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X-1 Bell
High-Speed Research Aircraft

The Bell X-1 is one of the most significant test aircraft in history since it was the first plane to conclusively break the sound barrier. The X-1 project began in 1944 when the US Army Air Force (USAAF) and the National Advisory Committee for Aeronautics (NACA) agreed on a joint program to investigate the possibility of supersonic flight. The feasibility of flight above Mach 1 depended on the development of powerful rocket engines and new materials to counter the heat generated by friction encountered at high speeds.

A contract was soon awarded to Bell for the construction of three XS-1 (experimental supersonic - 1) aircraft, though the 'S' portion of the designation was later dropped. The fuselage was patterned after a .50 caliber bullet to reduce drag. The portly shape also provided significant internal volume for a powerful rocket motor, fuel, and data collection equipment.

Though the X-1 had originally been designed for conventional takeoffs, all flights but one were carried aloft by a B-29 or B-50 Superfortress mother plane. The X-1 was lifted to an altitude of 20,000 ft (6,100 m) before being released to ignite its rocket engines. This technique was advantageous since it improved safety in ground operations and also vastly increased the aircraft's performance.

The flight test program began with a few test glides and powered flights, but the most important flight of the X-1 came on 14 October 1947. It was on this date that Capt. Charles Yeager became the first pilot to break the "sound barrier" when he reached Mach 1.06 at 43,000 ft (13,120 m) over the Mojave Desert near Muroc Dry Lake, California. A few days later, the X-1-1 also set an altitude record by reaching 71,900 ft (21,935 m).

Following the loss of the X-1-3 in a ground accident, NASA ordered a further three examples called the X-1A, X-1B, and X-1D to explore flight at Mach 2. Chuck Yeager set a new speed record of Mach 2.44 aboard the X-1A in 1953, but both this model and the X-1D were lost following propulsion explosions. Despite these dangers, the X-1-2 was rebuilt as the X-1E to conduct further experiments at Mach 2 and beyond. This model became one of the fastest and highest flying of the series thanks to its reduced weight and drag.

The X-1 program was completed in 1958, but its impact on aviation history is considerable. The three surviving X-1 models, including the historic X-1-1, have been preserved at sites across the country.

Data below for X-1-1
Last modified 27 September 2009

First Flight 19 January 1946 [unpowered glide]
9 December 1946 [powered flight]

CREW: one: pilot



Wing Root (X-1-1) NACA 65-110
(X-1-2) NACA 65-108
(X-1E) NACA 64A004
Wing Tip

(X-1-1) NACA 65-110
(X-1-2) NACA 65-108
(X-1E) NACA 64A004

Length 31.00 ft (9.45 m)
Wingspan 28.00 ft (8.53 m)
Height 10.85 ft (3.31 m)
Wing Area 130.0 ft (12.01 m)
Canard Area

not applicable

Empty 4,890 lb (2,220 kg)
Normal Takeoff 12,225 lb (5,545 kg)
Max Takeoff 13,400 lb (6,080 kg)
Fuel Capacity internal: unknown
external: unknown
Max Payload


Powerplant one Reaction Motors XLR11-RM3 rocket motor
Thrust 6,000 lb (26.69 kN)

Max Level Speed at altitude: 955 mph (1,540 km/h) at 40,130 ft (12,245 m), Mach 1.45
at sea level: unknown
Initial Climb Rate unknown
Service Ceiling 71,900 ft (21,935 m)
Range unknown
g-Limits unknown

XS-1 (later X-1) Original designation for series of joint US Army Air Force and NACA research aircraft to explore supersonic flight (hence the 'S' designation)
X-1-1 First X-1 completed and made the first unpowered flight of the program, was also the first aircraft to exceed Mach 1 on 14 October 1947 with Capt. Charles Yeager as pilot, also completed the only runway takeoff of the X-1 program, completed 82 flights and is now on display at the National Air & Space Museum
X-1-2 Second example built and flew the first powered flight, completed 74 flights
X-1-3 Third X-1 built but completed three years late due to propulsion development problems, exploded during ground operations and was destroyed along with its B-50 mothership
X-1A Modified X-1 design with a more traditional cockpit canopy, lengthened fuselage for increased fuel capacity, and improved fuel pumps; set a speed record of Mach 2.435 on 12 December 1953 and an altitude record of 90,440 ft (27,590 m) in June 1954 but was lost when an in-flight explosion forced the mothership to jettison the craft; completed 29 flights
X-1B Equipped with aerodynamic heating instrumentation for thermal research, completed 27 flights and is now on display at the Alabama Space and Rocket Center at Huntsville
X-1C Cancelled
X-1D Final model built but was lost when it had to be jettisoned from its B-50 mothership following a propulsion explosion
X-1E X-1-2 model rebuilt with an improved cockpit canopy, new 4% thick high-speed wing, and rocket-assisted ejection seat; achieved Mach 2.24 and a maximum altitude of 75,000 ft (22,880 m), completed 26 flights and is now on display at Edwards Air Force Base


United States (US Army Air Force)
United States (US Air Force)
United States (NASA)



  • Aviation Enthusiast Corner X-1 site
  • Chant, Christopher and Taylor, Michael J.H. The World's Greatest Aircraft. Edison, NJ: Chartwell Books, 2006, p. 281, Bell X-1.
  • Donald, David, ed. The Complete Encyclopedia of World Aircraft. NY: Barnes & Noble, 1997, p. 115, Bell X-1.
  • Dryden Research Center Photo Gallery
  • Miller, Jay. The X-Planes: X-1 to X-45. Hinckley, England: Midland Publishing, 2001, p. 20-52, Bell X-1, X-1A, X-1B, X-1C, X-1D, X-1E.
  • National Air & Space Museum X-1 site
  • Winchester, Jim. Concept Aircraft: Prototypes, X-Planes and Experimental Aircraft. San Diego, CA: Thunder Bay Press, 2005, p. 30-31, Bell X-1, X-1A.
  • Winchester, Jim. The World's Worst Aircraft: From Pioneering Failures to Multimillion Dollar Disasters. NY: Barnes & Noble, 2005, p. 184-185, Bell X-1 and X-2.

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