Vibration control and gust alleviation of highly flexible blended-wing-body aircraft

Suppressing the excitation from gusts that flexible vehicles experience in high-altitude, long-endurance flights is critical to improving their flight performance and maintaining stable flight. Aircraft designed for high-altitude, long-endurance flights tend to be more flexible due to the design requirements of their missions. The aircraft may experience external disturbances such as gusts throughout their flights which can cause large deformations in the flexible, lightweight wings. These disturbances can potentially excite unstable modes within the flexible aircraft, depending on the flight speed and gust strength. In this thesis the open-loop and closed-loop dynamic responses of a blended-wing-body aircraft subjected to different gust profiles are examined. Three flight speeds are considered: nominal, pre-flutter, and post-flutter. An LQR controller is then designed and implemented to examine the closed-loop dynamic responses of these same flight profiles. It is found that the controller is able to suppress vibration and wing root loading as well as delay the onset of unstable behavior.