The XLR11 was the first liquid-fuel rocket engine developed in the United States for use on airplanes. Designed and built by Reaction Motors, the engine used ethyl alcohol and liquid oxygen as propellants to generate a maximum thrust of 6,000 pounds. Thrust could be varied by operating the XLR11's four combustion chambers individually or in combination.
The engine was first used in the Bell X-1. On Oct. 14, 1947, it became the first airplane in history to fly faster than the speed of sound. The XLR11 also was used in the X-1A and X-1B and in the Republic XF-91. In 1959 and 1960, while development of a more powerful engine was still underway, a pair of XLR11s were used as an interim power plant for the initial flights of the X-15 research aircraft. After 24 powered flights, the XLR11 engines were replaced by the new XLR99 engine in November 1960.
TECHNICAL NOTES: Model: XLR-11-RM-5 Chamber arrangement: Four chambers Maximum thrust: 6,000 lbs. Weight: 210 lbs.