GB1279101A - Bladed rotors - Google Patents

Abstract

1279101 Variable pitch propellers DOWTY TECHNICAL DEVELOPMENTS Ltd 1 July 1970 [8 July 1969] 34258/69 Heading B7V [Also in Division F1] In an aircraft propeller the blades 27 mounted in a hub of a rotor are angularly adjustable for pitch, twist or camber about their longitudinal axes 35 by a fluid-pressure-operable motor having an element or plate 44 movable linearly and angularly with respect to the hub and being coupled to each blade by a respective link 67 having a pivotal connection at one end portion and a universal connection at the other end portion. The plate 44 has a cylindrical member 46 extending forwardly through an aperture, including a fluid seal 37, into a domed cylindrical casing 40, and a rearwardly extending cylindrical member 48 sealingly connected to a tube 50. Fluid under pressure is delivered under the control of a manually operated valve (not shown) through the tube 50 to cause displacement of the plate 44 to the right so that the links 67 pivotally connected thereto angularly adjust the blades 27 about their longitudinal axes 35. The movement of the plate 44 towards the right, i.e. the pitch-fining direction, is performed against a spring 56 and also against the effort of balancing weights 65 which bias the blades in the pitch-coarsening direction. The spring 56 bears at the other end against an annular flange member 52 which is free to move angularly with respect to the hub by means of a roller bearing 53. An auxiliary spring 59, stronger than the spring 56 also seats against the member 52 and encounters the plate 44 when the blades 27 move into a reverse pitch position and a sleeve 62 limits the extent of rearward movement of the member 44. The fluid motor may alternatively be double acting and may also be of the movable cylinder type.