Flight guidance concept for the launching and landing phase of a flying wing used in an airborne wind energy system

Abstract. Airborne wind energy (AWE) is an emerging technology that harvests energy by utilizing tethered airborne systems in wind fields. Given their favorable aerodynamic characteristics, employing flying wings as airborne systems holds considerable promise for system performance. Moreover, when designed as motorized tail sitters, they can provide vertical takeoff and landing capabilities. However, the processes of launching and landing present considerable challenges for these specialized flying wing airborne wind energy systems (AWESs). It is essential to consider the controllability at varying wind speeds and the limitations imposed by the tether. This work reviews existing industry approaches to launching and landing AWESs, highlighting their limitations, before introducing a novel guidance concept for flying wing AWESs. The proposed concept incorporates tethered multi-axial motion to address controllability constraints and enhance operational reliability. A comprehensive trim analysis examines the system's behavior during these phases under various wind conditions and guidance parameters, identifying operational limits. This novel guidance concept is integrated into the top level of a cascaded flight controller. The lower levels of this flight controller comprise a translational controller and a rotational controller. The performance of the overall controller is demonstrated through a simulation of a representative wind field. The results show that the control concept enables the desired launch and landing in simulations. It forms a base for future research covering the control of flying wing AWESs and the process of launching and landing within AWE.