GB315401A - Steering and propelling device for helicopter - Google Patents

Abstract

315,401. Oehmichen, E. July 13, 1928, [Convention date]. Helicopters; propelling; steering.-For propelling and steering a helicopter having a single lifting screw or a series of lifting screws with a resultant unbalanced torque, a series of propellers is provided, in s plane passing through the centre of gravity of the machine and perpendicular to the lifting axis, the thrust of which can be varied to produce an appropriate counter torque for varying and maintaining the orientation of the machine and also to give, when required, a resultant thrust to produce translational motion. The propellers may be of variable pitch or driven at variable speeds. Fig. 4 shows diagrammatically two such propellers p<1>, p<2> of variable, pitch driven by belts t' from the main engine Mo, and mounted on arms b<1>, b<2> extending from the body of the machine. The pitches of the two propellers are varied in the same or opposite senses by connections to a differential gear d<1>, d<2>, s, the pinion s being mounted on a shaft having a, lexer lm connected to a bar di for producing variations of pitch in the same direction. Differential variation of pitch is produced by turning a hand-wheel V, a propelling resultant being produced when the thrusts of the two propellers are unequal. A modification is described in which the differential gear varies the speed of the propellers by moving rollers keyed to the propeller shafts across the faces of friction-driving discs. The bar di may be connected also to a rear rudder. Fig. 6 shows a modification in which the pitch-control cables are passed around a drum ta provided with a hand-wheel V on a shaft o which can be moved bodily by a lever l<1>, return springs rs<1>, rs<2> being provided on the cables. An arrangement is described wherein the thrust of a constantly driven propeller is balanced or unbalanced by two variable thrust propellers similar to those already described. Any number of propellers may be used provided they can be controlled to give a balanced or unbalanced resultant.