,,ULTRA-LIGHT'' AND ,,LI GHT'' SAILPLANES

Abstract

The objective of flying by exploiting the air motions has been attempted and realized in different ways. At the start of the sport of soaring the main goal was endurance, based on slope soaring and bungie launching. When the possibility of thermal soaring was discovered and winch launching and aero-tow were introduced, the interest shifted towards cross-country distance, quickly followed by speed, the two objectives being intertwined. The development of hang-gliders and paragliders, aimed at low cost and freedom, started late but very successfully. The development of powered sailplanes also aims at freedom, in particular freedom from launching equipment and means of retrieving. The development of "ultra light" and "light" sailplanes (the object of this paper) also aims at low cost and freedom: freedom from expensive launching equipment, freedom from heavy bureaucracy (for instance, less demanding certification processes), freedom from the need of airfields. The recent introduction of the "World Class" can be seen as a compromise.  It is interesting to note that the objective to soar as often as possible, i.e., the ability to exploit very weak soaring conditions, has received little attention so far.