GB521190A - Improvements relating to wing flaps of aircraft - Google Patents

Abstract

521,190. Controlling aircraft. BLACKBURN AIRCRAFT, Ltd., amd STIEGER, H. J. Sept. 21, 1938, No. 27565. [Class 4] An aircraft wing has a flap, the chord of which is large relative to the chord of the wing as a whole (e.g. 40 per cent. to 60 per cent.) when the flap is in neutral position, mounted for movement about an axis below the flap and behind its leading 'edge or otherwise movable downwardly and rearwardly to open a slot between the trailing edge of the final part of the wing and the leading edge of the flap. The outer ends of the flaps may be used as ailerons. Fig. 2 shows a flap 3 pivoted about a fixed axis 4 and tiltable into any of the positions shown, the flap acting as an air brake when in the upwardly tilted position. The lower edge 7a of the fixed part of the wing acts as an air seal for small downward angles of deflection, after which a convergent slot is opened. Fig. 3 shows a modification in which a fixed slat 8 on the flap divides the slot into separate passages. In this case the lower entrance to the slot is closed when the flap is in neutral position by a projection 10 on the fixed part of the wing. Other forms are described in which fixed slats on the flaps contact with the wing and form continuations of the upper surface as the flap is downwardly deflected. The parts used as ailerons in a form similar to that shown in Fig. 2 have the leading parts of the undersurface cut away to delay the entry of the leading edge into the airstream as the aileron is upwardly tilted. The trim of the craft is preserved, as the centre of pressure moves backwards, by the reaction of the deflected airstream upon the tail planes. The fixed slat 8 may be replaced by one connected by links to the trailing edge of the fixed wing or to the leading edge of the flap so as to open to the desired extent as the flap approaches its fully-down position. This applies also to the other fixed slats described. In another form a closure for the lower entrance to the slot may be withdrawable into the wing or be angularly movable or resilient to permit the flap to be upwardly tilted.