Aerodynamic analysis and structural integrity for optimal performance of sweeping and spanning morphing unmanned air vehicles

Abstract

An optimized morphing unmanned aerial vehicle capable of sweeping and spanning its wings is proposed and analyzed aerodynamically and structurally in order to examine and improve its efficiency, flight transition analysis, and structural integrity. The lift to drag ratio of five different flight modes of the drone is examined using the Pollhamus lift theory to evaluate the aerodynamic performance during the transition phases. To verify Pollhamus lift theory in the determination of the aerodynamic loads for the four configurations of the morphing unmanned system, namely, fully compressed, fully expanded, fully swept, and fully expanded and swept, 3D panel and Vortex Lattice Methods are used. In order to improve the structural stability during the transition phase of the flight, a finite element analysis is conducted to approximate pressures on the wings of the unmanned system under a load and specific boundary conditions. The information from the finite element simulations is then utilized to determine the number of support rods needed for structural stability and the ideal positions of the rods. The vibratory qualities of the wings are also analyzed through modal and transient analyses. According to the results of the modal analysis, because of the low natural frequency of the wing, there is a strong possibility of flutter and a vibratory response due to the aerodynamic force and disturbances. The transient analysis demonstrates that the stress waves propagating through the wings, due to an excitation force, tend to localize around the circumference of the support rods.