Bell X-1

infobox Aircraft
name = X-1
type = rocket plane
manufacturer = Bell Aircraft

caption = X-1 #46-062, nicknamed "Glamorous Glennis"
designer =
first flight = 19 January 1946
introduced =
retired =
status = Retired
primary user = United States Air Force
more users = National Advisory Committee for Aeronautics
produced =
number built =
unit cost =
variants with their own articles =

The Bell X-1, originally designated XS-1, was a joint NACA-U.S. Army Air Forces/US Air Force supersonic research project and the first aircraft to exceed the speed of sound in controlled, level flight. This resulted in the first of the so-called X-planes, an American series of experimental aircraft designated for testing of new technologies and usually kept highly secret.

Design and development


On 16 March 1945 the United States Army Air Forces' Flight Test Division and the National Advisory Committee for Aeronautics (NACA) (now NASA) contracted Bell Aircraft to build three XS-1 (for "Experimental, Supersonic", later X-1) aircraft to obtain flight data on conditions in the transonic speed range.Miller 2001] The XS-1 was the first high-speed aircraft built purely for aviation research purposes and was never intended for production.

The X-1 was in principle a "bullet with wings" that closely resembled the shape of the Browning .50-caliber (12.7 mm) machine gun bullet that was known to be stable in supersonic flight. [ Yeager et al 1997, p. 14.] The pattern shape was followed to the point of removing a canopy. Instead, the pilot sat behind a sloped, framed window inside a confined cockpit in the nose. After the aircraft ran into compressibility problems in 1947 it was modified to feature a variable-incidence tailplane that allowed it to pass through the sound barrier safely.Wings on my Sleeve- Eric "Winkle" Brown]

Operational history

Bell Aircraft Chief Test Pilot, Jack Woolams became the first to fly the XS-1, in a glide flight over Pinecastle Army Airfield, in Florida, on 25 January 1946. Woolams would complete nine additional glide flights over Pinecastle before March 1946, when the #1 aircraft was returned to Bell for modifications in anticipation of the powered flight tests, planned for Muroc Army Air Field (now Edwards Air Force Base) in California. [Anderson, Clarence E. "Bud". [ "Initial Glide Flights."] ] Following Woolams' death on 30 August, 1946, Chalmers "Slick" Goodlin was the primary Bell Aircraft test pilot of X-1-1 (serial 46-062). He made 26 successful flights in both of the X-1 aircraft from September 1946 until June 1947.

The Army Air Force was unhappy with the cautious pace of flight envelope expansion and Bell Aircraft's flight test contract for aircraft #46-062 was terminated and was taken over by the Army Air Force Flight Test Division on 24 June after months of negotiation. Goodlin had demanded a US$150,000 bonus for breaking the sound barrier.Yeager and Janos 1986, p. 121.] Wolfe 1979 p. 52–53.] [Anderson, Clarence E. "Bud". [ "A Turning Point."] ] Flight tests of the X-1-2 (serial 46-063) would be conducted by NACA to provide design data for later production high-performance aircraft.

On 14 October 1947, just under a month after the United States Air Force had been created as a separate service, the tests culminated in the first manned supersonic flight, piloted by Air Force Captain Charles "Chuck" Yeager in aircraft #46-062, which he had christened ‘"Glamorous Glennis"’, after his wife. The rocket-powered aircraft was launched from the bomb bay of a specially modified B-29 and glided to a landing on a runway. XS-1 flight number 50 is the first one where the X-1 recorded supersonic flight, at Mach 1.06 (361 m/s, 1,299 km/h, 807.2 mph) peak speed; however, Yeager and many other personnel believe Flight #49 (also with Yeager piloting), which reached a top recorded speed of Mach 0.997 (339 m/s, 1,221 km/h), may have, in fact, exceeded Mach 1.Fact|date=March 2008 (The measurements were not accurate to three significant figures and no sonic boom was recorded for that flight.)

As a result of the X-1's initial supersonic flight, the National Aeronautics Association voted its 1948 Collier Trophy to be shared by the three main participants in the program. Honored at the White House by President Harry S. Truman were Larry Bell for Bell Aircraft, Captain Yeager for piloting the flights, and John Stack for the NACA contributions.


The research techniques used in the X-1 program became the pattern for all subsequent X-craft projects. The NACA X-1 procedures and personnel also helped lay the foundation of America's space program in the 1960s. The X-1 project defined and solidified the post-war cooperative union between U.S. military needs, industrial capabilities, and research facilities. The flight data collected by the NACA in the X-1 tests then provided a basis for American aviation supremacy in the latter half of the 20th century.


Aircraft #46-062 is currently on display in the Milestones of Flight gallery of the National Air and Space Museum in Washington, DC, alongside the Spirit of St. Louis and SpaceShipOne. Aircraft #46-063, now the X-1E, is on display in front of the NASA Dryden Flight Research Center headquarters building.


Later variants of the X-1 were built to test different aspects of supersonic flight; one of these, the X-1A, with Yeager at the controls, inadvertently demonstrated a very dangerous characteristic of fast (Mach 2-plus) supersonic flight: inertia coupling. Only Yeager's skills as an aviator prevented him from dying that day; later Mel Apt would die testing the Bell X-2 under similar circumstances.


Ordered by the Air Force on 2 April, 1948, the X-1A (serial 48-1384) was intended to investigate aerodynamic phenomena at speeds above Mach 2 (681 m/s, 2,451 km/h) and altitudes greater than 90,000 feet (27 km), specifically focusing on dynamic stability and air loads. Longer and heavier than the original X-1, with a bubble canopy for better vision, the X-1A was powered by the same Reaction Motors XLR-11 rocket engine. The aircraft first flew, unpowered, on 14 February 1953 at Edwards AFB, with the first powered flight on 21 February. Both flights were piloted by Bell test pilot Jean Ziegler.

After NACA started its high-speed testing with the Douglas Skyrocket, culminating in Scott Crossfield achieving Mach 2.005 on 20 November 1953, the Air Force started a series of tests with the X-1A, which the test pilot of the series, Chuck Yeager, named "Operation NACA Weep". These culminated on 12 December 1953, when Yeager achieved an altitude of 74,700 feet (22,770 m) and a new air speed record of Mach 2.44 (equal to 1620 mph, 724.5 m/s, 2608 km/h at that altitude). Unlike Crossfield in the Skyrocket, Yeager achieved that in level flight. Shortly after, the plane spun out of control, due to the then not yet understood phenomenon of inertia coupling. The plane dropped from maximum altitude to 25,000 feet (7,620 m), exposing the pilot to accelerations of up to 8g, during which Yeager broke the canopy with his helmet before regaining control. [ [ Major Chuck Yeager's Flight to Mach 2.44 In the X-1A] by Dr. Jim Young, AFFTC History Office, Edwards AFB]

The aircraft was transferred to NACA in September 1954. Following modifications, including the installation of an ejection seat, the aircraft was lost on 8 August 1955 while being prepared for launch from the RB-50 mothership, becoming the first of many early X-planes that would be lost to explosions.Miller 2001] [Thompson, Lance. [ "The X-Hunters."] Air & Space, February/March 1995, ISSN 0886-2257. Retrieved: 12 March 2008.]


The X-1B (serial 48-1385) was equipped with aerodynamic heating instrumentation for thermal research (over 300 thermal probes were installed on its surface). It was similar to the X-1A except for having a slightly different wing. The X-1B was used for high speed research by the US Air Force starting from October 1954 prior to being turned over to the NACA in January 1955. NACA continued to fly the aircraft until January 1958 when cracks in the fuel tanks forced its grounding. The X-1B completed a total of 27 flights. A notable achievement was the installation of a system of small reaction rockets used for directional control, making the X-1B the first aircraft to fly with this sophisticated control system, later used in the X-15. The X-1B is now on display at the National Museum of the United States Air Force, Wright-Patterson Air Force Base at Dayton, Ohio.


The X-1C (serial 48-1387) [Baugher, Joe. [ 1946-1948 USAAF Serial Numbers] 20 January 2008. Retrieved: 12 March 2008.] was intended to test armaments and munitions in the high transonic and supersonic flight regimes. It was canceled while still in the mock-up stage, as the birth of transonic and supersonic-capable aircraft like the North American F-86 Sabre and the North American F-100 Super Sabre eliminated the need for a dedicated experimental test platform. [ [ X-1A in flight with flight data superimposed] NASA Dryden photo number E-24911.]


The X-1D (serial 48-1386) was the first of the second generation of supersonic rocket planes. Flown from an EB-50A (s/n #46-006), it was to be used for heat transfer research. The X-1D was equipped with a new low-pressure fuel system and a slightly increased fuel capacity. There were also some minor changes to the avionics set.

On 24 July 1951, with Bell test pilot Jean Ziegler at the controls, the X-1D was launched over Rogers Dry Lake, on what was to become the only successful flight of its career. The unpowered glide was completed after a nine-minute descent, but upon landing, the nose gear failed and the aircraft slid ungracefully to a stop. Repairs took several weeks to complete and a second flight was scheduled for mid-August. On 22 August 1951, the X-1D was lost in a fuel explosion during preparations for the first powered flight. The aircraft was destroyed upon impact after it was jettisoned from its EB-50A mothership. [ Fact Sheet X-1] NASA Dryden Fact Sheet. Retrieved: 12 March 2008.]


The X-1E was the result of a reconstruction of the X-1-2 (serial 46-063), in order to pursue the goals originally set out for the X-1D and X-1-3, both lost in explosions in 1951. The cause of the mysterious explosions was finally traced to the use of Ulmer leather gaskets impregnated with tricresyl phosphate (TCP), a leather treatment, which was used in the liquid oxygen plumbing. TCP becomes unstable and explosive in the presence of pure oxygen and mechanical shock. [ [ NASA. Dryden Collections. X-1A. "Photo # E-24911"] ] This mistake cost two lives, caused injuries and lost several aircraft. [ [ Goleta Air & Space Museum. Edwards Air Force Base.] ]

The changes included:
* A turbopump fuel feed system, which eliminated the high-pressure nitrogen fuel system used in '062 and '063. (Concerns about metal fatigue in the nitrogen fuel system resulted in the grounding of the X-1-2 after its 54th flight in its original configuration.) [ Fact Sheet X-1E] NASA Dryden Fact Sheet.]
* A re-profiled super-thin wing (3⅜ inches at the root), based on the X-3 Stiletto wing profile, enabling the X-1E to reach Mach 2.
* A 'knife-edge' windscreen replaced the original greenhouse glazing, an upward-opening canopy replaced the fuselage-side hatch and allowed the inclusion of an ejection seat.
* The addition of 200 pressure ports for aerodynamic data, and 343 strain gauges to measure structural loads and aerodynamic heating along the wing and fuselage.

The X-1E first flew on 15 December, 1955, a glide flight under the controls of USAF test pilot Joe Walker. Walker left the X-1E program in 1958, after 21 flights, attaining a maximum speed of Mach 2.21 (752 m/s, 2,704 km/h). NACA research pilot John B. McKay took his place in September 1958, completing five flights in pursuit of Mach 3 (1,021 m/s, 3,675 km/h). before the X-1E was permanently grounded following its 26th flight, in November 1958, due to the discovery of structural cracks in the fuel tank wall.

pecification (Bell X-1)

aircraft specification

plane or copter?=plane
jet or prop?=jet
length main=30 ft 11 in
length alt=9.4 m
span main=28 ft
span alt=8.5 m
height main=10 ft
height alt=3.3 m
area main=130 ft²
area alt=12 m²
empty weight main=7,000 lb
empty weight alt=3,175 kg
loaded weight main=12,225 lb
loaded weight alt=5,545 kg
max takeoff weight main=12,250 lb
max takeoff weight alt=5,557 kg
more general=
engine (jet)=Reaction Motors XLR-11-RM3
type of jet=liquid fuel rocket
number of jets= 4
thrust main=6,000 lbf
thrust alt=26.7 kN
afterburning thrust main=
afterburning thrust alt=
max speed main=957 mph (Mach 1.26)
max speed alt=1,541 km/h
range main=5 minutes
range alt= powered endurance
ceiling main=71,900 ft
ceiling alt=21,900 m
climb rate main=
climb rate alt=
loading main=94 lb/ft²
loading alt=463 kg/m²
more performance=

pecification (Bell X-1E)

aircraft specification

plane or copter?=plane
jet or prop?=jet
ref=Miller, 2001Miller 2001]
length main= 31 ft
length alt=9.4488 m
span main= 22 ft 10 in
span alt= 6.9596 m
height main= 10 ft 10 in
height alt= 3.3 m
area main= 115 ft²
area alt= 35.052 m²
empty weight main= 6,850 lb
empty weight alt= 3107.107 kg
loaded weight main= 14,750 lb
loaded weight alt= 6,690.487 kg
max takeoff weight main=
max takeoff weight alt=
more general=
engine (jet)= Reaction Motors RMI LR-8-RM-5
type of jet=rocket
number of jets= 1
thrust main= 6,000 lbf
thrust alt= 26.7 kN
afterburning thrust main=
afterburning thrust alt=
max speed main= 1,450 mph (Mach 2.24)
max speed alt= 2,333.548 km/h
range main= 4 minutes 45 seconds
range alt= (powered endurance)
ceiling main= 90,000+ ft
ceiling alt= 27,432+ m
climb rate main=
climb rate alt=
loading main=
loading alt=
more performance=

ee also

similar aircraft=
* Miles M.52
* List of experimental aircraft
* List of rocket planes
* List of X-1 flights
* List of X-1A flights
* List of X-1B flights
* List of X-1D flights
* List of X-1E flights
see also=
* Mach number




* "Breaking the Sound Barrier." "Modern Marvels (TV program)". 2003.
* Hallion, Dr. Richard P. "Saga of the Rocket Ships." "AirEnthusiast Five", November 1977-February 1978. Bromley, Kent, UK: Pilot Press Ltd., 1977.
* Miller, Jay. "The X-Planes: X-1 to X-45," Hinckley, UK: Midland, 2001. ISBN 1-85780-109-1.
* Pisano, Dominick A., van der Linden, R. Robert and Winter, Frank H. "Chuck Yeager and the Bell X-1: Breaking the Sound Barrier". Washington, DC: Smithsonian National Air and Space Museum (in association with Abrams, New York), 2006. ISBN 0-8109-5535-0.
* Winchester, Jim. "Bell X-1." "Concept Aircraft: Prototypes, X-Planes and Experimental Aircraft" (The Aviation Factfile). Kent, UK: Grange Books plc, 2005. ISBN 1-84013-309-2.
* Wolfe. Tom. "The Right Stuff". New York: Farrar, Straus and Giroux, 1979. ISBN 0-374-25033-2.
* Yeager, Chuck, Cardenas, Bob, Hoover, Bob, Russell, Jack and Young, James. "The Quest for Mach One: A First-Person Account of Breaking the Sound Barrier". New York: Penguin Studio, 1997. ISBN 0-670-87460-4.
* Yeager, Chuck and Janos, Leo. "Yeager: An Autobiography". New York: Bantam, 1986. ISBN 0-553-25674-2.

External links

* [ Bell X-1 Milestones of Flight]
* [ NASA's History of the X-1]
* [ Goodlin's NASA biography]
* [ "American X-Vehicles: An Inventory X-1 to X-50", SP-2000-4531 - June 2003; NASA online PDF Monograph]
* [ Photo of Glamorous Glennis on display] at the National Air and Space Museum in Washington, DC.
* [ Yeager's personal website]

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