xlr11

This is the Bell X-1 46-062 (No. 1) nicknamed "Glamorous Glennis" and flown by Chuck Yeager breaking thru the sound barrier in level flight over Muroc (later Edwards AFB) on 14 Oct 47.

This a/c is now displayed at the NMUSAF in Dayton, OH. As per the NMUSAF website: "The XF-91, a high-speed experimental interceptor, was America's first rocket-powered combat-type fighter to fly faster than the speed of sound. The airplane had a number of unusual design features -- an inverse taper wing (wider at the tips than at the roots), a variable incidence wing that could be varied in flight (high angle of attack for takeoff and landing and low angle of attack for high-speed flight), a main landing gear that retracted outward with the tandem wheels being housed in the wing tips, and a rocket engine that augmented the standard jet engine to provide an outstanding rate of climb. The airplane made its first flight on May 9, 1949. Numerous other test flights were made, providing valuable research data, but the airplane was not put into production because it did not carry sufficient fuel for a flight of longer than 25 minutes and did not incorporate the latest type of fire control system. The XF-91 on display was transferred to the museum from Edwards Air Force Base, Calif., in May 1955. Engine: General Electric J47 of 6,700 lbs. thrust with afterburner and Reaction Motors rocket of 6,000 lbs. thrust."

This appears to be a Reaction Motors XLR-11 rocket motor. See: en.wikipedia.org/wiki/Reaction_Motors_XLR11