A design procedure for the handling qualities optimization of the X-29A aircraft

Abstract

A design technique for handling qualities improvement was developed for the X-29A aircraft. As with any new aircraft, the X-29A control law designers were presented with a relatively high degree of uncertainty in their mathematical models. The presence of uncertainties, and the high level of static instability of the X-29A caused the control law designers to stress stability and robustness over handling qualities. During flight test, the mathematical models of the vehicle were validated or corrected to match the vehicle dynamic behavior. The updated models were then used to fine tune the control system to provide fighter-like handling characteristics. A design methodology was developed which works within the existing control system architecture to provide improved handling qualities and acceptable stability with a minimum of cost in both implementation as well as software verification and validation.

CONDUIT - A new multidisciplinary integration environment for flight control development

“…Thus, as discussed in detail in Ref. 21, initial flight tests of the X-29 handling qualities indicated that the aircraft characteristics were Level 2 (adequate). The main deficiency reported by the pilots was sluggishness in the pitch axis.…”

“…The wing-canard planform results in a high level of instability that has a time-to-double amplitude near 150 msec. 21 There exist both low-and.…”

“…This corresponds well to the pilot comments concerning sluggish response in the pitch axis for the initial design. 21 CONDUIT was next used to determine how much of an improvement could be made within the confines of the baseline system architecture, the selected nine design parameters, and the available actuator authority. The key concerns were to meet the stability requirements, improve the moderate amplitude quickness, and reduce the required pilot compensation.…”