Longitudinal Flying Qualities Criteria for Single-Pilot Instrument Flight Operations

Experiments to determine the flying qualities of more than a dozen dynamic configurations have been conducted using the variable-stability Avionics Research Aircraft. Particular attention was paid to variations in long-period longitudinal characteristics and their effects on the performance of simulated IFR flights from takeoff through landing. Over the range of values tested, lift slope variations (-Z_w) had the greatest effect on pilot opinion, workload, and tracking error. Bounds for satisfactory flying qualities were found for three parameters: phugoid mode damping, stick force gradient (with respect to trim airspeed), and pitch/airspeed gradient.