Nonlinear Aeroelastic Simulation of X-HALE: a Very Flexible UAV

A very flexible unmanned aerial vehicle has been designed and manufactured at the University of Michigan. The vehicle is named X-HALE, whose flight tests are expected to provide important data of its geometrically nonlinear aeroelastic behavior coupled with the six rigid-body degrees of freedom. As the target of the aeroelastic design, the X-HALE vehicle will present unstable aeroelastic/flight dynamic behavior when subjected to finite disturbances. To design such behavior in the aircraft, nonlinear aeroelastic simulations of XHALE were performed using the University of Michigan’s Nonlinear Aeroelastic Simulation Toolbox (UM/NAST), which provides an estimation of the vehicle’s flight characteristics. The simulation cases include the achievement of the target aeroelastic/flight dynamic instability and the arrestment of the unstable motion without using a dedicated closed-loop control scheme.