GB576364A - Improvements in or relating to direct lift aircraft - Google Patents

Abstract

576,364. Helicopters. UNITED AIRCRAFT CORPORATION. July 21, 1943, No. 11878. Convention date, Dec. 28, 1942. [Class 4] A helicopter provided with manually-controlled mechanism for effecting cyclical and simultaneous pitch adjustment of the blade also comprises automatic means interconnected therewith for reducing the blade pitch in the event of the coning angle of the blades reaching a predetermined value and at the same time varying the setting of the manual control. Cyclical pitch variation is effected by means of a tiltable ring 28 actuated by a control lever 22. through crank arms 24, 25, simultaneous pitch adjustment being obtained by translational movement of the ring 28 through a second hand lever 54. The movements of the ring 28 are transmitted to the blades 18, 20 by means of levers 32, which operate cross-shafts 34 and levers 35, 36, 37, to rotate the blades about drag links 52. A second ring 38 pivoted at 60 to the rotor driving shaft carries arms 39, to the ends of which are attached cables 40 joined to the pitch-changing levers 37. In the event of the coning angle of the blades exceeding a predetermined value, the cables are drawn taut to decrease the pitch angle in proportion to the increase in coning angle and automatically vary the setting of the manual control mechanism. This ensures autorotation of the blades in the event of failure or partial failure of the engine. A torque compensating propeller 62 is provided at the tail of the machine.