Discus Launch Glider

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A Discus Launch Glider (DLG) is a radio controlled model sailplane launched using a 'discus launch' in which the glider is held by a wingtip and rotated around the flyer by hand before release. Using this method of launching the average flier can achieve launch heights of greater than 140 feet, with the top fliers exceeding 200 foot high launches.

The discus method of hand launching has now in effect replaced the older 'javelin style' launch, where a hand launched model glider would be launched over-arm, like a javelin would be thrown. The discus launch is far easier, more efficient and less physically demanding than the javellin launch.

Although some DLG designs utilise a traditional built-up construction using balsa wood and covering film, most DLG models are generally now constructed from composite materials, in the form of Kevlar, carbon fibre and glass fibre. Fuselages are moulded in Kevlar/carbon and epoxy, with wings either moulded as a hollow composite shell, or vacuum bagged over a wire-cut foam core.

Most DLG models use aileron, rudder and elevator control, with the ailerons also being used as camber changing flaps for different modes of flight and also as airbrakes for landing. A modern DLG model weighs only approx 9 or 10 ounces and has extremely sophisticated aerodynamics. Many pilots use computer radio transmitters with full mixing and flight mode capabilities in order to optimise performance and set up the models for flight as near perfectly as possible.

DLG models are used for both general fun/sport flying and also for contest flying.

F3K is the international contest class for radio controlled, hand-launched model gliders.

Although the roots of RC hand-launched gliders can be traced back to the late 1970's, F3K is a relatively new aeromodelling disipline, becoming officially recognised by FAI CIAM (the international body responsible for aeromodelling competition displines) with full official status in 2007.

F3K gliders are limited to a 1.5 metre wingspan and F3K competitions consist of a group of fliers completing a number of pre-defined flight tasks, centred around launching, flying and landing the model in a number of timed durations, using just the hand launch itself and thermal currents of rising air (thermals) to power the flight. Since thermals cannot be seen, F3K pilots rely on grounds signs such as surface-wind velocity, temperature, and direction and or they rely on signs such as circling birds, bugs, or rising particulates. The pilot uses these signs to resolve the approximate location of the thermal. For F3K tasks where longer durations are needed, positioning and maintaining the model glider in thermal rising air is paramount. Contest strategy includes determining the location of thermals before the pilot launches.

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