On YouTube That's scary fast considering how close by the passes are going.

Edit: Corrected link.

I think if you got hit in the head by a 200mph glider you'd still feel the hurt.

Have you seen the flash animation one of the DS guys did explaining how they get them going that fast?

Holy cow, I didn't even know that was possible.

http://en.wikipedia.org/wiki/Dynamic_soaring

I wonder if a variant on this technique could be employed as a generator. Instead of a static turbine sitting on the top ridge of a hill, some sort of larger angled turbine system whose blades shift position as they dip into the wind shadow behind the hill. You could generate serious energy like that.

I haven't been able to stop thinking about this exact topic since I first saw the demo yesterday afternoon.

If you've got that much difference between your fast airstream and your slow airstream, just stick a normal wind turbine in the fast airstream. Dynamic soaring is neat because it extracts some energy without a ground anchor, not because it extracts more energy than a system with a ground anchor.

Peter

"In 2002 Vince designed a wind turbine based on the principle of Dynamic Soaring"

I can't find any further references, though.

So you're saying that a simple turbine in the fast airstream couldn't be made to spin any faster by taking advantage of the dynamic soaring technique?

The way I understood the flash animation, it made it seem like the benefit of hitting both airstreams was such that the plane in effect always had a tail wind and it was almost as if it was always on a downward trajectory, picking up more speed every time it goes around (up to a point of course).

The wind coming over the ridge of the hill for the record-breaker was only just over 45MPH I believe.

Yes. I was going to say, "Yes, obviously", but in fact it got less obvious the more I thought about it. But I think the answer is, that you can only extract energy from relative speed, not absolute speed. Unless the shape of the hill is such that the lee air isn't just stagnant, it's bodily flowing in the opposite direction, then you can extract more energy from a ground-mounted turbine fed from the speed of the air relative to the ground, than you can from any flight manoeuvre which relies on the speed of some air relative to some other air. Dynamic soaring is like a gearbox: it can convert a low-speed, high-torque input into a high-speed, low-torque output, but it doesn't actually give you any more power.

Dynamo generators are more efficient at high speed than at low speed, but that's dealt with in real wind turbines by having an actual physical gearbox between the blades and the dynamo.

Peter

Ah, that makes sense.