Panzer IV H frontal hull armor seems wrong (test inside) BFC please take a look!

[Vanir Ausf B]

I'm pretty sure that is not true since T/D is calculated using actual thickness -- which is the same at every angle -- rather than equivalent thickness.

[Killkess]

Yeah, but for each different T/D u have a different slope modifier.. dont you? The slope modifier for 30 degrees is different if u look at a t/d of 0,5 or 2,0.

[dieseltaylor]

Wrong, look at this test i ran a while back: https://sites.google.com/site/cmx2tankvtanktests/

Not quite a complete proof as it was not solely tank to tank but with an FO also.

However very interesting work and again reveals the huge range of spotting results - 3 seconds to 133 seconds in a repeated test is quite a range.

What is interesting here is that it is a MkIV that does not spot Sherman who fires at it for over a minute. One of the great benefits for the Germans, unlike the Allies, they had a more smokeless propellant which meant spotting a distant gun firing was much more difficult.

The not spotting at all figures are interesting also with 11 German and 15 US never seeing the enemy tank before the test ended though being under fire - I am not quite sure how long it ran for and the difference between 4 and 4+ shots.

Can you help me on that noob? : )

Shermans had to get relatively close, due to both the armor and low-flash powder of the Panther which made it harder to spot. Sherman crews also had issues with firing from range as the Sherman's high flash powder made their shots easy to spot. Their gun sights were fixed magnification compared to the German's multiple magnification settings with added anti-glare filter. In Summer 1944, after breaking out of the bocage and moving into open country, U.S. tank units who were engaged at range from German defensive positions sometimes took 50% casualties before spotting where the fire was coming from.[35]

http://en.wikipedia.org/wiki/M4_Sherman

[Vanir Ausf B]

Yeah, but for each different T/D u have a different slope modifier.. dont you? The slope modifier for 30 degrees is different if u look at a t/d of 0,5 or 2,0.

Slope modifier is a function of T/D, but T/D for 30° is exactly the same as 0° since neither the actual armor thickness nor shell diameter change. I'll have to look at my stuff tomorrow to double check but I've been using that conversion for a while and it always seems to work out correctly.

siffo may be on to something regarding the ammo. Most penetration tables I've looked at only list M61 and M72. I don't know when M62 was issued or in what quantities. Need more information.

[noob]

Not quite a complete proof as it was not solely tank to tank but with an FO also.

It was soley tank to tank, the FO's were hidden behind high walls so they could not spot, they were there for CC purposes only.

The not spotting at all figures are interesting also with 11 German and 15 US never seeing the enemy tank before the test ended though being under fire - I am not quite sure how long it ran for and the difference between 4 and 4+ shots.

Can you help me on that noob? : )

The outliers don't interest me, what i was looking for was an average spotting time, and a bias in favour of the PzIV for combat, the test showed that the PzIV had a significant advantage over the Sherman at 2000m, both in spotting and combat, which would be expected if the German optics were superior, and the average spotting times, given absolutely no experience of being in a tank, seemed ok to me.

One can get bogged down in the details, or one off events, what i wanted was a general idea of the level of performance of armour in certain situations, so now, if i was playing a CM battle on a map over 2000m, i would feel more confident owning PzIV's than Sherman's, which makes sense if the optics are better.

Each test ran until one tank was either destroyed or retreated, the + means that tank was the one that held it's ground, and as i mention in the test, the PzIV forced the Sherman to retreat rather than get a kill, so at those ranges, the PzIV acts more as an area denial weapon than a kill weapon, however the Sherman crews were well shaken, and the sub system damage was significant

[Killkess]

Slope modifier is a function of T/D, but T/D for 30° is exactly the same as 0° since neither the actual armor thickness nor shell diameter change.

Ceteris paribus T/D remains the same regardless of angle, true. But the 1.22 slope modifier belongs to a given T/D ratio if i understand correctly. Change the ratio and the 1.22 changes.

[dieseltaylor]

Thanks noob that makes sense to me now. I am glad to see optics does come into the equation.

[siffo998]

siffo may be on to something regarding the ammo. Most penetration tables I've looked at only list M61 and M72. I don't know when M62 was issued or in what quantities. Need more information.

well i just multiplied the m61 FHA 30° (1500m) penetration value from

http://www.tarrif.net/cgi/production/all_vehicles_adv.php?op=getvehicles&vehiclesX=197

with 1.22:

=49 * 1,22 = 59,78mm

according to this result a penetration of the upper frontal hull of a pzIVH (even the 20mm at 72° = 70mm) is not possible at 1500m range...

but using the data from 75mm m62 (APCBC) ammo it should be possible (74,42mm at 0°, 1500m distance).

well quite a dilemma. looks like the shermans 75mm ingame are using mainly m62 ammo or at least cm uses the penetration values for m62 ammo but according to my memory the standard ammo for us tankers should be m61... even at around 1944.

i havent found anything about the use of m62 rounds in 75mm shermans only with the 76mm ones.

somebody with solid data or even availability of the ammo in the time frame?

[akd]

siffo may be on to something regarding the ammo. Most penetration tables I've looked at only list M61 and M72. I don't know when M62 was issued or in what quantities. Need more information.

M62 was used in the 76mm gun, no?

[Vanir Ausf B]

Yes, there was also a M62 76mm round. This is all very curious.

Lone Sentry has penetration tables from the July 1944 field manual FM 17-12 Tank Gunnery. The 76mm M62 is listed for the 76mm, but only the M61 and M72 are mentioned for 75mm, with only M61 is present on the penetration tables. Results from the the Shoeburyness tests conducted in May of 1944 are reproduced here and also do not list a M62 round for the 75mm. A little further down on the same page results for the Isigny live fire tests in July of 1944 again only lists the M61 round for the 75mm.

Over on the CMBN board John Waters, who knows far more about this stuff than I do, wrote :

Also as noted before 75mm M62 APCBC was more then capable of dealing with the PzKpfw IV H etc. Infact M62 was the round most fired in the ETO, the US converted thousands of M72 rounds to M62 after the Insigny live fire tests. Although its interesting the Soviets had no problems with the M72 rounds vs German armor.

So it seems that the M62 round was a late war modification to existing M72 rounds that would not have existed during the CMFI time frame and possibly not during the CMBN time frame.

[Vanir Ausf B]

Bad info deleted

[Vanir Ausf B]

Ceteris paribus T/D remains the same regardless of angle, true. But the 1.22 slope modifier belongs to a given T/D ratio if i understand correctly. Change the ratio and the 1.22 changes.

Ok, I think I see what you mean. I dug around and found a formula for the exact slope modifier at 30° for the specific T/Ds we are using. The formula is:

a x (T/D)ⁿ

where a=1.2667 and n=.0655.

Applying this to 75mm attacking 20mm thick armor we get a slope modifier of 1.16. So applying that to the numbers on Taffif.net we get M62 penetration of 79mm at 1000m and 71mm at 1500m. With M61 ammo we get 67mm at 1000m and 57mm at 1500.

Against the 80mm thick driver plate we have a modifier of 1.27 which gives us 77.5mm of penetration at 1500m for M62 and 62mm with M61 ammo.

Obviosly the question of M62 ammo is huge since it allows penetration of the Pz IV front hull at ranges of about 500m or more further than does M61.

[akd]

AFAIK, it was M62 fired from a 76mm gun that was tested at Isigny, so the comment does not make sense to me. I have never before heard of M62 projectile fired from the 75mm M3 gun.

[vossiewulf1212]

Ok not really specifically still testing this (other people doing a better job) but what is the penetration of the M1 57mm AT gun? Seeing same frontal hull penetrations on IVs at a range of 1000m.

[Vanir Ausf B]

For the 57mm gun APCBC Rexford's book give a value of 91mm penetration at 0°

[Vanir Ausf B]

July 1944 field manual FM 17-12 Tank Gunnery

Those ranges are in yards. Multiplied by 1.27 to convert to 0° we get penetration of:

500m: 100mm

1000m: 90mm

1500m: 80.6mm

WO 185/178, 1943 (don't know the month)

They Brits are nice enough to convert to 0° for us. Unfortunately the ranges are in yards so the numbers in meters would be a bit lower.

500y = 457m

1000y = 914m

1500y = 1372m

Rexford's book lists US APCBC penetration against FHA @ 0° as:

500m: 95mm

1000m: 86mm

1500: 79mm

These figures are very slightly lower than the US official July 1944 numbers listed above at 500 and 1000m, but nearly identical at 1500m.

Note the maximum range for Pz IV "upper hull front" vulnerability as 1470 yards which equals 1344 meters. This seems more pessimistic than the FM 17-12 numbers, but we are not given penetration numbers here to compare and they don't define vulnerability.

Interestingly it also references APC projectile M61a1. I Googled this and got very little but the Wiki entry for the Sherman 75mm gun states

M72 was replaced by the 6.8 kg (15 lb) M61 and later the improved M61A1 APC Shell

This makes me suspect that the 75mm "M62" shell is actually a mislabeled M61a1.

[siffo998]

Note the maximum range for Pz IV "upper hull front" vulnerability as 1470 yards which equals 1344 meters. This seems more pessimistic than the FM 17-12 numbers, but we are not given penetration numbers here to compare and they don't define vulnerability.

Interestingly it also references APC projectile M61a1. I Googled this and got very little but the Wiki entry for the Sherman 75mm gun states

i do not think that the term "upper hull front" used in the statistic is actually refering to the glacis plate. its more likely that it refers to the superstructere hull armor ingame because only values for upper frontal hull and lower frontal hull are listed for the frontal armor.

but thank you very much vanir for all the digging. you found a lot of interesting information to the subject.

i try to summarize everything into a few points:

1. 1. the 75mm m61 and a few m72 were the standard shells for the timeframe of cmfi and the m61 was the standard shell for the timeframe of cmbn. (for the shermans m4 75mm version)
   
   
2. 2. the m62 apcbc shell was introduced in late war (end of 1944-45?) for the 75mm cannon. though it was used by the 76mm version.
   
   
3. 3. the m61 (standart 75mm shell of the timeframe and m72 shell) are never able to defeat the panzer IVs glacis plate/ transmission cover at a range of 1500m. (must be closer than 500m?) -> but ingame the sherman 75mm is able to.
   
   
4. 4. the m61 is not even able to defeat the superstructere or lower hull front of the panzer IV H 1500m. infact using the penetration data shown by vanir they should not even be able to create armor spalling... which they constantly do right now ingame using a panzerIVH
   
   
5. 5. all tests made by me and vanirs data indicate that the penetration values for the sherman 75mm ingame are using the m62 characteristics and not the m61 like they should be... for example a m62 shell (71-79mm at 0° for 1500m) should be slightly able to penetrate the glacis plate of a panzer IV (70mm at 0°) which happens constantly ingame (sometimes partial, and very few armor spallings... look up my test at page 1)
   furthermore a hit a against the superstructere or lower hull armor of the panzer IV H (80mm at 10°/15°) shows constant armor spalling ingame (look up my test at page 1) at 1500m but according to m61 penetration data the standard m61 shell should have only a penetration capability of 62mm at 0°... (look up vanirs calculation a few post further up)
   
   

like vanir already said:

"Obviosly the question of M62 ammo is huge since it allows penetration of the Pz IV front hull at ranges of about 500m or more further than does M61."

by the way i have just looked up again charles (from BFC) post because he posted the ingame used penetration data for the sherman 75mm

http://www.battlefront.com/community/showpost.php?p=1239443&postcount=303

according to charles the sherman 75mm penetrates:

"M4A3 Sherman (75mm M3 L/40, firing APCBC) armor penetration versus face-hardened armor (average) at 300m at various armor slopes:

10°: 96mm

15°: 93mm"

but according to the data from vanir and this sites:

http://www.tarrif.net/cgi/production/all_vehicles_adv.php?op=getvehicles&vehiclesX=197

http://www.wwiivehicles.com/usa/guns/75-mm.asp

only the m62 shell could be able to defeat around 96mm of FHA armor at 10° so its pretty obvious that ingame the penetration characteristics of the m62 apcbc shell is used... but at least around 1943 this shell should be not available for the 75mm cannon... (like stated above vanir pointed out that it was only converted "late war" from m72 shells...)

i do not say that something is broken but a explanation would be nice because a change in penetration characteristics could have a huge impact in gameplay... !

i would suggest that in the future cm should use clear descriptions for each shell used ingame and not only use the terms AP, APDS and HE... this would prevent a lot of confusion... because obviously a lot of different shells were used... for example i`ve found some sources that say that the m61 shell was often used without a charge.

[noob]

yes thats true... but given the fact that those variations caused a weak spot or not in real life is a different story. after all you showed with your calculations that this few milimetres can cause either a penetration or not!

i`ve just setup a different test using cmfi.

setup:

this time wanted controlled conditions so i setup 5 lanes (1000m+/- distance). again five Panzer IV H early against 5 sherman m4a1 (mid). each pair of tanks in a own lank (elevated ground + huge stone wall so that the other tanks could not spot the pair in the lane nearby).

this time i wanted to see how a showdown between a panzer IV and sherman turns out at a range were the panzerIV should be clearly superior. (over 800-900m where it could bring its superior weapon to action but not at around 1500m were the shermans upper frontal armor becomes impervious.

i`ve even used only the same grass type for the whole scenario so that it would not influence the spotting abitlities of the tanks. (controlled conditions)

----------------------------

results:

after 12 rounds:

Shermans destroyed: 33

Panzer IVs destroyed: 32

--------------------------------

my two cents:

well doesnt seem like a real superiority to me. it`s pretty much the same if you are in a sherman or panzerIV right now.

i`ve seen multiple cases were a upper frontal hull penetration caused the rout or direct destruction of a panzer IV. so maybe if you cancel out those 3-4 cases you would really get a statistical superiority of the panzer IV in its "sweet range".

charles mentioned in his post that there are situations when it is better to be in a panzer IV and other situations were its better to be in a sherman. i will test it out at 300m later and we will see if the sherman is really the superior tank in close quaters.

I have just set up a CMFI test with 15 x M4A1 Sherman (mid) versus 15 x PzIVH (early) on a open flat map 350m by 2000m with the tanks at a distance of 1500m without any walls, so all tanks can get a LOS on each other.

After five rounds of testing the PzIV group hammer the Sherman group in each test, the PzIV group suffer around two to three destroyed tanks per test (one round the PzIV's suffered no destroyed tanks), to the Shemans 6 to 7 per test, the remaining Shermans that haven't had their crews dismount retreat behind a smoke screen, with only one or two PzIV's retreating and maybe one dismount, which leaves around 10 PzIV's standing their ground in their original starting positions, whereas there are no operational Shermans in their original starting positions after each test.

Up to now these tests show the PzIVH (early) is vastly superior to the M4A1 Sherman (mid) at 1500m, which i would expect if the PzIV gun and optics are better.

The specs for the test were:

Game setting Iron

Regular crews

0 for leadership

Normal motivation

Fit and Full supply

Three platoons (3 x 5 tanks) minus the Batt and Co HQ vehicles.

Clear, no wind, noon

All tanks start unbuttoned

p.s. i just ran some more of the same tests with all tanks buttoned at the start, the results are slightly worse for the Sherman's.

p.p.s. I ran the same tests with 5 PzIV's v 5 Sherman's (platoon v platoon) and got similar results, although the loss ratio for the Sherman's was slightly less in general, and slightly more for the PzIV's, however the PzIV's still held their starting positions, whilst the surviving Sherman's retreated behind a smoke screen.

[Vanir Ausf B]

I need to clarify a few things.

i do not think that the term "upper hull front" used in the statistic is actually refering to the glacis plate. its more likely that it refers to the superstructere hull armor ingame because only values for upper frontal hull and lower frontal hull are listed for the frontal armor.

I agree.

but thank you very much vanir for all the digging. you found a lot of interesting information to the subject.

You're welcome.

2. the m62 apcbc shell was introduced in late war (end of 1944-45?) for the 75mm cannon. though it was used by the 76mm version.

This was a working theory I had earlier in the thread, but I've change my thinking. As I said in my last post, I think what a few sources have been calling the "M62" was actually an improved version of the M61: the M61a1. As akd pointed out, the real M62 was a 76mm round.

When the M61a1 was introduced I do not know, but official US documents and tests during the summer of '44 strongly suggest it was the main US 75mm armor piercing round in service in the ETO by D-Day, so it almost had to have been present since at least early 1944 and maybe sometime in 1943.

So it looks to me that CMBN is correct to use M61a1 aka "M62". Whether or not it is appropriate for CMFI is an open question. I wouldn't assume anything without more information on introduction date.

[John Kettler]

What a great thread! Here's some information on the M61A1. It appears to be copied straight out of a wartime ordnance description.

http://www.wk2ammo.com/showthread.php?1204-Projectile-fixed-APC-M61A1-W-Fuze-B-D-M66A1-and-tracer

Projectile, fixed, APC, M61A1, W/Fuze B.D M66A1 and tracer

Cutaway model of a 75mm M61A1 APC cartridge as used in the main gun of the Sherman M4 tank. The projectile is a carbon steel, nose hardened body with an ogive shaped hole drilled in the base, threaded to receive the B.D. (Base Detonating) fuze M66A1. This fuze is delayed in its function, so the projectile can penetrate the target before exploding inside. The functioning of the fuze is simple: A brass cylinder with a firing pin on top is held away from the firing cap by an internally serraded brass ring, forming little plates that hold down the cylinder. At impact, the negative acceleration will throw the cylinder forward, bending away the plates and enabeling the firing pin to hit the firing cap. The ogive shaped hole is filled with a small amount of Explosive D. On top of the hardened nose a piercing cap is attached by means of four 1 cm wide crimps. The top of the piercing cap is threaded to receive an aluminium windshield.

The shellcase M18 is brass made and uses the M31 primer, that contains 150 grais of black powder to set off the main two pounds flashless granular powdercharge.

Weight of complete round: 19,92 Lb.

Lenght of complete round: 26,29 inch (668mm)

Length projectile: 13,22 inch (336mm)

Length shellcase: 13,82 inch (351mm).

Vo.: 2030 ft/sec.

Penetration: 3.4 inch (86,5mm) of face hardened armour @0 degrees at 1000 yards

This would probably be truly valuable, but it's not online

Firing tables : gun, 75mm, M3, M6 and M17 firing projectile, APC-T, M61 and M61A1 : shell, HE, M48 ; shell, smoke, WP, M64, 1948.

Author: United States. Dept. of the Army.

Publisher: [Washington : U.S. G.P.O., 1948]

M61 projectile

http://www.inert-ord.net/usa03a/usa5/75mm/index.html

All Sherman 75mm rounds listed here, by gun and projectile: M72 AP, M61, M61A1 APC

M72 =AP Shot M61=APC Shell, M61 APC=APCBC=AP Capped, Ballistic Capped

http://en.wikipedia.org/wiki/75_mm_Gun_M2/M3/M6

The complete rounds look like these.

https://docs.google.com/viewer?a=v&q=cache:tsN3UHsJCdsJ:www.armouredacorn.com/Refs-%2520Thumbprints%2520%26%2520Images/Ammunition/75mm.pdf+75mm,m61a1&hl=en&gl=us&pid=bl&srcid=ADGEEShdEkb43bjdYxOytYRZz2ierQWnNM2LbwQpwQ3ZyTT1Toriw_Y_igea36wKZXKIebzG9uKVgrtdTFYAe4Wd2KOoA57kQ6L5F6h9M0byeqA8oOoqjp0mHBD20JR5NbJ2bvUkZyV5&sig=AHIEtbRBFA3qb54O6lW17gDDb8WUzD77xA

Regards,

John Kettler

[Vanir Ausf B]

Yes, my own Google-fu had turned up all of those except the last link, which is interesting since it confirms that both M61 and M61a1 are ballistic capped.

[c3k]

Given the assumed (as stated above) use of M61a1 ammunition, is the penetration performance in CMBN approximately correct?

[Vanir Ausf B]

For the 57mm gun APCBC Rexford's book give a value of 91mm penetration at 0°

... at 1000 meters

[siffo998]

I have just set up a CMFI test with 15 x M4A1 Sherman (mid) versus 15 x PzIVH (early) on a open flat map 350m by 2000m with the tanks at a distance of 1500m without any walls, so all tanks can get a LOS on each other.

After five rounds of testing the PzIV group hammer the Sherman group in each test, the PzIV group suffer around two to three destroyed tanks per test (one round the PzIV's suffered no destroyed tanks), to the Shemans 6 to 7 per test, the remaining Shermans that haven't had their crews dismount retreat behind a smoke screen, with only one or two PzIV's retreating and maybe one dismount, which leaves around 10 PzIV's standing their ground in their original starting positions, whereas there are no operational Shermans in their original starting positions after each test.

Up to now these tests show the PzIVH (early) is vastly superior to the M4A1 Sherman (mid) at 1500m, which i would expect if the PzIV gun and optics are better.

The specs for the test were:

Game setting Iron

Regular crews

0 for leadership

Normal motivation

Fit and Full supply

Three platoons (3 x 5 tanks) minus the Batt and Co HQ vehicles.

Clear, no wind, noon

All tanks start unbuttoned

p.s. i just ran some more of the same tests with all tanks buttoned at the start, the results are slightly worse for the Sherman's.

p.p.s. I ran the same tests with 5 PzIV's v 5 Sherman's (platoon v platoon) and got similar results, although the loss ratio for the Sherman's was slightly less in general, and slightly more for the PzIV's, however the PzIV's still held their starting positions, whilst the surviving Sherman's retreated behind a smoke screen.

first thx for the effort of testing noob!

but the question is not if the panzerIV should be superior... the main question was: should the shermans75mm (using standard ammunition) should be able to penetrate the transmission cover at 1500m. and out of this question came another one: is the sherman 75mm ingame using the right ammo for the timeframe or are penetration values ingame wrong ?

my main test was a one on one showdown in controlled conditions.

your test is a platoon vs platoon or group vs. group test ->

i think there are too many variables to clearly say anything about the performance of one tank or another...

[Vanir Ausf B]

Given the assumed (as stated above) use of M61a1 ammunition, is the penetration performance in CMBN approximately correct?

It seems to be in the ballpark. You can always quibble a little here or there because every source you find will give different numbers to a greater or lesser degree. But Rexford's figures and the US July 1944 field manual data are pretty close to each other and they seem to match what people are observing in their game tests, generally.

I think a case could be made for increasing the Pz IV front armor plate thicknesses by a couple of millimeters. Rexford's book suggests up to 5mm variation in thickness of those plates, which the books says are based on actual measurements. This 1943 US diagram of a Pz IV G labels the glacis plate as 22mm thick, an oddball figure unlikely to have been arrived at by means other than measuring an example.