Thanks for the information Dave. So if the OL has a L/D ratio of 3, that leads to (L/D)² = 9. This is an interesting value compared to the usual (mine for example) 16 for soft ram kites with their tethers. On http://2e5.com/kite/nasa/reports/ there are detailed Nasa npw features comprising 2 < L/D ratio < 3.5, so a similar value. I don’t know if some among them can be reversible.
The reversibility is an important feature, allowing sweeping more and completely (unlike by using figure-eight or loop) by using the more powerful zone of the flight window (90°).
Concerning Payne’s figure 5, on the old forum Peter Sharp provided some comparable methods I attach below:
In the second drawing the crosswind forth and back issue is solved by hinges allowing the half-turn. I would prefer OL solving this by reversibility.
Concerning other features, these designs has an advantage to be able to have a single ground station allowing re-orientation when the wind changes. But in my opinion tests or/and an analysis of force would be required to know the real efficiency.
And I am not sure the requirement by the figure 5 of a large ground station would be a real disadvantage as the kite span would be as large as the diameter of the ground station which would facilitate take-off and landing. And also the same land would be used even without such a large station, that due to take-off and landing of a huge kite.
If no described pulley methods here are really advantageous, the yoyo mode could be used, the recovery phase occurring at each end of the transverse trajectory, so at each flight window edges, when the kite speed drops and the traction is lesser.