STUDY OF TANDEM ROTOR HELICOPTER DYNAMICS FOLLOWING POWER FAILURE AT HIGH SPEED
BOEING CO MORTON PA VERTOL DIV
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The report covers a parametric study of tandem rotor helicopter dynamics following power failure at high speed 200 knots plus. It was concluded that complete loss of power on a high-speed helicopter results in hazardous flight conditions. Installation of auxiliary propulsion and incorporation of high-inertia rotor blades greatly relieve the situation by increasing the time available for the pilot to initiate recovery. Installation of a collective pitch rate limiter and an engine failure warning horn are recommended, to assist the pilot in taking corrective action. Provided collective pitch inputs are limited to safe values, no serious problems arise in the structural design of rotor blades to meet the conditions encountered in recovery from high-speed power failure. Dualization of engines and fuel systems provides an adequate margin of safety against sudden and complete power failure.