ZSU-57-2

ZSU-57-2 (Ob'yekt 500)
Type	Self-propelled anti-aircraft gun
Place of origin	Soviet Union
Service history
In service	1955 – early 1970s (USSR) 1957 - present (other countries)
Used by	See Operators
Wars	See Service history and Combat history
Production history
Designer	Design Bureaus of Omsk Works No. 174 and Research Institute No. 58 in Kaliningrad, Moscow Oblast
Designed	1947–1954
Manufacturer	Omsk Works No. 174
Produced	1948 - 1955 (prototypes) 1957 – 1960 (serial production)
No. built	More than 2,023 (USSR) 250 (North Korea, old turrets on new hulls)  ? (PRC, Type 80)
Specifications
Weight	28.1 tonnes
Length	8.46 m with gun in forward position (6.22 m hull only)
Width	3.27 m
Height	2.71 m 2.75 m (with a tarpaulin top)
Crew	6 (commander, driver, gunner, sight adjuster, and two loaders)
Armor	8–15 mm
Main armament	2 x 57 mm L/76.6 S-60 anti-aircraft (57 mm S-68A variant) (300 rounds)
Engine	V-54, 4-stroke, airless (mechanical)-injection, water-cooled 38.88 liter V12 diesel 520 hp (388 kW) at 2,000 rpm
Power/weight	18.5 hp/tonne (13.81 kW/tonne)
Suspension	individual torsion bar with hydraulic shock absorbers on the first and last road wheels
Ground clearance	425 mm
Fuel capacity	830 l (including two externally mounted fuel tanks, 95 l each)
Operational range	420 km (road) 320 km (off-road)
Speed	50 km/h (31 mph) (road) 30 km/h (off-road)

The ZSU-57-2 (Ob'yekt 500) is a Soviet self-propelled anti-aircraft gun (SPAAG), armed with two 57 mm . 'ZSU' stands for Zenitnaya Samokhodnaya Ustanovka (Russian: Зенитная Самоходная Установка), meaning "anti-aircraft self-propelled mount", '57' stands for the bore of the armament in millimetres and '2' stands for the number of gun barrels. It was the first Soviet mass-produced tracked SPAAG. In the USSR it had the unofficial nickname "Sparka", meaning "pair", referring to the twin with which the vehicle is armed.

During World War II, ground-attack aircraft emerged as a significant threat to mechanized units on the move. Conventional towed anti-aircraft artillery (AAA) was an inadequate response under such conditions owing to the time needed to bring anti-aircraft machine guns into action. This experience made it clear that an anti-aircraft tracked vehicle, armed with small-bore or heavy machine guns, was needed. Vehicles such as the German Wirbelwind and specialized variants of the US M3 Half-track had been used to good effect in the final battles of World War II, both by the US and nations which had received the M3 through Lend-Lease.

In 1942, Soviet engineers developed the T-60-3. The vehicle, based on the T-60 light tank chassis, was armed with two 12.7 mm DShK heavy machine guns; but the prototype did not go into production because of flaws in the design. The SU-72 SPAAG and several other experimental vehicles based on the T-60 or T-70 light tank chassis and armed with 37 mm autocannon were also tested in 1942–1943. The ZSU-37 was based on the chassis of the SU-76M self-propelled gun (SPG) and armed with a 37 mm 61K anti-aircraft autocannon in an open-top rotating armoured turret. The vehicle entered production in February 1945 and was in small-scale production until 1948.