Bell X - 1 The Bell X - 1 , originally designated XS - 1 , was a joint NACA - U . S . Army Air Forces - U . S . Air Force supersonic research project built by the Bell Aircraft Company . Conceived in 1944 and designed and built during 1945 , it reached nearly 1 , 000 mph ( 1 , 600 km / h ) in 1948 . A derivative of this same design , the Bell X - 1A , having greater fuel capacity and hence longer rocket burning time , exceeded 1 , 600 mph ( 2 , 575 km / h ) in 1954 . The X - 1 was the first airplane to exceed the speed of sound in level flight and was the first of the so - called X - plane s , a series of American experimental rocket plane s designated for testing of new technologies and often kept secret . Design and development . On 16 March 1945 , the U . S . Army Air Forces Flight Test Division and the National Advisory Committee for Aeronautics ( NACA ) made a contract 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 . The X - 1 was in principle a " bullet with wings " , its shape closely resembling a Browning . 50 - caliber ( 12 . 7 mm ) machine gun bullet , known to be stable in supersonic flight . The pattern shape was followed to the point of seating its pilot behind a sloped , framed window inside a confined cockpit in the nose , with no ejection seat . After the rocket plane ran into compressibility problems in 1947 , it was modified with variable - incidence tailplane . An all - moving tail was tested in subsonic flight on the Curtiss XP - 42 research vehicle in mid - 1944 , and earmarked for future high speed research , but its first successful transonic flight was on the X - 1 , allowing it to pass through the sound barrier safely . The rocket propulsion system was a four - chamber engine built by Reaction Motors , Inc . , one of the first companies to build liquid - propellant rocket engines in America . This rocket burned ethyl alcohol diluted with water with a liquid oxygen oxidizer . Its thrust could be changed in increments by firing just one or more than one of its chambers . The fuel and oxygen tanks for the first two X - 1 engines were pressurized with nitrogen gas , but the rest used steam - driven turbopump s . The all - important fuel turbopumps were necessary to raise the chamber pressure and thrust while making the engine lighter , Operational history . The Bell Aircraft chief test pilot , Jack Woolams , became the first man to fly the XS - 1 . He made a glide flight over Pinecastle Army Airfield , in Florida , on 25 January 1946 . Woolams completed nine more glide flights over Pinecastle before March 1946 , when the # 1 rocket plane was returned to Bell Aircraft in Buffalo for modifications to prepare for the powered flight tests . These were held at the Muroc Army Air Field in Palmdale , California . Following Woolams ' death on 30 August 1946 , Chalmers " Slick " Goodlin was the primary Bell Aircraft test pilot for the X - 1 - 1 ( serial 46 - 062 ) . He made 26 successful flights in both of the X - 1 from September 1946 through June 1947 . The Army Air Forces 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 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 . 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 . On 14 October 1947 , just under a month after the U . S . Air Force had been created as a separate service , the tests reached their peak with the first manned supersonic flight , piloted by Air Force Captain Charles " Chuck " Yeager in aircraft # 46 - 062 that he had christened the " Glamorous Glennis " for his wife . This rocket - powered airplane was drop launch ed from the bomb bay of a modified B - 29 Superfortress bomber , and it glided to a landing on the dry lake bed . XS - 1 flight number 50 is the first one in which the X - 1 recorded supersonic flight , at Mach 1 . 06 ( 313 m / s , 1 , 126 km / h , 800 mph ) peak speed . 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 contributions of the NACA . The story of Yeager ’ s 14 October flight was leaked to a reporter from " Aviation Week " , and " The Los Angeles Times " featured the story as headline news in their 22 December issue . The magazine story was released 20 December . The Air Force threatened legal action against the journalists who revealed the story , but none was ever taken . On 5 January 1949 , Yeager used Aircraft # 46 - 062 to carry out the only conventional ( runway ) take off performed during the X - 1 program , reaching in 90 seconds . Legacy . 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 proved invaluable to further US fighter design throughout the latter half of the 20th century . 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 him from dying that day ; later Mel Apt would die testing the Bell X - 2 under similar circumstances . X - 1A . 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 ft ( 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 " Skip " 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 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 aircraft spun out of control , due to the then not yet understood phenomenon of inertia coupling . The X - 1A dropped from maximum altitude to , exposing the pilot to accelerations of up to 8g , during which Yeager broke the canopy with his helmet before regaining control . On 28 May 1954 , Maj . Arthur W . Murray piloted the X - 1A to a new record of . 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 . X - 1B . 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 U . S . 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 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 Research & Development Hangar . X - 1C . The X - 1C ( serial 48 - 1387 ) 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 - 1D . 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 " 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 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 . X - 1E . 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 ( serial 46 - 064 ) , 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 . This mistake cost two lives , caused injuries and lost several aircraft . The changes included : 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 .