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{{Short description|Experimental rocket-powered aircraft}}
{{About|the experimental aircraft|the Irish band|Bell X1 (band)}}
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{{Infobox aircraft
 |name = X-1
 |image = File:Bell X-1 46-062 (in flight).jpg
 |caption = X-1 #46-062, nicknamed ''Glamorous Glennis''
 |type = [[Experimental aircraft|Experimental]] [[rocket plane]]
 |national_origin = United States
 |manufacturer = [[Bell Aircraft]]
 |first_flight = 19 January 1946
 |introduction =
 |retired =
 |status = Retired
 |primary_user = [[United States Air Force]]
 |more_users = [[National Advisory Committee for Aeronautics]]
 |produced =
 |number_built = 7
 |unit cost =
 |variants =
}}

The '''Bell X-1''' ('''Bell Model 44''') is a [[Rocket-powered aircraft|rocket engine–powered aircraft]], designated originally as the '''XS-1''', and was a joint [[National Advisory Committee for Aeronautics]]–[[U.S. Army Air Forces]]–[[U.S. Air Force]] supersonic research project built by [[Bell Aircraft]]. Conceived during 1944 and designed and built in 1945, it achieved a speed of nearly {{convert|1000|mph|km/h kn}} in 1948. A derivative of this same design, the [[#X-1A|Bell X-1A]], having greater fuel capacity and hence longer rocket burning time, exceeded {{convert|1600|mph|km/h kn}} in 1954.<ref name=NTRS /> The X-1 aircraft #46-062, nicknamed ''Glamorous Glennis'' and flown by [[Chuck Yeager]], was the first piloted [[airplane]] to exceed the [[speed of sound]] in level flight and was the first of the [[X-plane (aircraft)|X-planes]], a series of American experimental [[rocket plane]]s (and non-rocket planes) designed for testing new technologies.

==Design and development==
===Parallel development===

In 1942, the [[United Kingdom]]'s [[Ministry of Aviation]] began a top secret project with [[Miles Aircraft]] to develop the world's first aircraft capable of breaking the sound barrier. The project resulted in the design of the [[turbojet]]-powered [[Miles M.52]], with a maximum speed of {{convert|1,000|mph|kn km/h}} (over twice the existing [[Flight airspeed record|airspeed record]]) in level flight, and able to climb to an altitude of 36,000&nbsp;ft (11&nbsp;km) in 1 min and 30 sec. The fuselage was shaped like a bullet, it had thin wings and a slab tailplane for controlled flight at the speed of sound and beyond. Miles' chief aerodynamicist, Dennis Bancroft, was interviewed many years later in 1997 on his reason for needing an all-moving tailplane in his 1944 design.
:::DENNIS BANCROFT: We thought the ordinary controls wouldn't work above the speed of sound. So, we had to make an all-moving tail plane, because an ordinary elevator would literally not function at all. We would go up to the speed of sound, lose all air control, and the aircraft would crash.<ref name="Faster Than Sound.">Bancroft, Dennis. ''[[Secret History (TV series)|Secret History]]'': "Breaking the Sound Barrier" Channel 4, 7 July 1997. Re-packaged as ''NOVA'': [https://www.pbs.org/wgbh/nova/transcripts/2412barrier.html "Faster Than Sound."], PBS, 14 October 1997. Retrieved: 26 April 2009.</ref>

In 1944, Miles was told to go ahead with the construction of three prototypes. In February 1946, with a first flight expected in the summer of 1946, the M52 was cancelled.<ref>Wood p.31</ref> In place of the manned full-scale M.52 it was decided to test 3/10 scale models of the aircraft, rocket propelled, dropped from an aircraft, and controlled by an autopilot. On the 10th of October 1948, a model achieved Mach 1.38 in level flight.
:::STACY KEACH (NARRATOR): One year after the X-1's historic flight, Britain broke the sound barrier with a one-third scale model of the M-52. Although unmanned and radio-controlled, it did finally vindicate the worthiness of its supersonic design.<ref name="Faster Than Sound."/>

The Bell XS-1 would have a conventional horizontal tail-plane but with trimming available on the stabilizer. It would be required for pitch control when a shockwave was preventing a deflected elevator from altering the pressure distribution and pitching force on the tailplane.

In September 1946, a DH 108 tail-less jet aircraft was practicing for an attempt on the world speed record when it experienced violent pitching oscillations at Mach 0.875 and broke up. The Bell XS-1 would have a conventional horizontal tail which provides pitch damping not present in a tail-less aircraft.

===Research studies===
[[File:XLR-11.jpg|thumb|upright|right|XLR-11 rocket engine]]
The XS-1 was first discussed in December 1944. Early specifications for the aircraft were for a piloted supersonic vehicle that could fly at {{convert|800|mph}} at {{convert|35000|feet}} for two to five minutes.<ref name="ley194811">{{Cite magazine |last=Ley |first=Willy |date=November 1948 |title=The 'Brickwall' in the Sky |url=https://archive.org/stream/Astounding_v42n03_1948-11_cape1736#page/n77/mode/2up |magazine=Astounding Science Fiction |pages=78–99}}</ref> On 16 March 1945, the [[U.S. Army Air Forces]] Flight Test Division and the [[National Advisory Committee for Aeronautics]] (NACA) contracted with the Bell Aircraft Company to build three XS-1 (for "Experimental, Supersonic", later X-1) aircraft to obtain flight data on conditions in the transonic speed range.<ref>Miller 2001, p. 15.</ref>

Bell built a rocket plane after considering the turbojet alternative. Turbojets could not achieve the required performance at high altitude. An aircraft with both turbojet and rocket engines would be too large and complex.{{r|ley194811}} The X-1 was, in principle, a "bullet with wings", its shape closely resembling a [[.50 BMG|Browning .50-caliber]] (12.7&nbsp;mm) [[machine gun]] bullet, known to be stable in supersonic flight.<ref>Yeager et al., 1997, p. 14.</ref> The shape was followed to the extent of seating its pilot behind a sloped, framed window inside a confined cockpit in the nose, with no ejection seat.

For the design of the XS-1 the many unknowns relating to transonic and supersonic flight meant seeking every available source of information from governmental agencies, powerplant manufacturers and research institutions. Foreign information became available in early 1946, shortly after the first glide test of the XS-1 in Jan 1946, when the British Ministry of Supply cancelled the Miles M.52 and ordered all research reports and other information be sent to Bell Aircraft.<ref>{{cite book | url=https://archive.org/details/projectcancelled0000wood/page/30/mode/2up | isbn=978-0-356-08109-0 | title=Project cancelled : A searching criticism of the abandonment of Britain's advanced aircraft projects | date=1975 | last1=Wood | first1=Derek | publisher=Macdonald and Jane's }}</ref><ref>{{cite book | url=https://archive.org/details/planespeakingper0000guns/page/168/mode/2up | isbn=978-1-85260-166-9 | title=Plane speaking : A personal viewof aviation history | date=1991 | last1=Gunston | first1=Bill | publisher=Patrick Stephens }}</ref>

Bell Aircraft aerodynamicists working with NACA laboratories predicted significant longitudinal trim changes during transonic flight. [[John Stack (engineer)|John Stack]] and [[Robert Gilruth]] at NACA recommended that Bell mount the elevator on an adjustable horizontal stabilizer.<ref>https://www.amazon.com/Meeting-Challenge-Supersonic-Flight-James/dp/B0006QV0BQ p.9</ref> Bell incorporated the stabilizer with rapid adjustment in pitch to accommodate large changes of trim.<ref>{{cite web | url=https://archive.org/details/sim_aerospace-engineering-1942_1947-08_6_8/page/22/mode/2up | title=Aeronautical Engineering Review 1947-08: Vol 6 Iss 8 | date=August 1947 | publisher=American Institute of Aeronautics }}</ref> A contractor test flight by [[Tex Johnston]] showed an unacceptable lost motion between the pilot's input to the horizontal stabilizer and the stabilizer actuator which was corrected before the XS-1 was handed over for the high speed research program.<ref>{{cite web | url=https://archive.org/details/texjohnston00john/page/112/mode/2up | title=Tex Johnston: Jet-Age Test Pilot | date=2014 | publisher=Smithsonian }}</ref> The whole tailplane could be moved or just the elevator at fixed stabilizer settings.<ref>High Speed Test Flying, Yeager, The Aeronautical Journal, December 1956, p.788</ref> It was placed as high as possible above the wing wake with a thinner section than for the wing to separate the high drag rise from the wing from compressibility effects on the tail. Initially, as increases in speed were made in small steps towards possibly unknown control difficulties the horizontal stabilizer was left at its pre-launch angle set on the ground as there was concern that adjusting it at high speed would cause severe control problems. Nevertheless, in October 1947, when test pilot Yeager ran out of elevator authority (no pitch control) at Mach 0.94 it took the test team by surprise until they realized that extra control was available by moving the horizontal stabilizer. The tailplane trim setting had to be accurately set on the ground to ensure a controlled drop at the beginning of a flight. [[Scott Crossfield]] relates an inadvertent one-degree error flipping the X-1 on its back after being dropped from the mother plane.<ref>https://archive.org/details/alwaysanotherdaw0000cros/page/n7/mode/2up  p.128</ref> The tailplane configuration was carried over to the X-1A series. All subsequent supersonic aircraft would either have an all-moving tailplane or be "tailless" [[delta wing]]ed types.<ref>Pisano, ''et al.''. 2006, p. 52.</ref>

[[Swept wing]]s were not used because too little was known about them. As the design might lead to a fighter, the XS-1 was intended to take off from the ground, but the end of the war made the [[B-29 Superfortress]] available to carry it into the air. {{r|ley194811}}

The rocket engine was a four-chamber design built by [[Reaction Motors Inc]]., one of the first companies to build liquid-propellant rocket engines in the U.S. After considering [[hydrogen peroxide]] [[monopropellant]], [[aniline]]/[[nitric acid]] [[bipropellant]], and [[nitromethane]] monopropellant as fuels, the rocket burned ethyl alcohol diluted with water with a [[liquid oxygen]] [[oxidizer]]. Its four chambers could be individually turned on and off, so thrust could be changed in {{convert|1500|lbf|abbr=on}} increments. The fuel and oxygen tanks for the first two X-1 engines were pressurized with [[nitrogen]], reducing flight time by about {{frac|1|1|2}} minutes and increasing landing weight by {{convert|2000|lb}}, but the rest used gas-driven [[turbopump]]s, increasing the chamber pressure and thrust while making the engine lighter.<ref>Miller, p. 23</ref>{{r|ley194811}}

==Operational history==
Bell Aircraft chief [[test pilot]] [[Jack Woolams]] became the first person to fly the XS-1. He made a glide-flight over [[Pinecastle Army Airfield]], in [[Florida]], on 19 January 1946. Woolams completed nine more glide-flights over Pinecastle, with the B-29 dropping the aircraft at {{convert|29000|feet}} and the XS-1 landing 12 minutes later at about {{convert|110|mph}}. In March 1946 the #1 rocket plane was returned to Bell Aircraft in [[Buffalo, New York]] for modifications to prepare for the powered flight tests. Four more glide tests occurred at [[Muroc Army Air Field]] near [[Palmdale, California]], which had been flooded during the Florida tests, before the first powered test on 9 December 1946. Two chambers were ignited, but the aircraft accelerated so quickly that one chamber was turned off until reignition at {{convert|35000|feet}}, reaching Mach 0.795. After the chambers were turned off the aircraft descended to {{convert|15000|feet}}, where all four chambers were briefly tested.{{r|ley194811}}<ref>Anderson, Clarence E. "Bud". [http://www.cebudanderson.com/initialglideflights.htm "Initial Glide Flights."] {{webarchive |url=https://web.archive.org/web/20070325164411/http://www.cebudanderson.com/initialglideflights.htm |date=March 25, 2007 }} ''cebudanderson.com''. Retrieved: 14 October 2009.</ref>

After Woolams died while practicing for the National Air Races in August 1946, [[Chalmers Goodlin|Chalmers "Slick" Goodlin]] was assigned as the primary Bell Aircraft test pilot for the X-1. Goodlin made the first powered flight on 9 December 1946. [[Alvin M. Johnston|Tex Johnston]], Bell's chief test pilot and program supervisor, made a test flight on 22 May 1947, after complaints about the slow progress of flight tests. According to Johnston, "The contract with the Air Corps defined the tests by Bell as onboard systems verification, handling characteristics evaluation, stability and control, and performance testing to Mach 0.99." After Johnston's initial flight at 0.72 Mach, he thought the airplane was ready for supersonic flights, after the longitudinal trim system was fixed, and three more test flights.<ref>{{cite book |last1=Johnston |first1=A.M. "Tex" |title=Tex Johnston, Jet-Age Test Pilot |date=1992 |publisher=Bantam |location=New York |isbn=9780553295870 |pages=81–86,104,115–126}}</ref>

The Army Air Force was unhappy with the cautious pace of flight envelope expansion and Bell Aircraft's flight test contract for airplane #46-062 was terminated. The test program was acquired by the Army Air Force Flight Test Division on 24 June after months of negotiation. Goodlin had demanded a US$150,000 bonus (equivalent to ${{inflation|US|.150000|1947|r=2|fmt=c}} million in {{inflation/year|US}}) for exceeding the speed of sound.<ref name="yeagerbio_86">Yeager and Janos 1986</ref>{{rp|96}}<ref name="right_stuff_52-53">Wolfe 1979, pp. 52–53.</ref><ref>Anderson, Clarence E. "Bud". [http://www.cebudanderson.com/aturningpoint.htm "A Turning Point."] {{webarchive |url=https://web.archive.org/web/20070402001246/http://www.cebudanderson.com/aturningpoint.htm |date=April 2, 2007 }} ''cebudanderson.com''. Retrieved: 14 October 2009.</ref> 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.

===Mach 1 flight===
[[File:Chuck Yeager.jpg|thumb|left|[[Chuck Yeager]] in front of the X-1 that he nicknamed the ''Glamorous Glennis''.]]
The first manned [[supersonic]] flight occurred on 14 October 1947, over the [[Mojave Desert]] in [[California]],<ref>{{cite web|url=https://www.britannica.com/technology/X-1-airplane|title=Bell X-1|publisher=Encyclopedia Britannica|language=English|accessdate=8 December 2022}}</ref> less than a month after the [[U.S. Air Force]] had been created as a separate service. [[Captain (United States O-3)|Captain]] [[Chuck Yeager|Charles "Chuck" Yeager]] piloted USAF aircraft #46-062, nicknamed ''Glamorous Glennis'' for his wife. The airplane was [[drop launch]]ed from the bomb bay of a B-29 and reached Mach 1.06 ({{convert|700|mph|km/h kn}}).<ref name=NTRS>{{cite book |last=Hallion |first=Richard P. |year=2012 |editor-last=Dick |editor-first=Steven J. |title=NASA 50th Anniversary Proceedings : NASA's First 50 Years, Historical Perspectives |url=https://www.nasa.gov/pdf/607087main_NASAsFirst50YearsHistoricalPerspectives-ebook.pdf |publisher=US National Aeronautics and Space Admin |pages=223–274 |chapter=Chapter 10: The NACA, NASA, and the Supersonic-Hypersonic Frontier |isbn=978-0-16-084965-7}}</ref> Following burnout of the engine, the plane glided to a landing on the dry lake bed.<ref name="yeagerbio_86" />{{rp|129–130}} This was XS-1 flight number 50.
[[File:Yeager supersonic flight 1947.ogv|thumb|Yeager exceeded [[Speed of sound|Mach 1]] on 14 October 1947 in the X-1.]]
The three main participants in the X-1 program won the [[National Aeronautics Association]] [[Collier Trophy]] in 1948 for their efforts. Honored at the [[White House]] by [[Harry S. Truman|President Truman]] were [[Lawrence Dale Bell|Larry Bell]] for Bell Aircraft, Captain Yeager for piloting the flights, and [[John Stack (engineer)|John Stack]] for the contributions of the NACA.

The story of Yeager's 14 October flight was leaked to a reporter from the magazine [[Aviation Week and Space Technology|''Aviation Week'']], and the ''[[Los Angeles Times]]'' featured the story as headline news in their 22 December issue. The magazine story was released on 20 December. The Air Force threatened legal action against the journalists who revealed the story, but none ever occurred.<ref>Powers, Sheryll Goeccke. "Women in Flight Research at NASA Dryden Flight Research Center from 1946 to 1995," ''Monographs in Aerospace History,'' Number 6, 1997, NASA Headquarters, Washington, D. C.</ref> The news of a straight-wing supersonic aircraft surprised many American experts, who like their German counterparts during the war believed that a swept-wing design was necessary to break the sound barrier.{{r|ley194811}} On 10 June 1948, [[United States Secretary of the Air Force|Air Force Secretary]] [[Stuart Symington]] announced that the sound barrier had been repeatedly broken by two experimental airplanes.<ref name=mjfmftsd>{{cite news |url=https://news.google.com/newspapers?id=UuFQAAAAIBAJ&pg=4694%2C4552556 |newspaper=Milwaukee Journal |title=Flights 'much faster than sound' confirmed by the U.S. Air Force |date=June 10, 1948 |page=1, part 1}}</ref><ref name=ppgfsnd>{{cite news |url=https://news.google.com/newspapers?id=AAwNAAAAIBAJ&pg=2734%2C2355693 |newspaper=Pittsburgh Post-Gazette |agency=Associated Press |title=Two U.S. planes fly faster than sound |date=June 11, 1948 |page=4}}</ref>

On 5 January 1949, Yeager used Aircraft #46-062 to perform the only conventional (runway) launch of the X-1 program, attaining {{convert|23000|ft|m|abbr=on}} in 90 seconds.<ref name="Miller pp. 21–35">Miller 2001, pp. 21–35.</ref>

===Legacy===
In 1997, the United States Postal Service issued a fiftieth anniversary commemorative stamp recognizing the Bell X1-6062 aircraft as the first aeronautical vehicle to fly at [[supersonic speed]] of approximately {{convert|1.06|Mach}}.

The Bell X-1 is also the subject of a toy version in the ''[[Arthur (TV series)|Arthur]]'' episode "Arthur's Big Hit". In that episode, Arthur's sister D.W. tries to let it fly out the window, but it ends up falling to the ground and breaking. This resulted in a classic moment in which [[Arthur Read|Arthur]] clenches his fist and punches D.W.; this moment has since become a popular meme.

==Variants==
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 disaster; later [[Mel Apt]] would lose his life testing the [[Bell X-2]] under similar circumstances.

[[File:Bell X-1A in flight.jpg|thumb|right|X-1A in flight]]

===X-1A===
('''Bell Model 58A''')
[[File:Bell X-1A.jpg|thumb|right|X-1A]]
Ordered by the Air Force on 2 April 1948, the '''X-1A''' (serial number 48-1384) was intended to investigate aerodynamic phenomena at speeds greater than Mach&nbsp;2 (681&nbsp;m/s, 2,451&nbsp;km/h) and altitudes greater than 90,000&nbsp;ft (27&nbsp;km), specifically emphasizing dynamic stability and air loads. Longer and heavier than the original X-1, with a stepped 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&nbsp;February 1953 at Edwards AFB, with the first powered flight on 21&nbsp;February. Both flights were piloted by Bell test pilot [[Jean "Skip" Ziegler]].

After [[NACA]] started its high-speed testing with the [[Douglas Skyrocket]], culminating in [[Scott Crossfield]] achieving Mach&nbsp;2.005 on 20&nbsp;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&nbsp;December 1953, when Yeager achieved an altitude of {{convert|74700|ft}} and a new airspeed record of Mach&nbsp;2.44 (equal to 1620&nbsp;mph, 724.5&nbsp;m/s, 2608&nbsp;km/h at that altitude). Unlike Crossfield in the Skyrocket, Yeager achieved that in level flight. Soon afterwards, the aircraft spun out of control, due to the then not yet understood phenomenon of [[inertia coupling]]. The X-1A dropped from maximum altitude to {{convert|25000|ft}}, exposing the pilot to accelerations of as much as 8g, during which Yeager broke the canopy with his helmet before regaining control.<ref>Young, Dr. Jim. [https://web.archive.org/web/20080215062652/http://www.af.mil/shared/media/document/AFD-080107-018.pdf "Major Chuck Yeager's Flight to Mach 2.44 In the X-1A"].   ''AFFTC History Office'', Edwards AFB. Retrieved 14 October 2009.</ref>

On 28 May 1954, Maj. [[Arthur W. Murray]] piloted the X-1A to a new record of {{convert|90440|ft}}.<ref name=Martin>Martin, Douglas |title=Arthur Murray. [https://www.nytimes.com/2011/08/05/us/05murray.html?src=recg "Test Pilot, Is Dead at 92"]. ''[[The New York Times]]'', 4 August 2011. Retrieved 6 August 2011.</ref>

The aircraft was transferred to NACA during September 1954, and subsequently modified. The X-1A was lost on 8 August 1955, when, while being prepared for launch from the [[Boeing B-50 Superfortress|RB-50]] mothership, an explosion ruptured the plane's liquid oxygen tank. With the help of crewmembers on the RB-50, test pilot [[Joseph A. Walker]] successfully extricated himself from the plane, which was then jettisoned. Exploding on impact with the desert floor, the X-1A became the first of many early X-planes that would be lost to explosions.<ref>Miller 2001, p. 21.</ref><ref>Thompson, Lance. [http://www.ufomind.com/area51/org/afftc/articles/airspace_9502.html "The X-Hunters"]. ''[[Air & Space]]'', February/March 1995, ISSN 0886-2257. Retrieved 12 March 2008.</ref>

===X-1B===
('''Bell Model 58B''')
[[File:Bell X-1B, NMUSAF, 2011.JPG|thumb|right|X-1B at the National Museum of the United States Air Force]]
The '''X-1B''' (serial 48-1385) was equipped with [[aerodynamic heating]] instrumentation for thermal research (more than 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 U.S. Air Force starting from October 1954, prior to being transferred to the NACA during 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 [[North American X-15]]. The X-1B is now at the [[National Museum of the United States Air Force]], [[Wright-Patterson Air Force Base]] at [[Dayton, Ohio]], where it is displayed in the museum's Maj. Gen. Albert Boyd and Maj. Gen. Fred Ascani Research and Development Gallery.

===X-1C===
('''Bell Model 58C''')
The '''X-1C''' (serial 48-1387)<ref>Baugher, Joe. [http://www.joebaugher.com/usaf_serials/usafserials.html "USAAS-USAAC-USAAF-USAF Aircraft Serial Numbers – 1908 to Present."] ''USAAS/USAAC/USAAF/USAF Aircraft Serials,''20 January 2008. Retrieved: 12 December 2010.</ref> was intended to test armaments and munitions in the high transonic and supersonic flight regimes. It was canceled while still in the mockup stage, as the development 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 vehicle.<ref>[http://www1.dfrc.nasa.gov/gallery/photo/X-1A/HTML/E-24911.html "Photo number E-24911: X-1A in flight with flight data superimposed."] {{webarchive |url=https://web.archive.org/web/20061207181208/http://www1.dfrc.nasa.gov/gallery/photo/X-1A/HTML/E-24911.html |date=December 7, 2006 }} ''NASA Dryden''. Retrieved: 14 October 2009.</ref>

===X-1D===
('''Bell Model 58D''')
The '''X-1D''' (serial 48-1386) was the first of the second generation of supersonic rocket planes. Flown from an [[Boeing B-50 Superfortress|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 of the avionics suite.

On 24 July 1951, with Bell test pilot Jean "Skip" 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 landing 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.<ref name="X-1 fs">[http://www.nasa.gov/centers/dryden/news/FactSheets/FS-082-DFRC.html "Fact Sheet X-1."] ''NASA Dryden Fact Sheet''. Retrieved: 12 March 2008.</ref>

===X-1E===
('''Bell Model 44''')
[[File:Bell X-1-3 being mated with the motherplane.jpg|thumb|left|Bell X-1-3, aircraft #46-064, being mated to the B-50 mothership for a captive flight test on 9 November 1951. While being de-fueled after this flight it exploded, destroying itself and the B-50, and seriously burning Joe Cannon. X-1-3 had completed only a single glide-flight on 20 July.<ref>Miller 2001, p. 25.</ref>]]
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 for the X-1D and X-1-3 (serial 46-064), both lost by explosions during 1951. The cause of the mysterious explosions was finally traced to the use of Ulmer leather<ref>Made by the Ulmer Company. James R. Hansen, "First Man" p. 134</ref> 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.<ref>[http://www.dfrc.nasa.gov/gallery/Photo/X-1A/HTML/E-24911.html "Photo X-1A (E-24911)."] {{webarchive |url=https://web.archive.org/web/20080920144335/http://www.dfrc.nasa.gov/gallery/Photo/X-1A/HTML/E-24911.html |date=September 20, 2008 }} ''NASA (Dryden Collections)''. Retrieved: 5 January 2016.</ref> This mistake cost two lives, caused injuries and lost several aircraft.<ref>Lockett, Brian. [http://www.air-and-space.com/edwards.htm  "Edwards Air Force Base History: Bell X-1 Explosions."] ''Goleta Air and Space Museum'', 3 July 1998. Retrieved: 5 January 2016.</ref>

[[File:Joe Walker X-1E.jpg|thumb|right|The X-1E, christened ''Little Joe'', with pilot Joe Walker]]
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.<ref name= "x-1e fs">[http://www.nasa.gov/centers/dryden/news/FactSheets/FS-083-DFRC.html "Fact sheet: X-1E."] ''NASA (Dryden Collections)''.  Retrieved: 5 January 2016.</ref>
* A re-profiled super-thin wing ({{convert|3+3/8|in|disp=or|abbr=out}} at the [[Wing root|root]]), based on the [[X-3 Stiletto]] wing profile, enabling the X-1E to exceed Mach 2.<ref>{{cite web |url=https://www.nasa.gov/centers/armstrong/news/FactSheets/FS-083-DFRC.html |title=X-1E |publisher=NASA |date=7 August 2017 |access-date=6 November 2022}}</ref>
* 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.<ref name = "x-1e fs" />

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

==Aircraft on display==
[[File:BellX1.jpg|thumb|right|X-1-1 #46-062 ''Glamorous Glennis'' at the National Air and Space Museum. Its color is [[international orange]].<ref>{{cite web|url=https://airandspace.si.edu/collection-objects/bell-x-1|title=Bell X-1|date=21 March 2016|website=si.edu |archiveurl=https://web.archive.org/web/20190731120658/https://airandspace.si.edu/collection-objects/bell-x-1 |archivedate=2019-07-31}}</ref>]]

* X-1-1, Air Force Serial Number 46-062 ''Glamorous Glennis'', is currently displayed in the Boeing Aviation Hangar of the [[Steven F. Udvar-Hazy Center]] in [[Dulles, VA|Dulles]], where it was moved during renovations to the [[National Air and Space Museum]]. The aircraft was flown to Washington, D.C., beneath a B-29 and presented to what was then the American National Air Museum in 1950.<ref>Staff, "Resting Place", ''Flight'', 28 September 1950, page 350.</ref><ref>{{Cite web |title=Bell X-1 Glamorous Glennis {{!}} National Air and Space Museum |url=https://airandspace.si.edu/collection-objects/bell-x-1/nasm_A19510007000 |url-status=live |archive-url=https://web.archive.org/web/20230609044526/https://airandspace.si.edu/collection-objects/bell-x-1/nasm_A19510007000 |archive-date=2023-06-09 |access-date=2023-06-09 |website=airandspace.si.edu |date=13 May 2022 |language=en}}</ref>
* X-1B, AF Ser. No. 48-1385, is on display in the Research & Development Hangar at the [[National Museum of the United States Air Force]], [[Wright-Patterson Air Force Base]], Ohio.
* X-1E, AF Ser. No. 46-063, is on display in front of the [[NASA]] [[Armstrong Flight Research Center]] headquarters building at [[Edwards Air Force Base]], California. It is usually seen in episodes of the TV series ''[[I Dream of Jeannie]]'', which was set at Cape Kennedy, Florida.

==Specifications (Bell X-1 #1 and #2)==
[[File:Bell X-1 line art EG-0081-01.png|thumb|Bell X-1 orthographic diagram]]
[[File:Bell X-1E line drawing.png|thumb|X-1E orthographic diagram]]

{{Aircraft specs
|ref=Bell Aircraft since 1935,<ref name="Pelletier">{{cite book |last1=Pelletier |first1=Alain J. |title=Bell Aircraft since 1935 |date=1992 |publisher=Naval Institute Press |location=Annapolis |isbn=1-55750-056--8 |pages=83–90 |edition=1st}}</ref> The X-Planes: X-1 to X-45<ref name = "Miller pp. 21–35" />
|prime units?=imp
<!--
        General characteristics
-->
|crew=1
|length ft=30
|length in=11
|length note=<br/>
::'''X-1A,  X-1B,  X-1D:''' {{cvt|35|ft|8|in|m}}
::'''X-1C:''' {{cvt|10.67|m|order=flip}}
|span ft=28
|span in=0
|span note=<br/>
::'''X-1E:''' {{cvt|22|ft|10|in|m}}
|height ft=10
|height in=10
|height note=
|wing area sqm=
|wing area sqft=130
|wing area note=⠀
::'''X-1E''' {{cvt|115|sqft|m2}}
|aspect ratio=<!-- sailplanes -->
|airfoil='''#1''' [[NACA airfoil|NACA 65-110]] (10% thickness)
::'''#2, X-1A, X-1B, X-1D''' [[NACA airfoil|NACA 65-108]] (8% thickness)
::'''X-1E''' [[NACA airfoil|NACA 64A004]]
|empty weight kg=
|empty weight lb=7000
|empty weight note=<br/>
::'''X-1A,  X-1B, X-1C, X-1D:''' {{cvt|6880|lb}}
::'''X-1E:''' {{cvt|6850|lb}}
|gross weight kg=
|gross weight lb=12250
|gross weight note=<br/>
::'''X-1A,  X-1B, X-1C, X-1D:''' {{cvt|16487|lb}}
::'''X-1E:''' {{cvt|14750|lb}}
|max takeoff weight kg=
|max takeoff weight lb=
|max takeoff weight note=
|fuel capacity=
|more general=
<!--
        Powerplant
-->
|eng1 number=1
|eng1 name=[[Reaction Motors XLR11-RM-3]]
|eng1 type=4-chamber liquid-fuelled rocket engine
|eng1 kw=<!-- prop engines -->
|eng1 hp=<!-- prop engines -->
|eng1 shp=<!-- prop engines -->
|eng1 kn=<!-- jet/rocket engines -->
|eng1 lbf=6000
|eng1 note=<br/>
::'''X-1E:''' [[Reaction Motors RMI LR-8-RM-5]] {{cvt|6000|lbf|kN}}

<!--
        Performance
-->
|max speed kmh=
|max speed mph=1612
|max speed kts=
|max speed note=<br/>
::'''X-1E:''' {{cvt|1450|mph|kn km/h}}
|max speed mach=2.44
::'''X-1E:''' M2.24
|cruise speed kmh=
|cruise speed mph=
|cruise speed kts=
|cruise speed note=
|stall speed kmh=
|stall speed mph=
|stall speed kts=
|stall speed note=
|never exceed speed kmh=
|never exceed speed mph=
|never exceed speed kts=
|never exceed speed note=
|range km=
|endurance=5 minutes powered flight<br/>
::'''X-1A,  X-1B, X-1C, X-1D:'''  4 minutes 40 seconds powered flight
::'''X-1E:''' 4 minutes 45 seconds powered flight
|ceiling m=
|ceiling ft=70000
|ceiling note=<br/>
::'''X-1A,  X-1B, X-1C, X-1D:''' {{cvt|90000|ft}}
::'''X-1E:''' {{cvt|75000|ft}}
|g limits=<!-- aerobatic -->
|roll rate=<!-- aerobatic -->
|glide ratio=<!-- sailplanes -->
|climb rate ms=
|climb rate ftmin=
|climb rate note=
|time to altitude=
|sink rate ms=<!-- sailplanes -->
|sink rate ftmin=<!-- sailplanes -->
|sink rate note=
|lift to drag=
|wing loading kg/m2=
|wing loading lb/sqft=
|wing loading note=
|fuel consumption kg/km=
|fuel consumption lb/mi=
|power/mass=
|thrust/weight=

|more performance=
}}

==Notable appearances in media==
<!-- All content about the aircraft in fictional and gaming use has been moved to [[Aircraft in fiction]], please see [[WP:AIRPOP]] -->
{{Main|Aircraft in fiction#Bell X-1}}

==See also==
{{aircontent
|related=
|similar aircraft=
* [[Miles M.52]]
|lists=
* [[List of experimental aircraft]]
* [[List of rocket aircraft]]
* [[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=
* [[Air Force Test Center]]
* [[Mach number]]
* [[North American X-15]]
* [[XS-1 (spacecraft)]]}}

==References==

===Notes===
{{Reflist|30em}}

===Bibliography===
{{Refbegin}}
* "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., R. Robert van der Linden and [[Frank H. Winter]]. ''Chuck Yeager and the Bell X-1: Breaking the Sound Barrier''. Washington, D.C.: 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|978-1-59223-480-6}}.
* Wolfe. Tom. ''The Right Stuff''. New York:  Farrar, Straus and Giroux, 1979. {{ISBN|0-374-25033-2}}.
* Yeager, Chuck, Bob Cardenas, Bob Hoover, Jack Russell and James Young. ''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 Leo Janos. ''Yeager: An Autobiography''. New York: Bantam, 1986. {{ISBN|0-553-25674-2}}.
{{Refend}}

==External links==
{{Commons}}
* [https://www.nationalmuseum.af.mil/Visit/Museum-Exhibits/Fact-Sheets/Display/Article/195763/bell-x-1b/  Bell X-1B] – [[National Museum of the United States Air Force]]
* [https://web.archive.org/web/20010525102328/http://history.nasa.gov/x1/ X-1 fiftieth anniversary] – [[NASA]]
* [https://history.nasa.gov/x1/goodlin.html Chalmers H. (Slick) Goodlin] – NASA
* [https://history.nasa.gov/monograph31.pdf American X-Vehicles – An Inventory—X-1 to X-50] – NASA
* [https://web.archive.org/web/20160705181559/https://airandspace.si.edu/collection-objects/bell-x-1 Bell X-1 – National Air and Space Museum]
* [http://chuckyeager.com/ General Chuck Yeager | The Official Website]
* [https://web.archive.org/web/20101124113643/http://ipmsstockholm.org/magazine/2001/11/stuff_eng_bell_x1_part1.htm Modeller's Guide to Bell X-1 Experimental Aircraft Part one], [https://web.archive.org/web/20100812072719/http://ipmsstockholm.org/magazine/2001/11/stuff_eng_bell_x1_part2.htm Part two]
* [https://books.google.com/books?id=QCgDAAAAMBAJ&pg=PA97 X-1 is Carried Aloft; Cockpit of the Bell X-1] – ''Popular Science''
<!-- September 10,2022 | video links in web page of this external link are broken and comment with alternate link not useful: * [https://web.archive.org/web/19970605043157/http://www.dfrc.nasa.gov/gallery/movie/X-1/index.html NASA video collection] --> <!--also at https://www.youtube.com/user/DrydenTV/videos -->

{{Bell Aircraft}}
{{X-planes}}
{{Authority control}}

[[Category:Edwards Air Force Base]]
[[Category:Rocket-powered aircraft]]
[[Category:Chuck Yeager|X-1]]
[[Category:1940s United States experimental aircraft|X-1, Bell]]
[[Category:American inventions]]
[[Category:Bell aircraft|X-1]]
[[Category:Articles containing video clips]]
[[Category:1946 establishments in the United States]]
[[Category:Aircraft first flown in 1946]]
[[Category:Supersonic aircraft]]
[[Category:Mid-wing aircraft]]
[[Category:Aircraft with retractable tricycle landing gear]]