The Cierva W.5 was a helicopter developed by the Cierva Autogiro Company in the United Kingdom. It was a single seater twin rotor helicopter- the rotors were mounted side-by-side on outriggers- with a wooden frame. It was powered by a 50 hp 4-cylinder air-cooled Weir engine. Its first flight was at Dalrymple, Ayrshire, on 7 June 1938, and it is considered to have been the world's second fully practical helicopter.