Did you ever once doubt that extreme radio-controlled airplane flying would exist, somewhere? Proof of just that is above, in a video showing practitioners of dynamic soaring, a technique that utilizes specialized wind phenomenon to get RC gliders looping through the air at world-record speeds nearing 400MPH. So how does it all work?
Just like the whirpool that forms behind a rock in a rushing river, wind flowing over a ridgeline tends to create a swirling eddy on the leeward side of the ridge. By whipping a glider through the eddy and then immediately looping back over the ridge, taking advantage of the shearing winds in the opposite direction, a sort of infinite loop of thrust can be tapped into. Bill Paterson, a seasoned dynamic soarer, has done up a Flash animation that explains this clearly.
Dynamic soaring requires specially reinforced gliders to stand up to the massive forces such speeds subject on the airframe. So next time you go ridge-hiking, if you see Bill and his buddies, radar guns out, hooting with joy--don't forget to duck for cover!