Robust lateral-directional control design for the F/A-18

Preliminary results on the application of modern robust control law design methods to the stability and command augmentation of the F/A-l8 systems research aircraft are described. Focusing on a low dynamic pressure sub-envelope, spanned by five trim points, some first steps are taken toward robust lateral-directional control law design.. We state the flight control objectives and develop the uncertainty and performance models and weights required for robust control design. A single robust linear controller is designed by ,&synthesis to cover the whole sub-envelope. On the basis of handling qualities and simulated response characteristics, the robust controller has good performance at all five trim points.