An Investigation of Large Tilt-Rotor Short-Term Attitude Response Handling Qualities Requirements in Hover

Short-term pitch and roll attitude and heading handling quality requirements for large rotorcraft in hover were investigated. The piloted simulation study, performed on the NASA-Ames Vertical Motion Simulator, focused on a large (heavy-lift) civil tilt-rotor aircraft. Five experimental test pilots representing the U.S. Army, Marine Corps, NASA, and rotorcraft industry evaluated the aircraft configuration for a range of bandwidth and phase delay values, and pilot offsets from the center of gravity, in moderate turbulence conditions, while performing modified versions of the ADS-33 Hover and Hovering Turn MTEs. Pilot comments and aircraft-task performance data were analyzed. Level 2 and Level 3 handling qualities ratings were recorded using Attitude Command/Attitude Hold (ACAH) response type. Refinements to the Hovering Turn MTE were developed in order to make it consistent with the Limited Agility MTE category in the hover and low speed ADS-33 requirements for large-amplitude attitude changes. Evaluated against this task, yaw bandwidth shows that significant relaxation of the Level 1 boundary from 2 to .25 rad/sec is possible to help account for large pilot offset from the center of gravity. Notation Variables  a Acceleration vector K Command model sensitivity coefficients r Yaw rate (rad/sec or deg/sec) s Laplace transform complex variable δ Pilot control input ζ Command model damping ratio θ Pitch attitude (rad or deg)  ρ Pilot offset vector from the center of gravity (ft) τ Time constant or delay (sec) φ Roll attitude (rad or deg)  ω Aircraft angular velocity vector ωn Command model natural frequency (rad/sec) ωBW Bandwidth frequency (rad/sec) Presented at the American Helicopter Society 66th Annual Forum, Phoenix, AZ, May 11-13, 2010. This material is declared a work of the U.S. Government and is not subject to copyright protection. Subindices cmd Command model, commanded lat Lateral cyclic lon Longitudinal cyclic p Pilot ped Pedal Abbreviations ACAH Attitude Command/Attitude Hold AGL Above Ground Level BW Bandwidth CG Center of gravity HQR Handling Qualities Rating LCTR Large Civil Tilt-Rotor MTE Mission Task Element OLOP Open-Loop Onset Point PID Proportional-Integral-Differential control RC Rate Command TCL Thrust Control Lever UCE Usable Cue Environment VMS Vertical Motion Simulator