PST-72025 1/72 KV-1S Soviet WW2 Heavy Tank model kitAfter defeat in Crimea and at Kharkov some Red Army high commanders suggested development of an "universal tank", something between a heavy and medium tank. By the way, in the 1960's-1970's tank designers around the world came to the conclusion that it was the right decision.
Soviet tank builders tried to develop such a tank. This tank was named the KV-13. It contained many brilliant ideas (some of those ideas were applied in the IS-2 tank), however it never served in the Red Army.
At this time, a new decision was made to fully re-design the KV-1. Soviet tank designers wanted to develop a new KV with lighter armor and higher speed - like the T-34-76 medium tank. The new tank was named KV-1S where "s" letter means "skorostnoy" or "speed". The KV-1S was lighter than its predecessor by up to 5 tons. The thickness of the frontal armor was lowered from 90 mm to 75 mm. The rear hull was re-designed. The existing road wheels were replaced with newer, lighter ones. The KV-1's transmission was re-designed as well.
The old gear-box was replaced with a new one and the tank received a new turret with a commander's cupola (the first Soviet tank with a commander's cupola was T-50 light tank). Both ZIS-5 or F-34 guns could be mounted on this turret. In addition, the new tank was armed with four machine-guns: the coaxial MG, the bow MG, the AA machine-gun, and the MG in the rear of the turret. Also, new tracks (608 mm width) were designed specially for this tank.
In the summer of 1942, the KV-1S prototype was tested. On August 20, 1942, the production of this tank had begun. However, when the KV-1S appeared in the war theatre, the Red Army was already in need of a tank with thicker armor and better protection. A total of 1370 KV-1S were built. In April 1942 its production was cancelled. Many tanks were sent in tank brigades because the reorganization of the Red Army had not begun yet. The KV-1S took part in all major operations of the Red Army including the Berlin operation.