It was completed around April or May 1922, and was tested from June onwards by Jose Maria Espinosa Arias at Getafe.
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This led to a military demonstration at Cuatro Vientos on 31 January, where the C.4 made a circular flight of 4 km (2½ miles) in 3½ minutes, at an altitude of over 25 m (80 ft).
In this configuration, the C.12 (now dubbed the Hydrogiro) flew from Southampton Water in April 1930, becoming the first rotary-wing aircraft to take off from water.
In 2008 it was on loan to the Mosquito Aircraft Museum at Salisbury Hall, near London Colney in Hertfordshire.
It joined Air Service Training Ltd in 1934, was impressed (as Rota HM580) in 1942, serving with 529 Squadron and returning to civil use by G.S. Baker based at Birmingham's Elmdon airport with its original registration plus the nickname Billy Boy and was not withdrawn from use until 1960.
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; Lioré-et-Olivier LeO C-301: Improved C-30s with uprated Messier oleo-pneumatic shock absorbers, flotation devices to facilitate ditching at sea and tripod main rotor support.
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By the end of the decade private flyers were moving back to the comforts and economies of fixed-wing aircraft and more C.30s moved abroad, leaving the Autogiro Flying Club at London Air Park, Hanworth as the major UK user.
In 1938 the British Aircraft Manufacturing Company assembled nine C.40s at London Air Park, Hanworth, and seven were delivered to the Royal Air Force.
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The Cierva C.40 was a British autogyro designed by J.A.J Bennett and assembled by the British Aircraft Manufacturing Company at London Air Park, Hanworth.
One of those flights, the eight minute trip from Cuatro Vientos airfield to Getafe airfield (10.5 km / 7 miles), was considered a giant's step and the "leap into glory" of Cierva's autogiros.
This was completed as the Type 611, test flown by Bert Hinkler at Hamble and then delivered to the Royal Aircraft Establishment by Cierva himself in Britain's first cross-country rotorcraft flight on 30 September that year.
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The C.8W bought by Pitcairn would make the first autogiro flight in the United States at Willow Grove, Pennsylvania on December 18, 1928.