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

Abstract. Airborne wind energy is an emerging technology that utilizes tethered airborne systems in high-altitude wind fields to harvest energy. The employment of flying wings as airborne systems holds considerable promise concerning system performance, given their favorable aerodynamic characteristics. Moreover, when designed as motorized tailsitter, they can provide vertical takeoff and landing capabilities. However, the processes of launching, defined as the transition from takeoff to energy-harvesting flight, and landing, defined as the transition back, present considerable challenges for such flying wing AWES. To ensure the safe operation of the flying wing, it is essential to consider the controllability at varying wind speeds and the limitations imposed by the tether. To address this, a suitable guidance concept for the launching and landing phases of the aforementioned flying wing AWES has been devised. The concept is subjected to analysis taken into account specific system parameters, including turning radius, operating height, and wind speed. In light of these considerations, a flight regime can be identified. This is considered in the design of a guidance controller, which represents the top level of a cascaded flight controller. The lower levels of the 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 and corresponding system parameters. The results indicate that the control concept successfully facilitates the desired launching and landing in simulations. Future research may build upon the developed guidance and focus on identifying additional and more arbitrary flight paths for launching and landing.