"armor Angling"

[Ken Estes]

Sorry, the measurements you cite are from the ground vertical. I am discussing the angle presented by the V and it is not nearly as sharp as what was attempted in the IS-3. Thus, they redesigned to avoid the prominent weld on the centerline of the prow. This had to be the weakness of the IS3. I recall they were shocked at the failures that took place, but I am on the road and will have to dig it up later.

 

IS-3 was much exaggerated in western reporting and intelligence. It had to be reworked postwar and was never repeated. There are also no good ergometrics inside, no turret basket and so forth. The hemi turret shape was the obvious success it introduced.

[JW Collins]

Flaws aside it still seems pretty fearsome. I wouldn't want to go up against one in a M26/46 Patton or early Centurion with the 17pdr gun.

[bojan]

Sorry, the measurements you cite are from the ground vertical. I am discussing the angle presented by the V and it is not nearly as sharp as what was attempted in the IS-3

 

??? Look at hull projection above and tell me which one has V at sharper angle?

IS-3 was much exaggerated in western reporting and intelligence. It had to be reworked postwar and was never repeated. There are also no good ergometrics inside, no turret basket and so forth. The hemi turret shape was the obvious success it introduced.

1. Yes it was.

2. All wartime tanks had to be reworked post war, T-34-85, SU-100, IS-2 included (T-34-85M, SU-100M and IS-2M were all done in '50s.). T-10 was PIP-ed IS-3 basically (development lead over IS-5*, which was lighter replacement for IS-4 with IS-3 front armor shape to IS-8, which then got renamed to T-10 when Stalin croaked.

3. S-shaped side hull shape was also popular, but mostly in cast versions.

*Post-war one, not WW2 IS-5 (which was IS-2 with 100mm gun). Here is 1st version with "German" style engine cooling:

Edited November 9, 2013 by bojan

[Edmund]

I can't tell. One of Kens pictures didn't load. But if Bojan has actual measurements I would have to go with that. Good pitures though. Not sure what no. 3 is. Never heard of S-shaped side hull before.

[bojan]

S-shaped is IS-3 side armor:

Double-S is US style side-hull castings, like on M48:

[BLAH]

On a modern note,

 

Mahmudiyah, where it was M1s versus T-72s in streets -- flanking (even if the flanking was by dumb luck) and crew training seems to have won that, rather than armor.

[Edmund]

Thanks Bojan. Great diagrams. Question. Is the IS-3 front upper glacis 110mm @ 56 or 140mm @ 56. Hard to see the number and want to be sure.

[bojan]

110mm for IS-3.

Edited November 13, 2013 by bojan

[Marek Tucan]

ISTR seeing comments from WoT developpers generally saying that for some time they tried to do IS-3 based on actual measurements, but they found that no two IS-3's they had access to were exactly the same WRT angles and thicknesses so they went for blueprint values

[Edmund]

110mm for IS-3.

 

Thanks. So at that slope it would be close to 250mm effective right? Or would it be more?

[bojan]

227mm LOS from straight on, but vs period AP pretty much well protected. Slope played huge part in it, eg T-54/55 100mm@60deg glacis was immune to 90mm AP and HVAP. Additional slope also helped vs early HEAT that had troubles fusing at sharp angles - usually everything over 60deg would be iffy.

[Ken Estes]

Ah, finally found it:

 

http://ciar.org/ttk/mbt/armor/armor-magazine/armor-mag.2002.ja/4RedStar02.pdf

 

 

Red Star – White Elephant?

Were the IS-3 and T-10 Series Soviet Tanks

the Monsters They Seemed in the 1950s?

Not According to Russian Sources…

by Chief Warrant Officer 2 (Retired) Stephen L. “Cookie” Sewell

One of the eternal symbols of the

Cold War in the 1950s was the annual

Moscow “October Revolution” Parade,

in which hundreds of tanks and armored

vehicles would thunder across

Red Square every November. Western

intelligence scanned for new weapons

to be introduced, and high on the list

for many years was the IS-3 “Joseph

Stalin” series of tanks, ending with the

T-10M in the early 1960s. To many

people, no other weapon personified

the “Evil Empire” and its domination of

Eastern Europe than these monstrous

tanks. As a point of fact, both the U.S.

and the U.K. created and fielded their

own heavy tanks specifically to combat

these monsters.

But were they really the threat that

they seemed? One joy of an open society

is open archives, which permit access

to a different picture of reality than

that once accepted as fact. The archival

view of these monsters today is that

they were enormously clumsy and disappointing

clunkers, armed with obsolete

guns and ineffective fire control

systems that were marginal at best.

Worst of all, more than 10,000 of these

heavy tanks were built at enormous

cost. Only a small percentage of that

number ever found their way into units,

and most lived out their lives rusting in

Siberian storage depots.

 

.....

 

 

....

While Western analysts raved about the

ballistic shape of the turret and the

seemingly invulnerable glacis, in reality

the crew worked under cramped and

dark conditions. Due to flexing and

cracking of the hull welds and road

wheel bearings that burned out all too

soon, the IS-3 did not meet minimum

Soviet operational standards

for reliability.

Consequently, the Soviets

found themselves in the

embarrassing situation of

tanks rolling off the production

line in Chelyabinsk

onto trains to go to the factory

in Leningrad for correction

of their defects.

Even in 1946 a committee

was formed to fix the problems

of what had become

the flagship Soviet tank,

and to prevent Western

intelligence agencies from

finding out how bad the

tank really was. As a result, the IS-3

began a nearly continual cycle of upgrades

and repairs, with every single

tank receiving three major rebuilds and

upgrades between 1948 and 1959.

....

 

 

 

[bojan]

Ken, it was discussed already here, problem was that IS-3 were built under "war regime" and did not fulfill standards of "peacetime regime". They were not only ones, almost all WW2 tanks were modified in '50s (T-34-85, SU-100, ISU-152, IS-2), embarrassment was in:

 

tanks rolling off the production

line in Chelyabinsk

onto trains to go to the factory

in Leningrad for correction

of their defects.

[Edmund]

227mm LOS from straight on, but vs period AP pretty much well protected. Slope played huge part in it, eg T-54/55 100mm@60deg glacis was immune to 90mm AP and HVAP. Additional slope also helped vs early HEAT that had troubles fusing at sharp angles - usually everything over 60deg would be iffy.

 

Thanks again.

[Ken Estes]

Yes, but note that the ill-fitted plates of the prow were under tension from the various hull flexing/cracking from design defects, thus the welds remained excessively vulnerable to impacts. Back to impact #16 of the photos Mobius provided. These are design flaws not subject to rebuilding. It goes beyond what you are saying about wartime standards vs peacetime and the need to rebuild all WWII models. The IS-3 tank well could be called Kotin's Folly.

 

Edit: of course the post-production refits could do nothing for the prow welding, except patch it, thus the frontal armor was never part of the announced fixes of the three major rebuilds.

Edited November 15, 2013 by Ken Estes

[Mobius]

227mm LOS from straight on, but vs period AP pretty much well protected. Slope played huge part in it, eg T-54/55 100mm@60deg glacis was immune to 90mm AP and HVAP. Additional slope also helped vs early HEAT that had troubles fusing at sharp angles - usually everything over 60deg would be iffy.

Being immune is one thing and not succeeding with a penetration qualification of 50% of the projectile mass passing behind the armor is another.

 

My web page on different penetration criteria.

http://www.panzer-war.com/page33.html

Edited November 15, 2013 by Mobius

[sunday]

Yes, but note that the ill-fitted plates of the prow were under tension from the various hull flexing/cracking from design defects, thus the welds remained excessively vulnerable to impacts. Back to impact #16 of the photos Mobius provided. These are design flaws not subject to rebuilding. It goes beyond what you are saying about wartime standards vs peacetime and the need to rebuild all WWII models. The IS-3 tank well could be called Kotin's Folly.

 

Edit: of course the post-production refits could do nothing for the prow welding, except patch it, thus the frontal armor was never part of the announced fixes of the three major rebuilds.

 

Aha! That could explain a lot

[rmgill]

Reading through the Carrier Platoon manual from the British Infantry Training Pamphlet, I find this little nugget..

 

Jinking
60. It will not always be possible for carriers to get into crest action unseen. It is essential

that the enemy should be confused regarding their exact intention. Therefore, carriers will change

their direction and make for a different position to that which they are in fact about to take up, making their final change of direction if possible when they are behind cover. This method of crossing open country is known as " finking."

It has the added advantage of presenting to the enemy an oblique target, thereby affording the carrier the maximum protection against armour piercing ammunition.

Crews should be practised in j inking across a piece of open country and finally taking up a crest action position behind a suitable piece of cover.

 

 

[Ozarks]

Angling would only work in gaming, not in the real world. Angling exposes too much of the sides. Not only are sides much thinner than glacis they normally have zero degrees angling of their own. If a tank had 45 degree glacis the tarm would need to turn 45 degrees to the side to create a deflection angle equal to that of the glacis but it would be trading a 45 degree angle against the heavy glacis for a 45 degree angle of the extremely thin sides. In addition it would be exposing a great deal of the side. The lateral width of the target area exposed would increase so that the overall target width exposed would be much greater than with taking the shot head on. With a zero degree approach the tank's own guns would be pointing back at the attacker ready to fire a return shot and the turret's front, its strongest aspect, would be facing the attack. Even the ancients had enough sense to keep their strongest defense against attack (sword, spear, arrows) facing the direction of the attack.

[Max H]

Working out the optimum angle for both sides isn't too hard. Front armour * cos(theta) should equal side armour * sin(theta), so side armour / front armour = tan(theta) where theta = the angle to rotate the tank from straight ahead. Fr'instance, in an ideal world a pz4 with 80mm front and 30mm side should spin ~20.6 deg, giving LoS of 85mm on both front and side.

[Arminius]

Yup!

 

And that´s IMO the same Approach, that Tank Designers use ...

 

Somewhere between 0 and 45 Degrees off line ...

 

This, of Course, should NOT include the Turret.

 

Hermann

[Marek Tucan]

Practical effect can be noticeable only if your sides are about as thick as front, otherwise it is much fiddling for no effect (the Pz IV example)... IOW mostly Tiger with its 100mm front, 80mm sides.

[Ken Estes]

...and if the enemy locations are all known.....

[Max H]

And conveniently grouped close together

[Argus]

... and your tracks get repaired in 20 seconds while eating projectiles like jelly beans

 

shane