Bioinspired Slotted Wingtips as Flight Control Devices for Airborne Wind Energy Harvesting Kites*

Airborne Wind Energy Harvesting (AWEH) systems offer improved harvesting strategies over ground-based wind energy systems due to increased wind velocity and reduced boundary layer effects at high altitudes. One example of an AWEH system is Toyota’s Mothership, a multifunctional kite platform that requires control authority to perform energy-extraction maneuvers at high altitudes. The Mothership cannot support traditional flight control devices due to its lightweight and flexible fabric-made skin. Birds fly adeptly in a wide range of altitudes and offer a variety of flight control solutions suited for light and flexible materials. Bird wings contain multiple feather groups that enhance birds’ control authority and maneuverability. One feather group, the slotted primary feathers near the wingtip, has been shown to alter aerodynamic forces, making it a viable flight control device. In this presentation, we explore the feasibility of implementing bioinspired wingtips on the Mothership for increased control authority. More specifically, we conducted wind tunnel experiments at Re = 2 x 10⁵ and acquired Particle Image Velocimetry (PIV) measurements to evaluate various bioinspired slotted wingtip configurations on a scaled semi-span Mothership wing. Results show that the wingtips significantly modulate lift and drag, allowing for changes in moments and increased maneuvering capabilities.