GB725594A - Steering control for helicopters - Google Patents

Abstract

725,594. Helicopters. THOMSON, A. C. April 7, 1953, No. 9444/53. Class 4. A helicopter includes a fuselage and jet-driven rotor, means fixed to said fuselage for applying a turning moment to said helicopter, means for deriving a turning effort therefor from rotation of said rotor, mechanism for reversing the direction of the turning moment while said rotor rotates in the same direction, a hollow post on said fuselage supporting a hub on which the inner ends of the rotor blades are mounted, a bearing between said post and said hub in alignment with the inner ends of the blades, a steering control carried by'said hub, and a control rod for said steering control and having a universal connection in said post concentric with said bearing. In the embodiment described, the rotor hub 13 supporting the blades 3 and 4, which are jet driven, is freely tiltable with respect to a shaft 19 fast to the helicopter. The hub also carries a lower bevel gear 45. Within the shaft 19 is a control rod 23, slidable axially and jointed to shaft 40 by a universal joint centred near the centre of tilting of the hub 13. Fast to the shaft 40 is an upper bevel gear 48. Meshing with the upper and lower bevels are two pinions 51, retained by a spider 27, and mounting rotatably two arms 10, 11 on which are mounted blades shown at 8 in the low drag position and at 61 in the high drag position. Shaft 40 also distributes fuel to the rotor jets by a rotary seal, and ignition current through a slip ring. In operation, if the helicopter is stationary, the blades 8 must rotate at half the rotor speed, If the pilot moves control rod 23 axially, the collars 56, 57 move the arms 58, 59 to alter the pitch of the blades 8, increasing or decreasing their drag. This drag is transmitted through the bevel gearing 51, 48 to the helicopter, and causes a rotation in either direction as the drag is increased or decreased. The control rod 23 is preferably operated by rudder pedals (see Fig. 1, not shown). In a modification (Fig. 8), the arms 58, 59 rotate a shaft 110 in the blades 106, which splits open the leading edge of the blade to increase the drag.