Patent GB-570404-A (GB)
Title: Helicopter
IPC: B64C27/04
Filed: 1943-05-28
Abstract: 570,404. Helicopters. BOSSI, E. May 28, 1943, No. 8596. Convention date, May 28, 1942. [Class 4] A helicopter comprises a motor driving a single rotor having a plurality of pairs of diametrically connected blades all driven in one direction, each pair of blades being free to execute a limited rocking movement about a horizontal axis at right angles to the longitudinal axis of the blades of the pair, and means being provided under the control of the pilot for feathering the blades of each pair. A variable pitch propeller at the rear of the aircraft for neutralising the back torque of the rotor is driven from the transmission between the motor and the rotor and a gyroscopic stabilizer is driven by a branch from the same transmission. An engine 14 drives, through a clutch 31 and free wheel device 36, a shaft 39 which drives through bevel gear 42, 43 shaft 41 and bevel gear 45, 46 a horizontal shaft 44. This shaft drives, through the bevel gear shown, a shaft 51 upon which two sleeves 52, 57 are rotatably mounted, the latter sleeve supporting an octagonal rotor hub 75. The sleeve 52 is driven from the shaft 51 through sun and planet reduction gear 55, 56a, 56 within a fixed casing 54 which supports the planet wheels 56a. The sleeve 52 drives the sleeve 57 through an elastic coupling comprising discs 70, 71 with interengaging projections separated by rubber blocks. A thrust bearing comprising two discs 60, 63 separated by ball races is mounted between two shoulders 64, 68 on the sleeve 57 and between a disc 61 and flange 65 carried by the aircraft frame, the upper or the lower of the discs 60, 63 remaining stationary depending upon whether the rotor is lifting or not. Two pairs of blades 83, 84 and 85, 86, at different levels, are provided. The blades of each pair are rigidly interconnected by a member 81, Fig. 5, and are rotatably mounted in a member 94 which can oscillate about a horizontal axis transverse to the axis of the blades within bearings in two opposite faces of the rotor, short slots 102 being formed in two faces at right angles to permit the movement of the blade stubs. The ends of the member 94 are closed by discs 97, 98 having vertical slots to permit the passage of arms 100, 101 by which the pair of blades can be rotated about the axis 89 of the blades. The two arms 100, 101 and two corresponding arms from the upper pair of blades are connected by ballended links 136, 137, 138 to a disc which is gimbal mounted upon a collar on the sleeve 57 so as to rotate therewith, -the outer edge of the disc having upper and lower ball bearings within a ring 121. This ring is prevented from rotating by pillars 124, 125 on the aircraft frame engaging pins 126, 127, projecting from the ring, but the ring can be tilted in any direction by cable connections from the pins 126, 127 and from two pins at right angles thereto to the pilot's control column. Tilting of the ring 21 consequently causes a cyclical variation of the incidence of each blade, the incidence of one blade of each pair increasing as that of the other blade decreases. When the speed of the rotor is low, rests 104 spring- hinged to brackets 103 on the hub prevent tilting movement of the blades about the transverse axes, but as the speed increases the rests swing outwards as shown in dotted lines in Fig. 3 to permit free movement of the blades. The shaft 44 drives, through a universal joint 182, a shaft 181 which drives through further gearing the transverse shaft of a two bladed variable pitch propeller at the tail of the aircraft at a speed which is a constant ratio of the speed of the main rotor. In the normal position of the propeller blades the thrust just balances the back torque of the main rotor but by varying the pitch of the blades through connections to rudder pedals, steering may be effected. The shaft 44 also drives a vertical shaft 156 upon which is mounted upon gimbals a heavy ring 165 having bearings within a ring similar to the ring 121 to which it is connected by four cables so that the two rings always remain parallel to one another. Thus any setting of the ring 121 by the pilot tends to be maintained by the gyroscopic action of the ring 165. A blower 15 driven by the engine draws in air from the upper and lower surfaces of the fuselage and, after cooling the engine, is discharged through a conduit 21 and through upper and lower openings near the tail of the fuselage. A flap valve in the conduit, controlled by the pilot, enables the blast to be directed upwardly or downwardly for tilting the aircraft. The aircraft is provided with one forward wheel and two rear wheels each mounted upon a shock absorbing pillar, the two rear wheels being carried upon the ends of transverse levers 191, Fig. 9, pivoted at 192 within the aircraft body and controlled by elastic cords 193.