ORIGINAL: KC36330
Officially Recorded it's 213.70 mph but that's with a piston engine, they haven't 'officially' got a turbine speed, a control line plane was faster but you asked radio controlled
the US Military has flown radio controlled drones in excess of Mach 2, but i guess FAI isn't going to consider those.
kc
here is 221 mph when converted
http://youtube.com/watch?v=QjR-KrlVlVE