Stabilization of the vertical take-off of a rigid flying wing for an airborne wind energy system

• Published in: CEAS aeronautical journal 2021-11, Vol.12 (4), p.895-906
• Main Authors: Fuest, H., Duda, D. F., Islam, T., Ostermann, T., Moormann, D.
• Format: Article
• Language: English
• Subjects: Aerospace Technology and Astronautics; Center of gravity; Control equipment; Design modifications; Engineering; Flight control; Flight envelopes; Landing; New technology; Original Paper; Takeoff; Tethers; Vertical flight; Wind forces; Wind power; Wind speed
• ISSN: 1869-5582; 1869-5590
• DOI: 10.1007/s13272-021-00545-3

Airborne wind energy is an emerging technology that harvests wind energy with flight systems connected via a tether to the ground. In the project “EnerGlider”, a flying wing is meant to fly fully automated by its own control units. This contribution discusses the challenges to control and trim this flying wing during vertical take-off and landing under the influence of a horizontal wind velocity. High wind velocities can lead to unstable and untrimmed states concerning the longitudinal motion of the flying wing. The paper analyzes the influence of design modifications of thrust vector and elevon area to enhance the flight envelope of the trimmed states to higher wind velocities. Besides, the tether force as additional control unit is considered for strong wind forces. It is demonstrated that a tether force acting behind the center of gravity can significantly enhance the robustness of the flight system concerning wind velocity. Moreover, the unstable flight states emerging during vertical take-off and landing can be stabilized with a flight control.