Twin-engined piston helicopters

1956 utility helicopter family by Kamov

1950s transport helicopter by Yakovlev

military helicopter family by the Sikorsky Aircraft Corporation

1948 liaison helicopter prototype by Bratukhin

military transport helicopter prototype

1946 prototype helicopter model by McDonnell Aircraft Corporation

1947 transport helicopter prototype by Bratukhin

prototype flying crane helicopter

1950s British helicopter

type of aircraft

1941 experimental helicopter by Bratukhin

type of aircraft

experimental mini-helicopter built by Nazi Germany in the early 1940s