Doug, with your past interests in r/c, have any of your old mates from the field gone on to the hill to give a go at dynamic soaring ?....The speed of this type of flying may even exceed some of the newer turbines....I'm not sure on that though, but I have known for quite a while that they do move ......I found this
LINK from 2002 about a speed posting from California........
Videos here... 8-)
So,...for wealthysoup and the others who really haven't seen fast R/C, here is what you can do without that noisy, oily, spinning fan on the front and even without a fire blowing hot air out the back of a turbine, real high speed is attained with only the power of gravity and wind :o......if you can build one strong enough to survive the "G" loading.......

If I hadn't started flying serious gliders with the
COGG in Ontario, back in the early 90's, I probably wouldn't have even heard of these guys ...........