715,119. Helicopters. Westland Aircraft Ltd. Application April 30, 1951. A high-speed rotor having four or a greater even number of blades is so arranged that a blade pitch variation of twice-per-revolution can be superimposed These abstracts of British Patent Specifications are condensed, by permission, from the official on the normal once-per-revolution cyclic variation, specifications. Copies of the full specifications are obtainable from the Patent Office, 25 Southampton over at least the tips of the blades, to reduce the blade lift over the lateral quadrants, and to increase it Buildings, W.C.2, price 2s. 8d. each. over the fore and aft quadrants, of their motion. In the arrangement shown for imposing pitch variations over the full length of the blades, each blade is con trolled by a push rod 4 operated by a swashplate 714,711. Landing skids. Dunlop Rubber Co Ltd. mechanism 2, 3 through gearing controlled by toothed and Handley Page Ltd. Application November 16, annuli 8, 9, of which the former is rigid with the swash plate. The gears 8, 9 drive final gear wheels A landing skid consists of a box-frame secured in 18, 22 through pinions 15, 17 and 19, 21 respectively, side an air-tube 8, the lower portion 9 of which is the gear ratios being such that the wheels 18, 22 revolve formed with a tread surface 10, and the ends 5 of which about their axes at twice the rotor speed. Wheel 18 are attached to fuselage struts 24, 27 by links 22, 25, carries a swinging link 26 and has a radial slot 27 26. The box-frame consists of side members 2 secured accommodating a block 28 carried by a pin 29 pro to clamping strips 12 and the sides of the tube 8 by jecting from the adjacent pinion 22, the block and air-tight connexions 13, and bolted to two transverse pin being free to move along a slot 30 in pinion 18. U-shaped end members against which the ends of the The link 26 is furnished with a pin 31 at its mid point, tube are drawn and secured in an air-tight manner by connected to the lower end of the push rod 4 and straps 5. Thin metal rectangular plates 37, 38 form projecting through a slot 32 in a retaining plate 33. the upper and lower surfaces of the box-frame, open If the gears 8, 9 are so relatively positioned that link ings 14 being provided to allow free air passage 26 occupies its central position, the pin 31 is co-axial between the upper and lower compartments of the with the axis 34 of pinions 18, 22, and only the normal tube 8. The tread 10 is upwardly inclined at its for cyclic movement can be applied to the push rod 4. ward end and provided with steel reinforcing wires 11, If, however, the gear 9 is rotated relatively to gear 8, the forward ends of which protrude beyond the tread pin 29 moves along slot 30 and thus rotates link 26 and are secured by a clamp 17. The tube 8 is inflated about its pivot 25 to displace pin 31 and thereby to a pressure of the order 7-8 lb./sq. in. above atmo impose a twice-per-revolution oscillation on push spheric. rod 4. This oscillation is superimposed, when desired, by the operation of a jack connected to the gear wheel 715,094. Helicopters. Saunders-Roe Ltd. Applica 9, the amplitude of the oscillation being governed by tion March 26, 1952. the extent of movement of the wheel 9. A helicopter rotor with collective and cyclic blade 715,657. Control systems. Bristol Aeroplane Co. pitch control mechanism is so arranged that the blades Ltd. Application April 15, 1952. are moved to an autorotative setting in the event of power failure by the automatic displacement of the The jack actuators 27 for the control surfaces 23 of an aircraft, particularly a guided missile, are operated by pressure derived from the fuel supplied by a pump 15 in excess of the requirements of the gas turbine engine 12. The actuators are operated by an accumulator 25 the pressure in which, if sufficient to operate the jacks 27, closes a valve 19 in the dis charge pipe from the pump 15. Should the pressure fall below this value the valve 19 opens and allows excess fuel to be delivered to a vane motor 18 coupled to a vane pump 21, which draws fluid from an exhaust tank 22 and delivers it past a non-return valve 24 to recharge the accumulator 25. Supply of fluid to the jacks 27 is governed by remotely-controlled valves rotor hub in response to a predetermined reduction in 34. In an alternative arrangement, not shown, the the driving torque. As shown collective and cyclic fuel pump delivery pressure is sufficient for operation pitch adjustment of the blades 16 is effected through of the actuators, but greater than that required for the links 15 by vertical and rocking movements respect fuel burners, the excess fuel being delivered to an ac ively of a control spider 13, a stop 23 limiting the col cumulator until the pressure rises to a predetermined lective pitch variation. The rotor hub 18 is connected value, when the fuel is diverted to the return side of to the top of the drive shaft 10 by a screw thread 17, the pump. Upon fall of pressure in the accumulator, and under normal conditions the driving torque on fuel from the pump is used to recharge the accumu the shaft 10 pulls the hub downwardly until an abut lator. When the actuators are inoperative and the ment 19 engages a collar 20 on the shaft. Reduction accumulator has been recharged excess fuel is returned of torque causes the hub 18 to rise until a lower to the supply tank. abutment 21 engages the collar 20, during which movement the pitch setting of the blades is reduced to the autorotative value. January 1955 31
Aircraft Engineering and Aerospace Technology – Emerald Publishing
Published: Jan 1, 1955
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