GB623582A - Improvements in and relating to aircraft with rotating wings - Google Patents

Abstract

623,582. Helicopters. CIERVA AUTOGIRO CO., Ltd., PULLIN, C. G., and WATSON, K. Nov. 12, 1946, No. 33580. [Class 4] In a rotary-wing aircraft provided with cyclic pitch control mechanism and a rotor hub mounted for tilting in at least one azimuth, the pitch control mechanism and hub are actuated by a common control member so that an angular displacement with respect to the airframe of the control plane, i.e. the tiltable plane with reference to which the blade pitch angle is constant, in at least one azimuth is accompanied by a related and not greater tilt of the hub in the same azimuth and sense. In the construction shown in Figs. 1 and 2, the hub 11 is mounted on a universal joint 40, through which passes a control shaft 35. The latter is connected to three levers 32 disposed as shown in Fig. 2, their outer ends being connected to the blade pitch control arms 23 by links 29. The ratio of the angular tilt of the control plane to the tilt of the hub is given by A.C the expression ---, the quantities A, B, C, D B.D being the lever-arm lengths shown. Collective pitch control is effected by vertical movement of the rod 42. In the embodiment shown in Fig. 3 the rotor blades 54 are carried by a cylindrical member 47 mounted on a fixed mast 45 by a bearing assembly 46 allowing the member to tilt in the longitudinal (XZ) plane. Pitch control of the blades is effected by vertical links 56 connected to a swash-plate 57. For fore-and-aft cyclic pitch control the swashplate is tilted by a hydraulic jack 74 through a double-armed lever 68, 73, link 67, bell-crank 65, and links 63, 64. The link 67 is normally horizontal, while the lever 68, 73 is carried by a bracket 72 fixed to the mast 45, and the arm 68 is attached to a further link 69 parallel to the link 67 and fixed to the tilting member 47. The lengths and disposition of the various links are so selected that movement of the arm 68 not only tilts the member 47 about the bearing 46, thus tilting the hub 49, but also tilts the swashplate 57 relatively to the member 47, in the same direction. Control in the rolling plane is effected by a jack 90 connected to the inner swash plate member 59 by links 87. For collective pitch control the swash-plate is moved vertically by a further jack 85, acting through a bell-crank 83, and a vertical link 82 connected to an arm 81.