Reaction Motors Inc. (RMI) was formed in 1941 by four members of the American Rocket Society, James Hart Wyld, John Shesta, Lovell Lawrence, Jr., and Hugh Franklin Pierce. The company developed the rocket engines used by the the early NASA (NACA)/Air Force X planes including the Bell X-1 that first broke the sound barrier in 1947 and the North American X-15. Reaction Motors was taken over by Thiokol Chemical in 1958 and became the Reaction Motor Division. Later the division became Thiokol Propulsion which was acquired by ATK (Alliant Techsystems) in 2001. Robert Holder was an employee at RMI.