SAL (model flight)
The SAL ( S ide A rm L aunch) is a throwing or start technique in the model aircraft , with the radio-controlled model gliders, so-called DLG s ( D iscus- L aunch- G lids) are flung into the air.
The model aircraft is picked up at one end of the wing and, depending on the technology, is thrown around the body axis of the thrower with one or one and a half turns. When the desired departure direction is reached, the aircraft is released. The take-off speed can be increased massively if you run one or more steps in the desired take-off direction before turning. This sequence of movements is vaguely similar to the discus throwing discipline , from which the name Discus-Launch-Glider derives.
Due to the forces that occur during the spin start (especially shear forces in the transition between the wing and the fuselage ) and aerodynamic loads (due to launch speeds of up to 120 km / h), this take-off method places enormous stress on the aircraft. That is why most of these models consist of a combination of light and resilient materials, such as composite materials with glass, aramid and carbon fibers , and they are often made in a shell construction, more rarely in a rib construction or Jedelsky full balsa construction. This makes these models lightweights (around 300 g), although they are usually equipped with 3 to 4 servos to control ailerons, rudder and elevator and, if necessary, flaps.
To exploit the plugged by the throwing technique in the model energy as possible, these models usually have very thin airfoils (z. B. the profile strak AG455ct-02f to 02f-AG47ct with about 6.5-7% relative thickness), often with flaps , a low C w value and a long tail lever arm. The rudders are usually offset downwards in such a way that they also have an aerodynamically effective surface under half of the tail girder or the fuselage tube, so that less torsional forces arise during the throw and the model is quickly stabilized around the yaw axis after it is released from the rotation .
For the spin start, these models are usually also equipped with an easy-to-grip pin, a fin or a hole at the end of the wing (throwing pin, "throwing blade"). This throwing aid must be an integral part of the aircraft within the wingspan ; Slings, loops, extendable or retractable or throwable throwing aids are not permitted according to the regulations.
This take-off technique in combination with the light and, thanks to the sophisticated aerodynamics, also very powerful models in gliding, allows extended gliding flights on the plane without a motor drive or other starting aids. Depending on the level of exercise and strength of the thrower, the standard span of 150 cm specified in the F3K competition class allows starting heights of 30 to 50 m to be achieved. The Swedish pilot Mattias Hammarskiold, for example, reaches throwing heights of over 60 meters. From these heights you can usually find usable updrafts without any problems on even slightly thermal days, which quickly carry the model higher due to the low load on the wing . Flight times of several hours - depending on the battery capacity of the remote control and neck relaxation - are often achievable.
Since 2008 the FAI has dedicated its own international competition class to the SAL / DLG with the F3K class . In July 2011 the first official FAI World Championship in the F3K discipline took place in Arboga, Sweden.
Individual evidence
- ↑ Airfoiltools - profile collection with illustration of the AG455ct-02f by Dr. Drela
- ↑ Competition rules class F3 of the FAI / CIAM from page 25 ( Memento of the original from August 20, 2012 in the Internet Archive ) Info: The archive link was automatically inserted and not yet checked. Please check the original and archive link according to the instructions and then remove this notice. (2012 edition, PDF, accessed October 6, 2012)
- ↑ Announcement / Bulletin of the FAI World Championships for Soaring Model Aircraft F3K in July 2011 in Arboga, SWE ( Memento of the original from December 26, 2015 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. PDF, accessed December 25, 2015
