An Alternative Method for Determining the Drag Force of Fixed-Wing Unmanned Aircraft Systems

Abstract

It is noted that in agriculture, fixed-wing unmanned aircraft systems successfully perform the tasks of crop monitoring, pest and disease detection across large areas remote from the operator. Further improvements in unmanned aircraft speed, flight range, and payload capacity can be achieved by reducing aerodynamic drag. Research in this area is constrained by the lack of affordable experimental facilities with satisfactory operating characteristics. (Research purpose) To develop an alternative method for determining the aerodynamic drag of the objects under study. (Materials and methods) Existing experimental facilities used to evaluate the aerodynamic characteristics of models were analyzed. The design of a differential aerodynamic rotary machine was described. The operating principle of the experimental facility is based on comparing the drag forces acting on the test model and a reference body. (Results and discussion) The factors limiting the development of aerodynamically efficient aircraft shapes were identified, including the high cost of wind tunnels and the disturbances generated behind the test model and the reference body during their circular motion in a standard rotary machine. It was proposed to replace the aerodynamic balance of the rotary machine with a differential mechanism, thereby exposing the test model and the reference body to identical external disturbances. (Conclusions) The use of reference bodies and a differential mechanism would increase the cost of the differential aerodynamic rotary machine by 31 percent compared with a standard rotary machine. At the same time, the accuracy of the experimental results would increase by 33 percent, approaching that achieved in wind-tunnel testing.