An Investigation of the Use of Feedback Control to Raise the Flutter Speed of an Aeroelastic System

Citation

Braham, Harold Stanley (1958) An Investigation of the Use of Feedback Control to Raise the Flutter Speed of an Aeroelastic System. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/5EVF-4945. https://resolver.caltech.edu/CaltechETD:etd-10082004-111321

Abstract

This study deals with the possibility of raising the flutter speed of an aeroelastic system by feedback control. Emphasis is given to feedback control through a control surface driven by a powered actuator. It is shown that only for certain aeroelastic systems is it possible to significantly raise the flutter speed by this type of feedback control. In addition, a second type of feedback control is considered, a jet reaction torquer acting on the wing itself. A marked increase in flutter speed is possible in essentially all aeroelastic systems with this form of control. Despite the fact that this type of controller requires more power than the control surface actuator, its use may be practical in many cases. The question of the reliability of the feedback control used to raise flutter speed is becoming less important in this era of missiles where the entire system is controlled by automatic devices. Part I discusses the basic problem. Parts II and III develop a general feedback theory. This theory, when applied to a specific aeroelastic system, permits ready determination of whether an increase in flutter speed is possible for that system. Parts IV and V consider numerical investigations of many systems using a control surface actuator. Analyses are made by both the general feedback theory and by analog computer, showing similar numerical results. Part VI considers the jet reaction torquer and the increase in flutter speed that it can achieve. Conclusions are presented in Part VII.

Thesis Files