Comparing: IS-3A vs. KV-5

In 1956–1957, the Military Armored Forces Academy developed a speculative design for a new loading system on the IS-3 and T-10 heavy tanks. The IS-3 variant featured a double-row ammo rack with an automatic loading system. The crew was reduced to three members: commander, gunner, and driver. The turret was redesigned in order to accommodate the loading mechanism. The vehicle existed only in blueprints.

Development was started in June 1941 at the Leningrad Kirov Plant and completed by August, but the German invasion prevented development from progressing to the prototype stage. The KV-5 was expected to share some components with the KV-1. A new turret was designed, incorporating the 107-mm ZIS-6 gun. Early plans called for a new 1,200 hp diesel engine, but later adjustments, recognizing wartime disruptions, replaced this with two V-2K engines.