GB632606A - Improvements in or relating to control systems for rotary wing aircraft - Google Patents

Abstract

632,606. Helicopters. SPERRY GYROSCOPE CO., Inc. Aug. 7, 1947, No. 21718. Convention date, May 15, 1945. [Class 4] In a helicopter rotor provided with cyclic pitch control mechanism, a controller carries the pitch-determining member and tilts the latter from a reference plane which is parallel to the tip-path plane and does not take part in pendulous swinging movements of the rotor drive shaft, whereby changes in the inclination of the tip path produced by the controller are also independent of such swinging movements. In the construction shown the pitch-determining member 30, 31 is mounted on a partspherical member 28 carrying a saturn ring 26 connected to a further part-spherical member 20 within the rotor drive shaft 14 and connected by links 27 to the rotor flapping links 17, so that the plane of the ring 26 is always parallel to that of the rotor-tip path. The ring 28 has a downward extension 33 to which is attached a ring 63 carrying the pitch-change mechanism. Collective pitch control is effected by a shaft 44<SP>1</SP>, the end of which carries a pinion 50 meshing with internal teeth on a ring 43, rotation of the latter causing vertical movement of blocks 41 engaging helical slots 42, resulting in vertical sliding movement of splined members 37 in sleeves 34 to operate the pitch-determining member 30, 31. For fore-and-aft cyclic pitch variation, a toothed ring 36 is rotated by a shaft 44<SP>11</SP> through gearing 65<SP>1</SP>, thereby rotating the sleeves 34 to cause relative axial movement of threaded members 37, 37<SP>1</SP>, one member being lengthened and the opposite one shortened to tilt the member 30, 31. Transverse cyclic pitch control is effected by a shaft 44 acting on two transversely-disposed threaded members similar to 37, 37<SP>1</SP>. The upper ends of the members 37 are connected to the pitch-determining member 30, 31 by Hooke's joints 39 and ball joints 46. Tilting of the members 20, 26, 28 and of the pitch control mechanism relative to the fuselage and rotor drive shaft is permitted by splined sections 144<SP>1</SP> and universal joints 145 in the shafts 44, 44<SP>1</SP>, 44". The pitchdetermining member 30, 31 may be connected by cables 45 to mechanism controlled automatically by a gyroscopic artificial horizon.