In this article series, you ask me questions, and I answer them! Email your questions to tankarchives@gmail.com, and I’ll answer them here (as long as they’re within scope, of course).
Previous Q&A
Q: What was the highest caliber gun mounted on a tank (not artillery or tank destroyer)?
A: Off the top of my head, the KV-2′s 152 mm howitzer was the biggest, but that was practically an SPG anyway.
Q: Were there German plans for autoloading tanks?
A: The T-25 was supposed to have an auto-loader. SerB says that the Waffentrager E-100 was, too. Aside from that, no idea, but there were probably some obscure autoloader projects.
Q: Is there any other kind of gun that the PzII Ausf J had aside form the 2.0 cm KwK 38?
A: Nope. The PzII Ausf J was meant to be a scout tank, so improving armament over the original PzII was not a priority. The tank quickly proved inadequate for its task, and was discontinued without receiving further modernizations.
Q: Were there tanks like E-100 planned by other nations (big gun on a heavy tank)?
A: Heavy tanks fell out of favour after the end of the war, so nothing quite like that. The closest thing was the BL-10 armed IS-7 SerB talked about, but that was never built.
Q: Were there Soviet rear turreted tanks? Why were they made? How did they compare in combat?
A: The reason for putting the turret in the rear was to allow for a larger gun. The gun’s weight would not shift the center of mass too much, the length would not interfere when fighting in the city or on bumpy terrain. Several Soviet rear-turreted tanks were planned, like the A-44, Object 416, and Shashmurin’s breakthrough tank. None were ever mass produced, so it is hard to judge how well they would have performed in combat.
Q: How legit is this?
A: Completely legit.
“Since the new 85 mm gun did not fully exhaust all possibilities of the new T-34 based SPG, work was done in the fall of 1943 to install weapons of higher calibers. A 122 mm A-19 gun was installed in the stock casemate. The mass of the SPG grew to 32 tons. Penetration compared to the D-5S-85 increased by 30%. The factory index of the vehicle was SU-D25
Aside from the SU-D25 project, UZTM developed a SU-85 with a powerful artillery system: a 152.4 mm D-15 howitzer designed by factory #9. The muzzle velocity was 508 m/s, with a 48-49 kg shell. Penetration was 28% higher than the 85 mm gun, and HE capability was 100% higher. The mass of the proposed SPG was 31 tons. It received the factory index SU-D15. With analogous armament, this medium SPG was lighter than the heavy SU-152 SPG on the KV-1S chassis”
Solyankin et al, Soviet Medium SPGs, 1941-1945