Patent GB-737175-A (GB)
Title: Improvements in or relating to retractable rotor blade sustention means for aircraftor rotary-wing parachutes
IPC: B64C29/00
Filed: 1952-06-20
Abstract: 737,175. Convertible aircraft. WOOD, R. T. June 19, 1953 [June 20, 1952], No. 15599/52. Class 4. A rotary wing aircraft or parachute comprises a hollow rotatable disc of aerofoil section, blades mounted in said disc for inward and outward substantially radial displacement, members for supporting the blades and universal coupling members connecting the support members to a central rotatable hub part, such that rotation of the disc causes outward displacement of the blades. The aircraft comprises a fuselage A, tail unit B, a circular disc and blade unit D, and an engine E, which drives both a propeller H and a compressor F for supplying fuel to jet burners G for rotation of the unit D. The fuselage may carry stub wings J. The disc D comprises a skin 3 secured to frame members 2 and is formed at its lower surface with a central aperture around the circumference of which the disc is clamped by a ring 5 to a cylindrical member 7 which has an inwardly directed flange located between bearings 8 and 9 housed in a stationary part 10 carried by a vertical column 11. The burners G are at the ends of radial conduits 12 integral with a central conduit 13 rotatably mounted within a stationary duct 14 connected to compressor F. The rotor blades 17, 18, 19, 20 are each mounted on a tubular spar 22 which telescopes over a further tube 21 formed with a cranked extension 23, 24, by means of which each blade is mounted on drag and flapping hinges 40, 37 for movement on a central hub portion 36. The free ends of the members 21, 22 carry sealing glands, thereby forming a sealed annular cavity, Fig. 4 (not shown), which is filled with liquid. The tube 21 carries a floating piston and is perforated at its outer end so that when centrifugal force acts on the blade it is moved radially outwards thereby forcing liquid from the annular cavity into the portion of the tube 21 outboard of the floating piston. The resulting compression of air in the inboard portion of the tube ensures the retraction of the blade when the rotor speed falls. Frictional clamps between the tubes 21, 22, Figs. 9 and 10 (not shown), hold the blades in the extended position, the clamps being actuated against spring action by cams operated by centrifugally operated weights, and spring-loaded latches, released by hydraulic pressure, lock the blades in the retracted positions, Figs. 13 and 14 (not shown). Each blade spar is supported for pivoting and sliding movement in a cradle 42 mounted in the disc D on an offset pivot, Figs. 5 and 6 (not shown) and controlled by an hydraulic jack 56, each connected to a master jack 100 each coupled to the rotary element 101 of a swashplate. The stationary element 103 of the swashplate carries cyclic pitch control rods 105, 106 and a part-spherical mounting 15 for the swashplate is moved axially of tube. 13 by rods 107 to effect collective pitch change of the blades. In a further embodiment, Figs. 15-18 .(not shown), a fixed fairing carrying laterally disposed control surfaces may be mounted behind the disc D, to which it may be sealed when the disc is stationary. The arrangement of the disc and blades is such that the disc and rotor is driven to achieve vertical take-off of the aircraft, after which the power from the engine E is transferred to the propeller H, with the stationary disc, housing the retracted blades, acting as a normal lifting surface. The jet nozzles G may be mounted on the ends of the blades and the mechanism may be incorporated in a rotary wing parachute or a convertible aircraft capable of use in the air or on the road.