IN-FLIGHT INVESTIGATION OF THE EFFECTS OF HIGHER-ORDER CONTROL SYSTEM DYNAMICS ON LONGITUDINAL HANDLING QUALITIES

Abstract : The results of a flight test program to investigate the effects of higher-order control system dynamics on the handling qualities of a fighter airplane are presented and discussed. This research was undertaken using the variable stability T-33 airplane as an in-flight simulator. This in-flight investigation was based on a similar fixed-base ground simulator program. Higher-order response characteristics were obtained by altering the elevator stick feel system dynamics and elevator actuator dynamics in conjunction with four different sets of longitudinal short period airplane dynamics. In the investigation, the dynamics of any of the three elements (feel system, actuator, and airplane) could be changed independently of the others. Three of the set of four airplane characteristics were investigated as a fighter in 'up-and-away' flight, and the fourth was evaluated as a fighter during landing approach. Thirty-two different configurations were evaluated by one evaluation pilot (Pilot B) and 35 configurations were evaluated by a second evaluation pilot (Pilot H). Essentially the same configurations were evaluated by both pilots and rated using a new pilot rating scale. Pilot H also rated the configurations for their pilot-induced oscillation (PIO) tendencies using a PIO rating scale. Pilot comments were recorded in flight and the comments and ratings were related to various handling qualities parameters and response characteristics of the configurations.