GB583017A - Safety device for twin rotor helicopters - Google Patents

Abstract

583,017. Helicopters. ROTARY RESEARCH CORPORATION. July 3, 1945, No. 16914. Convention date, Feb. 28, 1945. [Class 4] Twin rotor helicopters are provided with means for automatically shutting off the engine power in case of the failure of transmission of power to either of the rotors so that each rotor becomes free to auto-rotate. In the construction shown in plan, Fig.- 1, the vertical shafts of twin rotors are driven by bevel gears 19, 20 from a transverse shafting 18 driven by engine 14 whose magneto 39 is short-circuited to cut off power when failure occurs on one side of the shafting. Contact rings, on each of the rotor shafts, having a short conducting and a long insulating part form part of the circuit of a battery 35 and magnetic relay 36 ; in the normal driving relation shown in the Figure, the circuit cannot be completed through the brushes and the revolving rings, but if one of the rotors ceases to be driven it slows down With respect to the other and the circuit becomes closed when each pair of brushes is in contact with the conducting portion of its corresponding ring. The relay 36 then attracts an armature carrying a contact 38 to shortcircuit magneto 39. In modifications connected cam-rings operate plungers serving to close switches for short-circuiting magnetos or to allow pressure liquid to flow in hydraulic circuit-controlling means. Alternatively, the engine throttle may be controlled. Plungers may also be controlled to allow release of spring- actuated means for acting upon the magneto or engine-throttle.