The Bell X-1-1 was equipped with a 10 percent wing and 8-percent tail, (measured as the thickness divided by the chord of the airfoil), powered with an XLR-11 rocket engine and was air-launched from under a B-29A (45-21800). The X-1-1 was glide-tested at Pinecastle Army Air Field, Orlando, Florida, beginning on January 25, 1946.

The first powered flight of the X-1-1 was made on April 11, 1946, at Muroc Army Air Field with Chalmers "Slick" Goodlin, a Bell test pilot, at the controls.

On October 14, 1947, with USAF Captain Charles "Chuck" Yeager as pilot, the X-1-1 flew faster than the speed of sound for what is generally accepted as the first supersonic flight by a piloted aircraft. Captain Yeager ignited the four-chambered XLR-11 rocket engines after being air-launched from under the bomb bay of a JTB-29A (#45-21800) at 21,000 feet. The 6,000-pound thrust ethyl alcohol/liquid oxygen burning rockets, built by Reaction Motors, Inc., pushed him up to a speed of Mach 1.06 at an altitude of 45,000 feet.

On January 5, 1949, the X-1-1 aircraft with Yeager as pilot achieved the only ground takeoff of the X-1 program. He reached just over 23,000 feet before the limited propellant was exhausted.

Captain Yeager was also the pilot when the X-1-1 reached its maximum speed, Mach 1.45. Another USAF pilot. Lt. Col. Frank Everest, Jr., was credited with taking the X-1-1 to its maximum altitude of 71,902 feet.

The X-1-1 retired on May 12, 1950 after making eighty-two glide and powered flights with ten different pilots. On August 26, 1950 the aircraft became a permanent resident of the National Air Museum, In Washington, D.C.

The X-1-2 was also equipped with the 10-percent wing and 8-percent tail, powered with an XLR-11 rocket engine and was air-launched from under a B-29A (45-21800). The aircraft made its first powered flight on December 9, 1946 with Chalmers "Slick" Goodlin at the controls. As with the X-1-1 the X-1-2 continued to investigate transonic/supersonic flight regime. NACA pilot Herbert Hoover became the first civilian to fly Mach 1, March 10, 1948.

X-1-2 flew until October 23, 1951, completing 74 glide and powered flights with nine different pilots, when it was retired to be rebuilt as X-1E.

The X-1-3 was delayed due to a turbopump development problem. It eventually fell three years behind the delivery date with its arrivalto NACA High-Speed Flight Research Station at Edwards, California, in April 1951. The first glide flight was made on July 20, 1951. On November 9, 1951 following a "captive" flight the X-1-3 blew up under its own launch airplane, [EB-50A (46-006)] during static ground operations at Edwards Air Force Base, California. The B-50 was destroyed and the Bell pilot of the X-1-3, Joseph Cannon was severely burned.