British Patent Abridgments

An aircraft having wings with sharply swept‐leading‐edges has a pair of members providing auxiliary lift surfaces, which members arc movable between a retracted position within the wings and an extended position in which the lift surfaces project laterally of the aircraft, and a source of pressure fluid, each member having nozzle means at or adjacent to its trailing edge, which nozzle means, in the extended position of the lift surfaces, faces downwards and from which pressure fluid from the source can be expelled at high speed downwardly in the form of a sheet extending laterally of the aircraft to provide an effect equivalent to additional lift surfaces for the aircraft. The aircraft comprises a pointed body 5, sharply swept low aspect ratio wings 6, 7 and a power plant 34. Supplementary aerofoils 12, 13 arc pivotally mounted to extend transversely from or to retract into the leading edges of wings 6, 7 respectively under the action of jacks 33. The trailing edges of aerofoils 12, 13 carry slots which arc supplied with pressure gas from power plant 34, the gas emerging as thin sheets which enhance the lift of the aerofoils. Without such device the aerofoils would have to be of greater chord as indicated by dotted lines 10, 11. The flow of gas from the slots (which may comprise a plurality of discrete apertures) may be varied differentially to provide yawing or roll control of the aircraft. Another embodiment is described in which the supplementary aerofoils are of sector shape instead of the rectangular form shown.