Study about key dynamic problems of near space solar power aircraft
Abstract
Two key basic dynamic problems: low Reynolds number aerodynamics and low wing loading aircraft flight dynamics with high aspect ratio, which directly influence the success of the near space solar power aircraft, were studied in this paper. The main conclusions could be drawn in this paper as following. The results of our numerical simulations and experiments indicated that the decrease of the ratio of lift to drag along with the decrease of <italic>Re</italic> were well obtained, and the mechanisms were analyzed. Although the coefficient of the frication drag increased with the decrease of <italic>Re</italic> number, the more important factors, which made the aerodynamic efficiencies deteriorate, were the increase of the coefficient of the pressure drag and decrease of the coefficient of the lift caused by the laminar separation at the low <italic>Re</italic> number. The new kind of trailing-edge laminar separation bubble (TLSB) was found, and the nonlinear aerodynamic effects under the low <italic>Re</italic> number were caused by the sudden alterations of the laminar separation structures. A new kind of flight movement response mode was found in this paper, and the fundamental reasons that caused the flight movement of the near space solar power UAV unconventional were the coupling effects among the low wing loading, the high aspect ratio and the flight dynamics.
