Abstract: The quasi-steady aerodynamic model and unsteady aerodynamic model of an aircraft are established, based on wind tunnel test results of largeamplitude yawingmotion force oscillation, rollingmotion force oscillation and yawingrolling coupled-motion force oscillation. Using these models, the longitudinal dynamic responses are calculated with the oscillating control inputs. The simulation results show that, the dynamic responses of quasi-steady model and unsteady model are coincidence basically at low angle of attack; but, at high angle of attack, the lateraldirectional dynamic responses of quasi-steady model are stable, while the lateraldirectional characteristics of unsteady model are oscillating. This phenomenon is similar with the flight test results of F-16XL. The main reason is that the damping characteristics of coupled-motion unsteady model and quasi-steady model are different. These also show that the coupled-motion unsteady aerodynamic model is needed in flight characteristic simulation at high angle of attack.

Key words: unsteady aerodynamics, coupled motion, aerodynamic model, flight simulation, oscillating flight