In 1923, 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, with his C.4 prototype.

[4] He eventually earned a civil engineering degree and after building and testing the first successful autogyro, moved to the United Kingdom in 1925, where, with the support of Scottish industrialist James G. Weir, he established the Cierva Autogiro Company.

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 dissymmetry of lift between the advancing and retreating blades.

As a direct result, and with the assistance of the Scottish industrialist James George Weir, the Cierva Autogiro Company, Ltd., was formed the following year.

The resolution of these fundamental rotor problems opened the way to progress, confidence built up rapidly, and after several cross-country flights a C.8L4 was entered for the 1928 Kings Cup Air Race.

This machine allowed for change of motion in any direction – upwards, downwards or sideways – by the tilting of the horizontal rotors and also effected a minimising of some of controls used in more conventional aircraft of the period.

Autogyros were built in many countries under De la Cierva licences, including France, Germany, Japan, Russia and the United States.

After delay caused by heavy fog, the airliner took off at about 10:30 am but drifted slightly off course after takeoff and exploded after flying into a house on gently rising terrain to the south of the airport, killing 15 people, among them de la Cierva.

[7] Juan de la Cierva's work on rotor-wing dynamics made possible the modern helicopter, whose development as a practical means of flight had been prevented by a lack of understanding of these matters.

The understanding that he established is applicable to all rotor-winged aircraft; though lacking true vertical flight capability, work on the autogyro forms the basis for helicopter analysis.

[8] De la Cierva's death in an aeroplane crash in December 1936 prevented him from fulfilling his recent decision to build a useful and reliable aircraft capable of true vertical flight for the Royal Navy, but it was his work on the autogyro that was used to achieve this goal.

In 1966, Juan de la Cierva was inducted into the International Aerospace Hall of Fame for his innovation in rotor blade technology, using them to generate lift and to control the aircraft's attitude with precision.