SU-85

Infobox Weapon
name=SU-85


caption=SU-85 tank destroyer in Polish Army Museum.
origin=flagcountry|Soviet Union|1923
type=Tank destroyer
is_vehicle=yes
service=1943 - ? (out of service)
designer=Lew S. Trojanow
design_date=1943
production_date=mid-1943 - late 1944
number=2,050
variants=See Variants section
length=8.15 m (27 ft) overall
6.10 m (20 ft) hull only
width=3.00 m (9.84 ft)
height=2.45 m (8 ft)
weight=29.6 tonnes (65,256 lbs)
suspension=Christie
clearance=400 mm (1.31 ft)
fuel_capacity=540 l
810 l - 900 l (with additional fuel tanks)
speed=55 km/h (34 mph) (road)
vehicle_range=400 km (248 mi) (road)
primary_armament=85 mm (3.34 in) D-5T gun
secondary_armament=none
armour=45 mm(1.77 in)
engine=V-2 12-cylinder diesel
crew=4 (commander, driver, gunner, loader)
engine_power=503 hp (375 kW)
pw_ratio=17 hp/tonne (12.7 kW/tonne)

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 _ru. "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 enough firepower to destroy any German tank then available. However, in the fall of 1942, Soviet forces encountered 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. [http://www.battlefield.ru/content/view/64/44/lang,en/ "The Russian Battlefield"] ] By spring 1943, the Soviets had also received reports of the new Panther tank, although the Panther was not seen in combat until July 1943, during the battle of Kursk. This new generation of German vehicles meant the Red Army needed a new and more powerful tank destroyer.

In May 1943, work was begun on both a new anti-tank gun and a redesign to the armament of the SU-122. Developers of the former put their efforts to adapting an 85 mm gun, one of two types identified as best against the Tiger (the other being the 122 mm A-19). The SU-122, meanwhile, was rearmed with an existing 85 mm gun, the S-18, which was itself improved in the process. The production factory at Uralmash, which received the SU-122 design, attempted to reject the design as too expensive, since the larger gun breech meant that the entire hull would need to be modified, but it was required nevertheless to put the design into production.

Of the SU-85, several prototypes were rejected for design flaws, but after several changes, which included changing the gun to a 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 85 mm gun was effective against Panther and Tiger tanks at long range. The vehicle was small, highly mobile and well armored.

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, [(Zaloga 1984:181, Perrett 1987:84)] 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 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 clients states in Europe and elsewhere.

The SU-85 remained in service longer in North Korea and Vietnam. [(Perrett 1987:84)] 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. [(Perrett 1987:85)]

Variants

Former Soviet Union

* SU-85-I - First SU-85 prototype, rejected for space concerns. Armed with 85 mm S-18 gun.
* SU-85-IV - Second prototype also with a standard hull of the SU-122 but it had a larger ball mantlet, different from the one used in SU-85-I. Armed with 85 mm S-18 gun.
* SU-85-II - Third SU-85 prototype with the new 85 mm D-5S gun, a new TSh-15 sight and a new ball mantlet design.
** SU-85 - Main production model armed with 85 mm D-5T gun.
*** SU-85M - SU-85 with the casemate from the SU-100 tank destroyer, which was larger and could carry up to 60 rounds instead of 48. It also had the same commander's cupola as the one used in the T-34-85.
*** SU-85T - SU-85 converted into an ARV.
* SU-85-III - Fourth SU-85 prototype with a modified commander's cupola, with direct vision slots and covers.

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.

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.

ee also

* List of Soviet tanks - covers all periods

External links

* [http://www.wwiivehicles.com/ussr/tank-destroyers/su-85.asp SU-85] at WWIIvehicles.com