Method of making a leading edge structure of aircraft airfoil

Abstract

A leading edge structure of an aircraft airfoil comprises an outer skin, a front wall extended in the spanwise direction of the leading edge structure in a front section of the space defined by the outer skin so as to form an anti-icing duct together with a front part of the outer skin, and a plurality of ribs disposed in the space defined by the outer skin so as to form hot air passages. A laminar structure is formed by superposing upper and lower sheets of a superplastic titanium alloy, inserting a pair of core sheets of a superplastic titanium alloy between the upper and the lower sheet, and forming release agent layers in predetermined regions between the sheets. A structure having at least the outer skin, the front wall and ribs is formed by joining together parts of the superposed sheets corresponding to regions not coated with the release agent layers by diffusion bonding or welding, heating the laminar structure in a forming mold, supplying a superplastic forming gas into spaces between parts of the superposed sheets corresponding to regions coated with the release agent layers to subject the same parts of the superposed sheets to superplastic deformation and to press the upper sheet and the lower sheet against the forming surface of the forming mold.