Longitudinal flying qualitites 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 given to variations in long-period longitudinal characteristics and their effects on the performance of simulated instrument flight rule flights from takeoff through landing. Over the range of values tested, lift-slope variations (−Zw) 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 gradients (with respect to trim airspeed), and pitch/airspeed gradients.