Westland-Hill Pterodactyl

Pterodactyl was the name given to a series of experimental tailless aircraft designs developed by Geoffrey T. R. Hill in the 1920s and early 1930s. Named after the genus Pterodactylus, a well-known type of Pterosaur commonly known as the pterodactyl, all but the first were produced by Westland Aircraft Ltd after Hill joined them.

Captain G.T.R. Hill developed the Pterodactyl series in an attempt to develop a safer aircraft: many pilots lost their lives when their aircraft stalled, went into a spin and flew into the ground, and Hill wanted to develop a design which was resistant to stalling and spinning. The pioneer J. W. Dunne had previously developed stable aircraft in the form of tailless swept wings and Hill took Dunne's ideas as his starting point.

Helped by his wife, he constructed a prototype which was flown as a glider in 1924. The design gained official interest and in 1925 it was fitted with a 35 h.p. Bristol Cherub engine and taken to Farnborough. It was later demonstrated to the Secretary of State for Air, Sir Samuel Hoare.

All subsequent examples were funded under Air Ministry contract and built by Westland Aircraft, who took on Hill for this purpose. The first Westland-built type, the Pterodactyl I, was built to Air Ministry Specification 23/26. It took the form of a braced shoulder-wing monoplane with fully moving wingtips and a single pusher propellor. If both tips were moved in the same way they functioned as elevators, in opposite ways then as ailerons. It was designated the Mk. IA or IB according to which engine was fitted. It and subsequent models flew initially from RAF Andover, the Mk. IA flying in 1928.

The Mks II and III failed to gain Ministry acceptance.

The next model to be built was a three-seat cabin monoplane to Ministry Specification 16/29, in which the all-moving tips were replaced by conventional ailerons. An unusual feature was the use of variable wing sweep to provide longitudinal trim. Designated the Mk. IV, it first flew in 1931.

...
Wikipedia