I’m sorry I probably stole the thread from the Yahoo forum. Anyways, I will repost my reply for completeness:
To me this design is interesting for AWE, not because of an extra few % Betz limit, but because I see tether drag and then indirectly tether strength as a limiting factor for AWE. This design reels out when the energy harvesting is at its highest and so the practical loss of power compared to eg. Yoyo may not be very big.
The same reason (tether drag) will probably favor vertically looping AWE (yoyo) to horizontal looping AWE based on this design. Because if you have a slightly long tether (100 meter for a medium sized rig) the power loss when flying upwind a 200 m diameter circle i expect to be significant, and you are probably only at 30 m altitude in doing so.
I will add that geometry constraints make this approach more difficult. Without a tower the kite flying with 100 m tether, 30 deg elevation angle would be limited to a wingspan of 50 meter in order to not touch the ground. In practise you’d want more ground clearance both for safety and wind gradient…
If you decide on a tower, the sideforces will be huge and oscillating.
Peter Sharp’s thread on Yahoo here