How can this thing fly at 100mph unless it's thrown that fast? "A flick of the wrist"?
Pitchers get to speeds like that all the time. And if the wing is efficient but relatively low-lift the glider will drop and trade altitude for more speed before leveling out for a run.
This thing reminds me of a sloop's jib/mainsail combination, where one of the purposes of the jib is to direct wind over the back of the mainsail for more lift - which (for a boat) translates to still more thrust, (especially when sailing almost into the wind, where the combo lets you haul closer to straight upwind before it stalls out and leaves you "in irons").
I believe that combo gives you a better lift-drag ratio. If so, a similar setup should be useful both for aircraft and (to a limited extent) to wind turbines. (Darrius comes to mind.)
Using multiple wings to get more lift with less reach is well known from the early days of flight. Biplanes and triplanes can fly at very low speeds as a result, and the short wings let them do very rapid snap-rolls and other aerobatics that would tear the wings off longer designs using the same material. This thing looks like a modern-materials triplane - with the top and bottom wings
But I'd think usefulness for a wind turbine would be limited. A good HWT blade design closely approaches the Betz limit. I believe you can in principle beat that with significant separation of the blades in the up/down wind dimension. But this design explicitly depends on the multiple blades being close together, so that they act much like a very good single blade. Since we already HAVE very good single blades for HAWTs I don't see much help there - except maybe for making a lighter, stronger blade of a given size if you're willing to go to the trouble fabbing it.
VAWTs might be another issue. If it provides an insight into getting a darrius to behave more like two mills in series than like a single disk it might help there. Or maybe substituting airfoils for cylinder sections on a squirrelcage-style Savonius might improve its efficiency, getting it closer to the Betz limit.
But I don't think we're going to bust Betz in a single rotor - even a large one - and get the near-100% efficiencies that you can achieve with a water wheel. The Betz limit, if I understand it correctly, comes from the compressibility of the air. Pulling power from it slows it down, reducing the amount you can pull power from. You have to leave some power in the air to get it out of your mill and let more come in, and Betz calculated the best tradeoff. Water is incompressible, so you can get virtually all the energy out and leave just a couple percent to get it to flow away from the wheel. (Also your WHEEL size usually isn't the limit on how much water you can intercept. B-)
