GB386657A - Improvements in or connected with the construction of spars or girders particularly applicable for use in aircraft construction - Google Patents

Abstract

386,657. Aircraft framework. VICKERS (AVIATION), Ltd. and WALLIS, B. N., Byfleet Road, Weybridge, Surrey. July 17, 1931, No. 20510. [Class 4.] Aircraft spars, ribs, and girders of the type comprising three or more tubular booms stayed apart by diagonal members extending in a continuous zig-zag formation from end to end of the structure and secured to the booms by gusset plates have the diagonal staying members between adjacent booms so arranged that the apex of the V formed by the diagonal members reaching any given boom from one of its neighbours will lie approximately midway on that boom between the points at which it is intersected by the legs of the V formed by the diagonal members reaching it from its other neighbour. The invention is described with reference to a wing spar of the general type described in Specification 334,405, [Class 4, Aeronautics], comprising a number of bays of pyramidal form. In each bay, booms 30 .. 33 are secured to one another by diagonal bracing members 11 attached by gusset plates 10. In the middle of each boom section, pairs of gusset plates 10 secure two'diagonals 11. At the end of each section single U-shaped gussets 40 secure one diagonal only. The base of the U-plate abuts against the end of the boom section and is cut away to allow for the presence of means for securing adjacent lengths of the spar which may comprise externally threaded ferrules engaging threaded strengthening sleeves of the type described in Specification 334,405, or near the wing root where thicker booms may be employed the boom sections may be externally threaded and connected by internally threaded collars, in which case the U-shaped gussets are replaced by gussets similar to those shown at 10 and secured to either side of the collar. The diagonals 11 may be of the type described in Specification 376,364 and the spar may be assembled in the manner described therein. Cross ribs 38, Figs. 1 and 2, are connected to plates 39 clamped between adjacent boom sections, to which plates are also attached rib members 43. Ribs 38 comprise angle-section members 42 interconnected by cross bracings, and rib members 43 comprise thin tubes united by diagonal members 44 and gusset plates 45. Torsion stays 46 and stay wires 47 may also be attached to plates 32. The gusset plates 40 may be of progressively lighter construction towards the tip of the spar.