GB471123A - Improvements in or connected with aircraft frame structures - Google Patents

Abstract

471,123. Aircraft framework. VICKERS (AVIATION), Ltd., and WALLIS, B. N. Feb. 27,1936, Nos. 5885/36 and 1920 /37. [Class 4] A boom for use in cantilever aircraft structures is constructed in span-wise sections, the boom sections being constructed of multiple tubes, of uniform external size, arranged side-by-side, decreasing in number from the root of the structure outwards and being symmetrically arranged with respect to those in the root section. The tubes in each span-wise section may be varied in internal diameter along the span. In one form, Fig. 2, the boom comprises a root section A consisting of three side-by-side tubes each built up from an inner thick tube A<1> and an outer thin tube A<2>, an intermediate section B comprising two side-by-side tubes each constituted by a thick element B<1> and a thin element B<2> ; and an outer section C comprising a single tube constituted by a thick element C<1> and a thin element C<2>. In order more closely to adapt the wall thickness of the tubes to the loading, the elements constituting a tube may not only be of increasing internal diameter but the wall thickness of each element may be varied by cutting material away by progressively increasing amounts as at a<6>, a<7>, a<8>, Fig. 5. Side-by-side tubes and the elements constituting each individual tube are joined by means of serrated fish-plates engaging serrations formed on the side walls of the tubes, Fig. 11, and by bolts. The serrations may be formed with a small helical pitch. At the root-end of the boom internal distance pieces are located in the bores of the tubes and the fish-plates are extended to form spar attachment lugs. Fig. 13 shows the method of connecting the span-wise sections by fishplates h. Booms such as described may be interconnected by plate webs or warren girder bracing to form spars, the bracing members being attached to the fish-plates and the plate webs clamped between the tubes. When geodetic contour members are provided these extend between the booms and false leading and trailing edges respectively, and comprise sets of bracing members of greater depth than width twisted about their neutral axes until their depth is normal to the contour at all points, and the neutral axes of the bracing members intersect the axes of the tubes. Specifications 388,438 and 412,232 are referred to.