The Airborne Wind Energy section is general, and discusses energy kite performance in a broad way - the tether drag was well predicted and wasn't a surprise for our prototype.
The inability to turn the necessary tight paths and some degraded aero performance are responsible for most of the performance miss. Also hugely concerning was the struggle to saturate power at high winds.
It is important to separate and highlight tether drag in the context of the purported big benefit of airborne wind turbines accessing higher, faster winds. While they do indeed access higher winds, they do so via tether length and elevation angle, both of which carry losses. The net effect in almost all scenarios isn't a win.
The inability to turn the necessary tight paths and some degraded aero performance are responsible for most of the performance miss. Also hugely concerning was the struggle to saturate power at high winds.
It is important to separate and highlight tether drag in the context of the purported big benefit of airborne wind turbines accessing higher, faster winds. While they do indeed access higher winds, they do so via tether length and elevation angle, both of which carry losses. The net effect in almost all scenarios isn't a win.