WL, before you get very far into this whole project you should really look into getting a proper aerodynamic engineer, or at least an educated visionary, on side. Stuff like you're asking has SO much impact that such a guy could answer in a more integrated manner.

Anyway, back to the fun.... I've seen tests done where the drag of a simple round wire or rod had the same drag as a proper symetrical airfoil that was 10 times as thick as the diameter of the wire or rod. That's why I was suggesting an extruded slit foam jacket that would fit over the tether wire as it came off the reel. The foam being formed onto the wire as it goes out and split off of it and stored on a special low tension reel as it came off. Perhaps the foam fairing sleeve could contain the data communication and power leads to the kite/wing.

And for what it's worth I think you're on to something good here. Like you say it's a well know fact that if there's wind at all that it's much stonger even just a few hundred feet from the surface. I've come around to believing that your wing/kites can work well but I think there's a LOT of work and study that you/we have only just touched on in order to make it work as efficiently as I think it could be.

The other night I jumped over to http://www.grc.nasa.gov/WWW/K-12/airplane/foil2.html and played for a bit. It was interesting to note that even using the stock sized wing of 5x20 feet I was generating almost 800 lbs of lift just before stalling at only 40 mph and over 1200 at 50 mph with a 14% thick 7% camber wing. Sized up to something DC3 like at 70x15 and the numbers go to 8400 lbs at 40 mph and 13,100 at 50 mph. Even at 20 mph that large wing still has 2100 lbs of lift to work with. Not bad for a kite I must say.

In the end drag is always the enemy and just because kites fly despite the drag does not mean they are efficient. I've seen cometition models of various types "kite" up their towlines and can honestly say that I have never seen a classic kite that is capable of getting that much speed out of a simple pull. If your ARTAGS ever see the light of day then I think you'll find that most of the time the tether line will never angle back more than about 20 to 30 degrees from the vertical and will often be closer to vertical than that. But in that mode I suspect there will be plenty of lift to do what you are trying to accomplish.

Perhaps the guys with the number tallent can correct me if I'm wrong but at even a high angle of attack close to the stall the L/D is still around 15 to 1 ( I'm basing this on a Clark Y at Cl=1 and Cd=~.3) Converting that to vectors shows a very straight angle. Of course the tether will add it's own drag but I still can't see the angle to the wing being too far downwind although the tether may be leaving the reel at a lower angle what with the drag and weight of the tether assembly.