Objective  In order to meet the field operation requirements, the UAV needs not only a rotor with the function of flexible take-off and landing, but also fixed wings with the characteristics of long endurance. A new agricultural plant protection UAV with X-shaped rotor and fixed wing hybrid structure as well as tilting function was designed.

Method  According to the load dynamic requirements of farmland spraying operation, the airfoil and parameters of the lifting device of UAV were designed. The body structure of the plant protection UAV was built using SolidWorks software. The aerodynamic simulation analysis of the increasing lift and speed parameters of the plant protection UAV was carried out using the Fluent software and Spalart-Allmaras turbulence model.

Result  The simulation results showed that the lift coefficient was positively correlated with the attack angle and the airspeed, and the influence of the attack angle was stronger when it changed from 4° to 6°. The lift coefficient reached 0.81 when the attack angle corresponded to the 5°−30° tilt angle. At the airspeed of 5 m/s, the relationship between the attack angle and the tilt angle almost showed linear distribution. Forward tilt of the nose could increase the lift coefficient, and then increase the payload, so that the overall operational efficiency of plant protection UAV was improved.

Conclusion  The study provides a basis for the design of plant protection UAV with tilt wing, and also offers a new idea for improving the endurance time and operation efficiency of plant protection UAV.