GB485001A - Improvements in aircraft sustaining rotors - Google Patents

Abstract

485,001. Aircraft with rotary - wing systems. CIERVA AUTOGIRO CO., Ltd., BENNETT, J. A. J., and ELLIS, G. B. L. Nov. 12, 1936, No. 30935. [Class 4] A self-contained pivotal mechanism for mounting the blades of aircraft sustaining rotors includes two relatively rotatable parts, means for transmitting end load from one to the other of said parts comprising an elastic member of high resistance to end loading and low torsional rigidity, the relatively rotatable parts having in other respects a limited axial freedom relatively to each other and the whole being so arranged that the end load sustained by the pivotal mechanism is substantially transmitted by the elastic member, which is relatively short, being wholly contained within the pivotal mechanism. As shown, a blade root 9 is furnished with a goose-neck fitting 8 rigidly connected to a pivot pin 7. The pivot pin 7 is mounted in radial-bearings 5, 6 in a housing 4 provided in a drag-link 2 pivoted to the hub 1 about a transverse flapping axis which may be inclined to either or both the plane containing the hub axis and the radial blade axis or to the plane perpendicular to the hub axis. The pivot pin and housing 4 are connected through a short length of stranded cable 10. The cable is connected to an abutment plate 14 and to an adjustment nut 20. A spacing sleeve 17 and thrust bearing 16 are interposed between the pivot-pin and the nut. The bearings 5, 6 can float in the housing and a thrust bearing ring 22 is provided. During assembly the cable is initially tensioned by an end load slightly less than the minimum end load in flight and the clearance between ring 22 and flange 21 is such as to allow for stretch of the cable corresponding to an increase of end loading from the initial loading to a value somewhat greater than any value obtaining during flight. A dimensioned example is given in the Specification. The torsional rigidity of the elastic-member may have a value having regard to its effective axial length that the restoring couple corresponding to 3‹ twist does not exceed the limiting static friction-couple of the bearing 16. The member 10 may comprise a non-spinning type of cable. Specifications 420,322, 452,364, and 474,681 are referred to.