Hiller HOE-1 Hornet - (scan - 1984)

An experimental US Navy helicopter, The HOE-1 had ram jets on its rotor tips instead of a normal engine! It had many operational problems, and so didn't go into fleet service.

One of the first of its type, Hornet purchased by Navy to evaluate self-powered rotors as means of propulsion. By 1950, piston engines provided just enough power to carry aircraft, pilot, and small payload. Problem in 1950 helicopter design was need to counteract torque from rotor which caused fuselage to turn in other direction (Newton's Third Law of Motion). Potential methods to counteract this force--including tail- rotor thrusting, tandem rotors, counter-rotating rotors, etc.--meant additional weight and power, decreased payload, and increased cost. HOE-1 with self-powered rotor produced no torque. With no need for anti-torque devices, HOE-1 could lift useful load almost equal to its own weight. External gasoline engine was to get rotors up to ram-jet operational speed of about 50 rpm. NASA flight test program revealed excellent roll and pitch response plus generous rotor inertia; however, unfavorable fuselage oscillation of 0.8 cycle/sec also noted. Unfortunately, HOE-1 unacceptably noisy and had very high fuel consumption. (Some observers facetiously called it a machine for changing fuel into noise). Aircraft logged 28.5 hrs of flight time after acceptance 23 Jun 55. Beginning in early 50s, turbine- powered helicopters--having engines with higher thrust-to-weight ratios-- became practical. With this development, weight penalties associated with anti-torque devices became less significant and interest in self-powered rotors declined.

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