Abstract: A helicopter engine speed reference (66) is increased (117,118) in response to heavy rotor loading (102) in excess of a threshold at the current descent rate (FIG. 4 ). The reference speed is faded up (117,118) at a rapid rate to 107% of rated speed (119). After a fixed time interval (129), reduce rotor loading (122), reduced pitch angle below a threshold magnitude (121) and reduced roll angle below a threshold magnitude (120) will cause the reference speed to be faded down slowly (146,147) to rated speed (148). Automatic increase in engine reference speed is overridden to 107% of rated speed (203) when a battle switch is activated (201) and weapons are ready (202). Increases in engine reference speed are prohibited (207) when the helicopter is operating in quiet mode (206) or the helicopter is resting on its wheels (208).

Abstract: A helicopter engine fuel control anticipates sudden changes in engine power demand during yaw inputs to thereby minimize engine and main rotor speed droop and overspeed during yaw maneuvers. The rate (121,123) of yaw control (107) position change generates (110) a yaw component (104) of a helicopter fuel control (52) fuel command signal (70). The magnitude of the yaw component is also dependant upon the rate of yaw control position change (703). The fuel command signal yaw component (104) is overridden (113,115) when rotor decay rate (209,217) has been arrested during a sharp left hover turn (216); when the yaw component is removing fuel (239) during rotor droop (238); and when the yaw component is adding fuel (228) during rotor overspeed (227).

Abstract: A helicopter engine fuel control anticipates changes in main rotor torque in response to lateral cyclic pitch commands, to thereby minimize engine and main rotor speed droop and overspeed during left and right roll maneuvers. A fuel compensation signal (100,101) is summed with a helicopter fuel control (52) fuel command signal (67) in response both to a lateral cyclic pitch command signal (LCP) (107) from a pilot operated cyclic pitch control exceeding a left or right threshold magnitude (201,210) and a total lateral cyclic pitch command signal (TCP) (108) from a lateral cyclic pitch control system exceeding a left or right threshold magnitude (202,207,215,220). The magnitude of the fuel compensation signal is dependant upon the direction of TCP and LCP, e.g., left or right, and helicopter roll acceleration (115). Alternatively, the magnitude and duration of the fuel compensation signal is dependant upon the rate of change in commanded lateral cyclic pitch (107,400,407).

Abstract: The blade angle controlling pitch beam servo (26) of a helicopter tail rotor (22) is responsive to a main rotor torque signal (92) indicative of torque coupled to a helicopter main rotor (10) for providing torque compensation so that the helicopter airframe will not counter-rotate under the main rotor. The torque coupled to the main rotor is that amount of engine torque (76, 114) in excess of torque coupled to the tail rotor (81, 115) and helicopter auxiliaries (84, 116). The amount of torque compensation provided by the tail rotor is reduced by an amount indicative of aerodynamic forces (130) on the helicopter airframe.

Abstract: A variable frequency vibration controller includes a cantilever beam supported from the vibration prone structure whose vibrations are to be controlled. The cantilever beam has selectively shaped hollow interior portions into which fluid can be selectively injected or withdrawn to vary the total mass of the cantilever beam. The cantilever beam natural frequency is thus tuned to match or selectively mismatch the frequency at which the vibration prone structure is vibrating. Thereby, the beam is used to optimally absorb or excite the vibrations of the structure.