It is an almost isotopic playsail as the shape is a little different when a corner or a side of the tarp square is facing the wind.

There is a winch for each anchored station. 

Yes Joe, there is a central square filled with rectangular tarps. The idea is making a playsail with available elements and without transformation, lowing the cost.

With a central square a pseudo isotopic shape is more achievable. The four other rectangles and the four corners of the square are in a circle and form the eight main tethers toward the eight anchors with their respective winches, for eight wind directions covering wind changes. According to the wind direction there are two possibilities facing the wind: a corner, or a side with a rectangular tarp.

Here is Joe's design some years ago. The two counter rotating rotors avoid to roll sideway as one rotor does.

But the torque of soft spin bols would be hardly transferable with their periphery as there is no benefit of traction _ which occurs on a station anchored upwind _, contrary to Daisy or Rotating Reel.

"A soft bol can transfer traction force just as a soft tire does."

But in Wheelwind configuration the station receives the traction force, not the generator.

For Daisy and Rotating Reel systems the traction force allows more transferable torque.

For Dr. Beaujean's AWES it is different as it is a flygen.

For Wheelwind the generator is settled on the (soft or rigid) rotor periphery and on the sea or the ground. If the rotor is soft the torque is hardly transferable unless it becomes a Laddermill-like where the generator receives all the forces.

This discussion allows to see the limit of Wheelwind, even with Joe's configuration with two counter rotating rotors.

Said limit is the transferable torque as there are two different stations, one station for the generator on the rotor periphery, and one anchored station receiving the traction force.

Perhaps it would be a little better with a rigid rotor, but a rigid rotor doesn't scale well as you mention.

WheelWindCRtieDoublesOneAnchor.jpg

https://groups.yahoo.com/neo/groups/AirborneWindEnergy/conversations/messages/6959 

http://energykitesystems.net/WheelWind/WheelWindCRtieDoublesOneAnchor.jpg 

Perlan 2 glider 76,000 feet world altitude record flight into the stratosphere

Some evolutions, plans, descriptions are on 

https://www.kiteplans.org/planos/teega/teega.html#Getting_the_right_dimensions: "Background
The Nasa Para Wing (NPW) kites are extremely popular and it’s not hard to understand why.
First of all, they are cheap to buy and offer a cost-effective way into many power kite sports.
Second, you can easily build one yourself and there are many plans available on the internet.
Third, they pack down small and weigh very little so it’s easy to always have one with you.
Fourth, the time required for setting up to fly is minimal – a minute or two is enough!
Fifth, they are easy to launch, land and relaunch without assistance, regardless of size.
Sixth, they have a massive pull relative to their size.
Seventh, they are virtually unbreakable (but please remember that you are not!).
Eighth, because of their excellent low wind properties, they have a wide wind range." and "The Teega has an incredibly strong pull which is more evenly distributed across the flying window and holds up better through tight turns." and "The pull generated is very strong in the power zone (straight downwind) but small at zenith and to the sides." as disadvantage.

See also (within http://2e5.com/) http://2e5.com/kite/nasa/reports/:  "The maximum lift-drag ratio of the single-keel wing shown is about 2.5 while that of the twin-keel wing is about 3."

These single skin kites could be interesting as AWE use (reeling) at lower cost and allowing a better maximization of the swept area within a kite-farm as the above mentioned disadvantage ("The pull generated is very strong in the power zone (straight downwind) but small at zenith and to the sides.") could become an advantage to keep safe spacing between unities.