Flight Dynamics Modeling Based On 3 DOF Virtual Flight Test Device

The virtual flight test technology is a kind of wind tunnel test technology used to study the control law of aircraft.The flight model which installed on the VFT set can make free motion with flight control system in the wind tunnel.In this paper,a kind of three degree-of-freedom dynamic test rig is introduced,which enables simulation of the velocity vector roll and uncontrolled flight condition such as stall/departure/spin.The rotational motion of the three axis of the aircraft model is simulated by the combined motion of the 2-DoF gimbal.The flight dynamics model of the aircraft model which based on this device is developed in order to verify the feasibility of the device and forecast motion of the model.The modeling process is based on the multi-body dynamics theory.The Lagrange multiplier method is adopted to take into account the constraint relationship between the mechanism and the test model.And the influence of the friction moment of the mechanism is considered.The simulation results show that,the rig can provide the ability to realize the velocity vector roll,and the rotation of the curved rod is synchronous with the rolling motion of the aircraft model.The curved rod has an effect on the dynamic response of rotational rates,while the frictional torque makes a difference on both the dynamic response and steady state value of rotational motions.The mathematical model and simulation validation provides a guide for wind tunnel test.