Discus Launch Glider

The SAL ( Side Arm Launch ) is a throw or launch technique in the model airplane, with the radio-controlled model gliders, called DLGs ( Discus Launch Glider ), are thrown into the air.

Thereby, the model aircraft is made at one end of the support surface in the hand and - depending on the technique - a spun or a half turns around the body axis of the body of the thrower. Upon reaching the desired departure direction the aircraft is released. The departure rate can be increased massively when a restart is carried out by one or more steps in the desired direction before departure of the rotation. This movement has distant similarity with the athletics discipline discus what the name Discus Launch Glider stems.

Due to the centrifugal forces occurring during the start (especially shear forces in the transition wing - fuselage ) and aerodynamic loads ( by dropping speeds up to 120 km / h) does this start method an enormous stress on the aircraft. Therefore, most of these models are made from a combination of lightweight and durable materials, such as composites with glass, aramid and carbon fibers, and they are often manufactured in shell design, rare in rib design or Jedelsky - balsa construction. Thus, these models are lightweight ( 300 g), although they are usually equipped with 3 to 4 servos to control transverse, lateral and vertical rudders and flaps if necessary.

To exploit the inserted through the throwing technique in the model energy as possible, this model usually have very thin airfoils (eg, the profile strak AG455ct - 02f - 02f on AG47ct with about 6.5-7 % relative thickness), often with flaps, a low drag coefficient and a long tail lever arm. The tail fins are attached mostly displaced downward so that they have an aerodynamically active surface and below the tail boom or the fuselage tube, thus less torsional forces created during the cast and the model after being released from the rotation is stabilized quickly about the yaw axis.

These models are for the spin start usually with a good tangible pin, a fin or a hole at the end of the wing fitted ( throwing peg, " throw Blade" ). This litter assistance must be an integral, integrated part of the aircraft within the span; Loops, loops, from or retractable or droppable throwing aids are not permitted under the regulations.

This launch technique in combination with the light and by the sophisticated aerodynamics also very powerful glide models allows extensive glider flights in the plane without an engine or other starting aids. Depending on the exercise and strength of the thrower can be reached at the given Competition Class F3K standard wingspan of 150 cm initial height of 30 to 50 m. The Swedish driver Mattias Hammarskiold for example, reaches throw heights of over 60 meters. From these heights can be on even days only slightly thermal find most easily usable thermals that carry the model due to the low wing loading quickly higher. Flight times over several hours - depending on the battery capacity of the remote control and neck relaxation - are often accessible.

Since 2008, the FAI has dedicated the SAL / DLG with the class F3K its own international competition class. In July 2011, the first official FAI World Cup took place in the discipline F3K in Arboga, Sweden, instead.

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