Transient flight flutter test of a wing with tip tanks

Wing flutter was encountered during flight testing of the F2H-2 airplane with full wing tip tanks. As a result, more refined theoretical analysis as well as flight flutter tests were initated to establish corrective measures and to experimentally verify the stability of the improved system. The results from the flight flutter tests, utilizing the transient response technique, are presented. The method of excitation consisted of abrupt deflections of the ailerons resulting from stick bangs and data were measured by wing tip accelerometers. A comparison of the results with theoretical predictions is presented and indicates that reasonably good correlation was obtained. The influence on wing flutter of tip tank fuel transfer cycle, which was incorporated to control the center of gravity range of the tank during defueling, is indicated by the measured results and compared with the theory. The final configuration utilized a transfer cycle which was proven stable as a result of flight flutter testing. It is concluded that transient response measurements resulting from stick bangs provide a reasonably reliable and safe technique of flight flutter testing for wings with external tanks or heavy stores.