U.S. 76mm vs. Panther Hull Front

[rexford]

Did U.S. have HVAP during June '44?

M10 knocked out Panther at 500m with upper front hull penetration, which would only be possible with HVAP unless it went through MG port. M10 penetration data lists HVAP even though it may have been unavailable.

76mm HVAP slope effects in CM seem lower than U.S. test data. 76mm HVAP had 60° slope effect of 4.3 and it doesn't change with T/D ratio, CM slope effect at 60° is quite a bit lower and decreases with decreasing T/D. \

HVAP slope effect for 55° is about 3.3, so 60mm Panther front lower hull would have 3.3 x 60, or 198mm at 0° effective resistance to HVAP.

198mm front lower hull resistance would limit HVAP penetration range to about 600m.

[Harry Yeide]

6th Armored Group records suggest that VII Corps, at least, received its first HVAP ammo on or about 26 September 1944.

[KiwiJoe]

Don't forget Panther armour is only 85%. So its 51mm x 3.3 = 168mm @ 0.

[Guest Big Time Software]

U.S. didn't field HVAP until August.

However, CM models 'weak points' in armor (like MG ports). Roughly 1% of hits are on these weak points. That would explain a kill versus the Panther's glacis by a 76mm at 500m.

The M-10 got lucky.

Charles

[rexford]

CM appears to seriously underestimate armor resistance versus HVAP, if U.S. tests are considered:

CM HVAP slope effect vs. 47mm at 60°

2000m range : 99 penetration at 0°, 47mm at 60°, for 2.11 slope multiplier at 60°

U.S. Test Data

1200m range: 173mm penetration at 0°, 51mm at 55°, for 3.40 slope effect at 55°

U.S. Technical Manual TM-9-1907 lists 133mm at 0° penetration for 76 HVAP at 2000m.

We estimate that 60° HVAP slope multiplier is 4.3, from regression equation for 0°-55° data, more than twice the figure in CM.

All U.S. tests for HVAP show slope multipliers that exceed APCBC by large amounts, and are significantly higher than CM.

[rexford]

U.S. penetration test data for 76 HVAP shows 3.34 slope multiplier at 55° vs. 2.90" plate, and 3.40 slope multiplier at 55° vs. 2". Slope effect does not change with T/D.

300 yard penetration of Panther glacis by 76 HVAP in field test at Isigny, France, August '44.

Penetration at 300 yards is 2.63" at 55°, or 67mm. Armor is 80mm thick times 0.9 quality factor for 72mm effective.

Penetration ratio equals 67/72, or 0.93. Penetration probability about 20%, which is consistent with report on how shot penetrated glacis (paraphrased):

shot stuck in plate and stopped, then it suddenly pointed downward and entered the armor.

On subject of U.S. ammo penetration, tests of U.S. projectiles against a variety of plate appear to be consistent with TM-9-1907 data.

Fought battle with one Panther against 5 M5A1 with 37mm, Panther knocked out on frontal hit at 550m by penetration of weak spot in front lower hull armor. Guess one can't assume that 60mm armor is 37mm proof, even when 37mm penetration at 0° is less than plate thickness at 55°.

Shot probably hit rectangular weld line, which was noted to be vulnerable area.

Our studies of penetrations on Panther through front hull weld area, based on Allied firing tests, suggested that effective armor resistance was 2/3 computed, or about 100mm at 0°. Stuart 37mm probably didn't go thru here unless weld weakened by previous hits.

Interesting result.

[WolfLord]

Heh, don't get me started on this...just finished a battle which almost resulted in my monitor being tossed out the window. ONE...yes ONE Sherman 76 took out 3 of my Panther G's (not late) frontally at >500m. Not to mention he also got a hetzer and a Stug III...oh yeah...and a PzIV. To say I was annoyed would be a dreadful understatement. To add insult to injury, my tactics were sound and the Panthers were hull down in relation to the '76. I never did kill the bastard...aborted the mission when he took out my PzIV.

[Guest Andrew Hedges]

I was reading one of the US Army official histories -- I've forgotten which one -- and it had in it a mention of an M5 tanker who hit a Panther three times in the glacis with his 37mm gun and couldn't believe that he didn't knock it out. This was in Sept. 44.

Sort of a good reminder that not all historical soldiers had the detailed knowledge of German weaponry that we take for granted. Although, still, I think this guy must have been amazingly slow. September(!).

[Guest Big Time Software]

HVAP penetration equations were difficult to create, due to widely varying test results that we had to somehow make 'agree'.

However I think rexford may have misread CM's figures. Here's what CM has for the US 76mm HVAP:

At 500m/1000m/2000m, 30 degrees slope:

175mm, 149mm, 100mm

Here are the values given in Hunnicutt's Sherman book (the one I happen to have handy):

157mm, 135mm, 98mm

CM comes in about the same at 2000m, and a little higher at 500m and 1000m. CM comes in lower than some other test data, so we tried to strike a balance in the middle.Still, our equations are based on such limited data (tungsten data is hard to find in quantity) that I would like to return to this subject in the future.

As for slope multipliers... DOH!

I was scratching my head there because I could have sworn that CM already used the slope multipliers rexford suggests. And then I found a bug that makes the equations use regular APCBC multipliers! Well, at least it's an easy fix because the HVAP multipliers are already in there. One little fix and they'll be back...

Looks like we'll be releasing another patch in the future!

Charles

[This message has been edited by Big Time Software (edited 01-10-2001).]

[This message has been edited by Big Time Software (edited 01-10-2001).]

[Tiger]

Back to work you code-monkey!!

Seriously, thanks for all the hard work. I'm still having trouble believing that it's possible to have a software "game" company that can put out such a wonderful title, and cares enough to keep perfecting it; listening to their fans. I can count on both hands the number of buggy, unfinished games released by big publishers that one can only hope gets a proper patch eventually (if the bean counters deem it profitable). One thing though, do you guys at BTS still enjoy playing CMBO or has working on it for so long dulled your taste for it?

Tiger

[rexford]

Just picked up on fact previous messages used 30° HVAP penetration as 0°. Oops!

Sorry to keep beating on CM about HVAP slope effects, but it is a big deal to us and is published in several places. The game will be so much improved with proper slope effects.

Now, about that 75mm APCBC being above U.S. test data,...............

And rounds shattering because of brittleness when they shatter failed due to softness, where U.S. rounds were too soft to withstand back pressure on overpenetration and ........

If shatter gap is used in CM, then all the 75 APCBC penetration above 84mm or so doesn't count against Tiger I 80 side and PzKpfw IVH 80mm front, cause round fails due to "shatter gap", so .................

And Germans using battlesight aim to increase accuracy well above opposition, due to trajectory insights and ...............

The reference to 76mm penetration of Panther front lower hull is with HVAP, cause 76 APCBC couldn't penetrate 60mm @ 55° beyond very short range.

There is no attempt to be destructive here, we're sharing stuff cause CM is a good game and we want it to be as good or better than our rules (just the facts, maam, just the facts). Within bounds and good behavior, of course.

The great thing about CM is that infantry pins, panic and cowering are accomplished by the computer instead of repetitive and never ending boring morale dice rolls every turn. Partial sighting is terrific (we do play the game, inbetween writing messages and computing effective armor thicknesses).

We second the comment about flexible designers that respond to observations. It takes alot of eyes to craft something long lasting and comprehensive.

Thanks for the opportunity to nit pick and the honest consideration given to comments.

[Ari Maenpaa]

Rexford,

CM reports very clearly when a weak point penetration occurs. Weak points doesn't have anything to do with armor's quality/resistance. They just mean that there are some "holes" on the given armor area which can let even some peashooter to penetrate through. When I make armor penetration tests in CM, I usually completely ignore weak point penetrations. Of course not too many of them should occur.

Also my humble thanks for your insightful observations about CM. It serves us all to get this kind of things right. At least couple of other participants have earlier criticized CM's HVAP penetration values, but your articulation and reasoning are so clear that they can't be ignored. Same thing about the Jumbo’s frontal armor. And yep, it’s great thing that Charles is so open-minded to chance his code if a good reason arises.

Ari