rexford Posted January 14, 2004 Share Posted January 14, 2004 Info on T34 glacis thickness suggests a range from 42mm to 53mm, based on Jeff Duquette's measurement, German plate thickness range used in firing trials against T34 like armor and other info. SU 100 front lower plate, which was 45mm design spec, actually measured at 60mm by Allies. Following are estimated penetration ranges against T34 glacis if thickness is in 42mm-53mm range. Guess is that plate thicknesses under 45mm were relatively rare (most thickness specs allow no unders but do permit over thicknesses). Effective Resistance of T34 Glacis Due to Variations in Plate Thickness Glacis..Effect...Penetration Ranges (m) Thick...Thick...75L43...75L46...75L48 42......84......2008....2412....2088 43......87......1861....2266....1941 44......90......1720....2125....1800 45......93......1584....1988....1664 46......96......1451....1856....1531 47......99......1323....1728....1403 48......103.....1158....1563....1238 49......106.....1038....1443....1118 50......109.....922.....1327....1002 51......112.....809.....1214....889 52......116.....663.....1067....743 53......119.....556.....961.....636 Notes: Effective thickness after high hardness plate converted to good quality vertical 240 Brinell armor Germans use 42mm to 53mm plates when they fire on T34-like armor Battle reports have 75L46 Pak 40 penetrating to 1000m (matches 53mm glacis range) and 75L46 penetrating to 1600m max (matches 45mm glacis thickness) Jeff Duquette measures T34 glacis at 50mm-55mm, other measurements in 45mm to 47mm range, which supports second note [ January 13, 2004, 05:43 PM: Message edited by: rexford ] 0 Quote Link to comment Share on other sites More sharing options...
John Kettler Posted January 14, 2004 Share Posted January 14, 2004 rexford, Another fascinating bit of analysis, but I'm confused. Why does the 75/L 46 consistently outpenetrate the 75/L 48? Did a column somehow get switched? Regards, John Kettler 0 Quote Link to comment Share on other sites More sharing options...
Mr. Tittles Posted January 14, 2004 Share Posted January 14, 2004 Its a higher velocity gun. The L43 and L48 are related but the L46 is a slightly different animal. 0 Quote Link to comment Share on other sites More sharing options...
flamingknives Posted January 14, 2004 Share Posted January 14, 2004 The L46, IIRC, uses a larger powder charge. 0 Quote Link to comment Share on other sites More sharing options...
rexford Posted January 14, 2004 Author Share Posted January 14, 2004 Muzzle velocities for German 75mm guns: 75L43 APCBC: 740 m/s 75L46 APCBC: 792 m/s 75L48 APCBC: 750 m/s 0 Quote Link to comment Share on other sites More sharing options...
rexford Posted January 14, 2004 Author Share Posted January 14, 2004 The posted penetration ranges are based on average performance of the APCBC projectiles, level ground, no projectile descent angle and a somewhat pessimistic view of how the high hardness plate would perform. The ranges can vary widely based on variations from the assumed ammo and armor characteristics. The impact of variations in the assumed ground, armor and ammo conditions can be significant. 1. A 2 degree ground tilt can increase armor resistance by 11% or decrease it by 7% 2. German 75mm APCBC rounds for the abovenoted guns will be descending at about 1 degrees at 1600m, which decreases the assumed resistance by about -3.5% 3. German quality control tests showed that the velocity spread from worst to best ammo to defeat a given thickness could vary by 24%, which means that the best rounds could penetrate 16% more than average and the worst could penetrate 15% less Pavel noted on the Yahoo! Tankers site that Hetzer hits on the front hull glacis plate of T34/85 tanks failed to penetrate at very close range (early 1945), a result which at first was difficult to explain. If the T34/85 tanks carried glacis plates above 45mm thickness, were on a slight upward tilt and the Hetzers were firing below average ammo it is reasonable for the 75mm APCBC hits to bounce. 75mm L48 APCBC penetration at 100m with a 15% decrease from average would equal 115mm of vertical plate, which could be matched or exceeded by 50mm glacis thickness with a combination of ground tilt and above average penetration resistance. American tests of T34/85 plate from tanks found in the Berlin ruins showed that the armor varied in quality from poor to excellent. The question has been raised as to what impact above average glacis plates would have on T34 tank weight. Each additional mm of thickness adds about 55.5 pounds (25 kg), so a 5mm increase would add 278 pounds (126 kg) and 8mm would add 444 pounds (201 kg). So the bottom line is that German penetration ranges against T34 armor could and did vary widely based on expected variations in conditions, armor and projectiles. 0 Quote Link to comment Share on other sites More sharing options...
rexford Posted January 15, 2004 Author Share Posted January 15, 2004 Based on feedback and additional research following is final version of article on T34 glacis thickness variations: IMPACT OF VARYING T34 GLACIS THICKNESS ON GERMAN 75mm APCBC PENETRATION RANGES Info on T34 glacis thickness suggests a range from 42mm to 53mm, based on Jeff Duquette's measurement, German plate thickness range used in firing trials against T34 like armor and other info. Following are estimated penetration ranges against T34 glacis if thickness is in 42mm-53mm range. Guess after reviewing distribution of the limited sample of actual measurements in our possession is that design thickness of 45mm was most common thickness encountered and thicknesses under 45mm were much less common (most thickness specs allow no unders but do permit over thicknesses). EFFECTIVE RESISTANCE OF T34 GLACIS DUE TO VARIATIONS IN PLATE THICKNESS Glacis..Effect...Penetration Ranges (m) Thick...Thick...75L43...75L46...75L48 42.............84.....2008....2412......2088 43.............87.....1861....2266......1941 44.............90.....1720....2125......1800 45.............93.....1584....1988......1664 46.............96.....1451....1856......1531 47.............99.....1323....1728......1403 48...........103.....1158....1563......1238 49...........106.....1038....1443......1118 50...........109.......922....1327......1002 51...........112.......809....1214........889 52...........116.......663....1067........743 53...........119.......556......961........636 ========================================================= Notes: Effective thickness after high hardness plate converted to good quality vertical 240 Brinell armor using slope effects and armor resistance adjustments. Germans use 42mm to 53mm plates when they fire on T34-like armor. Three 45mm design thickness plates on SU 100 were measured at 60mm (front lower hull), 42mm (superstructure side) and 50mm (superstructure side). Battle reports have 75L46 Pak 40 penetrating T34 glacis to 1000m (matches 53mm glacis range) and 75L43 penetrating to 1600m max (matches 45mm glacis thickness). Jeff Duquette measures T34 glacis at 50mm-55mm, Su 100 measured at 42mm-60mm, other measurements in 45mm to 47mm range, which supports second note with exception of 60mm thickness. ========================================================= The above penetration ranges are based on average performance of the APCBC projectiles, level ground, no projectile descent angle and a somewhat pessimistic view of how the high hardness plate would perform. The ranges can vary widely based on variations from the assumed ammo and armor characteristics. The impact of variations in the assumed ground, armor and ammo conditions can be significant: 1. A 2 degree ground tilt can increase armor resistance by 11% or decrease it by 7% 2. German 75mm APCBC rounds for the abovenoted guns will be descending at about 1 degrees at 1600m, which decreases the assumed resistance by about -3.5% 3. German quality control tests showed that the velocity spread from worst to best ammo to defeat a given thickness could vary by 24%, which means that the best rounds could penetrate 16% more than average and the worst could penetrate 15% less Pavel noted on the Yahoo! Tankers site that Hetzer hits on the front hull glacis plate of T34/85 tanks failed to penetrate at very close range (early 1945), a result which at first was difficult to explain. An explanation for the failures against the T34/85 glacis might be related to some combination of the following possibilities: glacis plates above 45mm thickness slight upward tilt to ground increasing impact angle above average Russian armor below average ammo some hits landed on the 75mm thick driver hatch (two T34/85 driver hatch castings measured at 75mm, and T34/76 hatch on Jeff Duquette photo is about 40% thicker than 53mm glacis plate for 74m) 75mm L48 APCBC penetration at 100m with a 15% decrease from average would equal 115mm of vertical plate, which could be matched or exceeded by 50mm glacis thickness with a combination of ground tilt and above average penetration resistance. American tests of T34/85 plate from tanks found in the Berlin ruins showed that the armor varied in quality from poor to excellent. The question has been raised as to what impact above average glacis plates would have on T34 tank weight. Each additional mm of thickness adds about 55.5 pounds (25 kg), so a 5mm increase would add 278 pounds (126 kg) and 8mm would add 444 pounds (201 kg). So the bottom line is that German penetration ranges against T34 armor could and did vary widely based on expected variations in conditions, armor and projectiles. 0 Quote Link to comment Share on other sites More sharing options...
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