Preliminary Design Study of a Tail Rotor Blade Jettison Concept
Final technical rept.
UNITED TECHNOLOGIES CORP STRATFORD CT SIKORSKY AIRCRAFT DIV
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Loss of a significant portion of a tail rotor blade will cause severe imbalance of the tail rotor that can lead to secondary damage to the helicopter and possible injury to the occupants. A system that detects such blade loss and removes the imbalance by jettison of the residual portion of the damaged blade and its opposing blade can overcome the rotor imbalance and allow continued flight. Using the performance characteristics of the UH-60A BLACK HAWK helicopter, a prototype system was developed and its performance evaluation to determine the capability of the system to jettison rotor blades in a manner that would prevent secondary damage. Additionally, analyses were conducted to determine the dynamic stability characteristics of the UH-60A tail rotor in a two-bladed configuration and the ability of the helicopter to accommodate the loads developed during transition from four to two blades. Residual helicopter performance and the capability of the helicopter to be retrimmed following jettison of two opposing tail rotor blades was analyzed using the General Helicopter Flight Dynamic Model programmed on a PDP-10 Hybrid Computer.