ZSU-57-2 . The ZSU-57-2 is a Soviet SPAAG armed with two 57 mm autocannons. . Based on past experiences with SPAAG designs, Soviet engineers designed a vehicle that used a modified T-54 chassis, with much thinner armour. The vehicle was armed with twin 57 mm S-68 autocannon in a new, large, rotating, open-topped turret. The ZSU-57-2 consists of three compartments: driver's in the front, fighting in the middle and engine/transmission at the rear. The hull is more spacious in comparison with the T-54 because of the thinner armour and has different locations for some equipment.
The twin S-68s are recoil-operated and weigh 4,500 kg. Their construction was based on two 57 mm S-60 AA autocannons. The guns have a recoil of between 325 and 370 mm. The individual weapons cannot be swapped from one side to the other as they are mirror images. Each air-cooled gun barrel is 4.365 m long and is fitted with a muzzle brake. The guns are capable of firing up to 210–240 fragmentation and armour-piercing tracer rounds per minute, with a practical rate of fire of between 100 and 140 rounds per minute. Each clip has 4 rounds, each of which weighs about 6.6 kg; each projectile itself weighs 2.8 kg. Maximum horizontal range is 12 km with an effective range against ground targets of up to 4 km. Maximum vertical range is 8.8 km with a maximum effective vertical range of 4.5 km.
The main weakness of the ZSU-57-2 was the lack of a fire-control radar; the vehicle was equipped with an optical mechanical computing reflex sight as the sole fire control system, so it could engage targets thats were visible only. Night firing was also impractical. Also, the manual gunlaying and manual clip loading was difficult and time-consuming. The rate of fire was not high enough, particularly considering that air-cooled barrels require quite long pauses for cooling at high rates of fire and the turret traverse is not fast enough to effectively intercept high-speed attack jet aircraft at low altitudes. Also, the vehicle cannot perform aimed fire on the move. For these reasons the ZSU-57-2 was succeeded by the ZSU-23-4
Although the vehicle entered service in 1955 and in the same year the No. 174 Works located in Omsk began producing the hulls and turrets, the first vehicles were completed in 1957 after the first 249 57 mm guns were produced. A total of 5,300 of these weapons were produced by the end of the 1950s. The hulls and turrets were produced by No. 174 Works where the final assembly also took place. The ZSU-57-2 remained in production until 1960 when the No. 174 Works stopped producing the hulls and turrets for ZSU-57-2. More than 2,023 ZSU-57-2s were produced in Soviet Union
Weight - 28.1 tonnes
Length - 8.46 m with gun in forward position
Width - 3.27 m
Height - 2.71
Crew - 6 (commander, driver, gunner, sight adjuster and two loaders)
Armor - 8–15 mm
Main armament - 2 x 57 mm S-60 anti-aircraft autocannons w/300 rounds
Engine - V-54, 12-cylinder 4-stroke airless-injection water-cooled w/520 hp
Ground clearance - 425 mm
Fuel capacity - 830 l (including two externally mounted fuel tanks)
Range - 420 km (road), 320 km (off-road)
Speed - 50 km/h (31 mph) (road), 30 km/h (off-road)