T34/85 ineffective against STUGF/8?!

[Warren Peace]

I think their is something strange going on. I set up a gunnary range (trees, 900Meters). STUGF/8 owns T34/85. For some reason T34/85 shells do not penetrate STUG front armor. THe chart suggests that 85 should have no problem penetrating 80mM at this range. I also engineered the test to take away all the AP ammo from the STugs to keep the T34/85s alive. What I found is that an unusually large number of hits resulted in "broken" shot.

Does this sound right? Is the Stug Armor "extra-hard".

[offtaskagain]

The Stug III F/8s armor is spaced. It has a 30mm plate bolted over a 50mm plate but with a gap between the two. The gap causes the APHE fired by the T-34/85 to detonate after penetrating the first 30mm plate and leave the 50mm plate intact.

[John D Salt]

Originally posted by panzerwerfer42:

The Stug III F/8s armor is spaced. It has a 30mm plate bolted over a 50mm plate but with a gap between the two. The gap causes the APHE fired by the T-34/85 to detonate after penetrating the first 30mm plate and leave the 50mm plate intact.

Do you have a source for that, please?

I donlt have much in the way of StuGly reference materials, but Chamberlain, Dolyle & Jentz seems to imply that the 30mm applique was bolted directly on to the 50mm basic armour. If there was an air gap, I would have thought that this would have been mentioned, and I cannot recall ever hearing such a thing. One would also wonder why the F/8 should be superseded by the G with 80mm monobloc frontal armour, which would be less effective against 85mm APHE (but slightly better than 50mm plus a 30mm applique with no air gap).

All the best,

John.

[Andrew H.]

Hi John,

Technically, the term "gap" is wrong; what you have are two plates in contact. You can probably find everything you want to know on this subject here.

The short answer, though, is that two plates in contact resist *less* than one homogenous plate *unless* both plates are face hardened, in which case they resist more. I'm sure that there are a bunch of other factors that come into play, such as HE vs. no HE filler, too.

[Mikser]

Perhaps this a case of either ammo quality or the angle of incidence for the hits?

[ October 30, 2002, 02:03 PM: Message edited by: Mikser ]

[Bruno Weiss]

Mikser wrote:

Perhaps this a case of either ammo quality or the angle of incidence for the hits?

Or, perhaps a case of not enough play, too much think.

[John D Salt]

Originally posted by Mikser:

Perhaps this a case of either ammo quality or the angle of incidence for the hits?

I don't think so. If the 85mm is being modelled with stinky amn quality, this would show up in the information screen that appears for a selected unit when you hit "enter", wouldn't it?

Having run a very quick-and-dirty test myself, there does seem to be some evidence of 85mms not penetrating StuG IIIF fronts at ranges where the infmn screen shows they overmatch it by a comfortable margin. This may of course just be bad luck; longer testing might show there is no real effect.

Still, I'd be interested to hear what the BTS folks have to say on this.

All the best,

John.

[Vanir Ausf B]

It does appear that the 2 plates are a factor. In June 1944, at 1000m an SU-85 is given a "fair" chance of killing a StuG IIIG with 80mm armor, but only a "rare" chance against a StuG IIIF with 50 + 30mm armor.

Where it gets interesting is when you run the same test with a Sherman 76. The Sherman is given a "good" chance to kill both models of StuGs at 1000m, even though it is listed as using APCBC with "large HE charge" and it's penetration tables shows lower penetration figures than the SU-85.

[offtaskagain]

Originally posted by John D Salt:

Do you have a source for that, please?

Whoopsy, I got the wrong vehicle. You are right about the 30mm being bolted directly on to the main plate. Rexford posted somewhile back about 2 RHA plates stacked resists less than 1 plate of equivalent thickness. 2 Face hardened plates however was found to resist much better than 1 FH plate of equivalent thickness. As Andrew Hedges already stated that's what the F/8 had on front.

[Vanir Ausf B]

Originally posted by panzerwerfer42:

2 Face hardened plates however was found to resist much better than 1 FH plate of equivalent thickness. As Andrew Hedges already stated that's what the F/8 had on front.

My question on this is that if 2 FH plates resist better than one, why did the Germans move to a single plate with the later StuGs and Pz IVs?

[Mikser]

Production convenience?

[Renaud]

My guess would be (assuming that two face-hardened plates really are better than one) that it's more expensive to produce, face-harden and assemble two plates than to produce one thicker face-hardened plate.

Ren

[Gremlin]

Fwiw, if you ever want a highly detailed and richly illustrated reference on the beloved StuG check out Walter J. Spielberger's Sturmgeschütz & Its Variants (The Spielberger German Armor & Military Vehicles Series, Vol. II, Schiffer Publishing, 1993--also still available in the original German-language edition, iirc).

[Andreas]

Originally posted by Mikser:

Production convenience?

I think it is more likely to be degradation. Once on or two rounds penetrate the outer plate, it would be pretty much shredded, and no longer offer the additional protection. I don't think CM does model this effect though.

[Andrew H.]

In the thread I linked to above, Rexford mentioned that impact could cause the studs holding the plates together to bend, which would also cause maintenance problems.

[Vanir Ausf B]

I dunno. Seems to me having the armor penetrated would cause even worse maintenance problems.

[John D Salt]

Originally posted by Gremlin:

Fwiw, if you ever want a highly detailed and richly illustrated reference on the beloved StuG check out Walter J. Spielberger's Sturmgeschütz & Its Variants (The Spielberger German Armor & Military Vehicles Series, Vol. II, Schiffer Publishing, 1993--also still available in the original German-language edition, iirc).

You heartless, callous BEAST, you.

Do you realise how much money it would cost me if I bought all the Spielbergers I fancied?

I;ll forgive you if you have a copy to hand and can tell me whether the basic armour of the Ausf F/8 was face-hardened or not. I always thought it was MQ, with only the applique plate FH.

All the best,

John.

[Jeff Duquette]

I’m not not exactly sure why two face-hardened plates in contact should present “significantly” more ballistic protection, nor have I seen “formal” laboratory-firing trials that study this particular aspect of armor penetration. By “formal” laboratory I mean Shoesburyness, Aberdeen, Dahlgren, etc.

North African trials conducted in situ (i.e. in Theater) in which British uncapped 2-pdr. trials vs. the MkIIIH have been referenced as the original source for this theory. Two layered FH plates are perceived to have been of superior ballistic quality to a single plate of equivalent thickness.

The author states two FH plates in contact provided 11% better performance to a single FH plate of equivalent thickness. I would suggest that this level of detail is not obtainable from in situ firing trials. Even within controlled firing trials against RHA plate velocity needed for penetration can vary by 5% to 7% between successive firings. Penetration velocity variation is even higher in trials against FH plate. Experimental Error – particularly from in situ firing trials – can also be a function of ammunition lot, and ammunition quality. Barrel ware from the weapons being employed for such trials can also be a factor. Reduced muzzle velocity and therefore impact velocities will result in increased “apparent” ballistic protection. Moreover lower impact velocities would result in additional error to such trials. Impact velocities or even muzzle velocities could not typically be measured in these sorts of informal firing trials. Equipment to conduct such measurements would not have been something laying about in a typical 8th Army supply depot.

In my opinion a great deal more can be read into these sorts of in situ firing trials than was originally intended by the proctors of such trials. While these affairs were of importance they were typically much more impromptu experiments than the sorts of trials being conducted in the more formal testing environments of Shoeburyness, Dahlgren or the like.

Best Regards

Jeff Duquette

P.S. In my brief search of my home references, I was unable to find specific mention of layered FH plates on this model of Stug. I was disappointed that Spielberger provides no additional clues on this subject. However layering FH plates did seem to be somewhat common practice on various iterations of the MkIII and MkIV. I think it is quite probable this was also done on the Stug model in question, but this is only an “unreferenced” opinion. If I recall correctly the construction spec for layered 30mm+50mm plates was eventually modified to production with a single 80mm plate.

Some folks might read a fair bit into a design upgrade preference for single plate.

[ October 31, 2002, 12:21 AM: Message edited by: Jeff Duquette ]

[Wisbech_lad]

STUGF/8 owns T34/85

Point of order, shouldn't that be 0wnZ?