Sherman 75mm Penetration

[rexford]

Several past posts have noted that CM 75L40 APCBC outpenetrates U.S. test data in TM-9-1907(10% difference at point blank, 99mm vs. 90mm penetration). If U.S. service rounds were consistently weaker than test projectiles, one would expect game penetration to be less than published U.S. results.

Looked at another way, DeMarre equation analysis suggests that CM figures assume U.S. ammunition is same quality as German, which seems inconsistent with tests, common assumptions and nose hardness figures.

If 14.96# 75L40 APCBC penetrates 99mm at 0m/0° and 2030 fps, then 15# Panther round at 3068 fps would penetrate 179mm at 0m/0° based on DeMarre extrapolation. Since CM Panther ammo penetrates about 176mm at 0m/0°, game results seem to imply that German and U.S. APCBC are same quality and effectiveness.

DeMarre equation assumes that penetration is proportional to (velocity ratio) raised to 1.4283 power x (weight ratio) raised to 0.7143 power for similar diameter ammo. This equation works very well with U.S. APCBC and British ammo.

U.S. firing tests with German 75mm ammunition showed that panzer APCBC penetrated "somewhat more" than U.S. rounds at same velocity. German projectile nose and shoulder hardness was significantly harder than U.S., which would contribute to greater penetration capability.

75L40 APCBC penetration in CM just seems too high for U.S. tanks.

Regarding APDS:

http://members.nbci.com/_XMCM/mycenius/weapons/armour5.html

contains a little remark regarding firing tests with 57mm APDS against a Panther. Penetration effectiveness could not be determined due to difficulty in hitting the target!

Our book will also present a few examples out of Jentz' book where APDS hits armor with excess penetration and fails to penetrate. The number of published cases of APDS inaccuracy and penetration failures continues to mount.

John Salt's page on weapon accuracy contains some British firing test results that compare APDS accuracy to APCBC, and APDS is a distant second.

Using textbook data for APDS in every case is just not right, rounds flew off at angles and penetration was reduced to next ot nothing due to yaw. Random results in game are needed.

PzKpfw IVG is 30+50 front armor, which is non-controversial and should be changed in CM.

[:USERNAME:]

Its interesting that the report does not mention lower hull (panther) penetrations. It is either a very difficult area to achieve a hit on or gives protection due to its "downward" sloping effect.

I would assume that the panther did not have tracks on its turret sides.

Can anyone find a picture of a panther with its lowert hull holed?

Lewis

[Olle Petersson]

Originally posted by :USERNAME::

Its interesting that the report does not mention lower hull (panther) penetrations. It is either a very difficult area to achieve a hit on or gives protection due to its "downward" sloping effect.

If not "difficult" to hit, so at least unusual in combat.

Combat reports show that 90% of all hits on AFVs are more than 1m above ground. This would pretty much exclude the lower hull...

I assume one reason is that tankers go for hull down positions, another that the lower parts are concealed in undergrowth anyway and the aimpoint therefore gets up a bit.

Cheers

Olle

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[Jarmo]

About the lower hull. At what angle would a shot shot hit it?

Is the shot already going downwards fast enough for the

added angle to have any effect?

I could calculate it myself, but I'd have to pull a lot of

figures out of my butt..

[Paul Lakowski]

Originally posted by Jarmo:

About the lower hull. At what angle would a shot shot hit it?

Is the shot already going downwards fast enough for the

added angle to have any effect?

I could calculate it myself, but I'd have to pull a lot of

figures out of my butt..

Theres a formula for calculating ricochet and its clear that a degree or two more should not affect ricochet too much .

[:USERNAME:]

Originally posted by Jarmo:

About the lower hull. At what angle would a shot shot hit it?

Is the shot already going downwards fast enough for the

added angle to have any effect?

I could calculate it myself, but I'd have to pull a lot of

figures out of my butt..

Charles once addressed this. Depending on the gun/range there could be a degree or two that would be added to this "downward" slope. Also, the fact that gravity is working against the shell and forcing it down might help.

Anyway, every degree helps. Ive never seen a holed panther lower hull pic.

[Vanir]

It's hard to hit the lower hull of a Panther in CM. Set up some Panthers 700m or so across from some Allied tanks and run it a few times. It's been a while since I did this, but going from memory only about 5-7% of frontal hits were on the lower hull.

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You've never heard music until you've heard the bleating of a gut-shot cesspooler. -Mark IV

[Ari Maenpaa]

Originally posted by Vanir:

Set up some Panthers 700m or so across from some Allied tanks and run it a few times. It's been a while since I did this, but going from memory only about 5-7% of frontal hits were on the lower hull.

I put a veteran Sherman M4A1(76) to fire 100 HITS at a Panther G late at 800m range. It scored 17 hits on the lower hull. Those hits were penetrations EVERY single time. Did the Panther really has this big and soft belly in real world?

I also checked Russian Military Zone and Claus Bonnesen’s online archive (both have pics of destroyed Axis tanks) but couldn't find a picture of a frontal lower hull holed Panther.

Ari

[PzKpfw 1]

Originally posted by Ari Maenpaa:

I put a veteran Sherman M4A1(76) to fire 100 HITS at a Panther G late at 800m range. It scored 17 hits on the lower hull. Those hits were penetrations EVERY single time. Did the Panther really has this big and soft belly in real world?

I also checked Russian Military Zone and Claus Bonnesen’s online archive (both have pics of destroyed Axis tanks) but couldn't find a picture of a frontal lower hull holed Panther.

Ari

Ari this has been bugging me to, as the Panther's lower hull was realy not visible

or exposed, to the extent it seems in CM Ie,

Round ------- < glacis

as we see a hit comeing in on the hull is going to hit the glacis from dead on, now Allied tankers did on an occasion skip a round into the lower hull, but the main impact area was almost universily the glacis, or turret as the general aiming point was center mass. Even on rough terrain exposure would be minimal as the suspension system did the work. Now a Panther cresting an slope would expose the lower hull etc.

Regards, John Waters

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"We've got the finest tanks in the world. We just love to see the

German Royal Tiger come up on the field".

Lt.Gen. George S. Patton, Jr. February 1945.

[:USERNAME:]

This was also an issue with Panzer Elite. Everything was plinking the lower hull of the panther.

The germans went from 60mm to 50mm in this area. They must have known that this area was not vulnerable.

A descending shell "sees" this downward sloping area as being smaller also. A tall tank like a sherman will actually have to shoot down to hit this area if it is on the same level terrain as the panther.

Does the game distribute hits on a percentage basis? example:All vehicles that get hit get 16 percent on the lower hull? (I hope not... lets wait and listen for a BTS response... (sounds of crickets))

Lewis

[Vanir]

Originally posted by Ari Maenpaa:

I put a veteran Sherman M4A1(76) to fire 100 HITS at a Panther G late at 800m range. It scored 17 hits on the lower hull. Those hits were penetrations EVERY single time. Did the Panther really has this big and soft belly in real world?

Ok, I ran your test, everything the same as you did except with a somewhat larger sample size. BTW, next time use something more durable than a M4A1. It's a pain getting only 1-2 hits per run.

Total Hits: 130

Breakdown:

Turret: 39 (30%)

Upper Hull: 69 (53%)

Lower Hull: 11 (8.5%)

Tracks: 7 (5.4%)

Gun Hit: 4 (3%)

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You've never heard music until you've heard the bleating of a gut-shot cesspooler. -Mark IV

[This message has been edited by Vanir (edited 02-14-2001).]

[jgdpzr]

Vanir,

One thing you can do to extend the life of the Sherman in a test such as this is empty the Panther of all its ammo.

[Paul Lakowski]

Originally posted by Vanir:

Total Hits: 130

Breakdown:

Turret: 39 (30%)

Upper Hull: 69 (53%)

Lower Hull: 11 (8.5%)

Tracks: 7 (5.4%)

Gun Hit: 4 (3%)

Actually that sounds about right to me!! This sounds like the PzIV Vs Sherman debate, where some people got constant german advantage while others got constant Sherman advantage.

I noticed that if you run Steel Panthers the exact same scenario again and again the first time would advantage one side and the next time advantage the other side....

Has anyone noticed this on CM?

[Guest Big Time Software]

Lewis:

A descending shell "sees" this downward sloping area as being smaller also. A tall tank like a sherman will actually have to shoot down to hit this area if it is on the same level terrain as the panther.

At very close ranges, maybe. But I think we are talking about 50m or less. I welcome someone else to do the math since that isn't my cup of tea Charles has already said it would vary by only a degree or two, which is not very significant.

Does the game distribute hits on a percentage basis? example:All vehicles that get hit get 16 percent on the lower hull?

Yes, except the number is 12%. Vanir's test shows that statistically it is possible to be even less than that, but 12% is the number used in the equations.

We have said from day one that every mm of each and every vehicle is not simulated. This falls into the same category. However, it isn't as bad as you appear to think Lewis. Do an experiment if you will. Take the front profiles of a dozen random tanks/TDs, from different nations, and measure up how much of their front is lower hull. I would bet that the numbers are fairly similar. So while CM is certainly abstracting this, I doubt if it has a significant impact on the overall results.

I noticed that if you run Steel Panthers the exact same scenario again and again the first time would advantage one side and the next time advantage the other side....

Has anyone noticed this on CM?

When the odds are fairly even, this should happen if you play it out enough times. The reason why is quite simple -> compounding results of luck. If Side One manages to get a bit luckier in the beginning, it will get an ever increasing statistical advantage vs. Side Two, making it far more likely to be declared the "victor". Scenarios that are not as evenly based (at least in a shoot-out type situation) will likely come up consistantly in favor of the side with the edge.

Steve