Friday, July 31, 2015

Flight of the Pterodactyl

Photographs are fragile things, and some of the ones I come across have almost succumbed to age and elements. It's always a joy to find a unique one and digitize before it completely crumbles to dust, and such is the case with this photo, of the very unique 1932 Westland-Hill Pterodactyl Mark V.

A lot of people died in stall-spin-crash accidents in the early decades of aviation, making the idea of a safe, stall-proof airplane something many inventors strove for. (It still is a goal today - for instance, that's the primary reason Burt Rutan pursued his early canard designs). British inventor Captain Geoffery T. R. Hill believed that the answer lay in the concept of a flying wing, as opposed to the more traditional aircraft configuration. Hill was, no doubt, influenced by the earlier development of the Dunne flying wings, which sought the same safety goals, and which ultimately led to a Curtiss attempt at developing a safe "everyman's" airplane in 1930 (See our April blog post The Birth of the American Flying Wing).

Hill began small, and called his series of aircraft the Pterodactyl. The first one was initially tested as a glider in 1926, and then modified to incorporate a 30 hp engine. The British Air Ministry was suitably impressed, and offered to fund the development, as long as Hill worked through Westland Aircraft, where he then hired on. Subsequent versions, beginning with the Westland-Hill Pterodactyl Mark I, refined the concept through the beginning of the 1930s, but all were relatively small, low-powered aircraft. 

This all changed with the Mark V. The Air Ministry specified a fighter plane based on the concept, to be powered by a huge (given the size and weight of the plane) 600 hp Rolls Royce V-12 Goshawk engine. The tailless design allowed for a defensive machine gun turret to be mounted behind the pilot (missing from this photo), and there were plans to build a complementary version with a pusher prop and a turret in the nose.

Unlike the previous models in the Pterodactyl series, the Mark V included a stubby, straight sesquiplane lower wing. Roll and pitch control was through elevons and yaw control was through wingtip fins, each of which could only move outward. Initially, the fins were almost all rudder, but this design evolved to include a lower fixed fin.

The contract was awarded by the Air Ministry in 1931 with serial number K2770 being assigned to the project, and work started in 1932. By fall of that year, the plane was put through its paces in taxi tests and during one of these, the Pterodactyl hit a bump in the turf which caused the left wing to crumple due to a miscalculation in the structural stress analysis. By the time the wing structure was redesigned, another sixteen months had gone by, and the plane finally took its maiden flight in May, 1934.

The Mark V failed to impress the Air Ministry, however. It suffered from excessive pitch sensitivity inherent in flying wing designs, and was not nearly as fast as had been expected, turning in a top speed of only 165 mph. The RAF's Hawker Hart light bomber was a good 20 mph faster than this supposed fighter. The nose and engine were then extended forward in order to try to solve the pitching issues, and additional vertical fences were added to the bottom of the wings. The problems continued, however, and work on the Mark V was finally cancelled, after which plans for larger versions, including a twin-engine sea plane and a four-engined airliner capable of transatlantic flights, were abandoned.

YouTube has some footage of the earlier Mark 1A, which is the only plane of the Pterodactyl to survive, now preserved in London's Science Museum.

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