Research on Flight Dynamics Modeling and Simulation Technology of Large Transport Fixed-Wing UAV

The aerodynamic structure of large transport fixed-wing UAV is mainly composed of fuselage, wing, horizontal stabilizer, vertical stabilizer, engine, landing gear and so on. The aerodynamic interference between various aerodynamic structures presents different states with the change of speed. The flight dynamics model parameters must be modified according to the different speeds of the UAV in order to obtain a mathematical model with high confidence. In addition, it is necessary to adjust the control law strategy at different speeds to achieve stable and controllable flight within entire speed envelope which ensures the conformance with flight quality requirements of the UAV. Therefore, the flight dynamics model of large transport fixed wing is established based on wind tunnel data. In order to improve the confidence of the mathematical simulation model, the model was modified using flight test data. At each trim point, the nonlinear dynamics model is linearized to obtain the open-loop aero-dynamic characteristics of the UAV. On this basis, the stability enhancement loop is designed and the simulation verification is conducted. The results show that the reliability of the nonlinear aerodynamic model is high, and the trim results of the mathematical model are basically consistent with the wind tunnel test data. The distribution of the feature roots of the high-order and low-order linear models can maintain a good consistency. The mathematical model for 5-ton large transport fixed-wing UAV is established successfully, and the stability augmentation control strategy is proved to have good stability and maneuverability within the required flight envelope.