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Hello everyone! I'm a long time fan of wargames focusing on armored warfare (Steel Panthers and CM series, mainly Eastern Front) and also tank sims like Steel Beasts and Steel Fury. I always appreciated high level of detail and accurate, realistic modeling of equipment (like optics) and physical events (like spotting, targeting, shooting, ballistics, armor penetration and post-penetration damage). As time passes, games (some of them) become more and more realistic with help of much more armor & penetration data available today, than were not available 15 years ago. For example today we know that the mantlet of Tiger I tank is not uniform 100mm, which we believed 15 years ago. For years the 100mm was "official" because it was cited by reputable sources and authors. Another example is the armor thickness of IS-2 front turret and mantlet armor. All information that is available is that it's 100mm thick and that idea of thickening front turret armor was considered, but was rejected because it would cause the turret to be unacceptably unbalanced. But the turret is rounded and mantlet is not an uniform piece of steel. It's visibly thicker at center and thinner above and below, the new wide mantlet also had some area where mantlet armor and front turret armor were overlapped. Some sources claim 160mm thickness for IS-2 front turret armor. Some people wondered if the new wide mantlet was same thickness like old narrow one, or not ? For years I observed people citing various sources (books) and debating which one is more reputable - I wondered why nobody just take a ruler, visit some museum or monument and just measure it to end the discussion ? For almost decade nobody did anything to satisfy my curiousity, so one day I decided to do it for myself. Fortunately, I live in Poland. There are some nice samples of war production IS-2 tanks in my country, some in museums, some others on monuments. The nearest one is in small town of Lebork some 80km from the place I live - model with new one-piece front hull armor and wide mantlet. So one sunny day I just took a ruler, a camera, and went to visit the beast to measure it personally and "just know". Measuring it was not so easy, some parts are hard to reach, some are unreachable from either outside or inside, it turned out that the data I gathered was not consistent/unambiguous so I visited it again few month later to do some additional measurements and check again some details of armor layout - it turned oout that you have to know the armor layout to measure some elements correctly. With additional data I finally knew the maximum thickness of mantlet armor and was able to reconstruct the armor layout of front turret and mantlet of IS-2. While visiting friends I had also an occasion to visit another IS-2 example, model with an older two-piece front hull armor but same turret (wide mantlet) which is displayed as a monument in Nowa Huta (part of Krakow city). Measuremensts have shown that thickness of the mantlet is almost the same. The "almost" thing is probably effect of war production of crude cast armor elements. Few years later I got my hands on simple but functional ultrasonic thickness gauge (OK, OK, I admit - bought it just for armor measuring :-)). So I visited both IS-2 tanks again to confirm my measurements with ultrasonic meter and to measure some armor elements I could not measure with a ruler. Using the meter on a rough surface of crude Russian castings - that were covered with many laters of old paint - turned out to be next to impossible. But after some effort I managed to find some small, smooth places stripped from paint where I got solid readings. There were no problems with measuring RHA plates - they were much more smooth, so finding good place was much easier. Using the ultrasonic thickness meter I could confirm thickness of front armor plates, side armor, side and rear turret armor, and of course front turret. I also confirmed my previous physical measurements of mantlet armor. Now I could not only say how thick is armor in various places, but also reconstruct the armor layout of front turret and geometry of mantlet piece - it's theoretical geometry because the real one can differ up to +/-10mm from the "nominal" thickness. The casts are so raw and crude that such differences of +/-10mm are quite normal when measuring for example thickness of cast front hull armor "plates" in various places. Talking about armor layout and geometry - there were some differences between tanks I measured and drawings I have found on the net. There were also some differences between those two tanks I measured. I guess it's the effect of war production realities - every factory did everything to simplify the production and did their own cast moulds, so tanks from different factories and different production batches varied in details, there were some improvements and some reductions and simplifications also. Details and dimensions that were not very important, were changed if that simplified production. So there are no absolute dimensions. There are only dimensions I measured on two pieces of IS-2 tanks, and using this data I tried to guess what were the dimensions of the original project designed by some intelligent and rational engineer at drawing board. Some big dimensions shown on my drawings are still not measured, for example the exact height of the mantlet piece. I didn't have such a big calliper to do that , the height is derived from other data but it may be not more than +/-10mm off. Finally I satisfied my curiosity. And now while having such load of data, including ultrasonic measurements, I thought that it may come in useful for others, so maybe I'll do some effort to put all this data together in nice graphical form and publish it on some wargamer's forums. I have also uploaded all photos I did while visiting those tanks, some of them documenting the measurements I did. All results on my work are available for everyone in my public albums on flickr. https://www.flickr.com/photos/136792894@N05/albums I hope this data will be used to improve armor modeling of IS-2 tanks in Combat Mission Red Thunder and also some other games I enjoy to play (for example War Thuner). Here are links to flickr galleries with my work (drawings based on measuremensts). Is-2 Tank - results of armor measurements https://flic.kr/s/aHskrCY57j and galleries with photos documenting my visits and measurements: IS-2 Tank, Poland, Lebork 1 https://flic.kr/s/aHskqLEAcw IS-2 Tank, Lebork 2, Poland https://flic.kr/s/aHskrtkGkA IS-2 Tank, Poland, Lebork 3 (thickness gauge) https://flic.kr/s/aHskq9HPoj IS-2 Tank, Poland, Lebork 4 (thickness gauge 2) https://flic.kr/s/aHskqWLgQy IS-2 Tank, Poland, Krakow/Nowa Huta 1 https://flic.kr/s/aHskntK6iX IS-2 Tank, Poland, Krakow/Nowa Huta 2 (thickness gauge) https://flic.kr/s/aHskqPsCB6 Ih shorts, the results are: - the turret armor of IS-2 tank (model with wide mantlet) is 100mm all around. There are some differences due to crude castings, actual thickness vary from 90 to 100mm, with most of turret being 100mm. The armor of rounded parts (mainly front turret left and right of mantlet) becomes thinner up and down, where the angle increases. My drawing of front turret armor profile is approximate, I measured troughly only the front curved parts. - the turret armor in area of the gunsight port is thinner, about 80mm thick, but it's covered by 75-80mm thick part of mantlet armor. So armoring of this area is really 75...78mm of mantlet armor + 10-20mm of air + ~80mm of turret armor. - max nominal thickness of gun mantlet armor was 115mm in both tanks I measured. Mantlet in one tank was a bit "reinforced" in area around MG port and there up to 120mm thickness was measured, but the "original" shape would be 115mm. The mantlet is tapered up and down, becomes thinner where angle to vertical increases. I believe I reproduced the actual geometry of the cast moulds, being two cylinders 660mm in diameter, separated by 115mm (maybe they ment 110mm or 120mm in original plans, but on both tanks I measured it was 115mm). Such "model" when drawn, fits almost exactly to the measured mantlet profile. - the left part of mantlet covering the gunsight port is only 75 to 80mm thick. It may be up to 80mm thick at center and 75-77mm thick at height of gunsight hole. The actual measurements were from 74mm to 77mm at the height of gunsight hole, depending on place of measurement and tank. The IS-2 from Nowa Huta/Krakow was 75mm, the Is-2m from Lebork was closer to 80mm. So again, thickness of that part of armor is combination of 75mm of matlet + 80mm of turret armor. - The most thick part of mantlet is about 130mm above the gun and gunsight axis. In other words, the gun is mounted slightly below the thickest part of the mantlet. - the thickness of other parts of armor (the hull) is in accordance with known data. For the older hull, the upper front is 120mm cast, the slanted part 60-70mm thick, lower front hull 100mm thick cast, sides 90mm. The newer hull with single piece nose - upper front 100mm thick cast (NOT 120mm), lower front 100mm, the front-side parts of upper hull up to 135mm thick and gradually becoming thinner on their way back, to 90 or 100mm (I forgot to check) where they are welded to the rear 90mm RHA plates. Lower side hull 90mm. So I can confirm that IS-2m upper front hull plate is 100mm thick for cast front-hulls. So probably it's made from 90mm plates in RHA-made front hulls. Other thing I can confirm is that front-side belts of IS-2m upper hull are thicker than 90mm, they are up to 130mm thick. Unfortunately I didn't check them for older-hull IS-2 model from Krakow. Will do that on occasion. I wonder if I can attach some pictures here... let's try... Hi there... Regards, Amizaur P.S. If someday I get my hands on IS-2 tank with narrow mantlet, I'll check it too. I wonder it it's the same.
So. The Kingtiger in-game seems rather crude. Apart from a comparatively low def 3D model, a lack of data for the coax MG which fires out of the model center instead of besides the main gun, there's another problem. After a few test runs with 8 Kingtiger vs 8 IS-2 at a range of 1000m, I was shocked. The IS-2s seemed able to penetrate Kingtiger turret center front and knock it out. It was more than a year ago when CMRT was first released. At the time I thought it looked like KT's armor was assigned very bad quality. As I absolutely love this iconic tank, I felt bummed and moved on to other games. Friday came and I felt a bit CM itch. So re-downloaded and installed CMRT v1.03. Re-ran the test. Same deal. But this time I noticed, that the turret penetration hits were not on "turret front", but "weapon mount", as the hit texts and hit decals show. And every hit on the mantlet penetrates or at least partial, most of them knocking out the tank, rarely the tank survives but ends up with a destroyed main gun and coax. On the other hand however, hits that are on the "turret front" proper, either bounced or only induced armor spalling. Penetration only happens once in a blue moon. Thought this was very weird. There should be 180mm of armor behind the mantlet, which alone should be sufficient to stop the 122mm round. Why is it in CM that mantlet penetrations are fatal? And so I formed the theory of how CM game engine handles the damage modeling in this case. To demonstrate, I first drew a simple scheme of the real tank turret. The orange area is tank internal space and hits into internal is considered fatal. An incoming heavy AP round penetrates the gun mantlet, but is then stopped by turret front armor and the tank remains fine. Next is a picture of how CM's game engine handles the armor scheme. On the real tank, the combination of mantlet + turret essentially creates a "multi-layered", spaced armor. But as far as CM's game engine is concerned, there is no such thing. I believe the game engine only knows that, behind armor, whatever it is, be it turret armor, hull armor or gun mantlet, is tank internal space. I remember doing tests on Tiger I mantlet in CMBN, hits on the mantlet edge would penetrate while others wouldn't in the same test, despite real Tiger I mantlet edge being backed by 90mm(?) of turret front armor - It is the same problem. However, it becomes much more profound on the TigerII, because here we have 180mm of center turret armor, that is omitted by the game engine. Hits on the mantlet would go directly through to tank internal space. What should be an area that is almost impenetrable, has become a glaring weak spot.