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

[siffo998]

after some small testing in __Yossarian0815s thread here:

http://www.battlefront.com/community/showthread.php?t=106899

i`ve decided to set up some bigger tests using the cmbn and cmfi engine to compare the performance of the panzerIV Hs armor.

test setup:

1500+ distance open ground without obstacles.

1x platoon (5 tanks) of panzer IV H early (the first model with full 80mm frontal superstructere and lower frontal hull armor)

against

1x platoon (5 tanks) of sherman m4a1 (mid).

initially i tried to seperate each tank pair with lanes of huge stone walls on the map but it did not work because the other tanks could look and shoot over the walls so i removed them.

i then gave each panzerIV a small cover arc so that they would not return fire.

i hit the go button and waited until all panzer IVs were destroyed (i counted all hits to the frontal parts of the armor and how they turned out)

i repeated this test three times!

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

the results:

CMBN

Frontal Turret hits:

13 x full penetration

Weapon Hits:

1x no penetration but subsystem destroyed

Weapon Mount:

1x No Penetration

1x Partial Penettration

7x Full Penetration

Superstructere Frontal Hull:

2x No Penetration

14x Armor Spalling

1x Full Penetration

Upper Frontal Hull!:

1x Armor Spalling

4x Partial Penetration

5x Full Penetration

Lower Frontal Hull

4x No Penetration

2x Armor Spalling

Armor Skirts:

12x No Penetration ????

CMFI:

Frontal Turret:

15x Full Penetration

Weapon Mount:

2x Full Penetration

Superstructere Frontal Hull:

3x Armor Spalling

1x Partial Penetration

1x Full Penetration

Upper Frontal Hull:

1x Armor Spalling

4x Partial Penetration

3x Full Penetration

Lower Frontal Hull:

1x Armor Spalling

Armor Skirts:

1x No Penetration

Wheels:

1x No Penetration (damage to subsystem)

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

my conclusion:

i say it again:

something seems to be messed up with the upper frontal hull armor of the panzer IV! the upper frontal hull is the strongest part of the panzer IV armor! it wasnt reinforced to 80mm for the whole time of war. it stayed 50mm because these part was heavily sloped (around 60°)... theres no way that a sheerman 75mm should be able to penetrate it at 1500 but instead it is penetreted all the time!

look at these picture:

http://de.wikipedia.org/w/index.php?title=Datei:PzIV.Saumur.000a5s6s.jpg&filetimestamp=20070930034759

the upper frontal hull is the part where the tracks are places (heavily sloped)

the superstructere hull (where the mg is located) and the lower frontal hull (directly under the upper frontal hull) are the parts who were strenghened to 80mm because both were not really sloped at all (vulnerable parts).

bfc should really take a look into these armor values because maybe theres the same wrong value as in cmbn 1.0 with the tiger (upper frontal hull value was only 25mm instead of 60mm therefore the sherman 75mm was able to penetrate the tigers frontal armor -> changed in 1.01)

also i think the test clearly shows that theres some progression in armor modelling if you look at the armor skirt values... 12x hits to the armor skirts with no penetration at 1500m ? according to these results its safer to show the enemy the side of your panzer IV tanks instead the front (at least in cmbn). i seems to be fixed in cmfi.

hope bfc takes a look into this ! it was quite some work to put together the test. by the way i havent placed a save game but the setup is really easy to create by your self. all crews had regular experience with no multipliers.

[Vanir Ausf B]

In CMBN you can use tall bocage for lanes. Tanks can't see over it. In CMFI you would probably need to use the elevation tool to create tall berms.

Superstructere Frontal Hull:

2x No Penetration

14x Armor Spalling

1x Full Penetration

This actually looks about right given my earlier calculation.

something seems to be messed up with the upper frontal hull armor of the panzer IV! the upper frontal hull is the strongest part of the panzer IV armor! it wasnt reinforced to 80mm for the whole time of war. it stayed 50mm because these part was heavily sloped (around 60°)... theres no way that a sheerman 75mm should be able to penetrate it at 1500 but instead it is penetreted all the time!

This is the important part. Do you have a source for the 50mm thickness? I looked online for one but my Google-fu failed me. The only information I could find was in World War II Ballistics: Armor and Gunnery, which lists the Pz IV Ausf H glacis plate as only 20mm thick @ 72° angle from vertical. If that is correct it would resist equivalent to about 70mm @ 0°.

also i think the test clearly shows that theres some progression in armor modelling if you look at the armor skirt values... 12x hits to the armor skirts with no penetration at 1500m ? according to these results its safer to show the enemy the side of your panzer IV tanks instead the front (at least in cmbn). i seems to be fixed in cmfi.

If you look at the Pz IV from the front you will see that you are hitting the hull skirts edge-on so there is nothing behind them. Similarly, with the turret skirts there is nothing behind them from that angle but more skirts, except for a very small section on each side of the front turret.

[siffo998]

In CMBN you can use tall bocage for lanes. Tanks can't see over it. In CMFI you would probably need to use the elevation tool to create tall berms.

thanks for the tips!

This actually looks about right given my earlier calculation.

the performance of the superstructere and lower hull armor seems right to me too!

This is the important part. Do you have a source for the 50mm thickness? I looked online for one but my Google-fu failed me. The only information I could find was in World War II Ballistics: Armor and Gunnery, which lists the Pz IV Ausf H glacis plate as only 20mm thick @ 72° angle from vertical. If that is correct it would resist equivalent to about 70mm @ 0°.

well it seems like i was wrong i`ve just discovered at this site:

http://www.wwiivehicles.com/germany/tanks-medium/pzkpfw-iv-ausf-f2.asp

that the upper frontal hull armor (reffered at the site as lower front hull) seems to be 25mm at 73°.

(sources: Profile AFV Weapons #43 PanzerKampfwagen IV 1972, and Armour in Profile #8: PanzerKampfwagen IV (F2), Walter Spielberger, 1967

for the model G and H they used also 25mm but without any sources.

the importend question is if this 25mm at 73° are enough to stop or bounce of a sherman shell at 1500m ?

and which value used BFC for the game ?

anybody else with a better source ? maybe the model G and H used thicker glacis plates? it seems a bit weird to me to uparmor the hull to 80mm and leave a big part of the front practically unprotected by only 25mm !?

If you look at the Pz IV from the front you will see that you are hitting the hull skirts edge-on so there is nothing behind them. Similarly, with the turret skirts there is nothing behind them from that angle but more skirts, except for a very small section on each side of the front turret.

seems to be right but some of the skirt hits they received happened after they moved in panic and presented a part of their side armor.

[Vanir Ausf B]

well it seems like i was wrong i`ve just discovered at this site:

http://www.wwiivehicles.com/germany/tanks-medium/pzkpfw-iv-ausf-f2.asp

that the upper frontal hull armor (reffered at the site as lower front hull) seems to be 25mm at 73°.

(sources: Profile AFV Weapons #43 PanzerKampfwagen IV 1972, and Armour in Profile #8: PanzerKampfwagen IV (F2), Walter Spielberger, 1967

for the model G and H they used also 25mm but without any sources.

the importend question is if this 25mm at 73° are enough to stop or bounce of a sherman shell at 1500m ?

and which value used BFC for the game ?

anybody else with a better source ? maybe the model G and H used thicker glacis plates? it seems a bit weird to me to uparmor the hull to 80mm and leave a big part of the front practically unprotected by only 25mm !?

The source I quoted earlier gives 25mm @ 73° for the G but 20mm @ 72° for the H and J. I don't know which source is correct. As I stated above, 20mm @ 72° resists equal to 70mm. I'll run the 25mm calculation later today.

[YankeeDog]

Can't speak to the thickness controversy, and it's possible that there's a bug or a need for a tweak here. However, if I may play devil's advocate, bear in mind that with very long-range gunnery like this you also need to account for the trajectory of the round -- since at 1500m the round will be plunging a fair bit, this reduces the effective slope of the armor.

Edge effects can also come into play more often with relatively small plates like this -- in general, armor plate resists penetration less effectively near its edges, and a smaller plate has more edge relative to its overall surface area.

Finally, you have to consider the possibility of a skate/glide effect, where the projectile hits the highly sloped plate, and slides along it until it impacts the joint between this plate and the vertical plate adjacent. Again, joints and seams are usually weaker points in the armor.

I can't say for certain if any of these might be coming into play here, but BFC's armor penetration modeling is quite complex, and it wouldn't surprise me if one or more of them are involved.

[siffo998]

Finally, you have to consider the possibility of a skate/glide effect, where the projectile hits the highly sloped plate, and slides along it until it impacts the joint between this plate and the vertical plate adjacent. Again, joints and seams are usually weaker points in the armor.

I can't say for certain if any of these might be coming into play here, but BFC's armor penetration modeling is quite complex, and it wouldn't surprise me if one or more of them are involved.

fair point especially the glide effect. its a general question i think if a apc shell is at all able to bite into armor inclined at 73° when hitting head on at 1500m distance. but if the shell then slides along the upper frontal hull and penetrates the superstructere hull why does it say upper frontal hull penetration ? (in cmfi full upper frontal hull penetrations happened at least 3 times and in cmbn 5 times).

[John Kettler]

siffo998,

Saw your post over on Sim HQ while hunting for the glacis plate data. Sadly, it was merely a question! Here's something which should really help.

http://www.scribd.com/doc/88694462/Armour-in-Profile-No-8-PanzerKampfwagen-IV-F2 (Fair Use)

For the IV/F2, it's 25mm chrome molybdenum steel at 73 degrees, Brinell hardness 460-490. From what I can tell, this didn't change in later models, but I can't find the data I need.

If I had my GERMAN TANKS, Von Senger und Etterlin, this would've taken about 1 minute to find and post.

Regards,

John Kettler

[Jock Tamson]

at long range presumably the trajectory of the round is more of an arc. Enough for it to reduce the effective thickness of the plating to eg 25mm at a 50 degrees slope?

edit: YD beat me to it

[YankeeDog]

fair point especially the glide effect. its a general question i think if a apc shell is at all able to bite into armor inclined at 73° when hitting head on at 1500m distance. but if the shell then slides along the upper frontal hull and penetrates the superstructere hull why does it say upper frontal hull penetration ? (in cmfi full upper frontal hull penetrations happened at least 3 times and in cmbn 5 times).

No idea. What would probably actually be happen in a hit like that is the projectile would split the seam at the junction of the plates. It might not even penetrate in the strictest sense of the word, but if there's a large enough crack in the seam, you might as well call it a penetration as there will be significant spalling and even if uninjured, the crew is probably not going to want to continue to fight the vehicle with a sudden extra viewport through the front hull. And whether you want to call a seam penetration like this an "Upper Frontal Hull Penetration" or a "Superstructure Penetration" is largely an issue of semantics. Neither is technically accurate.

Again, I don't know whether a glide event like this is actually likely to happen in this particular penetrator vs. plate matchup. The dynamics here are extremely complex and you'd pretty much have to find real-world firing tests to know for sure.

[Vanir Ausf B]

I don't have a diagram to prove it, but I would bet money the plates overlap where they meet to minimize edge effects. That's how tanks are usually put together. Besides that, siffo's tests show more than half of hits on the glacis penetrating -- albeit with a rather small sample size -- which is unlikely to be attributable to edge effects anyway. I think the most likely explanation is that CM has the glacis plate at 20mm and its just a question of whether that is correct or not.

EDITED to add: the shell arcing thing could be a factor as well, but I don't know how much.

[siffo998]

I don't have a diagram to prove it, but I would bet money the plates overlap where they meet to minimize edge effects. That's how tanks are usually put together. Besides that, siffo's tests show more than half of hits on the glacis penetrating -- albeit with a rather small sample size -- which is unlikely to be attributable to edge effects anyway. I think the most likely explanation is that CM has the glacis plate at 20mm and its just a question of whether that is correct or not.

thats my guess to... i think we need a confirmation for the thickness of an IV H glacis plate (20 at 72° or 25 73°). a confirmation from bfc regarding the used thickness would also help...

i will run a additional test using F2 IVs. according to vanirs data they should perform better when hit at the upper frontal hull...

[Vanir Ausf B]

Good idea.

You may want to test Ausf J too. From what Bastables said in the other thread they should perform much better due to RHA.

[siffo998]

ok here are the results. i`ve only counted head on Upper frontal hull hits at 1500+m distance. same setup as above just 4 test rounds this times.

CMFI:

IV G (late)

Upper Frontal Hull:

Partial Penetration: 2x

Full Penetration 5x

CMBN:

IV J (early)

Upper Frontal Hull:

Armor Spalling: 2x

Partial Penetration: 2x

Full Penetration: 3x

Explanation:

according to vanirs data the IV G should have 25mm at 73° in comparison to the 20mm at 72° from the model H. In the test both tanks performed equally bad. there seems to be no difference between the upper frontal hulls.

I`ve used CMBN to test the model J. The model J showed by far the best results (RHA armor seems to work). Normally hits to the superstructere and lower frontal hull of a model G or H resulted in armor spalling. hits against these parts using a model J just bounced off without any ill effects (at least in most cases... i`ve seen a full penetration 2 times when the superstructere was hit).

the upper frontal hull showed only slightly better results (even though according to vanirs data the model J shares the same thickness of UFH armor with the model H).

so i clearly think all of these tests show that a total weak spot of the frontal armor from all IVs is the upper frontal hull part. seems a bit odd to me.

additional data regarding model G,H, and J glacis plate thickness and angle would be nice.

[Vanir Ausf B]

according to vanirs data the IV G should have 25mm at 73° in comparison to the 20mm at 72° from the model H.

I need to double check that. I was going off of memory when I wrote that and I wont have access to my stuff until later today.

I know for sure those were the correct armor values but I can't guarantee I assigned them to the correct tank models.

[MikeyD]

I would be a bit surprised if many rounds were striking the that 72 degree bow. Viewed from the front that's only a thin slice of of the frontal aspect. Rather like getting a ricochet hit off a Panther's gun mantlet, which I've only managed to do once in-game. Anecdotal evidence, I vaguely recall reading a US commander stating he had never seen a PzIV take a hit without a resulting penetration, often followed by a full brew-up.

[siffo998]

I would be a bit surprised if many rounds were striking the that 72 degree bow. Viewed from the front that's only a thin slice of of the frontal aspect. Rather like getting a ricochet hit off a Panther's gun mantlet, which I've only managed to do once in-game. Anecdotal evidence, I vaguely recall reading a US commander stating he had never seen a PzIV take a hit without a resulting penetration, often followed by a full brew-up.

well according to my first test in cmbn (page 1 of this thread) theres a chance of 14,51% that a hit strikes the upper frontal hull when facing head on. thats quite a bit!

i would be really pissed when in a PBEM game my panzer IV gets knocked out by a upper frontal hull hit and i know that he only was penetrated because wrong armor values were maybe used!

by the way when you look for example at these picture you can clearly see that the glacis plate is not at all a small part of the frontal armor...

http://www.ww2incolor.com/d/61420-4/WSS_IS_45-2

actually it forms the central part!

sorry but isnt it a bit strange that these central part of the armor forms (according to CM) the biggest weak spot of the frontal hull whereas both other big parts were uparmored!?

if the upper frontal hull was such an weak spot in reality why hasnt the german army used the weight of extra armor skirts instead for uparmoring these frontal part ?

[womble]

The arcing trajectory of the shell (muzzle velocity nearly 600mps) gives a very shallow angle of descent at the end of its 2.5s flight time at 1500m. Even if we average it out to a 3s flight, it's going up for 1.5s then down for the same. Equations of motion (s = ut + half a t-squared) say it'll be falling from about 12m above the line of aim starting at 750m. That's a pretty shallow parabola, even once you've added in windage.

This came up a while back; low misses have a good chance of getting past the rear end of the target, even at that sort of range, the angle of descent is so shallow.

[Vanir Ausf B]

Ok, I double checked my source. WW2 Ballistics: Armor and Gunnery lists the following armor thicknesses and angles for the Pz IV glacis plate:

D: ..... 20mm "hi-hard" @75°

E: ..... 20mm @ 71°

F1/F2: 25mm @ 73°

G: ..... 25mm @ 73°

H: ..... 20mm @ 72°

There is no entry for Ausf J so I assume it's the same as H. (?)

25mm @ 73° resists equal to 100mm @ 0°

Angle of decent for 75mm APCBC @ 1500m is 1.5°

Reducing armor angle to 71.5° to compensate for shell decent angle changes effective armor resistance to 92.6mm @ 0°

So basically the 25mm plate should be normally impervious to Sherman 75mm, but the 20mm plate versions are vulnerable.

Interestingly, this same source lists the actual measured production thickness of the driver plate and "upper nose" sections as 85mm thick compared to the official 80mm specs.

[eltorrente]

Angle of decent for 75mm APCBC @ 1500m is 1.5°

Reducing armor angle to 71.5° to compensate for shell decent angle changes effective armor resistance to 92.6mm @ 0°

Wow, that's much less of an angle than I thought it would be. Not that I've looked at the stats or done the math or anything... but I just assumed the round would be coming in several degrees steeper than that at that range. Interesting - thanks for posting.

[Andrew H.]

The other factor is shell/armor overmatch. I've forgotten the details, but because the diameter of a 75mm shell is 3x larger than 25mm armor (3.75x larger than 20mm armor), the armor (or slope?) is effectively reduced by some amount which may be significant in this context.

[Vanir Ausf B]

That is the T/D (thickness/diameter) ratio and it's factored onto the penetration figures.

[vossiewulf1212]

Siffo998, thanks for continuing to look at this issue. When I first started testing it last week I was seriously confused watching platoons of Pz-IVs get seriously stomped by Shermans at 1700-1500m on my 2k map. Hopefully since you've made the tests even more stringent than I did, BFC will take a look into this.

[siffo998]

Ok, I double checked my source. WW2 Ballistics: Armor and Gunnery lists the following armor thicknesses and angles for the Pz IV glacis plate:

D: ..... 20mm "hi-hard" @75°

E: ..... 20mm @ 71°

F1/F2: 25mm @ 73°

G: ..... 25mm @ 73°

H: ..... 20mm @ 72°

There is no entry for Ausf J so I assume it's the same as H. (?)

25mm @ 73° resists equal to 100mm @ 0°

Angle of decent for 75mm APCBC @ 1500m is 1.5°

Reducing armor angle to 71.5° to compensate for shell decent angle changes effective armor resistance to 92.6mm @ 0°

So basically the 25mm plate should be normally impervious to Sherman 75mm, but the 20mm plate versions are vulnerable.

Interestingly, this same source lists the actual measured production thickness of the driver plate and "upper nose" sections as 85mm thick compared to the official 80mm specs.

thank you very much vanir! thats very informative!

according to this data at least the model G should be safe from penetrations at the upper frontal hull at 1500m distance. (but it isnt ingame)

i`ve just checked the answers in simhq and brit44 posted that its:

20mm at 72° for the G and 20mm at 70° for the H according to Panzer tracks #4.

another different source and different numbers again... seems like theres no 100% right here. somebody needs to go to a museum and measure it

i wanted to test it in APOS from graviteam but they have no panzer IVs in it (and also no shermans).

it would be really nice to see which numbers were used by bfc and why!

by the way isnt it really strange that they uparmored the IVs front but at the same time decreased the strength of this plate? seems like it wasnt much of a weak spot in reality. i havent seen any pictures of panzerIV penetrated in this area either...

[siffo998]

Siffo998, thanks for continuing to look at this issue. When I first started testing it last week I was seriously confused watching platoons of Pz-IVs get seriously stomped by Shermans at 1700-1500m on my 2k map. Hopefully since you've made the tests even more stringent than I did, BFC will take a look into this.

well i`ve just found this source on the net:

http://www.google.de/imgres?imgurl=http://www.lonesentry.com/articles/ttt07/pics/panzer-iv-armor.jpg&imgrefurl=http://www.lonesentry.com/articles/ttt07/armor-german-tanks.html&h=550&w=400&sz=31&tbnid=tJ8cYjTNzeRQ1M:&tbnh=92&tbnw=67&zoom=1&usg=__SDVRtcWe7z3Qypa8irrranfk9TQ=&docid=gKoXWk1054s8DM&sa=X&ei=5ECSUOmSAo_64QTNnID4Dg&ved=0CDwQ9QEwAg&dur=335

it shows the panzer IVs glacis plate with 22mm without any information about the angle. but its also a panzer IV version with 50mm armor (1942 version). its from an us report from 1943.

by the way vossiewulf i`ve seen your test and i`ve seen similar beatings for the IV in my own ones.

heres a statement from charles the lead designer himself. it seems like the panzerIv vs. sherman controversy is on since the beta days...

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

by the way he says nothing about the upper frontal hull. just uses the armor values for the superstructere and lower hull

hes saying that a sherman should be superior at 300m range because of the obsolete armor of the panzer IV (fine with me) but hes also indicating that at higher ranges the panzer IV should be superior. test like yours and my own experience showed something different.

[Vanir Ausf B]

well i`ve just found this source on the net:

http://www.google.de/imgres?imgurl=http://www.lonesentry.com/articles/ttt07/pics/panzer-iv-armor.jpg&imgrefurl=http://www.lonesentry.com/articles/ttt07/armor-german-tanks.html&h=550&w=400&sz=31&tbnid=tJ8cYjTNzeRQ1M:&tbnh=92&tbnw=67&zoom=1&usg=__SDVRtcWe7z3Qypa8irrranfk9TQ=&docid=gKoXWk1054s8DM&sa=X&ei=5ECSUOmSAo_64QTNnID4Dg&ved=0CDwQ9QEwAg&dur=335

it shows the panzer IVs glacis plate with 22mm without any information about the angle. but its also a panzer IV version with 50mm armor (1942 version). its from an us report from 1943.

I'm not seeing a Pz IV with a 50mm thick glacis plate on that page. Are you sure you're not looking at the Pz III?