The term 'FLIER OF THE X-1' refers to the American test pilot Chuck Yeager, who was the first person to fly faster than the speed of sound in 1947. He achieved this feat while piloting the Bell X-1 rocket plane, which was part of a joint research project between the United States Air Force and the National Advisory Committee for Aeronautics. Yeager's flight marked a major milestone in aviation history and he was celebrated as a national hero.