Abstract: A wing, or similar article of airfoil section, has a variable geometry surface for the active control of shock strength and transonic wave drag. In one embodiment, the wing has a region of distensible skin (4) aft of the line of maximum section, which extends along the span of the wing in those areas that experience drag. Pressure means (10, 20, 30) within the wing outwardly deflect the distensible region and produce a local bulge in the expansion surface. This bulge induces pre-shock compression and reduces the effect of the shock. The bulge is retracted by the natural elasticity of the skin material (which can be a conventional aluminum alloy) upon removal of the applied pressure. In another embodiment, the wing has a ramp portion (14) which is outwardly deflectable for the same purpose. The invention is applicable to supercritical and natural laminar flow wings.

Abstract: The manoeuverable supercritical wing section with a t/c ratio of 8-9%, flexible at 70%-80% chord by means of a flap to induce expansion thereover, and perhaps having a minimum curvature region on the upper surface just ahead of the flexing region.

Abstract: A supercritical aerofoil having a large leading edge radius of curvature, a radius of curvature over substantially the whole upper surface appreciably higher than the mean radius over the front half of the lower surface, a concave surface to the rear half of the lower surface, and a thickness/chord ratio of 10- 14%.