After the appearance of the German tanks Tiger and Panther, the Soviet command needed effective techniques to combat them. The existing SU-152 and SU-122 self-propelled guns, despite their reliability, had a significant drawback: they had a low rate of fire.
In 1943, a group of designers led by Lev Gorlitsky began to create an artillery mounted SU-85. Construction was carried out at the Urals plant of heavy engineering and the tank T-34 was taken as a basis. An armored combat cabin was installed on the chassis of the tank. The thickness of the frontal armored sheet was 45 mm.
Armed with an 85-mm cannon, D-5S-85, which was placed in the cabin on a special carriage meant this gun had higher rates of fire, power, and range in comparison with the SU-122.
The SU-85 was intended for firing directly. The self-propelled nature of the gun allowed it to fight the German Tiger and Panther tanks at distances of 600-800 meters. In addition to the main sight, there was also a mounted panoramic sight, designed to fire from closed positions.
In addition, the SU-85 designers got rid of the fifth tankman’s place. This created additional free space and allowed for storage of extra ammunition, which included 48 shells. The SU-85 only needed a crew of 4 people. For self-defense, the crew used sub-machine guns and hand grenades.
The SU-85 had a weight of 29.2 tons and had excellent manoeuverability and patency. A twelve-cylinder V-shaped diesel engine V-2-34 with a power of 500 hp facilitated this. It meant the SU-85 could reach a maximum speed of up to 47 km / h. The maximum power reserve was 400 km and was directly dependent on road conditions.
In 1943, the SU-85 took part in the battles for the Dnieper. In the autumn of 1943, self-propelled units participated in the battles during the liberation of Left-bank Ukraine. Despite the effectiveness of the SU-85, it still had its shortcomings. Major General Katkov noted the following:
“The SU-85 self-propelled gun is currently quite effective in combating heavy Wehrmacht tanks. For its effectiveness and maneuverability, it is not inferior to the T-34, and with the new 85-mm cannon, it shows itself in combat quite well. However, using the fire and armor of their tanks “Tiger”, “Panther” and “Ferdinand”, the Germans are trying to impose a fight over long distances – 1500-2000 meters. In such conditions, the power of 85-mm guns and the frontal armor of the SAU SU-85 are not enough…”
Despite such misgivings, the SU-85 actively participated in covering the infantry and tanks until the end of the war. After the appearance of the new SU-100 in 1944, the SU-85 began to recede into the background. From August 1943 to August 1944, only 2050 units of SU-85 were created.