The Kamov Ka-20 (NATO codename Harp) was a Soviet specialist anti-submarine helicopter was a precursor of the Ka-25. The Ka-25 was the end result of a requirement of the Soviet navy in 1957 on board a helicopter anti-submarine warfare. In response developed Kamov Ka-20 which first flew in 1960. In July 1961, the Kamov Ka-20 Harp first appeared during the celebration of Soviet Aviation Day with two mock air-to-surface missiles.
The Kamov Ka-20 was a twin-engine helicopter powered by two turboshaft engines provide 670kW Glushenkov a top speed of 220 kmh and a range of 650 km. The Ka-20 was much larger than the Ka-18. Although larger and twin-turbine engine, which is clearly derived from the Ka-15 and Ka-18, and, judging by a search radar housing under the forward fuselage was considered as a new anti-submarine helicopter. It has since come to be regarded as the prototype of the Ka-25 ("hormonal" NATO codename).