Patent GB-410532-A (GB)
Title: Improvements in and relating to aircraft having rotative wings
IPC: B64C27/02
Filed: 1932-11-26
Abstract: 410,532. Aircraft with rotary wing systems. LA CIERVA, J. DE, Bush House, Aldwych, London. Nov. 26, 1932, No. 33559. [Class 4.] A machine supported by a rotary wing system with autorotative articulated blades has means for cyclically changing the pitch angle of the blades to effect a change in the plane of rotation of the blade tips, movement of the pilot's control in any azimuth bringing about a change of pitch angle which is a maximum in an azimuth at right angles to that of the movement of the pilot's control, and the phase of the increased pitch being in advance of the control displacement with reference to the direction of rotation of the rotor. Means for varying the mean pitch angle separately or in conjunction with the longitudinal control may be provided. Alternatively the change in the plane of rotation may be effected by tilting the rotor axis. The rotor axis also may be displaceable longitudinally to adjust the longitudinal trim of the craft. The rotor hub 37, Fig. 5, is mounted on a substantially vertical axle 78 carried by a head 71 on a pyramidal structure above the fuselage and the blades are articulated about horizontal axes 39 on this hub. The axle 78 is disposed to the rear of the C.G of the machine so that a line joining the C.G. to the intersection of the rotor axis with the plane of the pivots 39 is inclined rearwardly about 6‹. The blade spars are also articulated about vertical axes 41 and the blades themselves 38 can tilt about the spars and have levers 93 connected by links 90 to a ring 84 having a ball-bearing 83 upon a ring 75 tiltable about a spherical bearing 76 on a sleeve 73. The ring 84 is constrained to rotate with the hub 37 by pins 87 engaging lugs 88 and the ring 75 is prevented from rotating on the sleeve 73 by pins 79 engaging slots 77, the sleeve 73 being splined to slide upon the axle 78. Arms 80, 80<x> are formed on the ring 75 and have pin and slot connections with bell-crank levers 52, 48 connected to rods 51, 47 actuated respectively by the lateral and longitudinal controls so as to tilt the ring in azimuths at right-angles to the directions of the control lever movements. The mean pitch of the blades is varied by a rod 74 adapted to move the sleeve 73 in co-operation with a spring 96. Instead of tilting the blades about their axes they may be provided with flaps to change their camber, or tiltable blades may be actuated by moving servo-flaps at their trailing edge. Alternatively the blade pitch may be varied by tilting the pivots 39. The rods 51, 47, 74 have rubber compression springs 106 incorporated in their ends. The rotor is started, or its rotation is assisted by a toothed wheel 95, on the hub 37, which engages a pinion on a shaft in a casing 85 this pinion being driven through a clutch from a shaft 86 having a universal joint 105 and telescopic connection 104 with a shaft 103 driven from the engine. The clutch is actuated by a member 92. The pilot's control comprises a lever 44, Fig. 8, pivoted at 44‹ on a rock shaft 49 and connected by a link 45 to a bell-crank lever 46 on a transverse shaft 113. The rod 47 is connected to the lever 46 and the rod 51 is conected to a lever on the end of the rock shaft 49. A two-armed lever 115 on the shaft 113 is connected by elastic members 116 and cables 117 to a lever 119 working over a locking quadrant to enable the control to be elastically biassed in either direction. The initial tension may be adjusted by members 118. Similar elastic members are connected to a lever 122 on the rock shaft 49 and cables connected thereto, after passing over pulleys, are secured to a lever 127 on a rock shaft 128 provided with a hand lever 129. Frictional damping means are provided for the controls, a lever 132 on the shaft 113 being connected by a link 133 to a slotted plate 134 adjustably clamped to a fixed bracket by a hand-wheel 136 to damp longitudinal movements of the lever 44. Lateral movements are damped by a slotted quadrant 140 and clamping wheel 141. A rudder bar 55 is connected by cables 56<x> to the rudder and through spring connections to a steerable wheel beneath the tail, a slotted plate 142 in one of the cables being clamped by a wheel 143 to damp movements of this control. The machine need not have a rudder if it is directionally stable. The rod 74 for varying the mean pitch of the blades is connected to a lever 97 moved by chain gear from a hand-wheel 101. Alternatively the lower end of the rod 74 may be held by the spring 96, Fig. 5, against a cam 162, Fig. 10, geared as shown to the shaft 113, the cam being so shaped that when the lever is in its extreme forward position the pitch of the blades is zero or negative and as the lever is pulled backward the pitch angle first rises to a normal positive value, then slightly diminishes, and rises to a much larger positive value when the lever is in its extreme rearward position for retarding descent at the moment of landing. The lever may also throw in the clutch 92 and apply the wheel brakes when in its extreme forward position and means may be provided for preventing the lever from reaching this position during flight. A modification is described in which the head carrying the axle 78 is tiltable in two directions by the pilot's control. In this case the arms 93 and links 90 of Fig. 5 control only the mean pitch of the blades, being connected to the ring 84 on the ring 75 which is movable vertically on the axle 78 by a cam moved by Bowden mechanism. The machine is provided with tail fins and the horizontal fin may be adjustable through a small range for effecting longitudinal trim. Two landing wheels are placed some distance in advance of the C.G. Specifications 264,286, [Class 4], and 393,976 are referred to.