Nolinear Static Aeroelastic Analysis and Optimization for High-Altitude Solar-Powered UAV With Large Aspect Ratio

According to the static aeroelastic characteristics of Solar-Powered UAV (SP-UAV) with large aspect ratio, this paper develops a nolinear aeroelastic analysis method which takes into account both the calculation accuracy and efficiency. Firstly, we establish the finite element model of the geometric nonlinear structure, which is verified by the static test of the whole UAV to reduce the calculation error caused by the simplified method of structure model. Then, the aerodynamic model of SP-UAV is established by using Curved Vortex Lattice (CVL), and the structure-aerodynamic coupling interpolation is realized by the Thin Plate Spline-interpolation (TPS) method, so as to complete the full static aeroelastic analysis. The analysis indicate that the calculated results of the longitudinal trim are well match the first flight condition. In particular, considering the elevator efficiency loss occurred in longitudinal trim analysis of the UAV, we design an optimization scheme to improve the efficiency of the elevator by about 15%. The simulation results show that the loss of elevator efficiency of flexible solar UAV with high aspect ratio is non-negligible, with the maximum value higher than 40% under high dynamic pressure. In actual flight, the speed of UAV must be reduced as much as possible to minimize the loss of rudder efficiency, while the elastic control method should be considered in flight control.