Inherently stable descending flight of a tailless flapping wing micro air vehicle by upward wing elevation

Maneuverability of flapping wing fliers inevitably goes with inherent system instability. Inherent instability means that flapping wing systems require a flight controller and that these vehicles are prone to crashing. This work proposes a design feature to stabilize the descent of a flapping wing aerial vehicle. The vehicle is based on the KUlibrie, a flapping wing nano robot that is under development at KU Leuven. A computational study indicates that upwardly elevated wings provide inherently stable descending flight. The vehicle performs a free flight starting from different initial conditions. The system dynamics display convergence towards a limit cycle. Wing elevation and center of gravity position determine pitch and roll stiffness with respect to vertical descent and climb. The same effects that stabilize descent also destabilize climbing flight.