A predecessor of NASA. It was established in 1915 to ‘supervise and direct the scientific study of the problems of flight, with a view to their practical solutions’. By 1946, NACA had almost 7 000 employees at six centres throughout the USA. The organization's research and testing programmes resulted in the Bell X-1 rocket plane breaking the sound barrier on 14 October 1947. NACA subsequently developed the X-15 rocket plane and ideas for crewed spacecraft, but was replaced by NASA in 1958.