Gun penetration data, CMAK vs. CMBB

[Keke]

In short, why do guns that were presented in CMBB have 10% or more penetration power with their 'regular' AP-rounds in CMAK? For illustration purposes I list a few tank guns and their penetration values (@ 100 metres, slope = 0).

_________CMBB_____CMAK

75/L48___131_______144

75/L70___176_______194

88/L56___154_______170

75/L38____90_______104

76/L52___123_______142

Based on info available at various armor sites, the values of CMBB seem to be closer to reality. Now was there a game engine related reason to boost those values for CMAK? :confused:

[Ace Pilot]

Could it be that there were changes in ammo from year to year?

[Keke]

Originally posted by Ace Pilot:

Could it be that there were changes in ammo from year to year?

No. FE there are no changes in AP-ammunition for the German guns listed above throughout the years.

[ February 17, 2004, 10:21 AM: Message edited by: Keke ]

[Keke]

Btw, for easier comparison, download Chris' Databases available at here

[Redwolf]

Newer data.

Another point to consider is that BFC never documents whether the numbers are against homogenous or face-hardened armor. Since the traget doesn't say whether its skin is FH or not it isn't all too useful for comparisions.

I am still waiting for somebody to confirmt he higher Sherman gun penetration. I was under the impression that they got new ammo around october 1944 but before that could forget about killing a Tiger from side or rear. Is that info outdated?

[ February 17, 2004, 11:30 AM: Message edited by: redwolf ]

[Keke]

Originally posted by redwolf:

Newer data.

What are the sources for this newer data, if I may ask?

Originally posted by redwolf:

Another point to consider is that BFC never documents whether the numbers are against homogenous or face-hardened armor. Since the traget doesn't say whether its skin is FH or not it isn't all too useful for comparisions.

It doesn't make the penetration values irrelevant, and beyond comparison, does it?

Originally posted by redwolf:

I am still waiting for somebody to confirmt he higher Sherman gun penetration. I was under the impression that they got new ammo around october 1944 but before that could forget about killing a Tiger from side or rear. Is that info outdated?

I bet it is the patriotic bonus American weapons seem to have in all American-made wargames.

[Redwolf]

Keke, I have no idea what precisely BFCs sources are, except the usualy assumption is that Lorrin Bird (rexford on this forum) is working pretty closely with them. But since he spoke against some CM values in the past he is not the single source.

Of course FH versus homogenous armor doesn't outright invalidate the penetration stats but it makes them hard to compare. The difference between HF and homo armor (hehe) is certainly around the same ballpark as the differences between CMBB and CMAK.

[Keke]

Originally posted by redwolf:

Keke, I have no idea what precisely BFCs sources are, except the usualy assumption is that Lorrin Bird (rexford on this forum) is working pretty closely with them. But since he spoke against some CM values in the past he is not the single source.

Rexford, where art thou when you're needed?

Originally posted by redwolf:

Of course FH versus homogenous armor doesn't outright invalidate the penetration stats but it makes them hard to compare. The difference between HF and homo armor (hehe) is certainly around the same ballpark as the differences between CMBB and CMAK.

So the guns perform the same, but the tables are now for different type of armor?

Is it by any chance because only homo armor was used on the western front?

[Redwolf]

As I said, I have no information on the source of the difference in BFC's opinion.

I doubt they'll tell us as they will get into a round of demands for changes for a new patch.

[Keke]

rexford?

[rexford]

Originally posted by redwolf:

Newer data.

Another point to consider is that BFC never documents whether the numbers are against homogenous or face-hardened armor. Since the traget doesn't say whether its skin is FH or not it isn't all too useful for comparisions.

I am still waiting for somebody to confirmt he higher Sherman gun penetration. I was under the impression that they got new ammo around october 1944 but before that could forget about killing a Tiger from side or rear. Is that info outdated?

American APCBC for the Sherman 75mm did not change any from 1942 through 1945 in terms of penetration capability, based on the figures I've seen and the firing test results that are available.

During a British test against a captured Tiger in Afrika, 75mm APCBC from a Sherman penetrated the Tiger 80mm design thickness side hull at 17.5 degrees angle and 100 yards range. In another British test, 75mm APCBC penetrated the Tiger side hull (80mm design thickness) at 800 yards with no side angle to the hit.

Based on an analysis I conducted of 20 firing test results against the Tiger 60mm and 80mm design thickness plates, those Tiger plates resisted with an average effective thickness of 84.5mm and 63.4mm after comparison to penetration data.

Given that the average Sherman 75mm APCBC round penetrates 82mm vertical at 500m, a typical Sherman firing on a typical Tiger tank would defeat the 80mm design thickness side armor on a small percentage of the hits at 500m.

In CMBO, Shermans with 75mm APCBC penetrate 89mm vertical at 500m and Tigers have 80mm side armor, so side kills are maybe a little higher than one would expect from our analysis.

During the combat where Michael Wittmann was killed by a 17 pdr round, the Sherman 75mm crews reported that their rounds bounced off the Tiger side armor at about 800 yards. While the average Tiger 80mm design plates resisted like 84.5mm, they could vary in quality with 16% resisting like less than 80mm and 16% resisting like more than 90mm.

The higher Sherman 75mm APCBC penetration in CMAK is due to the publication of face-hardened figures for the round instead of homogeneous armor performance.

Sherman 75mm APCBC penetrates about 82mm of homogeneous armor plate at 500m and about 95mm of face-hardened plate, with the difference being that an armor piercing cap protects the nose from the shattering effects of face-hardened armor so the round is more devastating against that type of armor.

Regarding why the German penetration figures went up in CMAK for 75L43, 75L48, 75L70 and 88L56 APCBC compared to CMBB, I don't know. Our book uses lower figures.

Where are you people getting CMAK figures for the Panther 75L70?

What is interesting is that the 75mm M72 AP solid shot used by the early Shermans could penetrate about 92mm of homogeneous armor at 500m, which made that round vastly superior to the 75mm APCBC against Tiger side and rear armor. The U.S. eventually phased out 75mm M72 AP due to the following issues:

1. ammo tended to shatter

2. no HE burster so less damage and crew injuries

3. no windscreen so it lost velocity FASTER than 75mm APCBC

4. no armor piercing cap so ALOT less face-hardened penetration than 75mm APCBC

5. powder charges tended to vary alot

The Americans were going to toss thousands of 75mm M72 AP rounds but someone decided to drill out an HE burster cavity and place caps on the round, which became a APCBC projectile.

The German 75mm capped round had superior face-hardened armor performance compared to Sherman 75mm AP and APCBC, and the British used those German rounds in their Grants, and may have used them in Lees and Shermans, based on the limited materials I've seen.

In British tests against a PzKpfw IIIH with a Grant (Cairo, May 1942), 75mm M72 AP barely got through the front hull armor at 500 yards while 75mm APCBC just barely defeated the frontal plates at 1000 yards. The German 75mm capped round defeated the PzKpfw IIIH hull front at 1000 yards with plenty to spare.

Lorrin

[ February 18, 2004, 06:47 PM: Message edited by: rexford ]

[Keke]

Thanks Lorrin. Educational as always.

[Wol]

Rexford writes

"The higher Sherman 75mm APCBC penetration in CMAK is due to the publication of face-hardened figures for the round instead of homogeneous armor performance. "

but not all face-hard armour resists equally, even if it has the same metalurgical consisteny. So what were the details of the plates from which these figures were derived? How deep was the face layer/transition layers/ What hardness was the face/back layer? & the metalurgical properties.

I realise that FH armour was little used, butI doubt if even all German FH armour was produced to the same formulae.

cheers

Wol

[Redwolf]

Thanks Rexford.

Did I understand that correctly that the numbers in the CMAK unit display are against FH?

CMAK has Panthers and Panzer IV/70 when you play in Italy with penetration as follows:

Angle 100m 500m 1000m 2000m

0 194 176 156 123 armor piercing (ap)

30 147 134 120 96 925 m/sec

60 65 60 55 46 aPcbc

0 59 53 46 35 high explosive (he)

30 49 44 39 31 700 m/sec

[rexford]

Originally posted by redwolf:

Thanks Rexford.

Did I understand that correctly that the numbers in the CMAK unit display are against FH?

CMAK has Panthers and Panzer IV/70 when you play in Italy with penetration as follows:

Angle 100m 500m 1000m 2000m

0 194 176 156 123 armor piercing (ap)

30 147 134 120 96 925 m/sec

60 65 60 55 46 aPcbc

0 59 53 46 35 high explosive (he)

30 49 44 39 31 700 m/sec

The American and British penetration figures presented in CMAK seem to be mostly face-hardened armor values, while the German are most likely homogeneous since no Allied tanks carried face-hardened after the early Stuarts.

The above stats for Panther 75L70 work out to 199m at 0m and vertical. Seems high.

British stats for Panther APCBC at 0m have 188mm, our computations are about the same.

British have Tiger APCBC doing 156mm vertical at 0m, CMAK seems to be much higher.

Brits have about 138mm vertical for 75mm L48 APCBC at 0m and 0 degrees, our calcs are about the same, CMAK is much higher.

German face-hardened armor resisted about the same as American face-hardened for tanks, which was about the same as British, where Americans and Brits made and fired upon thick face-hardened plates for penetration data to compare with German tanks.

Germans used face-hardened armor on:

PzKpfw III front hull and turret, hull rear

PzKpfw IV front hull and turret

Panther D all over the hull and early Panther A (front hull and hull side)

StuG IIIG and IVG front

and other vehicles

The CM penetration models seem to change from game to game as they improve them.

The Germans used alot of tanks with face-hardened armor in France, but CMBO uses homogeneous armor penetration stats for Allied guns. But they overstate Allied penetration in quite a few cases because they equate Allied ammo quality as equal to German.

In CMBB the realization surfaces that face-hardened panzers and homogeneous armor on panzers requires two sets of penetration stats for Russian and Allied lend-lease weapons. In addition, it is recognized that American ammo was softer than German and carried larger HE bursters, so Sherman 75mm APCBC and PzKfw IVH 75mm APCBC penetrate different amounts of homogeneous plate at 619 m/s (German penetrates about 15% or so more).

Russian ammo in CMBB is recognized as being much softer than American (50 average Rockwell C noses on Russian vs 54.5 on American vs 63 on German), and flat nose Russian APBC penetrates even less on low angle hits due to nose shape. Although APBC flat nose has much lower slope effects than APCBC as the angle increases.

The above is a summary of what I've seen thru the various games.