The flutter characteristics of the wing with control surface in subsonic flow were studied. The structural natural frequencies and normal modes were obtained by commercial FEM code, MSC/NASTRAN, and unsteady aerodynamic forces were calculated by the modal function method. Flutter speed was calculated by the V-g method. The flutter speeds and flutter frequencies of the wing with and without pitching motions or control surface motions were calculated, and how the natural frequencies and generalized masses of such motions affect on the flutter characteristics was investigated. It is concluded that such motions can reduce flutter speeds and must be considered for an accurate flutter prediction, and that especially, the magnitude of the natural frequency of control surface motion has very important relations with the flutter characteristics of the wing.
