Spent a nice day yesterday as club liaison for a group of quadcopter racers who took over our RC field for a local race.
It couldn't be a nicer group of people to spend a day with, they were polite as hell, serious about racing, and -- at least after one of the other club members left and took his fixed-wing stuff with him -- there wasn't an ARF in sight. In fact, I don't think there was a single kit-built either. Everything is put together from a chassis here, a controller board there, ESCs from somewhere else (and often with task-specific software loaded on), quite a few of the transmitters are running custom software. It was an interesting day.
The only disappointment for this spectator was that the rules are arranged to reward the guy who doesn't crash, so the racing was a lot less zoomy than the after-race play.
The level of technology that these folks are dealing with is amazing -- they assemble their craft, then download custom firmware into the ESCs and flight controllers (and sometimes transmitters), they have to tune the control loops for optimal performance, and all the while they need to debug all the inevitable problems that crop up.
Here's a video took by the 1st-place finisher -- I'm pretty sure this is the after-race play, given how fast he's going. Turn the sound of if you don't like metal music (why do they do that? is there a law someplace?)