It is a simple and light way of controlling a flying model aircraft in circular flight. The aircraft is connected to the operator by a pair of lines, attached to a handle, that work the elevator of the model.
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Why fly Control Line? Control Line flying is a unique way of experiencing the flight of your model. Unlike Radio Control, you are directly attached to your model through a set of lines. The model is only a short distance away, and the pilot is able to tell what the model is doing, even without looking. It is totally possible to fly a CL model "eyes off", even through manoeuvres. Due to the proximity to the flier and to spectators, Control Line offers both unique challenges and unique advantages over other forms of model aviation. Control line sport flying is also a lot cheaper than RC sport flying, and takes a lot less room. Noise is less a concern, since the airplane gets no more than 80 feet off the ground, at the worst. With electric power available these days, C/L flying is even quieter!
Control line (also called U-Control) - The elevator of the model allows the model to be controlled in the pitch axis. It is constrained to fly on the surface of a hemisphere by the control lines.
Pre-flight Checks. - Immediately before each flight, the flyer must verify the actual conditions and the proper functioning of all parts contributing to an efficient and safe flight of the model and the proper fitting and fixation of the various parts, with special reference to engines and propellers. - Immediately after the helper has launched his model, he must leave the starting area and remove his equipment unless the helper is needed for the normal functioning of the relevant class as allowed by the class rules.
Safety Thongs. - A safety thong connecting the handle of the Control Line models to the pilot’s wrist, and strong enough to prevent accidental release of the model, shall be worn as required by corresponding FAI events. - The safety thong should have a minimum amount of slack to preclude accidental release or interfering with the controls. Releasing the controls during flight or before the model has come to a complete stop shall constitute a foul if the safety thong restrains the model and lines from flying free; if the contestant releases the controls and the safety thong during flight or before the model has come to a complete stop, the contestant shall be barred from further participation in the event and all of their previous flights cancelled. In those events not requiring the use of a safety thong, releasing the controls during flight or before the model has come to a complete stop shall bar the contestant from further participation in the event and void their previous flights in the event. - The safety thong may be a point of attachment for conducting the pull test or the thong may be tested separately from the test of control handle, lines, and control mechanism. When the thong is tested separately, it must be pulled to the test load specified for the particular model involved. The method of thong attachment shall also be able to withstand the required pull test. - Failure to use a safety thong in those events for which they are required shall constitute an infringement.
How do I learn to fly? Like with RC, its best to have an instructor. The two-hands-on-a-handle approach is good - the student pilot holds the handle, and the instructor stands slightly behind and to the right. - The instructor's left hand should be on the trainee's left shoulder and the right hand wrapped around the trainee's hand on the handle. A third person will be needed to launch the model. - An instructor can also help you pre-flight, pull-test and adjust your airplane before it actually takes to the air. Remember that if your airplane is not balanced correctly it won't fly well. For learning purposes, nose heavy is good. - The basic idea behind flying a control line airplane is that when you tilt the handle back towards yourself, you pull on the top line. This causes the airplane to go up. - Inversely, when you tilt the handle the other way, the airplane goes down.
The big temptation for the beginner is to use the wrist to control the airplane‌Don't use the wrist. Instead, aim your arm at the airplane, keeping the wrist stiff in the "neutral" position. Moving the entire arm up (pivoting at the shoulder) will cause the airplane to rise until it is right where you are pointing. Lowering the arm will cause the plane to descend. This rule works, until you start to fly inverted MAKE SURE THAT YOUR FLYING CIRCLE IS FREE OF OBSTRUCTIONS, THAT ANY SPECTATORS (WATCH OUT FOR SMALL CHILDREN!!) ARE FAR AWAY FROM THE CIRCLE AND THAT YOUR CIRCLE IS FAR AWAY FROM ANY ELECTRICAL WIRES! Getting dizzy while flying can be a problem, but after a few flights you will not get dizzy anymore. The smaller airplanes will tend to go around faster than the big ones (since the line lengths are shorter). In any case, you will usually get dizzy after the flight rather than while you are actually flying, since you are concentrating on your airplane rather than on the surroundings. To handle postflight vertigo, after the flight is over, stand in the middle of the circle with your eyes shut. The world will seem to go around in the other direction, but the nausea and vertigo will disappear. When the world stops spinning, you can again open your eyes.
The control lines are usually either stranded stainless steel cable or solid metal wires of anywhere from 0.008 in (0.20 mm) to 0.021 in (0.53 mm). Sewing thread or braided fishing line may be used instead of wires, but air resistance is greater. A third line is sometimes used to control the engine throttle, and more lines may be added to control other functions. Electrical signals sent over the wires are sometimes used in scale models to control functions such as retracting undercarriage and flaps.
There is also a control system that uses a single solid wire, this is called Monoline. When the pilot twists the wire around its axis, a spiral inside the airplane spins to move the elevator. While it can be used with some success on any type of model, it is best for speed models where the reduced aerodynamic drag of the single line is a significant advantage. The control provided is not as precise as the two-line control system. Almost all control-line models are powered with conventional model aircraft engines of various types. It is possible to fly control-line models that do not use on-board propulsion, in a mode called "whip-powered", where the pilot "leading" the model, whose lines are attached to a fishing or similar pole, supplying the necessary energy to keep the airplane aloft, in a fashion similar to kite-flying. A full-fuselage aerobatic control line Strega in flight
There are four main contest categories for control line models: •Team Racing, •Stunt/Aerobatics, •Speed, •Combat Team Racing (F2C) Team racing is also known as F2C under the FAI classification. In this event, three teams will compete simultaneously in a flying circle. Each team will consist of a pilot and a mechanic. Coordination and communication between a pilot and its mechanic is of utmost importance. The objective of the race is to complete 100 laps within the fastest timing as possible.
Though this category involves high level of expertise, beginners can work their way up by starting with profile models, commonly known as Class A. These planes have speed slightly slower (2.2s/lap - 2.8s/lap), and they are easier to manage when flying with two other pilots at the same time. As the planes are going at similar speeds (1.8s/lap to 2.0s/lap), the differentiating factors are fine details like the tuning of the engine and pit stop timing.
At the world championship level, a good pit stop is less than three seconds!
Stunt/Aerobatics (F2B) - Stunt/Aerobatics tests on the precision of the pilot in his referencing and visual skills as he brings the plane through to make creative patterns in the sky. A lot of time and effort may be involved in perfecting the movements, but appreciation given by the audience proves everything worthwhile! In a competition, the pilot will be tested on different sets of manoeuvres. A panel of judges will be situated at a spot outside the flying circle and give scores based on how precise the shapes are. Sounds tough, but it is a very worthy challenge because it tests on many concepts of control line flying and other Technical knowledge. Competition aside, this category can be very relaxing and graceful as the plane follows through the patterns within the scope of the hemisphere. Stunt flying is quite forgivable, make a mistake and you will usually still have enough time to salvage it or at least minimize damage.
Speed (F2A) Control Handle and Pylon Fork. A pylon with supports, will be placed at the disposal of the competitors by the organisers. It is compulsory that a pylon fork and control handle of standard dimensions as specified, be employed. A safety strap connecting the competitor's wrist to the control handle must be provided by the competitor and used during all flights.
A typical FAI 0.15 cubic inches (2.5cm3) speed model – with control lines stored on reel between flights. Very long inboard wing acts as a fairing for the control lines, greatly reducing aerodynamic drag. Control Handle and Pylon Fork.
Combat (F2D) - A combat event is a contest during which eliminating heats are followed by a final in which two competitors with their model aircraft fly in the same circle at the same moment for a predetermined time, the object being to cut a streamer attached on the longitudinal centre line of the opponent's model aircraft, points being awarded for each cut taken. Combat Model Aircraft Model aircraft in which the propulsion energy is provided by a piston motor(s) and in which lift is obtained by aerodynamic forces acting on surfaces which remain fixed in flight, except for control surfaces. The longitudinal centre line shall be defined as the axis of the propeller in case of a single engine model aircraft and the axis of symmetry in the case of multi-engine model aircraft.
Flight Circle
Combat Site - A combat site must consist of three concentric circles which shall be marked on the ground. The pilot circle: The flight circle: The pitting circle:
radius 2 metres. radius 20 metres radius 22 metre
Pilot Circle
FAI Control-Line events held nationally, are conducted in accordance with FAI Rules that can be found in the FAI Sporting Code Section 4 Aeromodelling Volume F2: Control-Line Model Aircraft. Specifically, these are: •F2A –CL SPEED •F2B –CL AEROBATICS •F2C –CL TEAM RACING •F2D –CL COMBAT •F2E –CL DIESEL MOTOR COMBAT •F2F –CL DIESEL PROFILE TEAM RACING •F2G –CL ELECTRIC SPEED
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