Helicopter rotor construction and improved rotor blade therefor having a retractible trailing portion

摘要

1,081,332. Helicopter rotor blades. BÍLKOW G.m.b.H. April 5. 1965 [April 15, 1964], No. 14322/65. Addition to 1,081,331. Heading B7W. A helicopter rotor blade has a spar forming the leading edge, and the trailing edge portion is retractable into the spar. The blade is intended for use on convertible aircraft, this retraction producing a drag reduction when the rotor is stopped. The retractable portion has a flexible skin 9 attached to the spar 3 and to a longitudinally movable bar 8 at the trailing edge. Ribs 7 are pivotally mounted on the spar and the bar and have upper and lower limbs (20, Fig. 3, not shown) which maintain the shape of the skin when extended. The forward ends of the limbs (20) may be urged together during retraction by co-operating ramps (18) on the spar (3) and the limbs, to reduce the thickness of the trailing edge portion. The bar (8) may be moved longitudinally by the rotation of a link (22) connected to the bar by a further link (22a, Figs. 7 and 8, not shown), by an hydraulic ram (28, Figs. 9 and 10, not shown), by the rotation of a plate (36) coaxial with the rotor axis and connected by an actuating rod (37) to the bar (Fig. 11, not shown), or by a push-rod (42) extending through a drag hinge (41) of the blade and connected to the bar by a bell-crank (45, Figs. 12 and 13, not shown), this bellcrank having an arcuate groove (44) which a ball on the push-rod (42) engages and which permits feathering of the blade.