In a crosswind yo-yo device, after the power cycles are complete, and the tether is fully extended, the kite must be retracted to start the power cycles again. It occurs to me that perhaps we can get the same or better results if we retract the kite after each cycle rather than wait until all the power cycles are complete. Retraction can be performed on each side of a ‘lazy eight’ pattern. The most efficient retraction is performed when the kite is located outside of the wind window where the resistive forces on the kite are minimum. If this method is used, then the following advantages are obtained:
- The tether is always extended so that the kite can be at it’s maximum height without incurring, substantial cosine, cubed losses.
- With a long tether, the size of the wind window is enlarged, so the kite can travel a longer distance for each cycle.
- Since retraction occurs at each cycle, there is no need for a special program for retraction.
- Retracting the kite while it is turning stabilizes the kite and enables the turning radius to be smaller.
For example, at a wind speed of 12 m/s the optimum unwind speed is 4 m/s. If we assume that it takes eight seconds to traverse the wind window, then we would unwind 32 meters on each pass. If it takes 4 seconds to rewind, then the rewind speed is 8 m/s