Aerofoil Surface for Controlling Spin

摘要

The invention concerns craft of the type in which a fan directs a jet of fluid (4) over a curved canopy ( 1 ). The canopy ( 1 ) is shaped to divert the flow from a radial to an axial direction to produce lift. A problem is that rotation of the fan causes unwanted rotation of the canopy ( 1 ). The problem is solved using vanes (6) on the canopy ( 1 ) that have an adjustable surface area; and by providing a control system to adjust the effective surface area so as to compensate for the tendency of the rotor to rotate the canopy. The vanes ( 6 ) can be designed to slide in and out of the canopy (1) to obtain the required adjustment. In a preferred arrangement the vanes are arranged between upstream and downstream ends of the flow at a position where the effects of changes in swirl angle with varying rotor speed at least partially compensate for consequential changes in the tendancy for the canopy to spin.