Patent GB-556865-A (GB)
Title: Improvements in or relating to helicopters
IPC: B64C27/18
Filed: 1942-04-22
Abstract: 556,865. Helicopters. WEIR, Ltd., G. & J., and PULLIN, C. G. April 22, 1942, No. 5423. [Class 4] t A helicopter is supported by a single rotary wing system driven by jet-reaction nozzles mounted on the blade tips and supplied from a passage in a fixed hub-support. The rotor hub is freely rotatable about a member having a spherical seating upon the fixed hub-support so that the member can tilt in any direction upon the support but it is prevented from rotating about a vertical axis. The blade roots are pivoted about radial axes upon members having spherical seatings in the rotor hub and are connected by links to a swash plate so that the angle of incidence of the blades automatically varies as the coning angle varies and in a direction to keep the coning angle stable. These connections also ensure that the blades assume an incidence suitable for autorotation when power is shut off. The blade roots are interconnected to a slider on the rotor axis so that they can only move together in planes passing through that axis but can have a limited amount of relative lag and lead in the direction of rotation. The swash plate is tiltable and vertically adjustable by the pilot for controlling the rotor which tends to set itself with its axis parallel to or coincident with the axis of the swashplate. Means for braking the rotor are provided. The ratios of the amount of variation of blade incidence to the amount of movement of the swashplate and to the variation in the coning angle are pre-adjustable. As shown, a fixed hub-support 28 is mounted upon the fuselage of the aircraft by arms 27, and heated gases are fed to the rotor from a generator 31 through a trunk 32. The fuselage has an elevator 24, rudder 26 and fin 25. The hollow fixed hub-support 28 has a spherical upper end 47, Fig. 2, having an annular opening 62 bridged at intervals by connecting pieces between the upper and lower parts of the sphere, and a tiltable hub-support, comprising upper and lower parts 48, 49 with closely fitting packings 52, 53, is seated upon the spherical end 47. A cap 54, secured to the member 48, is splined at 56 to a shaft 57 having a universal joint 58 to permit tilting of the shaft in any direction but preventing rotation about the axis of the shaft. The joint is mounted on a flared portion 60 which is supported by the upper part of the member 47 and serves also to direct the gases through the opening 62. A fairing 61 directs the stream at the lower edge of the opening. Rotatable upon the tiltable hub-support ball bearings 66, 67 is a hub 65 having three cylindrical projections 74 carrying spherical seatings 76 for radial members 75 upon which the blade roots 82 are pivoted upon ball bearings 83, 84. Flared tubes 114 terminating at holes 115 in the hub 65 convey the gases to tubular spars in the blades. Packings 77a and rings 88 prevent escape of gases at the blade roots, and a cap 70 and rings 71 prevent escape of gases from the hub. Friction material 78 damps the movements of the members 75. Mounted on the top of the cap 70 is a pillar 125, Fig. 4, on which slides a sleeve 126 connected by ball-jointed links 127 to the upper sides of the blade roots 82 so that the blades cannot flap independently of one another. When at their normal coning angle the axes of the blades intersect at the centre of the sphere 47. At the leading side of each blade root 82 is a lug 90 through which is screwed a hollow shaft 91 the axis of which is convergent outwardly towards the axis of the blade. Consequently, by screwing the shaft 91 into or out of the lug 90, and if necessary screwing it in from the opposite side, the distance of its end 92 from the axis of the blade can be adjusted. A lock-nut 130 secures the shaft 91 in any adjusted position. The end 92 of each shaft has a spherical bearing to take the eye 131 of a link 94 connecting it to an arm 95 on a ring 96 rotating upon a swashplate member 98 gimbal mounted on a collar 101 slidable on the hub support 28. The links 94 are adjustable in length. The collar 101 can be raised or lowered by a lever 106 connected through the linkage shown to a control lever 36, Fig. 1, for varying the mean pitch of the blades. A lug 102 on the member 98 is pivoted to a lever 34 ball-jointed at 35 to a support on the fuselage so that the member 98 can be tilted in any direction. A brake drum 109 is mounted on the hub 65 and is acted upon by expanding shoes 111 carried by a disc 112 secured to the member 49. The gases pass through tubes at the leading edge of each blade and issue through a flat nozzle 121, Fig. 9, within the thickness of the blade. Alternatively, they may issue through a broad flat nozzle 124, Fig. 11, just above the thickest part of the blade. A weight 122, Fig. 9, helps to balance the blade about its longitudinal axis.