This two-seat biplane was specially designed to compete in the Guggenheim Safe Aircraft Competition held in the USA in October 1929. The prizes of $100,000 encouraged 27 entrants to attempt to comply with the very stringent requirements, not least of which was the 10 to 1 glide angle required after engine-cut. Other requirements were a top speed of 110 mph, a stalling speed no greater than 35 mph, a rate of climb of 400 fpm at 1,000 ft and take-off and landing runs no greater than 300 ft and 100 ft respectively.
The near-sesquiplane wing layout of the Gugnunc was braced by interplane struts of Warren-girder form with few bracing wires and was similar to that employed previously on the Hare and later on the H.P.42, This very simple wing structure nevertheless was equipped with a complicated control-surface arrangement. The inboard sections of leading edge slat were interconnected with the trailing edge flaps and the outboard sections of slats and interceptors were automatic, to control the stall.
Long-stroke oleo legs were fitted to the undercarriage to cope with the high rate of descent. The Gugnunc, G-AACN, powered by a 155 hp Armstrong Siddeley Mongoose II, was flown for the first time on 30th April 1929. In the Guggenheim competition only one other aircraft was able to match the performance of the Gugnunc - the Curtiss Tanager biplane, itself equipped with Handley Page slats. It was the Tanager that was declared the winner by reason of its somewhat better glide angle although neither machine had achieved the required figure of 10 to 1. To decrease drag the Gugnunc was flown during the competition with aerofoil-shape fairings over the undercarriage oleos and a simple engine cowling.
The Gugnunc became K1908 when acquired by the RAF in December 1930, probably to be used for slow-speed research. In formation with the Cierva C19 Autogyro K1696 and the Westland Pterodactyl IV K1947, the Gugnunc took part in the RAF Display at Hendon on 27th June 1931.
The Gugnunc was finally pensioned-off in July 1934, when it was presented to the Science Museum, who still have it in their store.