Reaction Motors/Thiokol XLR11
Reaction Motors/Thiokol XLR99

Reaction Motors Inc. was formed in 1941 by four members of the American Rocket Society. 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 famous North American X-15.
Reaction Motors was taken over by Thiokol Chemical in 1958 to become the Reaction Motor Division. Later the division became Thiokol Propulsion which was acquired by ATK (Alliant Techsystems) in 2001.