StuG BS discussions

[Yoozername]

It would be interesting to see the British test data and details.

[Mobius]

ORIGINAL: Yoozername

It would be interesting to see the British test data and details.

It can't be all British tests. 90mm (actually 3.55") is what the graphs of the US technical manual TM 9 1907 is saying.
(I just checked.)
That over states penetration because it uses a poor (or older) standard quality of plate.

[Mobius]

All right. The 76mm looks to penetrate 3.6". The 75mm penetrated 3.55".
There is part of the page of the manual TM 9 1907 showing the velocity and penetration of the 76mm M62 APHE round.

The way the graph it works is you look at the 2000 f/s on the left side. Follow the red line over to the 0-degree curve line then down to read the penetration amount.

You can also follow the 2000 f/s line over to the 76mm M1 line that runs from upper left to lower right. Find where it intersects this line and follow that down to the bottom and read the range at which this velocity and penetration occur.

[Mobius]

While looking for the above scans I came across this table in an old file archive. I have no idea of what country compiled it so I can't use it. But it does show that the Russian 76mm penetrate FH armor better than RHA. It also show 2 versions of the BR350B shell.

[Yoozername]

What angle is that for? 90?  You don't know where it came from? 

[Mobius]

ORIGINAL: Yoozername

What angle is that for? 90?  You don't know where it came from? 

It appears to be at 0. And matches close to Russian Certified Penetration values. But the numbers seem a little contrived - like they might be calculated from a formula not test results.

Something wierd goes on when I plug the numbers into my data curve program. The penetration goes down steeply until around 800-1000 meters then levels off magically at long range. This on all the data, even though the BR350 and BR350A do not have the ballistic caps of the BR350B.
[Edit]I guess that's not true. They all have ballistic caps. The 350B is just a longer beefier heavier projectile.

I just downloaded a few more pages from what looks like the same source but haven't read through the text.
[Edit] These new pages are not the same as that Russian penetration page. They are some workup tables for Lorrin Bird's book. It looks like the tables in his book were averages of four different calculation methods and these pages show the individual rows of numbers.

[Yoozername]

I would say that is the most detailed Soviet data I have ever seen.  I agree, that it is interpolated or cranked by a program.  I haven't seen much Soviet penetration data as far as face-hardened armor, especially from the Soviets.  The numbers seem low as far as the 'benefit' of attacking face hardened armor.  4-5mm?
 
It would seem that your US AP rounds do fit into that data I posted.  I just am wondering about the German 75mm not falling close.  It wouldn't matter what German 75mm AP round I suppose.  I would have assumed 75mmL48, but I suspect that panther, L43 or L48 or even L46 would be about teh same at the chosen velocity.

[Mobius]

It does serve one additional useful purpose. It gives me a way of finding the ballistic coefficient of the 350A. As the penetration at 612m/s must be the same for both guns. Since the penetration is 68 at 612m/s then it must be 612m/s at 400 meters when the muzzle velocity is 655 m/s.
I need two velocities at two ranges to derive the BC.

The table appears to be Russian. The Germans or anyone else probably wouldn't have known there were two types of BR-350B rounds. I didn't.

[Edit]The BR-350B was used in the PT-76 tank. So that table could have been made anytime between 1943 and the Vietnam war. And newer BR-350B could have been introduced post WWII.

[Yoozername]

I should have mentioned the quote was for a Panther 75mm round...

During WW II, German tank effectiveness was due in large part to the superior effectiveness of the ammunition, which is related to nose hardness considerations.
British tests against homogeneous armor at 610 m/s impact velocity, which are documented in Miles Krogfus' AFV News article, resulted in:

102mm penetration for German 75mm APCBC
90mm penetration for U.S. 76mm APCBC
75mm penetration for Russian 76mm APBC

U.S. penetration tests for Sherman 75mm indicate 89mm penetration at 610 m/s.

Based on the above figure at 610 m/s, the Panther 75mm penetration is estimated at 188mm at 935 m/s and 0m range (DeMarre equation extrapolation). Actual U.S. tests with Panther 75mm APCBC obtained 190mm penetration at
0m and 935 m/s

[Mobius]

ORIGINAL: Yoozername
Based on the above figure at 610 m/s, the Panther 75mm penetration is estimated at 188mm at 935 m/s and 0m range (DeMarre equation extrapolation). Actual U.S. tests with Panther 75mm APCBC obtained 190mm penetration at
0m and 935 m/s

[/quote]Ah, ya.
Vs. 220-240 BHN armor.


I'm assuming this is the typical test plate.

[Yoozername]

Mobius
 
Did you say you don't have cross-sectional drawings for these Soviet rounds?  I have them if you need them

[Mobius]

ORIGINAL: Yoozername

Mobius

Did you say you don't have cross-sectional drawings for these Soviet rounds?  I have them if you need them

No, I have them. Do your drawings have "Using weapons(s): Field gun ZIS-3 and tank gun D-56T" on the right bottom?

[Yoozername]

http://www.scribd.com/doc/25044683/Projectile-and-Warhead-Identification-Guide-Foreign
 
Yes.  The 350A is very interesting.  I have read that the front was supposed to snap off.

[Mobius]

ORIGINAL: Yoozername

http://www.scribd.com/doc/25044683/Projectile-and-Warhead-Identification-Guide-Foreign

Yes.  The 350A is very interesting.  I have read that the front was supposed to snap off.

Wierd. Maybe that had something to do with the original naval design of flat head shells. Like the Japanese Type 88 and Type 91 they are designed to travel far underwater. The windscreen snaps off and a beveled flat nose 50% of the diameter is left. The purpose of these are to hit short of an armored ship and travel underwater to strike below the belt.

[Yoozername]

I have read one description that says the nose is designed to act like a cap.  Its purpose is to take the initial shock, gouge the armor and snap off.  The rest of the AP then goes through.  I would suspect that it would fail miserably against sloped armor. I would also expect varying performance against armor at other angles. The Soviet penetration values for 20% and 80% are certainly not very close together.

So it looks like the BR-350 and BR-350B are similar but the 'B' has less HE filling. The BR-350A is a much different animal altogether. I would like to see actual data of this round striking sloped and face-hardened armor.

Also, since none of these rounds have a true cap, how is it that the data that was posted show better penetration against face-hardened armor?

[Mobius]

ORIGINAL: Yoozername
Also, since none of these rounds have a true cap, how is it that the data that was posted show better penetration against face-hardened armor?

Must be the blunt nose. The reason most pointed rounds fail against FH armor is the tip shatters as it takes the most force. A cap spreads the load over a larger area. If it is spread out less force per square cm. Penetration of FH armor punches out a plug of armor.

[Yoozername]

Perhaps for vertical armor, but I would still question sloped armor penetration since it would contact on a small area.
 
Do you have any info on German use of T-34 against T-34>?

[Mobius]

ORIGINAL: Yoozername
Do you have any info on German use of T-34 against T-34>?

No.

What it might be like I have Yugoslav test of T-34/85 vs T-34/85.

[Ratzki]

Thought this might be a help to the discussion:
Talking about face hardened armor
"... Use of this kind of armor must be restricted to cases where the damage to the enemy weapon caused by the armor reduces its penetration, which is not the case at high obliquity, where a weapon that stays in one piece is more likely to ricochet completely away with minimal target damage than one whose nose is broken off and thus whose middle body and base can continue to punch through the plate even after the nose has ricochetted off. Also, face-hardened armor fails by having the armor in the projectile's path punch through the plate back where it acts as a second solid-shot-type projectile, increasing target damage; this is made worse by the fact that such a "plug" of armor can be ejected from a brittle face-hardened plate at striking velocities well below those where the projectile itself can penetrate the plate, which severely compromises the protection afforded by the plate."

From "TABLE OF METALLURGICAL PROPERTIES OF NAVAL ARMOR AND CONSTRUCTION MATERIALS"
by NATHAN OKUN (Revised 5/3/98)

[Yoozername]

As far as the BR-350A striking the sponson armor from the front on a 'G' model StuG, it would more than likely snap off its nose after penetrating the outer plate (30mm @50 deg).  It would, of course, lose mass (nose snapped off) and become deflected off its course by penetrating the armor as well as losing velocity.  It now has to pierce the inner superstructure wall.  The AP round may actually detonate it's HE burster before hitting the superstructure itself. 

I seriously doubt the T34/76 firing this round has a chance against the sponson/superstructure combination.  Even if its dead-on attack of the plate with no side angle.

In the case of the upper bow armor with a thickness of 80mm and the slope it had; I would not give the round a chance of penetrating.  The lower bow armor might be susceptible at very close ranges.  If the StuG is hull down, this large area of the StuG may not be a viable target.  Tracks hung on this plate may give marginal extra protection.

The driver's visor area and the corresponding superstructure area to the left (when facing the front), might be susceptible.  The driver's visor bolt-on armor (50+30mm) was for all G models but the other side was 80mm plate.  These small areas might be susceptible at very close range.  Again, photographic evidence shows the hits in this area seem to pop the nuts right off the bolts.  I have not seen that many penetration pics on these areas that might be from the time period in question.

The gun itself, when protected by the box mantlet, would be susceptible to damage from a dead-on hit on the 50mm front-mantlet plate.  Photos show it knocked off and the fasteners missing in many cases.  The AFV was certainly shown in photos with gun change-outs.  Unfortunately, the game does not model Gun-Kills. Gun kills were historicallyevident in StuGs as well as other vehicles.



But there appears to be some areas of the mantlet that overlaps the superstructure and the armored cross-bar that connects along the top of the superstructure.  Its my opinion that while there is some weak areas to the box mantlet, it is not as bad as some think.  The gun is uniquely sunken into the AFV.  A enemy shooting from the side could not reach some of these areas on the mantlet.

The extremely sloped areas above the driver and above the ammunition area could be immune to this round. The AP round striking this area is almost 'riding' the slope with much of its side in contact with the plate. I don't even see that it would snap off the frontal 'knob' of the 350A. If anything, it might just ride up the armor itself. I can't see it cracking off the frontal piece of the AP projectile.