Denizen Posted August 7, 2003 Share Posted August 7, 2003 Sparked by the suprising vulnerabilty of the IS-2 turret front in CMBB, several months ago I set out to research the tank in more detail, in part to find out how its designers could have justified an obvious design flaw in the IS-2 armor protection. We have all seen how well the glacis of the IS-2 resists some of the most powerful shots in CMBB, only to be decidiedly unimpressed by its turret protecion; how could the red army have accepted such an oddity? Limited by the few western publications availible on the IS-2, I found only confusion. Some, like the decades old Russian Tanks by John Milsom, agreed with the BFC take on the IS-2 turret armor thickness, while others, notably Zaloga's Red army handbook gave a wild turret armor figure some 60mm in excess of the data BFC used; 160mm turret front. When I brought this up on the board months ago, I was told that even the experts like Zaloga make mistakes on these things. Well, I certainly could believe that given the errors I had seen made by other 'experts' notably Ian Hogg who in the Greenhill AFV "Data Book" confuses the IS-2 with the IS-3, saying both entered production in 1945 Knowing that the data in such books could be flawed, I studied the availible pictures carefully and noticed something that would turn out to be important. The Differences between the IS-2 models produced at the very end of 1943/very early 1944 and those produced once production escalated in mid 1944 were not limited to the hull. As many will know the early IS-2 variants had the stepped front hull similar to that of the KV, but a close examination will reveal large differences in the turret as well. All of the earlier tanks a narrow mantlet with the gunsight hole on the gunners left and the mg hole on the gunner's right, the two holes being roughly equidistant from the gun itself. However the later tanks had a mantlet that streched to the gunner's left a considerable distance, the sight being on the far left side and the mg on the gunner's right, the sight being a considerble distance from the main armament. This pictoral evidence was enough to show that not only did two different mantlets exist, but the differnce between them was great enough to have changed the internal layout of the turret itself. This led me to believe that rather than being a simple difference in manufacturing technique, there was a change in the tank design that required replacement of the old mantlet. Here however, I ran out of information. Despite the obvious visual difference in the tank, no book I could find even mentioned the existance of more than one mantlet design. I thought about it for a while and came up with the possiblility that maybe the Zaloga turret armor measurement and the Milsom measurement were in facgt measurements of two differnt mantlets. I brought this up on the board some time ago, but it was quickly dimissed by the mention that the curved nature of the mantlet meant that different parts could have differt thinknesses, zaloga picking the small thick part while the Milsom measurement was the majority of the area. This made sense certainly, but it did not explain why the factories went through the pain of significantly changing the mantlet in the first place. Certainly there had to have been some sort of problem with the ealier desgin, but what was it? Playing CMBB it certainly seemed logical for them to have up-armored the mantlet, but this was purely conjecture. Since the later mantlet was visibly larger, it seemed reasonable to rule out the early one from being too difficult to build, so that the raeson for the change would have to be related to battlefield performance. Perhaps the sight was too close to the gun on the early mantlet? This possibility was quickly ruled out (foolishly as it turns out) upon discovering that the T-34 sight was just as close, and countless variations of T-34 had progessed without any movement of the mg. So I came to the conclusion that the mantlet design had to be changed due to weaknesses in protection. Unfortunatley, I had no proof. Living several thousand miles from the nearest IS-2 there was no way to examine it in person. I did however find some hope. On the now well-known baattlefield.ru site, the IS-2 section had a breief mention of the mantlet change, the first I had seen, and furthermore this statement was made: "Statrting in May 1944 a new turret with widened porthole was manufactured, which resulted in the sight being moved to the left. The armor protection of the tank's mantlet was improved and the armor thickness of the sides of the lower hull was increased. Well, I was wrong about the gunsight, but here I finally had information that the the larger late mantlet was indeed thicker than the small one in the early tanks. I got to this stage a few months ago, but then I had to face the inevitable question; how much thicker. Obviously the dozens of books I in my collection had no answer to this question, and neither as it turned out, did battlefield.ru. So then where was I to turn? I scoured the internet and local libraries for any information at all, again, only to find that if the answer was out there it had to be in Russian. So I order a few books in russian, from armybook.com. However, not knowing a word of Russian I knew I was up for a challege. Once my books arrived I began to translate them at a snail's pace for that magical sentace I knew would be there somewhere. And, at long last I've found it! Proof can be found in 'IS tanks' a special issue of the journal Tankomaster, page 55. Here is a literal translation of the sentance, using the Random House Russian English dictionary: "By protection alteration part turret armor increased to 130mm that factor increased more greater" This then means that the base thickness of the late turret was 130mm, and perhaps the thickest parts were more, to explain Zaloga's measurement. It took sweat, tears, and a lot of time but I think I have finally sorted this issue out. The later turret design/mantlet is at least 130mm thickness, far apart of the 100mm thickenss of the earlier one. CMBB uses a 100mm value for both, and given the attention to CMAK now, that egreigious error will likely stay in CMBB forever. Oh well; but please pass the word on, I don't want to know I wasted all those hours translating russian for nothing. [ August 07, 2003, 03:14 AM: Message edited by: Denizen ] 0 Quote Link to comment Share on other sites More sharing options...
Tero Posted August 7, 2003 Share Posted August 7, 2003 Originally posted by Denizen: Sparked by the suprising vulnerabilty of the IS-2 turret front in CMBB, IRL the vulnerable area was under the gun. The reports I have read about tank-vs-tank engagements with IS-2's almost invariably say the disabling/KO'ing hit was made under the gun or above/through the drivers vision port. That would suggest the turret ring was the weakest point in the behemoths armour. Furthermore, if memory serves, the turret front forms a shot trap which directs ricochets through the drivers compartments roof when the turret is turned forward. [ August 07, 2003, 03:34 AM: Message edited by: Tero ] 0 Quote Link to comment Share on other sites More sharing options...
Other Means Posted August 7, 2003 Share Posted August 7, 2003 very well done on your extensive research. what i think would convince BFC is if you go to a tank museum in Russia & remove a cross section of the turret. yes, shipping may cost a bit but i'm sure a couple of pairs of Levi's & some "Earth Wind & Fire" albums & the authorities would lend you a junior hacksaw. seriously, well done. maybe you could send a photocopy of the relevant pages to BFC. not sure if they'd address it but how hard could it be? as long as people don't start clamoring for the IS-3 model or something. damn, i've missed a perfectly valid opportunity to say "sumfink". 0 Quote Link to comment Share on other sites More sharing options...
Kanonier Reichmann Posted August 7, 2003 Share Posted August 7, 2003 Well done Denizen. I reckon even Rexford a.k.a. Lorrin Bird would be suitably impressed with the extent of the research you have conducted. Two thumbs up in my book. Regards Jim R. [ August 07, 2003, 08:49 AM: Message edited by: Kanonier Reichmann ] 0 Quote Link to comment Share on other sites More sharing options...
YankeeDog Posted August 7, 2003 Share Posted August 7, 2003 This thread should be preserved as a case example of how to argue and present evidence for a change in the game modeling. Short of original manufacturing blueprints or cross-sectioning a late IS-2 turret and measuring the armor thickness, you couldn't ask for more. I suspect if this information had come to light a year ago, or perhaps even 6 months ago, BTS would be willing to reconsider the IS-2 stats. It's too bad your hard work is too late to be used this time around, but you should definitely document and preserve your research. While I doubt BTS will revisit the East Front in the initial release of CMX2, I suspect it's only a matter of time before they do revisit Barbarossa to Berlin. I hope your information is in their hands when they do. Thanks again, YD 0 Quote Link to comment Share on other sites More sharing options...
Denizen Posted August 7, 2003 Author Share Posted August 7, 2003 Tero: The early turret mantlet was horizontally narrow, but it extened from the top of the turret to the bottom. Given its lesser thickness, the area of the early mantlet under the gun was certainly a weak spot. While you mentioned 'reports', there are in fact photographs of early IS-2 tanks knocked out, with the whole of the manlet having separaed itself from the turret. The rebuilt mantlet corrected this problem. As for the "drivers vision port", you will note that the tank in its earliest versions (ie IS-1) had a stepped front hull like the KV. While the glacis was sloped, the part of the front hull with the driver's vision port was *vertical*. This error was corrected in the IS-2 from the beginning of 1944 onwards. The new front hull, completely sloped had a vision port flush with the hull surface itself and a protective 'lip' of armor to boot. While the vision port area was a vulnerability in the earlier version, the bulk of the IS-2s were built with vision ports proven to survive nearly every foreign projectile. As for the turret ring, yes the IS-2 was vulnerable if it was hit there, but so was every other tank. The downward curve on the mantlet could have sent projectiles into a vulnerable area at the ring, but changes in frontal protection meant the later versions had as much armor at the ring as any other place on the tank. Having looked at dozens of photos of knock out IS-2s I have only seen serious turret ring damage on the earlier versions, the late version were usually only destroyed by hits to the side of the tank, or of course by bombs. [ August 07, 2003, 02:06 PM: Message edited by: Denizen ] 0 Quote Link to comment Share on other sites More sharing options...
MikeyD Posted August 7, 2003 Share Posted August 7, 2003 You can tell the Soviets weren't happy with their turret protection (their data showed that by far the highest penetrations were against the turret) by the lengths they went to in designing the IS-III. The shot trap dropped to nearly 0 in that design. The IS-III's main problem may have been it was simply too ambitious to pull off successfully. A fault found in many U.S. tanks of the 1950s... and 60s... and 70s. 0 Quote Link to comment Share on other sites More sharing options...
Amedeo Posted August 7, 2003 Share Posted August 7, 2003 Denizen, I'm glad you 'resurrected' this old issue. In fact I was dubious about the IS-2 armour stats from the beginning, and it's more than two years that I tried to collect evidence from different sources, including Russian ones, to find reasonable data. If you do a search on this forum you will quickly find out what was discovered in the past. In CMBB the IS-2 (late model) is probably incorrectly represented first and foremost because the front hull plates were only 100mm thick (cast version, 90mm rolled). Moreover they modelled also the plating of the rear MG port but, AFAIK, this was done only in the postwar IS-2M modernized models. For what concernes the 130mm mantlet, well, you can read here: http://armor.kiev.ua/Tanks/WWII/IS2/is2_1.html that the 130mm mantlet was planned but discarded because it sported unsormontable problems for a turret that was projected for an 85mm gun, was used to mount a 122mm gun and wasn't able to accept a further armour mass increase in its front part. So, if you have time, please check the context in which your 130mm mantlet reference was made. For what I saw it was only a projected mod that was impossible to carry out. Regards, Amedeo P.S. And there's also the issue regarding the DOI for the BR-471B APBC, does that Tankomaster article says anything about it? 0 Quote Link to comment Share on other sites More sharing options...
MikeyD Posted August 7, 2003 Share Posted August 7, 2003 Ouch! Amedeo's link is nothin' but question marks! A Cyrillic Russian site, I suspect. Here's an English language IS-2 site (might be the same one) that notably had two separate drawings with the late IS-2 upper hull at 120mm, though the consensus is that it shouldn't be. http://www.battlefield.ru/is2_1.html 0 Quote Link to comment Share on other sites More sharing options...
dieseltaylor Posted August 7, 2003 Share Posted August 7, 2003 Right or wrong the Order of Lenin goes to Denizen for his valiant efforts and the way he has presented his argument. Splendid sleuthing. Armedeo - you could have said the link was totally in Russian ....... But nice work , I think. Thanks to you both as an inspiration to the rest of the board. And now there are Russian players perhaps the translating can become easier 0 Quote Link to comment Share on other sites More sharing options...
Amedeo Posted August 7, 2003 Share Posted August 7, 2003 BTW one can find the last discussion about IS-2 armour on this forum here . 0 Quote Link to comment Share on other sites More sharing options...
Denizen Posted August 7, 2003 Author Share Posted August 7, 2003 First of all, thanks for all of the attention! I will read some more to sort some more of this out tonight, but for the moment I have a few comments: Amedeo: I ran across a reference that that a new turret assembly for the IS-1/IS-85 that mentioned a new assembly to mount the 100mm naval gun as used in the SU-100 but rejected due to its excessive size/weight (different center of gravity than 122mm) Are you certain that the linked refernce is reffering to a change rejected *after* march 1944? We know from pictures that the assembly of the mantlet and indeed the majority of the turret went through a significant change during this period. If the 130mm matlet for the IS-2 was rejected, what were the specifics of the new mantlet they created? I had assumed from photographic evidence that they came up with a whole new turret able to fit the 130mm mantlet, discarding the interim IS-1 turret, just as they came up with a new front hull. As for the thickness of the glacis plate, I avoided quoting a figure ealier beacuse even my Russain sources are in disagreement... I'm looking into this further now 0 Quote Link to comment Share on other sites More sharing options...
rexford Posted August 8, 2003 Share Posted August 8, 2003 The original narrow mantlet width was designed for the 85mm gun IS-1, where the barrel was relatively narrow and did not have a muzzle brake. The gunsight on the original narrow mantlet IS-1 worked just fine cause the gun did not get in the way when one was sighting a moving target. I don't believe there were plans to upgun to 122mm when the IS-1 was first designed, based on the mantlet design. But only 108 or so IS-1 were built before the Russians went with 122mm guns due to inadequacy of 85mm against Tigers and Panthers. The first IS-2 with the narrow mantlet and 122mm gun with large muzzle brake fouled things up, cause the gun barrel and brake got in the gunners way when trying to lead a moving target. The mantlet width was increased so the gunner could see around the long and wide 122mm gun barrel and not be blocked by the muzzle brake. The Russian Battlefield site states that the turret armor and weight could not be increased due to the unbalanced turret weight, where the original turret design was for an 85mm gun. The much heavier 122mm gun messed up the turret balance. A post on the Yahoo!Tankers site showed a 110mm mantlet thickness stenciled on an IS-2 that the Germans had captured. British Intelligence figures on the IS-2 mantlet and turret front did not exceed 100mm, which could be due to casting variations (Russians used casting molds till they fell apart, and maybe a little while afterwards). The 160mm width may come from some British figures where the basic mantlet was shown as 100mm and there was a small lip of the turret front that extended below the mantlet left/right edges a small bit. Add the two and it is about 160mm, but the small lip would suffer from edge effects and would not really add much. Drawings of the IS-2 mantlet side view show a big thickening around the gun, which might scale as around 160mm. The "best data" appears to be the German thicknesses stenciled on captured IS-2 tanks, 110mm mantlet and 100mm turret front. Actual wartime measurements (maybe), or figures copied from Russian tank crew manuals (could be). Anyway, odds are that early IS-2 and late IS-2 had same turret and mantlet thicknesses if one takes the weight restriction commentary at face value. [ August 07, 2003, 06:56 PM: Message edited by: rexford ] 0 Quote Link to comment Share on other sites More sharing options...
Private Bluebottle Posted August 8, 2003 Share Posted August 8, 2003 You might want to contact Roman Alymov at tank_driver@mail.ru. He posts semi-regularly to the tanknet site. Apparently he is a volunteer who works at Kabinka restoring AFVs. He might be able to help you. 0 Quote Link to comment Share on other sites More sharing options...
Denizen Posted August 8, 2003 Author Share Posted August 8, 2003 rexford: you are correct that RBF does state that the turret had balance problems, however as I mentioned in the first post, the same webpage says just a few lines down that the movement of the gunsight created a new turret complete with armor improvements. Thus the weight problem was only a temporary issue for the *early* variants. The new turret had an enitrely redesigned front, include changes in the cg such that more weight on the front *was* possible. Without the weight argument to resort to then, we can only look at the german/british measurements of the tanks, but if you take another look at the photo from yahoo tankers, you will see it is an *early* variant, thus the thickness of the *early* mantlet was roughly the 110mm figure painted on it by the germans. Could the discrepancy with the British figures then have something to do with measurements coming from both an early and a late tank? With the weight problem resolved, and the necessity of designing another mantlet for the gunsight, it only seems logical that the armor improvements were included as well, as indicated by RBF and the book i mentioned ealier. Oh, and thanks for responding, now we can have a real debate. [ August 07, 2003, 08:22 PM: Message edited by: Denizen ] 0 Quote Link to comment Share on other sites More sharing options...
Denizen Posted August 8, 2003 Author Share Posted August 8, 2003 Amdeo: As I mentioned previously, even Russian sources disagree on the thickness of the late model glacis plate, after looking through my books I have found the same 100mm cast hull and 90mm rolled hull, however, the Encyclopedia Tankob disagrees. http://www.armybook.com/summary.html?code=0103008105 While I usually never trust a single source for anything, when books disagree it is only logical to believe the more comprehensive work. As the owner of approximately 150 books directly covering armor, Encyclopedia Tankob is in my opinion, the Jane's of historical armor. With a bibliography that has as many words as some armor books do in their entirety, and an endorsement by a Russian historical society (if that makes any differance to you) this is the source i trust most. It gives a 120mm figure for the hull armor and 160 for the thickest part of the turret. Short of having the blueprint in hand, it won't get any more accurate than that. Unless of course, you are lucky enough to get vacation time. As a sidenote I would like to mention that book has some information on western tanks that is supposedly classified this side of the ocean 0 Quote Link to comment Share on other sites More sharing options...
rexford Posted August 8, 2003 Share Posted August 8, 2003 "It gives a 120mm figure for the hull armor and 160 for the thickest part of the turret." Does it identify where the thickest parts were and how large an area they covered? Could be a small area. Using the thickest sections of an armor plate is not a very exact way to express things, since small local areas may be designed thicker than 95% of the area. A small area around the gun or a vision port could be the max. The IS-1 and IS-2 mantlet is curved and tapered, with 76mm at the upper and lower edges and a maximum in the middle (the apex). So one figure for the mantlet thickness is not correct, and one Russian book actually stated 76mm for the IS-2 mantlet thickness (forget which reference). I'am not sure what the "improvement" to the IS-2 turret armor means. Could be more thickness, or maybe just that mantlet armor was more resistant than turret front (if mantlet is 110mm thick and turret front is 100mm, using a wider mantlet means more area is protected by 110mm as opposed to 100mm). So turret armor "improvement" could be a higher average thickness when mantlet and turret front armor combine for an average thickness, with a greater area of mantlet on later tanks. The unbalancing of the IS-2 turret by the 122mm gun is not going to be undone by some relatively minor changes in the IS-2 turret armor layout or shape, since the turret configuration did not change that much. Compare the IS-1 and IS-2 late model turret shape and armor thicknesses: they are similar. From my past examinations of photo's and scale models, the KV-85 and IS-2 turrets look very much alike (I made IS-1 tanks by taking the KV-85 turret and placing it on an early model IS-2), although I haven't really done a scientific analysis. There are sources that use 120mm for the IS-2 nose armor (lower front hull), and others that state 100mm. Drawings on the Russian Battlefield show 100mm. But that is another issue. Please note that rounded Panther mantlet stayed at 100mm cast and rounded through D, A and G models, and was also tapered with thinner thickness at upper/lower edges. Even after the IS-2 and ISU-122 appeared, and with full knowledge of what SU-152 and ISU-152 hits could do, Panther mantlet stayed the same thickness (suggests that thickness was determined by factors other than enemy weapon performance). Russian sources state 120mm for IS-1 and IS-2 early front upper hull, which might be continued for late model IS-2 if the author of a book is not careful. The thickness of the late model IS-2 glacis is an interesting point, but whether 100mm or 120mm the 88L71 APCBC is going to bounce off the 60 degree from vertical slope. At 90mm rolled armor and 60 degree slope, 88L71 is still going to bounce at just about every combat range, which would seem to be the design objective of the glacis armor. [ August 07, 2003, 10:31 PM: Message edited by: rexford ] 0 Quote Link to comment Share on other sites More sharing options...
IntelWeenie Posted August 8, 2003 Share Posted August 8, 2003 Originally posted by dieseltaylor: And now there are Russian players perhaps the translating can become easier Well, I'm not *Russian*, but I guess I am still *Russian speaking*. I was a Ru linguist in the US Army for several years, so if anyone who doesn't know a lick of Russian needs some translating done, give me a jingle. It's been 8 years since I hung up the boots, so I don't remember everything (just the cuss words ), but I can dust off my dictionaries and certainly try. 0 Quote Link to comment Share on other sites More sharing options...
rexford Posted August 8, 2003 Share Posted August 8, 2003 "The new turret had an enitrely redesigned front, include changes in the cg such that more weight on the front *was* possible." The changes in the shape and turret weight do not appear to be radical. It was the gun that unbalanced the turret, not the armor layout, and putting more thickness on the turret front and mantlet is not going to improve things with regard to the center of gravity, it is going to make it worse. The turret weight issue is still alive for the IS-2 tanks regardless of some minor changes in shape and thickness. "Without the weight argument to resort to then, we can only look at the german/british measurements of the tanks, but if you take another look at the photo from yahoo tankers, you will see it is an *early* variant, thus the thickness of the *early* mantlet was roughly the 110mm figure painted on it by the germans. Could the discrepancy with the British figures then have something to do with measurements coming from both an early and a late tank?" The British had the same mantlet and turret front armor on all IS-1 and IS-2 tanks, which was only slightly less (100mm vs 110mm) than the Germans stenciled on the early IS-2. Looking at the British figures there is nothing to suggest 160mm for the typical mantlet thickness that a hit will have to defeat. The British had 100mm for the mantlet with a small area of 60mm turret front that the mantlet overlapped, and the ballistic resistance value of the 60mm would be negligible. There could be small isolated areas on the late model IS-2 mantlet and turret front where 160mm existed, maybe around the gun barrel and at the edges of the turret front where it met the mantlet (to reduce the impact of edge effects, which decreases armor resistance). But the typical thickness that a hit would have to defeat would seem to be 110mm and 100mm (mantlet and turret front) regardless of maximum thickness. Maximum and minimum armor thicknesses really tell one little about the typical resistance. [ August 07, 2003, 10:45 PM: Message edited by: rexford ] 0 Quote Link to comment Share on other sites More sharing options...
Denizen Posted August 8, 2003 Author Share Posted August 8, 2003 Does it identify where the thickest parts were and how large an area they covered? Could be a small area This is really what I have been looking for all along, and as far as I can tell this information does not exist. The simple fact is that not all curved armor had the has the same ratio between thickest/thinnest parts. The unbalancing of the IS-2 turret by the 122mm gun is not going to be undone by some changes in the IS-2 turret armor layout or shape, since the turret configuration did not change that much. Compare the IS-1 and IS-2 late model turret shape and armor thicknesses: they are similar. Similar, but not the same. If you look carefully at photos you will see that the early turret has a broad curved surface on the front end, while the late turret has a visible 'snout' such that the vertical distance between the driver's periscope and the bottom of the turret changes by 15 cm or so, and a simlar thing happens on the top of the turret. It would also appear that the mounting of the gun was moved back into the turret several centimeters as well. The front excesses were effectively shaved off. Together these factors would have had an impact on the cg. Its a subtle change on the outside, one which many a moddler has overlooked, but given the massive weights involved, even a reltively small change in distance could put it back into balance For the glacis there are fewer clues, certainly 100mm would have been enough at that angle, but I suspect the designers may have been reluctant to reduce the overall thickness from the previous hull design out of the fear of not being ready for the 'next threat'. Additionally, given the fact that the post war moderniztion program did not involve replacing the glacis, I have to wonder if the IS-2 would have seen almost three decades of service if its armor was no better (or worse) than the T-54, to say nothing of the later heavies. Even though I am well aware that russian equipment was built to be in service until or even after reaching obsolesence, you have to wonder how the IS-2 outlived it sucessor(s) (thougth lets not talk about the IS-3 in this thread) PS Lorrin I have read your book; you don't need to rewrite it in this thread. [ August 07, 2003, 11:21 PM: Message edited by: Denizen ] 0 Quote Link to comment Share on other sites More sharing options...
Denizen Posted August 8, 2003 Author Share Posted August 8, 2003 The British had the same mantlet and turret front armor on all IS-1 and IS-2 tanks, which was only slightly less (100mm vs 110mm) than the Germans stenciled on the early IS-2. Perhaps I have been caught up in semantics, but are you implying that the British never had a late model to measure either? Where then do the western estimates of the late IS-2 come from? 0 Quote Link to comment Share on other sites More sharing options...
Denizen Posted August 8, 2003 Author Share Posted August 8, 2003 The debate is reminding me of the T-64/T-72 debacle back in the seventies, for a while even Jane's thought they were the same tank because they looked so similar. To this day enthusiast-level publications still see the T-72 as the T-64 replacement. From my past examinations of photo's and scale models, the KV-85 and IS-2 turrets look very much alike (I made IS-1 tanks by taking the KV-85 turret and placing it on an early model IS-2), although I haven't really done a scientific analysis. The devil is in the details; if the stalist russia had made more of an effort differentiate the nomenclature of its desgins there would have been a tank called IS-2.5 0 Quote Link to comment Share on other sites More sharing options...
Denizen Posted August 8, 2003 Author Share Posted August 8, 2003 For purposes of clarity I will rewrite my argument: Ballistic protection between the early and late variants of the IS-2 differed significantly, not only relating to the redesigned hull but to the turret and mantlet as well. The early desgin suffered a number of flaws do to the pace at which the program developed. Not unlike the earliest Panther, the early IS-2 suffered from a variety of protective failures, ranging from the flattened front face of 'curved' turret armor, the un-reinforced mantlet installation which brought about breakages of the mantlet from the turret itself when hit, as well as the various problems of vertical hull plates creating shot traps vulnerable spots. However, what few people seem to realize, is that just like the Panther, or better yet the Sherman, the IS-2 saw its flaws removed througth development based on combat experience. Comparing the early IS-2 and the late IS-2 is a comparision along the lines of the first M4 and the last of the 'easy-eights', meaning that the changes were so significant that the result could hardly be seen as the same vehicle. Indeed by the time the IS-3 finally became availible, the IS-2 had progressed to such a point that the IS-3 was almost redundant. Aside from introducing the frying-pan turret, the IS-3 has no claim to fame. I am first and foremost a historian at heart, and frankly I find it disheartening that most of what the west is recording in histories when it comes to military engineering is the contemporay picture of what we knew when it happened. We need look no further than the fact that a game showcasing the war that cost more lives to Russia than any nation has ever lost in history (excepting native Americans) uses predominantly German source material. True, a few voices have brought about interesting realizations from the east, but this branch of histroy is fading away faster than it is correcting itself. I don't claim to have answers from everything, but in the case of the IS-2 I think history has allowed the significance of an engineering feat to fade into history. The way I see it, the akward child of the KV grew into one of the most capable designs of its time. It had more explosive firepower than a tiger, at the weight of a Pather, with the speed of a Sherman, and the complexity of a panzer IV. Hopefully we can find an answer to whether it had the protection of a tiger, or a tiger II. Moving on, I will take a shot in the dark and ask; does anyone know of the existance of scematics of the particular parts making up the IS-2 mantlet and its connection to the turret? More and more it seems as though all we have to go on for armor thickness is conjecture. Might anyone have any idea where the 100mm mantlet figure came from? Usually armor measurements are lsited as maxiumums, so it seems odd that a german photograph showing 110mm could be the same piece of metal even tanking into account manufacturing techniques. Furthermore does anyone have a armor measurement that is proven to be taken from a late model IS-2? If the late model never made it into western hands, how can we trust old figures? Published data before the cold war ended indicated 100mm largley, and not Zaloga's 160mm which I am inclined to believe he measured, after all I am fairly certain he was the first westerner to discover the mystery KV tank from the finnish army museum. That KV incidentally brings up another issue, the infamous KV-1 that the Germans designated "c" but which has since fallen into the vaccuum of history only to be resurrected by Zaloga's writing. [and photos] I do not think it impossible for details of the last variant of a quickly replaced series to have been erroneously covered by history, but it would seem that some on this board do not share that view. :confused: Possibly I spend to much time looking at pictures! [ August 08, 2003, 12:54 AM: Message edited by: Denizen ] 0 Quote Link to comment Share on other sites More sharing options...
Kanonier Reichmann Posted August 8, 2003 Share Posted August 8, 2003 Originally posted by Denizen: PS Lorrin I have read your book; you don't need to rewrite it in this thread. Why am I reminded of that famous quote in the film Patton..."Rommel, you magnificant bastard...I've read your book!" Regards Jim R. 0 Quote Link to comment Share on other sites More sharing options...
rexford Posted August 8, 2003 Share Posted August 8, 2003 How many books list 100mm for the Tiger E mantlet? The 100mm is actually the top and bottom edges and the other areas go up to 140mm to 150mm in many areas and over 190mm in a few isolated areas. So if a book stated 190mm maximum mantlet armor it would be as irrelevant as if it said 100mm although 190mm would be correct for the max. Books are wrong alot, even heavyweight ones. My personal opinion is that the IS-1 and IS-2 mantlet was 100mm thick on all WW II models, and the 110mm came from the slight protrusion at the apex that shows up on some photo's. All of the drawings and photo's I've seen suggest that the IS-1 and IS-2 mantlet was rounded and did not have a flattened out area at the apex (except for a slight rectangular protrusion). I see no indication that the IS-2 turret was redesigned to eliminate the unbalanced weight distribution that Russian Battlefield says kept the armor protection the same on IS-1 and IS-2. If the turret was redesigned to do away with the bad center of gravity, then it would have to add armor thickness to the sides and rear of the turret. Provide evidence that early and late IS-2 turret side/rear armor was significantly increased in thickness if it is so clear that the center of gravity problem was resolved. ;o) Adding or rearranging armor on the mantlet is not going to improve things with regard to turret weight balance, the gun is the big sticking point. British data shows the same mantlet/turret armor thicknesses on IS-1, early IS-2 and late IS-2. I believer that Zaloga's 160mm thickness for the mantlet is not correct if it refers to the typical thickness that a shot would land on. The Russians improved the glacis armor because the 30 degree from vertical 120mm thick plate on the IS-1 and IS-2 was getting blown open by Panthers and Tigers and 88L71 ATG. So they put the armor at 60 degrees from vertical which stopped everything at all ranges, HOWEVER: 1. despite the nearly inpenetratable glacis plate, the nose armor was kept at 100mm/30 degrees (Russian Battlefield suggests weight limits eliminated chance of increasing nose thickness or slope), and Russian Battlefield says 100mm/30 deg on the nose was considered okay because few hits struck the nose (which is contradicted by the Russian Battlefield article on IS-2 in action combat, where plenty of tanks were penetrated via the front nose armor). 2. glacis was widened to improve gunsight visibility but thickness was kept the same since turret weight unbalance was problem, there may have been a slight improvement in turret protection since 110mm mantlet covered areas that were previously protected by 100mm turret front So the Russians improved IS-2 glacis but nose and mantlet/turret front armor stayed the same. I think that the Russian Battlefield statement on an armor improvement to the turret is being stretched beyond the breaking point in trying to justify increased mantlet thickness. No relationship has been proposed between more mantlet armor and a solution to the turret weight unbalance problem. I'am an engineer and don't see any numbers that support a solution to the turret unbalance problem which would allow the mantlet to be thickened. Weight appears to have kept the nose thickness down to previous levels on all IS-2 tanks (100mm), and weight limits appear to have constrained the turret front/mantlet armor as well (100mm to 110mm). [ August 08, 2003, 12:33 PM: Message edited by: rexford ] 0 Quote Link to comment Share on other sites More sharing options...
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