Experimental Characterization of a Force-Controlled Flexible Wing Traction Kite

In order to use flexible wing kites effectively for power generation their size must be increased and aerody-namic performance should be systematically improved. Validated models are essential for an efficient design process. The largest uncertainty in current modeling ap- proaches is the apparent wind speed v a experienced by the kite. In this work we develop an in-flight measure- ment setup for the apparent wind speed vector. An air data boom with a Pitot tube and a pair of wind vanes is used to measure the relative flow below the wing, at suf-ficient distance not to be influenced significantly by the wing itself. we propose a mechanistic model for the resulting aero- dynamic coefficient c R . A sole dependency of this coefficient on the angle of attack, as it is common for rigid airfoils,mustberejected. Instead,wefindthatthecoeffi-cientstronglydependsonthewingloadingandtoalesserextentalsoonthepowerratio,i.e.thenon-dimensionalpitchparameterofthewingandtheinflowangle,asas-sumedin[2]. the majorly the