GB551156A - Improvements in or relating to aircraft - Google Patents

Abstract

551,156. Helicopters. UNITED AIRCRAFT CORPORATION. May 8, 1941, No. 6009. Convention date, April 6th 1940 [Class 4] A helicopter comprises a main, power-driven, direct-lift rotor of variable pitch controlled by manually actuated means which simultaneously adjusts the engine throttle. The main lifting rotor has articulated blades variable in pitch simultaneously or cyclically, and a rear rotor rotating in a plane at right angles variable in pitch both manually, and automatically by a wind vane, to balance the torque of the main rotor and to effect steering movements of the machine. An additional rotor may be provided at the rear and be adjustable in pitch to control the longitudinal balance, or both rear rotors may be replaced by a single rotor of the feathering paddle type the phase of the feathering. being adjustable to give a thrust in any direction. All of the rotors are driven from a single engine through a one-way clutch. An engine 16 drives through a series of belts 42 a drum 40 having a free wheel coupling to a shaft connected by bevel gears to a main rotor shaft 62 and through a flexible coupling to a shaft 66 which drives the rear rotor 78, Fig. 3, through bevel gears. The main rotor comprises three blades pivoted about the stub shafts articulated at 120, 122, 124, Fig. 5, to three plates 112, 114, 116 pivoted about horizontal pivots 106, 108, 110 on a member secured to the shaft 62. Movements about the pivots 120, 122, 124 are cushioned by links 126 having rubber buffers 132, 134 bearing against sleeves engaged by brackets 130 on the blades. Each blade has upper and lower straps 144, 146, Fig. 6, between which is pivoted a tubular sleeve 148 having ball-ended projections 150, 152 connected respectively to links 156, 154. The latter extends to one and of the pivot bolt 106, 108 or 110 and the former to a member 176, Fig. 4, connected by a ball race to a plate 158 movable axially along and in any direction transversely to the shaft 62. One of the links 156 is triangulated so that the member 176 follows the rotor. The plate 158 is supported on two vertical links 178, 180 connected to the ends of horizontal arms on a shaft 186 having another horizontal arm connected by a link 190 to one end of a lever 192 by which the plate 158 is raised and lowered to vary the pitch of the blades as a whole. The plate 158 is connected by a link 234 to the apex of a forked lever 236 pivoted on the main frame and movable by a rod 232 connected by the linkage shown to a lever 220 by which fore and aft movements are given to the plate 158. The lever 220 is pivoted on a shaft 222 having a two armed lever at its rear end connected by cables to lever mechanism, not shown in Fig. 4, by which the plate 158 is given transverse movements. The rod 190 carries a lever 202 forming part of the throttle control transmission so that the engine output is automatically varied as the mean pitch of the main rotor is varied. A centrally placed pedal 216 can act on the lower end of the locking quadrant of the lever 190 to reduce the pitch of the rotor momentarily when required, Two other pedals 266 are connected by cables extending along the rear outrigger to a lever 268, Fig. 3, connected by an arm 270 and link 272 to a rod 274 extending through the hub of the rotor 78 to a link connected to the leading edge of the rotor. A lever 282 carrying a wind vane 280 also acts on the pitch control of the rotor 78, and the vane may be set permanently to give a bias to the control for offsetting the torque reaction of the main rotor. Fig. 13 shows an additional lifting rotor 344 driven by bevel gearing from the rotor 78 and adjustable in pitch by a link 360, sleeve 358, bell crank 364 and rod 368. Fig. 11 shows a rotor driven by gearing 290, 292 and comprising pivoted blades 302 having their leading edges connected by links to one end of a lever pivoted at its centre 312 within the hollow driving shaft. By tilting the lever the end 314 may be excentred in any direction to vary the direction of thrust of the rotor. A fixed vane may be provided on the rear outrigger. The landing gear comprises two main landing wheels on shock absorbing struts carried by lateral outriggers and two subsidiary wheels on shock absorbers arranged centrally fore and aft of the main wheels.