United Technologies Corporation

Sikorsky Aircraft Corporation

James F Keller

James B Dryfoos

Donald L Fogler, Jr

Phillip J Gold

Nicholas D Lappos

Donald W Fowler

Joseph P Skonieczny

A model-following aircraft control system in which a roll rate command in Euler coordinates is integrated to provide a bank angle command, which has actual bank angle subtracted therefrom to provide a command error that is converted back to aircraft body coordinates for use, so long as the pitch attitude of the aircraft does not approach zenith or nadir. But, while the absolute value of the pitch attitude exceeds 85.degree. the last error generated before exceeding 85.degree. is converted to body coordinates for use by the aircraft, and the initial integrated value of attitude command, for use when the pitch angle reverts below 85.degree., is formed as the sum of said last error and the actual attitude angle of the aircraft.

Maintaining attitude error constant in Euler singularity protection

A turn coordination inhibit system (150) inhibits a rotary winged aircraft control system from operating in an automatic turn coordination mode when a pilot desired to perform a sideslip maneuver, e.g., a flat turn. When automatic turn coordination is not engaged (132,212,215), e.g., the aircraft is not in a coordinated turn, and either aircraft bank angle (119) exceeds an inhibit threshold magnitude (210) or a pilot yaw command provided by a pilot sidearm controller (155) exceeds a minimum threshold value (243), e.g., the sidearm controller is out of detent in the yaw axis, automatic turn coordination is inhibited (152). Automatic turn coordination remains inhibited until both aircraft bank angle falls below a reset threshold magnitude (230) and the sidearm controller is back in the detent position for the yaw axis (243).

Turn coordination inhibit for rotary wing aircraft control system

A fire control system (55) azimuth command and elevation command provides a flight control system attitude reference in response to operation of the flight control system in a coupled aiming mode. The coupled aiming mode is engaged in response to the continuous operation of a pilot switch (920) the azimuth command and elevation command being below respective threshold magnitudes (940, 941), and the operation of the fire control system (55). During operation in the coupled aiming mode, the azimuth command and elevation command replace the yaw attitude feedback error signal and pitch attitude error signal, respectively, as the aircraft attitude reference. During integration of the fire control system and the flight control system, the flight control system is made less sensitive to small pilot command stick inputs below a stick input threshold magnitude, so that small or inadvertent pilot commanded yaw and pitch maneuvers will not affect the yaw and pitch attitude reference commanded by the fire control system azimuth and elevation commands. However, intended pilot commanded yaw and pitch maneuvers (70) maintain full authority at all times.

Helicopter integrated fire and flight control having azimuth and pitch

A helicopter flight control system (21) includes a model following control system architecture which automatically provides a coordinating yaw command signal to the helicopter tail rotor to coordinate helicopter flight during a banked turn. The control system processes information from a variety of helicopter sensors (31) in order to provide the coordinating yaw command signal on an output line (72) to the tail rotor (20) of the helicopter.

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James F Keller