GB600013A - Improvements in helicopter aircraft - Google Patents

Abstract

600,013. Helicopters. DEHN, F. B. (Bell Aircraft Corporation). July 7, 1944, No. 13024. [Class 4] In a helicopter rotor incorporating a stabilizing inertia member, cyclical pitch variations are imparted to the rotor blades by a pilot-operated control member which reacts against the inertia member. In the form shown in Fig. 3, the rotor hub 34 is mounted for universal tilting movement on the driving shaft 30, the upper end of which carries the inertia member comprising a rod 32 with enlarged ends. A link 39 carried by the rotor hub is connected by vertical links 36, 42, to the rod 32 and the outer race 43 of a saturn ring, respectively. In the event of the shaft 30 being displaced from the vertical, the member 32 tends to maintain its horizontal plane of rotation and, acting through the links 36, 39, feathers the rotor blades to restore the shaft to the vertical. The pilot may impart cyclical feathering movements to the rotor blades by tilting the saturn ring 43, 44, by a control member 35, the link 39 pivoting about the point 38 as fulcrum. In the embodiment according to Fig. 5, a flywheel 55 driven by a shaft 57 passing through the main rotor shaft 30 engages a disc 59 connected by links 60 to a lower saturn ring 62, through the race of which pass pilot-operated control screws 70, 75, connected to an upper saturn ring 64, the outer race of which is attached to a vertical link 66 connected to the rotor hub 69. According to a further modification, Fig. 6 (not shown), the inertia member is placed below the lifting rotor and is connected to the pilot-operated control member by cables passing over pulleys mounted on the rotor hub. Figs. 7 and 8 show a construction in which the pitch of the rotor blades may,be varied simultaneously by equal amounts by means of a pilot-operated bell-crank 154 connected to a tiltable member 145 which actuates a verticallyslidable sleeve 138, connected to the inertia member 133 which operates the pitch control arms 124 of the rotor blades through links 131, 128, 129, 126. Cyclical pitch variations are imparted to the blades by a gimbal 168 actuated through control arms 175. Specification 580,231 is referred to.