SU-85

The SU-85 was a Soviet self-propelled gun used during World War II, based on the chassis of the T-34 medium tank. Earlier Soviet self-propelled guns were meant to serve as either assault guns, such as the SU-122, or as mobile anti-tank weapons; the SU-85 fell into the latter category. The designation SU-85 is derived as follows: 'SU' stands for the Samokhodnaya Ustanovka - self-propelled carriage, while "85" signifies the bore of the vehicle's armament, the 85 mm D-5T gun.

Development history
Early in World War II, Soviet tanks such as the T-34 and KV-1 had adequate firepower to defeat any of the German tanks then available. By the fall of 1942, Soviet forces began to encounter the new German Tiger tank, with armor too thick to be penetrated by the 76.2 mm guns used in the T-34 and KV tanks at a safe range. The Soviets also had received reports of a new, more heavily armoured German tank then under development, the Panther tank. Although the Panther was not seen in combat until July 1943, the new generation of German vehicles meant the Red Army needed a new, more powerful main gun for their armoured formations.

In May 1943, work was begun on a new anti-tank gun. Developers turned to adapting an 85 mm heavy anti-aircraft gun for this purpose. The gun was far too large to fit into the turret of the T-34 or KV-1, but it was thought it could be mounted in the chassis of the SU-122. Meanwhile, the SU-122 was rearmed with an existing 85 mm gun, the S-18, which was modified and improved in the process. Initially the production factory at Uralmash attempted to reject the design since the larger gun breech meant that the entire hull would need to be modified, but they were required to do so nevertheless, and the modified design was put into production.

Several prototypes of the SU-85 were created, and rejected for design flaws. After several changes, including another armament change to the D-5T, one was put into service as the SU-85. At the same time, the 85 mm D-5S, which had proven both effective and reliable, was modified to include a telescopic sight and a new ball mantlet design and retitled the SU-85-II.

Description
The SU-85 was a modification of the earlier SU-122 self-propelled howitzer, essentially replacing the 122 mm M-30S howitzer of the SU-122 with a D-5T high-velocity 85 mm antitank gun. The vehicle was small with good mobility. The trade-off was its relatively light armor.

Production history
SU-85 production started in mid-1943, with the first vehicles reaching their units by August. When the up-gunned T-34-85 medium tank entered mass production in the spring of 1944, there was no point in continuing production of a tank destroyer without superior firepower, so SU-85 production was stopped in late 1944 after 2,050 vehicles had been produced. It was replaced on the production lines by the SU-100 tank destroyer, armed with the more powerful 100 mm D-10S gun.

There were two versions: the basic SU-85 had a fixed commander's cupola with a rotating periscope and three vision blocks; the improved SU-85M had the same casemate as the later SU-100, with a commander's cupola as used on the T-34-85.

Service history


The SU-85 entered combat in August 1943. It saw active service in Soviet, Polish and Czechoslovak forces on the Eastern Front until the end of the war. It was obsolescent by 1945, and was withdrawn from active service not long after the war, to be exported to many Soviet client states in Europe and elsewhere.

The SU-85 remained in service longer in North Korea and Vietnam. The similar SU-100 remained in service much longer, and some SU-85 and SU-100 were converted and used as command and recovery vehicles.

Former Soviet Union

 * SU-85 Basic version with four periscopes and no commander's cupola.
 * SU-85M Improved version with SU-100 style cupola.

Poland

 * WPT-34 (1960s) - Polish repair and maintenance vehicle with a superstructure replacing the casemate, a crane, a large-diameter telescoping snorkel for deep fording operations as well as a large-spade type earth anchor in the rear. It was converted from SU-85 tank destroyers as well as T-34 medium tanks and SU-100 tank destroyers.

General references

 * Perrett, Bryan (1987). Soviet Armour Since 1945, London: Blandford. ISBN 0-7137-1735-1.
 * Zaloga, Steven J., James Grandsen (1984). Soviet Tanks and Combat Vehicles of World War Two, London: Arms and Armour Press. ISBN 0-85368-606-8.