US Sherman Tank

[Marek_Tucan]

Originally Posted by cbo

The overall armour protection of the Sherman remained much the same through the war. Shermans produced 1942-43 had 51mm of armour on the front hull, sloped at 56 degrees while those made in 1944-45 had 63mm of armour, but only sloped at 47 degrees. The main difference was that the front armour was one piece of RHA armour on the latter ones while the earlier types had a front built up of several pieces of RHA and cast armour with some protruding bulges etc. This probably wasn't as strong as the later type.

Not only the glacis was upgraded - AFAIK the gearbox cover was at first 51mm, rounded, while later 63...107mm, cast, rounded and it takes up some 20% of Sherman hull forntal profile.

There were small changes in the turreet armour as well, but not much.

The largest change would be wider moving gun shield, so it covered the entire width of the fixed gun shield. Plus of course better cast armor quality in later times.

17-pdr APDS round was a somewhat erratic performer.

Saw somewhere a hint the erratic performance wasn't as much fault of the APDS as the fault of a secrecy - the APDS was simply top secret when it came to use so few people knew how to handle it - ie mostly the difference in trajectory between an AP shot and APDS. Is that true or was there really something wrong with the rounds themselves?

[cbo]

Originally Posted by Marek_Tucan

Not only the glacis was upgraded - AFAIK the gearbox cover was at first 51mm, rounded, while later 63...107mm, cast, rounded and it takes up some 20% of Sherman hull forntal profile.

..but it is the lower part and thus the part that wasnt very likely to be hit. The profile of the late war differential housing was perhaps better, but IIRC most of the added thickness was found at the very tip and thus a very small part of the frontal profile. The part highest up was still only 51mm.

The largest change would be wider moving gun shield, so it covered the entire width of the fixed gun shield. Plus of course better cast armor quality in later times.

The wider gun shield was only found on the 76mm armed tanks and was the same thickness as the shields on other late war Shermans. And this was only 13mm thicker than the shield found on earlier types and only 13mm thicker than the front hull armour anyway. So not much of an issue, really.

Saw somewhere a hint the erratic performance wasn't as much fault of the APDS as the fault of a secrecy - the APDS was simply top secret when it came to use so few people knew how to handle it - ie mostly the difference in trajectory between an AP shot and APDS. Is that true or was there really something wrong with the rounds themselves?

Never heard that before. AFAIK the problem with the 17-pdr APDS was occasional erratic behaviour due to faulty sabot separation. If the projectly left the sabot correctly, it was accurate, but when it didn't, there was no telling where the projectile would end up. That is why a pot-type sabot was later introduced for the 20-pdr. The erratic performance of the 17-pdr APDS meant that it was not recommended for use it at ranges beyond 1000 yards, at that recommandation persisted as long as the WWII type sabot round was in service (still in effect in 1952).

cbo