Juan de la Cierva y Codorníu (21 September 1895 – 9 December 1936) was a Spanish civil engineer and pilot. His most famous accomplishment was the invention in 1920 of the Autogiro, a single-rotor type of aircraft that came to be called autogyro in the English language. After four years of experimentation, De la Cierva developed the articulated rotor which resulted in the world's first successful flight of a stable rotary-wing aircraft in 1923 with his C.4 prototype.
De la Cierva was born in Murcia, Spain to a wealthy family. After several successful experiments with aviation as a boy, he eventually earned a civil engineering degree. He moved to England in 1925, where with the support of Scottish industrialist James G. Weir, he established the Cierva Autogiro Company.
At the outbreak of the Spanish Civil War, De la Cierva supported the forces of Francisco Franco, helping the rebels to obtain the De Havilland DH-89 'Dragon Rapide' which flew General Franco from the Canary Islands to Spanish Morocco. His brother was killed by the Republican army in Paracuellos del Jarama.
The gyroplane (autogiro)
Juan de la Cierva started building aircraft as early as 1912, and in 1919 he started to consider the use of a rotor to generate lift at low airspeed, and eliminate the risk of stall.
In order to achieve this, he utilised the ability of rotor to autorotate, whereby at a suitable pitch setting, a rotor will continue to rotate without mechanical drive, sustained by the torque equilibrium of the lift and drag forces acting on the blades. This phenomenon was already known, and was available as a safety feature to allow controlled descent in the event of engine failure. With de la Cierva's autogiro, the rotor was drawn through the air by means of conventional propeller, with the result that the rotor generated sufficient lift to sustain level flight, climb and descent.
Before this could be satisfactorily achieved, de la Cierva experienced several failures primarily associated with the unbalanced rolling movement generated when attempting take-off, due to asymmetry of lift between the advancing and retreating blades. This major difficulty was resolved by the introduction of the flapping hinge. In 1923, de la Cierva's first successful Autogiro was flown in Spain by Lt. Gomez Spencer.
This pioneering work was carried out in de la Cierva's native Spain. In 1925 he brought his C.6 to England and demonstrated it to the Air Ministry at Farnborough, Hampshire. This machine had a four blade rotor with flapping hinges but relied upon conventional airplane controls for pitch, roll and yaw. It was based upon an Avro 504K fuselage, initial rotation of the rotor was achieved by the rapid uncoiling of a rope passed around stops on the undersides of the blades.
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