SU-85

SU-85
SU-85 tank destroyer in Polish Army Museum.
Type	Tank destroyer
Place of origin	Soviet Union
Service history
In service	1943 - 1950s (USSR)
Production history
Designer	Lew S. Trojanow
Designed	1943
Produced	mid-1943 - late 1944
No. built	2,050
Variants	See Variants section
Specifications
Weight	29.6 tonnes (65,256 lbs)
Length	8.15 m (26 ft 9 in) overall 6.10 m (20 ft) hull only
Width	3 m (9 ft 10 in)
Height	2.45 m (8 ft)
Crew	4 (commander, driver, gunner, loader)
Armor	45 mm(1.77 in)
Main armament	85 mm (3.34 in) D-5T gun
Secondary armament	none
Engine	V-2 12-cylinder diesel 500 PS ( 493 hp, 368 kW)
Power/weight	16,89 PS/tonne (12.43 kW/tonne)
Suspension	Christie
Ground clearance	400 mm (16 in)
Fuel capacity	540 l 810 l - 900 l (with additional fuel tanks)
Operational range	400 km (248 mi) (road)
Speed	55 km/h (34 mph) (road)

The SU-85 (Samokhodnaya ustanovka 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 tank destroyers; the SU-85 fell into the latter category. The designation "85" signifies the bore of the vehicle's armament, the 85 mm D-5S gun.

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 Soviet command also had reports of the Panther tank, that was in development then and possessed thicker armor than the Tiger; both represented an advance in German tank design. Although the Panther was not seen in combat until July 1943, the new generation of German vehicles meant the Red Army would need a new, more powerful main gun for their armoured formations.

In May 1943, work was begun on a new anti-tank gun. Military planners directed the design bureaus of both Gen. Vasiliy Grabin and Gen. Fyodor Petrov to modify the 85mm anti-aircraft gun for use as an anti-tank weapon. Petrov's bureau developed the D-5 85mm gun. Though much too large for the T-34 or KV-1 turret, it was thought the gun could be mounted upon the chassis of the SU-122 self-propelled gun to give the weapon mobility. The version of this gun intended to be mounted upon the SU-85 was called the D-5S, with the "S" standing for self-propelled. Initially the production factory at Uralmash rejected the proposed design. Nevertheless, the administrators at Uralmash were persuaded to proceed, and the new design was put into production. The weapon was later modified to include a telescopic sight and a new ball gun mantlet. This vehicle was retitled the SU-85-II.