We're talking Speed here. At a line length of 17.69 meters 9 laps equal 1 Kilometer. Speed is checked by 3 timekeepers.

The airplanes have high aspect ratio inboard wings and outboard tailplanes only to minimize drag. One blade propellers are popular because they are more efficient. Models are launched from a dolly.

High performance engines with 2,5 ccm capacity for the International class. If they don't turn at least 40000 RPM they are considered trash.. Top speeds are around 300 km/h !!!
Tuned pipes raise engine power quite drastically - if they are perfectly tuned to resonance. Flyers would like to add some hot but prohibited incredients, so official standard fuel is provided by the contest organizer.              
  For the pilots aerodynamics is measured in RPM only. During the flight the pilot is forced to put his hand into a fork of the pylon to prevent unlawful whipping. To circle the pylon 9 times within less than 12 seconds is frightening - that's real sport !