Thanks a lot, Reinhart, for pointing this out!
‘six times more power in a two-kite MAWES conﬁguration compared to a single-kite system of equal total planform area’ https://cdn.syscop.de/publications/Leuthold2018.pdf
That’s certainly and eye opener.
Just after: “This large value may be due to the underestimation of tether drag mentioned previously.”
I would think that tether drag has to be one of the principle factors in this large gain, but I would not be totally surprised that a single system with a tether moving around the wind window and no drag reduction measures would be significantly less efficient than one in which a small tether section moves. I guess in a real world system what practical drag reduction measures are available would be a critical factor; still you have to think that achieving effective drag reduction on the relatively short top sections is going to be easier than drag reduction on an extended section of the tether.
Do you know has a working prototype of this configuration ever been tested?
No for what I know. Furthermore, I do not have precise data such as measured power curves (and not only simulations) concerning rigid wings.