Reaction Motors, Inc. (RMI) was an early American maker of liquid-fueled rocket engines, located in New Jersey. RMI engines with 6,000 lbf (27 kN) thrust powered the Bell X-1 rocket aircraft that first broke the sound barrier in 1947, and later aircraft such the X-1A, X-1E, and the Douglas D-558-2 Skyrocket. A 20,000 lbf (89 kN) thrust RMI engine also powered the Viking research rocket, the first large liquid-fueled US high-altitude rocket. RMI was merged with Thiokol in 1958, where it produced the XLR-99 engine that powered the X-15 rocket aircraft.

The SAM-N-2 Lark project was a solid-fuel boosted, liquid-fueled surface-to-air missile developed by the United States Navy to meet the kamikaze threat. It was developed as a crash program to introduce a medium-range defensive layer that would attack targets between the long-range combat air patrols and short-range anti-aircraft artillery. This produced a design with roughly 30 miles (48 km) maximum range and subsonic performance, suitable for attacks against Japanese aircraft.