The latest world records is topped by a pulse jet (reaction motor is the class) at about 395 kph (245 mph) then 10cc at 345 kph (214 mph), open FAI (2.5cc) at 335 kph (208 mph) with the video of the record flight at http://www.flyrc.org.uk/record/control_line.htm then FAI in a competition at about 325 kph (202 mph).

The video is interesting because it shows everything that darock mentioned about using the pylon. It's main use is to stop any whipping and to keep a constant line length to get an accurate speed. I think timing starts one lap after the handle is in the pylon. I remember where someone did an analysis of the engine speed from the soundtrack and the Irvine was 4 stroking at 19,000 before release and got to about 40,000 in the air when the pipe cut in.

The Doolings started with the .61 and the first ones were all spark ignition but came in 2 types, a 7 fin and 9 fin, but I don't know which came first. Some time later they were pure glow. The .29's were only glows (and IMHO the best looking engine ever made ).