Design Issues for Russian IS Tanks

[rexford]

Back in 1999 Valera Potapov published some very interesting and useful data on his site regarding the development of the IS tank series that resulted in some of the problems that plagued the IS-2. Since some of that material is no longer on his site I would like to present the highlights of his 1999 presentation:

1. IS-1 tank with 85mm goes into production October 1943 and ends with 40 tank output during January 1944. This suggests that quite a few IS-1 tanks with 85mm gun were in action.

2. The IS-1 turret and mantlet were sized for the weight and gun associated with the 85mm main weapon. The 100mm turret front and mantlet allowed a perfect balance with 85mm weapon. The narrow mantlet also allowed good vision around the relatively narrow gun barrel that did not have a muzzle brake.

3. Starting December 1943 the IS-2 with 122mm gun was produced. Breech limited rate of fire to 1-1.5 shots per minute. Putting a larger gun in the turret unbalanced the turret to the point where the turret armor could not be increased without changing many of the turret rotation mechanisms, which was not desired (slows production). So turret armor is retained at 100mm max.

Putting the larger 122mm gun in the narrow mantlet designed for 85mm gun creates problems seeing and firing on moving targets due to size of 122mm gun muzzle brake and distance from mantlet. Valera stated that it became all but impossible to use the telescopic sight, which suggests that the gunner had to use the turret top "gum drop" sight.

The widened mantlet which shifted the sight to the left and improved telescope use was produced starting May 1944.

4. Starting January 1944 breech is changed on IS-2 allowing 1.5-2 shots per minute.

5. During March 1944, Russian firing tests conducted with 76.2mm gun firing on IS-2 tank from 500 to 600 meters. Tank's armor partially penetrated on all sides and while only a few rounds make it completely through, most hits create major splintering and fragmentation inside the turret. "This explains the considerable losses of IS-1 and IS-2 tanks in the winter-spring of 1944".

Armor tempering improvements resulted from identification of problems.

6. IS-2 later version has 110mm at 60 degrees glacis, which is impossible target for Tiger II "88". Turret front armor at 100mm (rounded) is penetrated at 2000m and beyond by Nashorn in photo reports that I have.

Russians realize that nose armor on later IS-2 tanks is vulnerable to 88L71 (we estimate that 88L71 APCBC penetrates 127mm at 30 degrees at 2500m, Panther penetrates at 500m), but believe that relatively few shots hit nose, and increasing nose armor slope would have major changes to driver compartment.

IS-2 development and combat action sections on Russian Battlefield describe several penetrations of IS-2 nose armor.

SUMMARY:

IS tank development initially for 85mm gun, which creates some problems when 122mm gun is installed, and limits turret armor thickness.

Nose armor is also limited by design considerations when uparmoring is pursued.

IS-1 with 85mm gun could penetrate Tiger 100mm frontal armor at 1000m, but would be inferior to Panther.

[Redwolf]

[deleted post assigned to wrong thread]

[ 01-05-2002: Message edited by: redwolf ]</p>

[Priest]

Rexford I do not think I have said this but thanks i always find your posts interesting and they expand my knowledge. Please keep going especially on the Russian armor because it is something I am trying to learn more about.

[busboy]

Good post. The IS series of tanks would have been vastly more effective if they had been equipped with the 100mm navel gun, which had a smaller round (quicker reload) and better armor penetration than the 122mm.

The facts on internal spalling are really intiresting to me. That statistic really negates the thick armor. In addition, the fact that "only some rounds managed to fully penetrate" in firing tests, then that means armor quality varried greatly.

The pet question that I entertain is: how much trouble would the Allies have been in if WW3 started right after WW2? Facts like thatonly go to strengthen my mental battle images in favor of the Anglo-Americo-Germanic forces.

IS-IIIs stunk!

[The Commissar]

2 shots per minute for the IS-2?! Combined with the low quality Soviet optics and inability to use even the ones they have due to the problems rexford listed?!

Here's the first unit on my list of "vehicles I will never buy in a QB".

[Iron Chef Sakai]

How did the IS III's suck?

[offtaskagain]

<blockquote>quote:</font><hr>Originally posted by Iron Chef Sakai:

How did the IS III's suck?<hr></blockquote>

The glacis fell off when they hit a bump.

[busboy]

Well, I didn't say it "sucked" as I didn't want to sound too harsh. (with exception of the Peng challenges, things are generally very civil around here)

However, it does suck!

The turret, no matter how well "shaped" you think it is, limits gun depression. It has a slow rotation rate. Considering the ammo is two piece, in a SMALL turret with a BIG breech, reload time is tremendous.

In the desert, an environment where a heavy tank like the IS-3 would in theory dominate, the Israeliis TORE APART the IS-III. The M-46 and M-47, and Centurion tanks admitedly couldn't penetrate their front armor, but through superior tactics they flanked and wasted 'em.

Combat experiance is all I need to see to show how horrid those tanks are.

I remember a Patton anicdote. Patton was present with Zhucov (damn, I can't spell his name, sorry) at a Russian victory parade, in Berlin I believe. The Russian general was particularly proud of the heavy tanks in the parade, and he gloated to Patton:

You see those tanks there my dear General? They are capable of engaging targets more than 2 KM away.

Patton, without mission a beat replied:

My dear General, if my tankers were to open fire on your tanks at any range less than 500 M, I'd have them tried and shot for cowardice.

Zhucov's interpreter said it was the only time he'd ever seen him too shocked to speak.

The heavy tank in question was almost certianly the IS-III. (Described as "a new heavy tank" in the sources I found it in)

[The Commissar]

<blockquote>quote:</font><hr>Originally posted by busboy:

In the desert, an environment where a heavy tank like the IS-3 would in theory dominate, the Israeliis TORE APART the IS-III.

<hr></blockquote>

Now my knowledge of the 6 day war is admittedly limited, I do believe there were occasion when the JS-III did come out victorious when it was used properly.

Here is a excerpt illustrating this from a book entitled 'Tank vs Tank' by Kenneth Macksey:

"The Israeli assault on the Jiradi Pass took the strong Egyptian defense by surprise, although after the initial penetration, the Egyptians recovered. Their resistance left the patrol of Sgt Shuval wrecked at the raodside. Nearby are knocked out M-48s of Major Ehud Elad's armored battalion. They had attempted to move off the road, and found the ground free of mines but in deep sand. M48s to the right were crippled by mines, to the left, others were wrecked by gunfire from JS3 tanksand anti-tank guns."

<blockquote>quote:</font><hr>Originally posted by busboy:

The M-46 and M-47, and Centurion tanks admitedly couldn't penetrate their front armor, but through superior tactics they flanked and wasted 'em.

<hr></blockquote>

You see, its not as much the fault of the tank design as it was the fault of the people using said tanks. Again, the book I have previously quoted supports this fact by a paragraph shortly following the one above:

"...He (Lt. Ein-Gil and his company of M-48s) reached the pass almost unharmed, the shaken Egyptian gunners missing such fast moving targets or deserting their guns which fell silent. Once through, but badly strung out, Haim took charge, ordering Ein-Gil to shoot up the outlfanked JS3s on the backwards slope. The gunners of the JS3s, with slow-traversing turrets, had been unable to track the speeding M48s, and their vehicles begun to erupt to hits through their thinner side armor..."

A rather obvious lack of proper communications (a simple warning to the IS-IIIs that the enemy had broken through would allow time for rotation to face the enemy), lack of knowledge of the ability of your fighting equipment and men (could a few guns in identified positions really be trusted to hold out? We all know what happens to identified guns in CM...), and an apparent inability to adapt to circumstances, which is a sign of bad leadership on the part of the Egyptains.

<blockquote>quote:</font><hr>Originally posted by busboy:

My dear General, if my tankers were to open fire on your tanks at any range less than 500 M, I'd have them tried and shot for cowardice.

<hr></blockquote>

Damn. I don't get it. Can someone tell this dufus what that was supposed to mean?

[Iron Chef Sakai]

I agree with the above post wich was whati was getting at.

Now the centurion tank was pretty gross.....hehe

Also in response to that Patton quote to Zhukov,...Patton was a blow hard and over rated. Bradley was a much better general. Patton was our equivelent to Monty in my opinion.

[busboy]

Iron, you're entitled to your opinion, but so am I. I say you're wrong. Comparing Patton and Monty is rediculias unless you mean they both loved the spotlight. Bradley was reliable, a battle winner, but not the best we had.

Patton overrated? Hell, look at statistics, or look at how others held him. He was the only General the Germans really feared ("Monty was reliable" they said.) Stalin himself said that the Red Hordes couldn't have done as well as Patton's 3rd Army did.

Dorry if you don't like flamboyant cavalrymen, there's always gonna be folks who don't, I know.

Commissiar, my knowledge of that war is limited too, but what I do know comes from, among a few other sources, that very book you quote from! I agree with your annalesys, but what I'm saying is that even in the desert where a tank like the IS-III is tactically best suited, it could be overcome by more numerous, and more universally useful tanks.

Don't get me wrong, I'm not saying that the IS-III isn't a monster (especially in infantry support) I'm just saying its overrated in a tank vs. tank sense.

As for the Patton quote, Patton was baisically calling the Russians cowards for developing a weapon system that could engage targets from a long range. He was telling the Russian that he'd want his tankers to courageously charge to point blank range to allow more personal and efficient killing. Of course, for a Sherman 76 to kill an IS-III, it'd have to anyway. It was Patton's disrespectful audacity that really shut Zhucov up.

[Grisha]

The decision to arm the IS-II with a 122mm gun was based on its primary function - breakthrough against fortified infantry positions. While capable(and designed) to go toe to toe with heavy German armor, the consensus was that the IS-II would encounter infantry positions far more frequently than German panzers.

[Brian]

The rating of Generals is always very hard and based more often than not upon personal perceptions.

Until recently, I rated Montgomery pretty lowly, considering him to have been quite unimaginative. That changed when I read an excellent book, perhaps the first which attempted to explain the reasons why he made the decisions he did, in NW Europe, rather than simply talking about the decisions themselves. Now, I still believe he was unimaginative but I can understand why he made the decisions he did, much better.

Patton, I've never had much time for, but again, thats purely a personal perception - based around his flamboyance and his self-promotion. I didn't think he was a particularly good commander, he was merely better than those he faced, whose forces were usually considerably inferior to his own.

Bradley has always struck me as a solid performer. He wasn't flamboyant, he wasn't super-imaginative but he got to where he was meant to, usually on time, which is all that can realistically asked of most military commanders.

Personally, I'd rate Slim as being perhaps one of the best British commanders, unfortunately he was stuck in a backwater for most of the war.

[busboy]

Well Brian, if you read "The Patton Papers" you might change your mind there too. Of course, our own opinions have so much to do with the debate, but you'd be suprised.

Patton took on oponents that are considered the best the Germans had. He defeated Rommel's Africa Korps in El Guitar (sp) and Runstedt in the Falaise Pocket (which Patton could have closed but was stopped by SHAEF.)

Again, this is all opinion. I myself am rather like Patton, so I have a natural tendency toward his type of leadership anyway. Some people can't understand this personality, though. I understand that, and thats why I don't force the isse.

But its still a load of fun to debate!

[Priest]

Iron Chef,

Patton was similiar to Rommel if anybody. Monty was similiar to Goofy. Honestly how can you say that? I can understand that folks can make arguements about who was good and all but to compare Patton and Monty is to compare oil and water.

[Triumvir]

And none of them -- not even the vaunted Germans whose officers came from the ranks -- could hold a candle to Bill Slim. Because Slim was defeated badly in 1942, and after two years, SMASHED his opponents without a flicker. He fought manoeuvre and attrition -- look at Imphal and Kohima for examples of the two -- and made damn sure that he won because he knew that adage better than any other general did; battles are won by generals, but wars are won by soldiers. Not just combat troops, but the lowly supply sergeants and drivers who make sure that the combat troops have enough to eat and fight with. Slim cared for them all, in a way that no other general did.

Monty, Patton, Bradley and Eisenhower all stayed apart from the men they commanded. But for thirty five years, veterans of Burma would cluster around Slim when he attended the annual dinner for the Order of the Burma Star. It's a signal trait for a general officer to be respected not just for his rank, but as a man.

[Iron Chef Sakai]

<blockquote>quote:</font><hr>Originally posted by busboy:

Iron, you're entitled to your opinion, but so am I. I say you're wrong. Comparing Patton and Monty is rediculias unless you mean they both loved the spotlight. Bradley was reliable, a battle winner, but not the best we had.

Patton overrated? Hell, look at statistics, or look at how others held him. He was the only General the Germans really feared ("Monty was reliable" they said.) Stalin himself said that the Red Hordes couldn't have done as well as Patton's 3rd Army did.

<hr></blockquote>

Ok, find me in writting where Stalin himself said that the Communist armies were inferior to that of the 3rd army commanded by Patton.

The red army was fighting much larger german forces then the western allies were. If the Soviet Union was not at war with Germany, how well do you think Patton's 3rd army would have done against say....Army Group South?

I was comparing Patton to Monty not as tacticians, but as for both being gigantic glory hounds. They had no problem sacrificing their mens lives for some extra added glory, wich is poor leadership.

I'm sorry to burst your bubble, but Patton was not any where near the realm of a Hannibal or Napolean. Patton just beleived his own hype. Patton and Monty were just 2 compettive little brats both trying to out do each other.

[Porajkl]

Well, we are now off the topic, aren't we?

I just wish that BTS will model rate of fire of this beast correctly, so it wouldn't pose to big threat to Germans. Also SU-152 had rate of fire around 2 rounds per minute. I remember CC3, when I didn't buy almost anything else but those SU-152s because they had rate of fire like SU-76

Those SU-152 were really tank and infantry vaporizer with such huge gun and abnormal rate of fire. Well, that was until I installed indepent patch from some people who corrected a lot of errors so the game became more realistic...

[The Commissar]

<blockquote>quote:</font><hr>Originally posted by busboy:

He defeated Rommel's Africa Korps in El Guitar (sp) ...<hr></blockquote>

Now, once again, I am no expert in on the Afrika Korps (and I so do hate intruding on topics I am not completely in tune with), but wasn't the Korps in a state of disrepair and severe neglect when it came to supplies? Was El Guitar during or after the siege of El Alamein (sp?)? Im tempted to think after, when the British pushed the Afrika Korps back to where they started. This would mean that the "poor" Germans were in a very tight spot. Even Rommels skills could not make tanks lacking the necessary fuel start moving.

[The Commissar]

<blockquote>quote:</font><hr>Originally posted by Porajkl:

Well, we are now off the topic, aren't we?

I just wish that BTS will model rate of fire of this beast correctly, so it wouldn't pose to big threat to Germans. <hr></blockquote>

I wonder if BTS will allow us to have more then an hour of combat in CMBB. This way, we can use some of the weaponry with more effect. Things like the IS-2, SU-152, or the Sturmtiger for the Germans really need time to get into position and pound away at the enemy. Given such time, they will be formidable foes, but without it, they will be little more then overpriced and overrated trinkets with no real use on a CMBB battlefield.

Hey we have 6 kilometer maps, so we can hope right?

[Iron Chef Sakai]

<blockquote>quote:</font><hr>Originally posted by The Commissar:

Now, once again, I am no expert in on the Afrika Korps (and I so do hate intruding on topics I am not completely in tune with), but wasn't the Korps in a state of disrepair and severe neglect when it came to supplies? Was El Guitar during or after the siege of El Alamein (sp?)? Im tempted to think after, when the British pushed the Afrika Korps back to where they started. This would mean that the "poor" Germans were in a very tight spot. Even Rommels skills could not make tanks lacking the necessary fuel start moving.<hr></blockquote>

Your absolutly right Commisar, the british had been having their way with the afrika korps for quite sometime before Patton's army gained any success.

Patton did not defeat Rommel, it was mainly Hitler refusing to resupply the army at key points in the campaign, and of course the British and Commonwealth armies.

[Andrew H.]

Patton was a very good general, so was Monty. Patton was probably better, but Rommel was much better than Patton, so there. Monty hurt his reputation by occasionally lying about things after the war (i.e., Caen), but his inability to take Caen is not a sign of incompetence.

Monty in Africa was just what the british needed: a commander who could meticulously arrange his superior forces so that he would get some benefit from having superior forces (i.e., they wouldn't be defeated in detail again. While not nearly as sexy as deep encircling probes, or something, it was exactly what was needed to win at Alamein.

And, yeah, a lot of commentators have pointed out that with a little more cavalryman's flair at the end of Alamein, Monty might have been able to surround and capture all of the Afrika Korps. Maybe this is right, but sending out long, unsupported tank forces to try and trap Rommel, who always seemed to turn initial british victories into british defeats once the british overextended themselves, seems like something one should think twice about doing.

Monty in Normandy was faced with the task of keeping casualties as low as possible due to the british manpower situation. So he had to be cautious. And while he did have problems advancing very far against the Germans in his sector, the same must be said about all allied commanders.

Patton's best performance was in the breakout. The contours of this are well-known, of course, but Patton did his part perfectly -- he covered huge amounts of ground, captured lots of troops and materiel, and suffered very few losses. It's not really fair (or accurate) to denigrate Patton's performance here as being against already beaten troops...while these troops were probably already beaten, Patton had to make sure that they stayed beaten long enough to capture much of France. (Remember, the German troops later forgot that they were beaten at the end of this year). Patton's performance particularly stands out when you remember that one problem the allies had in France was that very small numbers of German troops were able to delay much larger Allied forces. Not that this turns Patton into Napoleon, but being able to do something that no other allied general in the west can do bespeaks a certain amount of competence; the Germans would agree with this assessment. (Patton would disagree; he thought that he was napoleon).

Patton's reinforcement/relief action during the battle of the bulge was also handled very well: he got his entire army up, on the road, and to the shoulder of the bulge very quickly.

[Iron Chef Sakai]

Discussing who was better, Monty, or Patton is like discussing who the better obscure minor league right fielder is.

The truth of the matter is that Patton and Monty, Zhukov,or Runstedt were decent generals of the 20th century and thats all that can be said.

There have been countless numbers of generals that exceed the skill of these people skills

[Tanaka]

<blockquote>quote:</font><hr>Originally posted by The Commissar:

Now, once again, I am no expert in on the Afrika Korps (and I so do hate intruding on topics I am not completely in tune with), but wasn't the Korps in a state of disrepair and severe neglect when it came to supplies? Was El Guitar during or after the siege of El Alamein (sp?)? Im tempted to think after, when the British pushed the Afrika Korps back to where they started. This would mean that the "poor" Germans were in a very tight spot. Even Rommels skills could not make tanks lacking the necessary fuel start moving.<hr></blockquote>

...and don't forget, even before El Alamein, the Allies had broken both German and Italian N African codes... so they knew every step the Fox would give, even before it moves

Does any one remember Kasserine and the 1st Armor Div ? How it ended ? Who was the commander of the 7th Army ?

[Brian]

<blockquote>quote:</font><hr>Originally posted by Triumvir:

And none of them -- not even the vaunted Germans whose officers came from the ranks -- could hold a candle to Bill Slim. Because Slim was defeated badly in 1942, and after two years, SMASHED his opponents without a flicker. He fought manoeuvre and attrition -- look at Imphal and Kohima for examples of the two -- and made damn sure that he won because he knew that adage better than any other general did; battles are won by generals, but wars are won by soldiers. Not just combat troops, but the lowly supply sergeants and drivers who make sure that the combat troops have enough to eat and fight with. Slim cared for them all, in a way that no other general did.

Monty, Patton, Bradley and Eisenhower all stayed apart from the men they commanded. But for thirty five years, veterans of Burma would cluster around Slim when he attended the annual dinner for the Order of the Burma Star. It's a signal trait for a general officer to be respected not just for his rank, but as a man.<hr></blockquote>

A good point, which comes out in all the books about Slim. When asking a Burma veteran, where they served, they would invariable say, "With Slim!" Ask most other veterans and they'd say, "Under Patton". "Uncle Bill" as was known, both to himself and his men, rose through the ranks, from Corporal to Lieutenant, through to Field Marshal. He was one of the few to ever do so and never forget that it was because of his men that he won victories, not himself.