
The '''ZSU-57-2 Ob'yekt 500''' is a Soviet self-propelled anti-aircraft gun (SPAAG), armed with two 57 mm autocannons. 'ZSU' stands for Zenitnaya Samokhodnaya Ustanovka (), 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 after World War II. In the USSR, it had the unofficial nickname Sparka (), meaning "twin mount," referring to the twin autocannon with which the vehicle is armed.
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The '''ZSU-57-2 Ob'yekt 500''' is a Soviet self-propelled anti-aircraft gun (SPAAG), armed with two 57 mm autocannons. 'ZSU' stands for Zenitnaya Samokhodnaya Ustanovka (), 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 after World War II. In the USSR, it had the unofficial nickname Sparka (), meaning "twin mount," referring to the twin autocannon with which the vehicle is armed.
== Development history == === Origins === During World War II, ground-attack aircraft emerged as a significant threat to mechanized units on the move. Conventional towed anti-aircraft artillery (AAA), as well as vehicle Mounted smaller machine guns like the ones found on the ZiS-12 were 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 autocannons 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 Germans, the US and nations which had received the M3 through Lend-Lease.
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