For an unpowered aircraft, the utmost flight time is limited by factors such as climatic conditions and pilot endurance.???? ???? ??????? ?? ?? ??? ?????? ?? ????? ???? ?? ?? ????? ??????? ?? ???? ??? ?? ??????? ????? ????? ??????? ???????? ("??? ???") ? ??????? ??????????? ????? ???. ???? ?? ??????? ? ??? ??? ??? ??????? ??????.[?]On a set-wing ai