Body-freedom flutter analysis and flight test for a flying-wing aircraft testbed

The paper presents a systematic study on the body-freedom flutter via a novel nonlinear aeroservoelastic modeling method and flight test validation. The nonlinear aeroservoelastic model established in the study includes the dynamics of the servo actuator, the geometrically nonlinear structural dynamics, and three-dimensional unsteady aerodynamics to predict the phenomenon of body-freedom flutter and describe the nonlinear aeroelastic characteristics. To verify the accuracy of the model in predicting the body-freedom flutter boundary and nonlinear vibration behavior, a flying-wing aircraft was designed and manufactured. Then, the structural properties and dynamic characteristics of the aircraft were determined via ground vibration tests and used to update the finite-element model. Afterward, the flight tests for body-freedom flutter were carried out after the hardware and software were prepared. Finally, a typical body-freedom flutter was identified from the flight test data. The study showed that the flutter speed and frequency in the flight test agreed well with those predicted via the nonlinear aeroservoelastic model.