Suppression of Flutter on Interfering Lifting Surfaces by the Use of Active Controls.

Abstract : An investigation into the possible increase in flutter speed of interfering lifting surfaces by the use of active controls was conducted. The study was designed so that the methods developed to determine the maximum increase in flutter speed could be applied to complex air vehicle configurations throughout the Mach number/altitude range of modern aircraft. The unsteady aerodynamic forces on the lifting surfaces were computed by using doublet lattice aerodynamic computer programs. The structural features of the lifting surfaces were represented by either experimentally measured or analytically computed vibration frequencies and mode shapes. The results of the study indicated that the use of active controls to suppress flutter on interfering lifting surfaces can be more effective than suppressing flutter on isolated surfaces. (Author)