GB1258505A - - Google Patents

Abstract

1,258,505. Helicopter rotors. VIKING AIRCRAFT CORP. 25 March, 1969, No. 15602/69. Heading B7W. A rotary wing system 36 for an aircraft 10 comprises a hub assembly 70, Fig. 5, mounted for rotation about an axis which may be tilted relatively to the aircraft, a number of blades 96, 97, 98 connected thereto by rigid spars 102 and ball-joints 99, 100, 101, Fig. 4, a rotating blade pitch control means 130 with pitch links 158, 159 attached by universal joints to respective arms 146, 147, 148 of the pitch control means 130 and to the blades at points 151 spaced from the pitch change axis of the blades. The system is mounted on a mast 34 extending substantially from the centre of gravity of the aircraft 10 preferably of the autogyro type. In the embodiment of Figs. 4 and 5, a tubular member 40 is mounted by means of a ball joint 60 on the mast 34 and the hub assembly 70 is mounted by means of bearings 74, 76 to rotate about the tubular member 40, the rotary wing system 36 being tiltable to the side by means of cables 66, 68, Fig. 4, to provide lateral control, and forward or backward by cables 67, 69 to provide pitch trim of the aircraft. The pitch control means 130 may be pulled down by a manually controlled cable 166 against a spring 136 to alter the collective pitch but cyclic pitch control is not provided. This arrangement substantially reduces flapping as, when the advancing blade 97 is pushed up, the pitch control will rotate it into a lower pitch angle so that the lift is reduced. For a jump take-off the blades may be prerotated in their full feather position by supplying compressed air or exhaust gases through the centre of the shaft 38 and tubular spars 102 in the wings to nozzles 120, Fig. 3, in the blade tips and then the pitch control cable 166 is released thereby changing the blades to maximum pitch. In an alternative embodiment, Fig. 8, a shaft 168 is fixed to the mast 34 and connected by a ball-joint 60 to the inner portion 178 of the hub about which the outer portion of the hub, carrying the blades, rotates on bearings 74, 76. The blades are controlled in cyclic and collective pitch by a conventional swash plate assembly 214. The system 36 may be powered or prerotated by means of a drive shaft 252 which drives the hub 170 through gearing 260. A gear drive or compressed gas propulsion may be used to rotate the blades in either form of the invention. The rotor may have three or more blades.