Flight Path and Flight Dynamic Analysis of the Starting Procedure of a Flying Wing for an Airborne Wind Energy System

Abstract

Abstract Airborne Wind Energy is an emerging technology that harvests wind energy with flight systems connected via a tether to a generator at the ground. A flying wing promises a high energy output during the power generation phase due to its aerodynamic efficiency, while being able to take-off as a tailsitter. Yet not part of the generation phase, the starting procedure raises main challenges to the flight system in general but especially to a flying wing. A fast transition from hover to crosswind flight is striven under minimal power consumption and high wind robustness, while considering the limited trim range of the flying wing in hover state. This paper conducts a detailed analysis of the stationary trim states of the flying wing from thrust-borne to wing-borne flight and introduces a lateral yaw-roll transition to keep the angle of attack in controllable limits at all times. Based on the trim states, different options for the starting procedure are evaluated and an appropriate path is selected that entails a straight-lined transition segment to enter forward flight, followed by curved flight to built up tether tension and to navigate into the power-generation zone. The first part of this transition from hover to horizontal forward flight is demonstrated in the simulation to verify the selected flight path.