An investigation of lateral tracking techniques, flight directors and automatic control coupling on decelerating IFR approaches for rotorcraft

An investigation of lateral tracking techniques, flight directors and automatic control coupling on decelerating IFR approaches for rotorcraft

Baillie, S.
Kereliuk, S.
Hoh, R.

National Research Council Canada, National Aeronautical Establishment

1988-10-30

An in flight simulation experiment was performed to investigate the impact on handling qualities and certification of various issues associated with low minima decelerating flight directed IFR approaches for rotorcraft. These issues were the use of crab versus sideslip techniques to maintain lateral tracking under crosswind conditions, the effects of various methods of vertical axis (glideslope) display, guidance and control, and the benefits of coupling flight director signals directly to the rotorcraft control actuators. The program was performed at the Flight Research Laboratory of the National Aeronautical Establishment (NAE), using the NAE Bell 205 Airborne Simulator and was partially funded by the United States Federal Aviation Administration. Experimental results demonstrated that crab technique approaches were satisfactory for all approach speeds and wind conditions investigated (up to 30-knot crosswinds). A factor not addressed in this study was the visual orientation of the landing pad at breakout to flight with visual references. Sideslipping approaches were also shown to be satisfactory until the steady state lateral acceleration exceeded approximately 0.07 G. While coupling of the collective actuator directly to the flight director provided the best glideslope tracking, evaluations showed that the configuration with a 2-cue (pitch and roll) flight director, using only a raw glideslipe presentation, provided satisfactory handling qualities and was considered by F AA and DOT representatives to be certifiabIe for IFR flight. Coupling of any single axis of control to the flight director was demonstrated to provide slight workload relief benefits and the collective axis was judged to be the most likely candidate axis for this implementation.

Wind profiles
Velocity distribution

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National Research Council Canada

Campus only

National Aeronautical Establishment, Aeronautical Note NAE-AN-55, NRC no 29604

Aerospace Engineering Reports

report

(c) 1988 National Research Council Canada