British Patent Abridgments

In order to shorten the length of the takc‐off run of an aircraft provided with an annular wing which houses a propeller the transverse planes containing the leading and trailing edges are inclined obliquely to the longitudinal axis of the wing. In the illustration the wing 2 has its leading edge 1 and trailing edge 8 so arranged that the airflow induced through the wing by a propeller H creates an area of negative pressure 3 which facilitates take‐off. Further the leading edge is provided round its upper periphery with a blowing slot 4 directed to the interior of the wing to accelerate the boundary flow over the upper leading edge and thereby move the area of depression aft. A further blowing slot 7 is provided over the lower portion of the interior of the duct some distance back from the leading edge. The boundary layer flow over the rear portion of the wing 2 is controlled by a blowing slot 10 and increased lift is obtained by downward deflexion of the air flowing through the wing. This is achieved by flaps 11 mounted on or forming the trailing edge of the upper part of the wing and articulated flaps 14, 15 mounted at the mid‐height of the trailing edge 8. The flaps 11 may be hinged to nest against the inner wing surface when retracted or they may conform to the inner and outer profiles and be mounted for pivotal movement within wing cut‐outs or they may be formed as part of the wing trailing edge to provide a slot when deflected. Flaps 14 and 15 are operated by linkwork and a jack to take up deflected positions in which flap Mis given a small positive incidence and flap 15 a large positive incidence about their common pivot. A fuselage 22 is housed centrally within the wing 2 and secured to it by wings 23, provided with control surfaces 34, and a fin 28 which extends aft of wing 2 to terminate in upper and lower rudders 31. Wings 23 have anhedral and are co‐planar with further wings 24 which terminate in fairings 25 to form landing skids or to enclose landing wheels. It is stated that the propeller H could constitute the fan of a ducted‐fan turbo‐jet unit.