Out here, the Cowra MAC invented something called Plank Racing as part of their annual Oily Hand weekend. It's basically a time trial, where models have to do 10 upright laps, 2 wingovers, 2 loops, 2 lazy 8s, and 2 inverted laps in the minimum time. The model has to have exposed controls, a sheet wing of no more than 9mm thickness, and 52' minimum line length. You get 1 minute to start the engine, and mufflers aren't allowed. Other than that, there are no restrictions. It's great fun, and you can build a model out scraps in about half an hour.