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,Weir w5/Cierva w5 article on All-Aero Copters website and it is considered to have been the world's second fully practical helicopter.James G. Weir biography at helicopter-history.org
Pitch and Yaw control was achieved by tilting the rotor disks, roll control by differential pitch input to the rotors. Rotor thrust was controlled directly by the motor speed, which damped the response heavily.Book: Principles of Helicopter Aerodynamics Ch 1.1 The first successes/ By J. Gordon Leishman (2edn, 2006, ) Cambridge Aerospace Series
References
Reference to the W.5 in the history of British research and developments in the Helicopter field on the website by Vic Flintham