ShVAK cannon
The ShVAK (Russian: Шпитальный-Владимиров Авиационный Крупнокалиберный (ШВАК), romanized: Shpitalnyi-Vladimirov Aviatsionnyi Krupnokalibernyi, "Shpitalny-Vladimirov Aviation Large-calibre") was a 20 mm autocannon used by the Soviet Union during World War II. It was designed by Boris Shpitalniy and Semyon Vladimirov and entered production in 1936. ShVAK were installed in many models of Soviet aircraft.