Heave control of amphibious hovercraft

Describes progress on the development of a heave control system for amphibious hovercraft. The central element in the inner loop of the system is an axial flow lift fan whose blade angles are continuously varied by a feedback signal coming from a pressure transducer located in the cushion of the hovercraft. This is enclosed by an outer loop feedback of heave acceleration. Experiments on the Cranfield Whirling Arm Facility have shown that the system provides a rapid and effective means of controlling the heave motion.