rexford Posted June 18, 2001 Share Posted June 18, 2001 On most tanks, firing at the front armor with a lateral angle increases the resistance, but that funny glacis armor on IS-III changes things. Shots aimed directly along hull facing will impact the glacis at 58° from normal. If a shot is angled at 15° to one side of hull facing, the glacis impact angles will be: 53.6° on near side armor closest to firer 64.1° on far side armor furthest from firer Is this an academic point given the thicknesses? 120mm glacis armor on IS-III attacked by 128mm APCBC and 88L71 APCBC has following resistance at abovenoted angles: 128mm APCBC 336mm at 0° lateral angle (58° impact) 283mm at 15° lat angle (15° near side hit) 454mm at 15° lat angle (15° far side hit) 88mm APCBC 368mm at 0° lateral angle 310mm at 15° lat angle and near side hit 508mm at 15° lat angle and far side hit The turret appears to be set up so that hits on front aspect have very high resistance even though armor thins out as it gets higher on turret (220mm where it meets hull to 110mm at top). Angle increases as thickness decreases, from 45° at bottom to 90° at top. The thickness vs angle profile for the turret front is open to debate, some sources list at 160mm with round shape, starting angle may be 45° with increases towards top. The 200mm mantlet seems to be the only vulnerable area to 128mm hits. The front lower hull (120mm at 53° from vertical), would resist at 277mm and might be penetrated at point blank range. The side hull armor presents more resistance than the Panther glacis: 85mm at 55° on Panther front 90mm at 60° on IS-III hull side, plus 30mm at 30° spaced from hull covering hull side IS-III hull side resists Tiger II hits with 279mm resistance if hit has no lateral angle, which will defeat almost all hits when cast armor deficient is considered. IS-III versus Tiger II would be one very interesting match-up. P.S. American analysis of IS-2m found in Berlin ruins showed that lower turret areas, where they fit into turret ring, were very brittle and might crack on defeated hits higher up on turret, due to impact stresses carried to turret race. Which would effectively disable tank gun. One might suspect that there would be some "Achilles Heel" areas on IS-III that may not be obvious from armor thickness calculations. [ 06-18-2001: Message edited by: rexford ] Link to comment Share on other sites More sharing options...
Jarmo Posted June 18, 2001 Share Posted June 18, 2001 Ahh.. another one! I love reading these and pretending to understand. Link to comment Share on other sites More sharing options...
Freak Posted June 18, 2001 Share Posted June 18, 2001 I think I understand: the IS-3 is inpenetrable, right? [ 06-18-2001: Message edited by: Freak ] [ 06-18-2001: Message edited by: Freak ] Link to comment Share on other sites More sharing options...
PzKpfw 1 Posted June 18, 2001 Share Posted June 18, 2001 <BLOCKQUOTE>quote:</font><HR>Originally posted by rexford: One might suspect that there would be some "Achilles Heel" areas on IS-III that may not be obvious from armor thickness calculations. [ 06-18-2001: Message edited by: rexford ]<HR></BLOCKQUOTE> Ya Rex like an 8.8 cm KwK. 43 impact on the IS-3 glacis causing the plates to crack on the first hit, or the IS-3 hitting a bump & causing the same thing ...... Their is an photo of an IS-3 from WW2 that shows the cracked glacis after X country testing, the weld seems have let go & you can see inside the tank. Regards, John Waters [ 06-18-2001: Message edited by: PzKpfw 1 ] Link to comment Share on other sites More sharing options...
Paul Lakowski Posted June 18, 2001 Share Posted June 18, 2001 The area were the turret meets the turret ring is probably a weaked zone offering less resistance than the LOS thikness suggests. Link to comment Share on other sites More sharing options...
Paul Lakowski Posted June 18, 2001 Share Posted June 18, 2001 [ 06-18-2001: Message edited by: Paul Lakowski ] Link to comment Share on other sites More sharing options...
offtaskagain Posted June 18, 2001 Share Posted June 18, 2001 Did the IS-3 have a weak mantlet like the 2s or was that fixed? Link to comment Share on other sites More sharing options...
PzKpfw 1 Posted June 18, 2001 Share Posted June 18, 2001 <BLOCKQUOTE>quote:</font><HR>Originally posted by panzerwerfer42: Did the IS-3 have a weak mantlet like the 2s or was that fixed?<HR></BLOCKQUOTE> That was one of the IS-3 improvements over the IS-2. A Soviet study on causes of tank's KO done in 1943 & 1944 found their main loss of tanks, was to turret front penetrations, the IS-3 was designed to fix it. Regards, John Waters [ 06-18-2001: Message edited by: PzKpfw 1 ] Link to comment Share on other sites More sharing options...
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