It is reasonable to date the prehistory of the Helicopter Association from the arrival in this country of Juan de la Cierva in 1925, at the invitation of lames Weir and his Associates.

The helicopter idea had intrigued designers from the earliest days of aeronautical experiment but, so far, often to their detriment and the derision of their contemporaries. Cierva had been first in translating the theory of auto-rotation into practical terms and had proved that both stability and control in flight could be achieved regardless of forward air speed. The freely rotating rotor system of the Cierva Autogiro and other early gyroplanes, such as those of Kay and Hafner, provided the missing link which all had been seeking and from this point development proceeded by logical rapid sequence to the flight of the first potentially safe and controllable helicopter in Germany in 1937.