Wing-store flutter analysis of an airfoil in incompressible flow

The flutter of two-dimension al airfoil with external store is analyzed to investigate the effects of pylon stiffness on flutter speed. Among the 40 configurations studied, five were tested in the wind tunnel to verify the analytical results. The variations of wing-store flutter speed with the pylon stiffness can basically be divided into three types. The curves of the normal and flutter frequencies vs pylon stiffness have the same pattern. They can be sketched approximately by the aid of the normal frequencies of the two degenerated two-degree-of-freedom systems, i.e., the freely hinged and rigidly connected store eases. A limiting flutter speed for very small pylon stiffness is deduced, which is useful to identify which type of flutter the configuration studied belongs to.