Wind Tunnel Testing of Tethered Inflatable Wings

A wind tunnel testing approach for tethered inflatable wings is presented. Use cases for such wings range from airborne wind energy systems to high-altitude communication platforms. The tests were conducted for two tethered inflatable wings, one made out of nylon fabric and the other an ultra-high-molecular-weight polyethylene fabric. They were tested within a speed range of 15-32.5 m/s for three tether attachment configurations. Stereo photogrammetry data, force and moment measurements, and wake pressure measurements were recorded for each speed and test configuration. These measurements provide an experimental database for aeroelastic model validation and comparison with high-fidelity computational fluid dynamics studies. The effects of wing fabric material and tether attachment configurations on aerodynamic performance were explored and found to have a profound impact. These tests also highlight the possibility of passive aeroelastic tailoring of the wing configuration to achieve desired aerodynamic performance in the form of high lift and load alleviation. Some testing challenges and possible sources of measurement uncertainty are also discussed.