Abstract：In order to improve the flutter critical dynamic pressure of swept trapezoidal frame-skin rudder with a low aspect ratio, the effect of balanced mass on the rudder mode and flutter critical dynamic pressure were compared at multiple-cavity positions in this paper. In conclusion, the balanced mass added at the intersection of leading edge and root chord can increase the flutter critical dynamic pressure, but the balanced mass added at the intersection of leading edge and tip chord is counterproductive, blindly adding balance mass won’t reduce the risk of rudder flutter. The cavity filled with balanced mass should be determinedat the specific position where the degree of bending and torsion mode shape coupling can be reduced.
