Sherman 75mm vs. Tiger side armor test

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Yoozername
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RE: Sherman 75mm vs. Tiger side armor test

Post by Yoozername »

It seems the US thought that a 25 degree obliquity was enough to make the Tiger upper hull completely safe but a dead on shot was good to 1000 m???



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RE: Sherman 75mm vs. Tiger side armor test

Post by Mobius »

Well you see the actual TM 9 1907 tables above that I posted. If correctly read the wrought armor of 3.2" would be penetrated out to only about 750yds. Of course this is soft US test plate armor not the harder German armor.
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RE: Sherman 75mm vs. Tiger side armor test

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From the looks of this data on The Handbook of Ballistic and Engineering Data for Ammunition July 1950 the test armor was from 2" to 3.5".

Also, I'll have to rerun the naval ballistics program as this says the M61 is only 14.9lbs.

If you look where the average of the 6 shots that penetrated 3" of armor @ 0-degrees were was 1797 f/s. To me this looks more like 950 yds.

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RE: Sherman 75mm vs. Tiger side armor test

Post by Yoozername »

You beat me to posting that data. What jumps out is the difference in velocity between Army and Navy Ballistic Limit for the same plate. I assume they are shooting at the same 'quality' and type of plate. As an example: the homog, 3 in. 0 deg velocity. 1594 vs. 1797? That is a wide margin.

I am sure most of the data seen in the charts is extrapolated. It seems so linear in most cases. So perhaps 2-3 plates are used and a draftsman makes a line.

Note the 3in/20deg/Navy difference in velocity between Homog and FH. 1925 vs. 1658? That is huge.
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RE: Sherman 75mm vs. Tiger side armor test

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Here is what the Germans thought of the M3 75mm gun against the Tiger I. I believe its from 1944 so almost assured its M61A1 ammunition. The rounds are coming in at 30 degree obliquity.

Penetration Table 02: Sherman A2, Sherman A4.
Tiger I vs. Sherman
Sherman vs. Tiger I (75 mm M3)
(88 mm KwK)
Front: Turret 0 m
Mantlet 0 m
DFP* 0 m
Nose 0 m
Side: Turret 100 m
Superstructure 100 m
Hull 900 m
Rear: Turret 100 m
Hull 0 m
* DFP = Drivers Front Plate
Source : JENTZ, Thomas L.; Germany's TIGER Tanks - Tiger I and II: Combat Tactics; ISBN 0-7643-0225-6
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RE: Sherman 75mm vs. Tiger side armor test

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The BL(Navy) criteria is a complete penetration. I don't know what the BL(Army) is. But the BLN is close to the German criteria.
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RE: Sherman 75mm vs. Tiger side armor test

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I would guess its similar to the IP and CP of the Soviets.  army is Initial and Nay complete
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RE: Sherman 75mm vs. Tiger side armor test

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M72 MQ and FH


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RE: Sherman 75mm vs. Tiger side armor test

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There are a lot of different data sets for the 75mm M3 M61. I have 8 of them that I normalize and average to get out 75mm gun data.
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RE: Sherman 75mm vs. Tiger side armor test

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I was actually more interested in that data since it gives M72 performance against MQ and FH and also 90 and 60 deg armor as well as by being fired by two different weapons (M2 and M3 75mm guns)
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RE: Sherman 75mm vs. Tiger side armor test

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That WO info looks suspiciously like a republication of the US data. British tests may reflect better to find a 75mm Mk V tests. While this has a slightly better muzzle velocity 2050 to the US 2030 it should be more reflective of WO testing.
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RE: Sherman 75mm vs. Tiger side armor test

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I am just looking for M72 data as a starting point.  But, yes, the Brits prob had early experience with M72 and also the transition to the M61.  Notably the HE issue.
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RE: Sherman 75mm vs. Tiger side armor test

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The M72 had a higher drag factor so it lost velocity faster than the M61. And was nearly a pound lighter than the M61, though that could be counted in the AP cap and the windscreen. So the M72 may had slightly more up close punch but wasn't so good at range.

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RE: Sherman 75mm vs. Tiger side armor test

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I am not sure I follow that.  It seems from the data you posted, that the M61 'delivers' 12.5 pounds (see plug w/o cap or windshield) while the M72 is a ~ 14 pound AP shot?  The 'filled' M61 w/M66A1 fuze weighs 14.9 pounds, compared to the M72 13.94.  They supposedly have the same velocity if they share the same optics?  In any case, I agree that the M72 at close range (barring severe quality issues) might have been a better chance against the Tiger sides.  I am starting to suspect that the 'cap' use was making up for poor penetrator manufacturing in the US.
 
I have been reading lately of the US ammunition woes during WWII.  Not only the HE shell problems with all the sub-contracters but also the AP it seems.  Lots could vary and these problems came up early.  As early as Sicily, there were major problems.  The tests from May 44 of shoots on homog. plate showed very poor showings of the M61 and other US 'cap' antitank rounds.
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RE: Sherman 75mm vs. Tiger side armor test

Post by Mobius »

ORIGINAL: Yoozername
I am not sure I follow that.  It seems from the data you posted, that the M61 'delivers' 12.5 pounds (see plug w/o cap or windshield) while the M72 is a ~ 14 pound AP shot?  The 'filled' M61 w/M66A1 fuze weighs 14.9 pounds, compared to the M72 13.94.  They supposedly have the same velocity if they share the same optics? 
The velocity bleeds out because of the higher drag factor so besides not having the same velocity at say 1000m it makes it a less accurate round.
Against homogenous armor penetration engineering formulas say all that counts is cross-sectional density. So caps count as weight. (Though we don't rely on penetration engineering formulas in PCO.)
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RE: Sherman 75mm vs. Tiger side armor test

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Yes, that's true the M72 was basically a slug with a tracer.  But the 57mm and the 90mm (I believe), had APBC with no cap as designs.  It seems the M3 gun was given the APCBC M61 version as it's armor piercing round for most of the ETO. 
 
APC (which is actually APCBC) rounds, give up 'vertical' performance against homogenous armor.  They literally have a cap of steel on the front that the penetrator must be pushed through before the penetrator gets to the target armor.  Caps count as weight that must be accelerated down the gun tube.  I believe I read that the M61 had 2# of gunpowder to the M72 1.9#.  They both had the same velocity though.  This due to the M72 lighter weight. 
 
The M61 seems to be able to not ricochet against sloped homogenous armor compared to face hardened.  But in the case of the Tiger I side armor, the armor is too tough and it has a T/D favorable ratio that seems to negate most M3 75mm hits except those that are dead nuts square-on.
 
 
 
 
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RE: Sherman 75mm vs. Tiger side armor test

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Since the Soviets produced that chart of shell penetrations included the LL 75mm M72 and not the M61 leads me to believe the US sloughed off the M72 on the Soviets. At least until stocks ran out and there was enough M61s for all.
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RE: Sherman 75mm vs. Tiger side armor test

Post by Yoozername »

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The M72 info here appears to show it is inferior to M61 against frontal attack against PanzerIII, But look at the note regarding side armor. They mention Valentine homog armor penetrated. Seems it was hard armor too. Is that 1600? 2.5 inch?
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RE: Sherman 75mm vs. Tiger side armor test

Post by Mobius »

ORIGINAL: Yoozername
The M72 info here appears to show it is inferior to M61 against frontal attack against PanzerIII, But look at the note regarding side armor. They mention Valentine homog armor penetrated. Seems it was hard armor too. Is that 1600? 2.5 inch?
It looks like 1600 yds.
350 BHN isn't far out of the norm for that thick of plates.
German
BHN
55-80......250-290
35-50......300-350
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RE: Sherman 75mm vs. Tiger side armor test

Post by Yoozername »

http://wargaming.info/1998/us-army-1944-firing-test-no1/

The test firing two weeks before D-Day is most interesting.  This site presents it well but it is in several wargaming sites.  I think the M61 test might have the 70mm/60mm Homo 0 and 30 degree data mislabeled.  But firing the M61 against this homo armor shows that the armor effects drop off.  The M61 is not fired against the 100mm or 120mm armor during the tests.  I suppose the TD doctrine said that 75mm shermans had no worries about fighting bigger tanks than Panzer III and possibly Panzer IV.

CONSOLIDATION OF DATA FROM ORDNANCE BOARD PROCEEDINGS 23114 AND 26594
75mm APCBC M61 – HE filled versus Inert loaded
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75mm APCBC M61 - HE filled versus Inert loaded[/align]
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