it into four pieces. There was no point in firing any longer and the shards were passed off to scientists. They confirmed what was already obvious: German armour was too brittle. The quality of welding was also poor. Weld seams cracked under fire and components that were welded on broke off.

BESA 15 mm capable of defeating German 30 mm thick armor plating, complete or full penetration means the shot makes it through.

The impressive results against tanks with 30 mm thick armour weren’t relevant for long, as the Germans had an upgrade ready. Some Pz.Kpfw.III tanks began arriving with applique armour nominally 30 mm thick welded to the front. The plate was surface hardened with an outer hardness of 740 BHN and inner hardness of just 460. 2-pounder shot could penetrate this armour when they hit it, but could not penetrate the main armour behind it. There was only one saving grace: after one or two shots the applique armour fell into pieces or broke off.

And here is where the 2 pdr starts to have the trouble against 50 mm plate.

Pz.Kpfw.III Ausf.J tanks with 50 mm thick front armour were spotted in January of 1942. The British called these “Mark III New Type”. Laboratory analysis of captured vehicles showed that this armour was also surface hardened, but not as much as before. The hardness of the outer side was 530 BHN and the inner side was 375. This armour no longer shattered when hit with 2-pounder shot. On the contrary, British shot fell apart into pieces when hitting it, leaving just a small dent. Penetration could only be achieved at close range. Regular AP shot penetrated the front from 100 yards (91 m), shattering in the process. Improved shot with a higher muzzle velocity penetrated from 300 yards (274 m) leaving a jagged hole 45 mm in diameter.

It’s specifically not homogeneous armor, it’s face hardened which is specifically meant to shatter rounds, hard countering uncapped rounds but being countered itself by capped rounds.

Laboratory analysis showed that if the shot could penetrate the shallow hard outer layer then it could effortlessly go through the rest of the plate, which was much softer. Testers estimated that penetration with ordinary shot could be reached from 200 yards (183 meters) and from 400 yards (366 m) with improved shot. Higher quality American 37 mm shot could penetrate from 600 yards (549 m). 6-pounder shot penetrated this armour from 800-900 yards (732-823 m), shattering in the process. The American 75 mm gun managed to penetrate the front at a range of up to 700 yards (640 m) with semi-AP and 1700 yards (1554 m) with proper AP. The performance of the armour was considered to be high when it came to defeating uncapped shot, but worse than British I.T.80 armour against APC shot.

[Henge11220]

In Cairo and Soviet trials with 2 pdr 50mm is only enough to get partial penetrations, deep dents.
Tank Archives is good, but one nuance is that he simplifies “partial penetration”/PTP to “it went through”.

Which isn’t supported.

StuG in the USSR

At all.
Same failure happens against 38t.

[FlipAllTheTables]

You missed the point.

The 50 mm German armor that you’ve been comparing to I.T.80 all this time, and saying that the 2 pounder struggles against the German armor while it goes through I.T.80, is not RHA. It is FHA, which specifically performs good against uncapped AP, and according to the documents even you have shown, the only 2 pounder rounds that were shot at this 50 mm armor were specifically the standard AP and the high velocity AP, but never a capped round.

And in fact, the armor is stated to be good against uncapped rounds, but specifically worse than I.T.80 against capped rounds.

[Henge11220]

In reality the shell body just isn’t sturdy enough, so even capped shell M51 APCBC failed at point blank.
But when the shell was big enough, and the velocity low enough, the inadequate hardening didn’t matter, since the shell had too much advantage over the armor.

You’ll notice that the better hardened French shell in the Soviet trial penned at 400m 50/50 despite using a shallow armor piercing cap, but with resistance coefficient iirc of >2000, which isn’t consistent with their estimate that it would perform worse.
It’s because the armors high hardness throughout raised the coefficient of resistance and it didn’t plug easily like it’s British counterpart. The FHA isn’t necessary to cause the same kind of failure.

It happened with the sides of Panther vs 37mm APCBC.

Similarly if you read more you’d know the US metallurgical review of German and Japanese armor. It’s quite positive.

The reason 2 pdr AP failed is because of intentional brittleness, soft base, and a very long tracer cavity (proportionately). If you break through the nose the projectile only has the soft base to feed into the plate.
German Armor was just enough to break the nose of these shells.
And it’s also why after combat experience, both Soviets (before the war) and Germans, even Japanese, developed hard base shells.

The resistance coefficient for M51 APCBC failure is over 2700 iirc which is pretty impressively bad, but clearly shows the shell is destroying itself.

This issue was reposted by a TE writer, one revised diagram for side attack on a Tiger shows at 25 degrees the upper side can be attacked iirc, under 800m by 76 APCBC

[Henge11220]

The shells that failed badly on StuG and 38t included APC, as well as for 37mm (M51 and PzGr for 38t). According to the theory, you’d think it would pen. It failed. FHA oversimplification doesn’t explain the failure.

[FlipAllTheTables]

@Henge11220

In Cairo

The tests I linked of tank archives talking about the Pz.IIIs are the ones from Egypt.

The first image you post shows just a table that summarizes the results obtained.

The second image is for results against 32 mm FHA + 30 mm RHA. And the 1st image shows that every single gun performs worse against it.

@Henge11220

It happened with the sides of Panther vs 37mm APCBC.

The Chieftain's Hatch: US Guns, German Armour, Pt 1

@Henge11220

The shells that failed badly on StuG and 38t included APC, as well as for 37mm (M51 and PzGr for 38t). According to the theory, you’d think it would pen. It failed. FHA oversimplification doesn’t explain the failure.

There’s no mention of APC being used for the 2 pounder, they only say “AP shot”. And 37 mm M51 is stated to perform better than the 2 pounder against the front of both the StuG and the Pz.38(t). It penetrates (albeit at a short distance), while 2 pounder is just said to fail.

It could also be a question of “shatter gap” on the M51 APC shot. I’m not completely aware of how it works, but if I recall correctly, very high speeds can lead to a projectile shattering and not-penetrating, but at longer range, the lower velocity can actually make the projectile not shatter and penetrate. Apparently 76mm M62 had such issues.

[Henge11220]

Shatter gap is wrong and misleading in several ways
Penetration occurs through driver’s plate and no other distance for 60mm.

APC is from the 37mm gun on 38t against 50mm of StuG and fails.

600 yards it will defeat 40-50mm@30… Would need details. Cairo shows it’s rated for 72mm FH at 600 yards.

This isn’t shatter gap it’s just consistently bad like M62.

[Henge11220]

But something interesting is true, after repeated his to the front (3) by 6 pdr the entire front of the Panzer III broke away around the driver port, taking much of the side with it.

So using Killakiwi hatch logic, maybe the entire superstructure plate of Pz III should be a weakspot.

[KillaKiwi]

@Henge11220

So using Killakiwi hatch logic, maybe the entire superstructure plate of Pz III should be a weakspot.

Using my logic:
The round can penetrate the armor so it’s not actually a weakspot, it’s simply too weak to stop the shell in the first place.

Or what is your definition of a weakspot?

[Henge11220]

my bad, that was #3 shot
first didn’t penetrate, 2nd torn off hand sized chunk
and 3rd…

Misremembered, it was only the MG port side that came off.

[KillaKiwi]

Well, that’s generally the case with add-on armor.
It’s not as effective as a homogeneous plate and it will fall apart.

But we also don’t have historical correct armor or shells in the game.

Like every 2pdr has excess to HV and APC rounds.
German and Japanese tanks don’t have FHA and HHA is simply better by 1.25 than RHA in the game.