Patent GB-484376-A (GB)
Title: Rotating-wing aircraft
IPC: B64C27/02
Filed: 1937-07-21
Abstract: 484,376. Aircraft with rotating-wing systems. CIERVA AUTOGIRO CO., Ltd. July 21, 1937, No. 20227. Convention date, July 22, 1936. [Class 4] In an aircraft having a normally autorotative sustaining rotor, the connections of the blades to the hub include screw-threads such that outward radial movement of the blades under the action of centrifugal force is accompanied by an increase of bladepitch-angle and means are provided for rotating the blades on the connections, in opposition to the action of centrifugal force, into a position of low pitch - angle and retaining them and for thereafter releasing the blades for movement to a higher pitch-angle under the action of centrifugal force. In one form, an aero-engine 9 drives an airscrew 10 and initiates rotation of the rotor. The engine crankshaft 33 is coupled by a device 34 to a shaft 38, which through disc elements 46, 47, on application of fluid pressure to move through pillars 51 a pressure plate 49 against the action of a spring 48, is clutched to a shaft 41 carrying a bevel gear 43. The gear 43 meshes with a bevel gear 44 which, through shaft 22 having a slip-joint 36 and universal joints 37, 37a, and bevel gear 58, drives the rotor through a bevel gear 59. The rotor is mounted for pivotal movements of the kind described in Specification 393,976. The pinions 19 on gimbal ring 18 are pivoted to members 20<1>, 21<1> carried by the pylon structure 20, 21. The rotor is mounted on pinions 17 projecting inwardly from the ring 18. The rotor is tilted by lateral or longitudinal movements of a control lever 23 through arm 29 and link 31 and arm 25 and link 32 respectively. The rotor-hub-member 68 rotates in bearings 62, 63 in a member 16 which is mounted on the journals 17. The hub member 68 drives through gears 76, 75 a tachometer shaft 74. The rotor blades are mounted on members 80 connected by a drag-pivot 95 to a member 85b. A friction - disc shock-absorber is incorporated in the pivot 95. The member 85b is connected to a member 85a by a six-start acme screw-thread. The member 85a is mounted for flapping movements about an axis 88 in a hub member 89. Drooping of the blades is limited by stops 90, 91. The tangent of the pitch angle of the screw-thread is given a value between 110 and 180 per cent of the static coefficient of friction of the threads. Axial movement of a rod 140 which is unlocked by rotation, operates through a lever 136 a piston in a cylinder 120a, which is replenished with oil from a reservoir 121a, to force oil through a pipe 78 to force upwardly a piston 79. The piston 79, through a rod 126, moves a piston 125 to force oil past a valve member 131 and through flexible conduits 115 to cylinders 100 mounted on the members 85a. The cylinders 100 are provided with plugs to permit escape of air during filling the system with oil. Oil admitted to the cylinders moves pistons the piston rods of which are connected to levers carried by the members 85b. Thus the members 85a are rotated relatively to each other and the blades are moved to zero pitch position for starting. Movement between the members 85a, 85b is limited by abutments 102. The cylinder 120 is maintained full of oil from a reservoir 121 connected to the cylinder through ports 124. In order to co-relate engagement of the clutch in the rotor drive and movement of the blades to their zero pitch position, the lever 136 is detachably connected to the handle of the control valve of the clutch by a link 144 and a butterfly nut 146. As shown in Fig. 1 the clutch-operating cylinder is connected by a conduit 149 to the engine feed pipe 150 which is fed by the engine oil pump 151 connected to the oil tank 134. When pressure on the oil in the cylinder 120a is relieved by operation of the control 140 the blades move axially under centrifugal force and the pitch is increased to the flight valve. The hydraulic system while working at a pressure of 300 lb. per sq. inch is capable of giving pressure of 400 lb. per sq. inch. In a modification, compression of a metallic-bellows housed in the rotor hub forces fluid to expand metallicbellows to cause relative rotation of the members 85a, 85b.