Control Line Flying is one of the oldest forms of model aircraft aviation and the largest model aircraft sport practised worldwide due to its affordability. Over the past five decades Control Line has developed into a high level international competition sport.
The four international Control Line contest categories are SPEED (F2A), PRECISION AEROBATICS (F2B) , TEAM RACING (F2C) and COMBAT (F2D).
The international rules are formulated and defined by the Federation Aeronautique Internationale (FAI). World Championships are held every two years.
Speed
(F2A)
A flight is timed over nine laps once the pilot has placed his handle in a pylon fork at the centre of the circle. In the international class, F2A , engine capacity is 2.5cc (.15 cubic inches)The flight radius is 17.69 metres making nine laps equal to one kilometre.
Top speeds are above 300 kilometres per hour. Engines have glow plug ignition and operate at around 36000 rpm ,developing over two brake horsepower.
Percision Aerobatics (F2B)
Also called STUNT, the international class, F2B , has a program of sixteen predetermined advanced manoeuvres involving square ,round and triangular loops that is performed with corners specified at 1.5 meter radius. Points are given for precision by a panel of judges. All manoeuvres except the overhead eight should have their low level at 1.5 metres above the ground. It takes nerve and adrenalin to do this repeatedly.
To complete all sixteen manoeuvres takes about five minutes. Line length up to a maximum of 20 meters are used and the average speed of the model is around 85 kilometres per hour. Wingspan around 1.5 metres.
Team
Racing (F2C)
A pilot and mechanic compete as a team to fly a small 350 gram,65 cm wingspan model over a tarmac or concrete surface. Lines are 15.92 metres long.
Three teams compete simultaneously in the same circle and the object is to complete the predetermined amount of laps including three pit stops as fast as possible. The mechanic stands at a pit area outside the marked flight circle. He starts the engine and releases the model at the start signal and then stand alert for re-fuelling.
To pit the pilot actuates a fuel shutoff valve by a quick down elevator movement so that the model can approach the mechanic at the optimum speed of around 50 kilometres per hour. The mechanic will catch the model by the wing, refill the fuel tank and restart the engine with his finger. Ground time for a good pit stop is around three seconds. Races can be won or lost based upon the speed at which a pit stop can be done.
The race course is 100 laps equating to 10 kilometres. Flying speeds are around 200 kilometres per hour which means the pilots have to turn one lap in 1.8 seconds.
Combat
(F2D)
In a circle laid over grass, two pilots fly models that have paper streamers attached to the tail of their aeroplanes. The object is to cut the opponent’s streamer with your propeller, and to stay airborne.
At the end of the four minute bout the amount of cuts made and airtime are given points to determine the winner of the bout. The contest is run by matching competitors that haven’t collected two losses until a single winner remains.
In the international class, F2D, the pilots are assisted by two mechanics each and are allowed one spare model per bout. Aeroplane speed are ridiculously fast.
