Comparing blade-element theory and vortex computations intended for modelling of yaw aerodynamics of a tethered rotorcraft

The development of airborne wind energy systems involves many design compromises, which encourages the use of systematic optimization approaches, that rely on simple engineering models for each component. In this paper, we present results concerning rotary-based airborne wind energy devices, that are operating like autogiros tethered to the ground. This configuration results in operating conditions at unusual rotor inclinations with respect to the incoming flow. We therefore focus on the description of the aerodynamics of the rotor, comparing blade-element momentum and free-vortex approaches, so as to determine if simple aerodynamic models are adapted for being used in initial design phases.