GB623470A - Improvements in or relating to helicopters - Google Patents

Abstract

623,470. Helicopters. UNITED HELICOPTERS, Inc. April 23, 1947, No. 10880. Convention date, Feb. 21, 1944. [Class 4] A helicopter with coaxial contra-driven lifting rotors is provided with tilting or swash-plate systems for cyclic pitch control of the rotor blades, the systems being interconnected for simultaneous adjustment along the axis of the rotors for differential collective pitch variation for steering purposes, while a further control system effects additional adjustment of the blades of one rotor and is so connected to the swash-plate systems as to effect simultaneous collective pitch variation for height control. General arrangement.-In the form illustrated, hollow coaxial shafts 42, 38 carry the upper and lower rotors 19, 20 respectively, and are driven by a transmission shaft 32, incorporating a clutch, through bevel gearing 34, 35, 36. Cyclic pitch control.-The direction of flight of the aircraft is controlled by a column 24 carrying a hand wheel 23 jointly operating cables 140, 146, 151 connected to a tilting ring 62 mounted on a ball joint 64 and connected to the pitch control arms 71, 72 of the lower rotor 20 by vertical links 67, 68. The tilting ring 84 controlling the pitch of the upper rotor blades 19 is mounted on transversely disposed pivots 82, and is connected to the links 67, 68 by members 75, 76, 77, 78 and to the upper rotor pitch arms 111, 112 by linkages 88, 89, 103, 104, 107, 108. Differential collective pitch control.-The rudder bar 28 is connected to an arm 122 carried by a threaded sleeve 126, rotation of which causes vertical movement of the ball joint 64 and hence of the rings 62, 84, to impart equal and opposite pitch variations to the respective rotors and thus unbalance their reaction torques. Simultaneous collective pitch control.-A control lever 26 operates two arms 114, 121 simultaneously, the latter being carried by a threaded sleeve 124 engaging the sleeve 126, so that rotation of the arm 121 effects vertical movement of the tilting rings 62, 84 to vary the rotor pitches equally, but in opposite senses. The arm 114 is carried by a threaded sleeve 116, rotation of which moves an axial shaft 44 vertically, the upper end of the shaft being connected to the links 103, 104 of the upper rotor pitch control mechanism by a pivot 96. The linkages are so arranged that movement of the shaft 44 superimposes on the upper rotor a pitch variation of twice the magnitude, but of opposite sense, to that imposed by the movement of the tilting ring 84, so that operation of the lever 26 results in equal variations of the respective rotor pitches.