The F3P acronym stands for:
F = Flying model
3 = Radio control
P = Indoor Aerobatics
The Federation Aeronautique Internationale (FAI) class of F3P is an aerobatic event for radio controlled model aircraft flown indoors. Competitors fly a complex sequence of known manoeuvres to the highest degree of precision possible. Judges are positioned immediately behind the pilot and evaluate the quality of each manoeuvre.
F3P models are allowed to be up to 2 meters (78.74”) in wingspan and length, but can not exceed 300 grams weight (10.58 ounces). Any powerplant may be used so long as it does not generate any kind of emissions, or exceed 42 volts. Construction materials generally used are foam, carbon fiber, and mylar. At the 2013 World Championships, the average F3P model was 39” long, 34” wingspan, and approximately 70 – 125 grams (2.5 – 4.4 ounces). Two-cell lipos were used by all competitors for power supply, with the top models using counter-rotating coaxial motor systems. At the 2015 World Championships, some aircraft weighed just under 40 grams with power supplied by one-cell lipo, and two-cell lipo aircraft weighed as little as in at 60 grams.
Even though takeoffs and landings are not judged, F3P models must takeoff and land on the “runway” without assistance. After takeoff, a maximum of two 180 degree turns are permitted prior to commencing the aerobatic sequence. An F3P sequence consists of six center manoeuvres and five end (turnaround) manoeuvres, all of which are judged. The manoeuvres include elements and combinations of lines, loops, rolls, knife-edge, stall turns, torque rolls, and tail slides.