That .25 would fly a sig kadet seniorita around pretty nicely, and with enough fuel in the fuse, you could keep her up for a long time. One problem, though, that engine requires a light airframe, and doesn't produce a lot of thrust, so flying on a real windy day would almost be impossible. However, in 10 mph winds (maybe up to 15, but that would be pushing it) you could point the nose upwind and stay put!