Free flight is the oldest form of model flying. It offers fun and exercise in the open. With models ranging from gliders to rubber powered and diesel or glo-plug engine types, they are built from plans or kit sets. Gliders can be launched by a towline or hand launched with a pair of fast feet. After release, they are free to soar in the rising air currents. Rubber powered models are popular both as a competition class and for sports flying.