SEMI-DYNAMIC THERMALLING

Computer analysis of three-dimensional flight of a sailplane climbing in a thermal has been done. Special attention was paid to consideration of the dynamic energy exchange between a sailplane and a thermal. It was found that in strong and narrow thermals the circling flight is not optimal. In this case, the "semi-dynamic" thermalling gives a higher rate of climb. This way of climbing in a thermal entails some almost aerobatic manoeuvers; thus it is delicate to perform it in practice. Some ideas about the instruments necessary for the propor semi-dynamic thermalling are also given.