Discus Launch Glider (DLG), Radio Controlled
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A Radio Controlled Discus Launch Glider (DLG in short) is a model aircraft glider (one that does not have a motor) designed with a pull resistant wing and fitted with a peg that allows the pilot to grab his plane by the wing tip and launch his glider after rotating in a discus motion. This motion involved turning around in a circle while running into the wind. The glider will then be released by letting go of the wing. DLG's have to be designed with several considerations in mind. First and foremost, as with any glider, it has to have a low wing loading (weight/wing surface area). Second, the wing has to be able to withstand the pull involved in the launch. A peg has to be installed in the launching wing if desired. the wing and tail surface design is made to be as aerodynamic as possible to ensure maximum launch hights. The tailboom has to be stiff enough so it does not flex too much when launched, and the rudder pushrod should be mounted on the opposite side of the launch peg to compensate for any flex in the boom.
DLG's can be broken into two major categories: ones with ailerons in the wings, allowing them to control the camber of the wing (concaving the bottom part to create more lift or to break) and ones with no ailerons. Both groups tend to have fully functional tail surfaces such as rudder and elevator. Ailerons also allow the pilot to de-camber the wing, thus reducing it's drag in order to launch it higher.
A consideration in the design of the tail surfaces is the reaction of the plane when it is being launched. In order to control the flex of the boom (that cannot be avoided), the rudder is made to have equal inertia both on the top and on the bottom of the boom, so that it keeps the boom from twisting in one particular direction. The elevator is placed in front of the rudder and has a continuous outline in order to avoid the turbulence associated with the meeting point between surfaces.
