The
BellThe Bell Aircraft Corporation was an aircraft manufacturer of the United States, a builder of several types of fighter aircraft for World War II but most famous for the Bell X-1, the first supersonic aircraft, and for the development and production of many important civilian and military helicopters...
X-1, originally designated
XS-1, was a joint
NACAThe National Advisory Committee for Aeronautics was a U.S. federal agency founded on March 3, 1915 to undertake, promote, and institutionalize aeronautical research. On October 1, 1958 the agency was dissolved, and its assets and personnel transferred to the newly created National Aeronautics and...
-U.S. Army Air Forces/US Air Force supersonic research project and the first
aircraftAn aircraft is a vehicle which is able to fly by being supported by the air, or in general, the atmosphere of a planet. An aircraft counters the force of gravity by using either static lift or by using the dynamic lift of an airfoil An aircraft is a vehicle which is able to fly by being supported...
to exceed the
speed of soundSound is a vibration that travels through an elastic medium as a wave. The speed of sound describes how far this wave travels in a given amount of time. In dry air at , the speed of sound is . This equates to , or about one mile in five seconds...
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 AeronauticsThe National Advisory Committee for Aeronautics was a U.S. federal agency founded on March 3, 1915 to undertake, promote, and institutionalize aeronautical research. On October 1, 1958 the agency was dissolved, and its assets and personnel transferred to the newly created National Aeronautics and...
(NACA) (now NASA) contracted
Bell AircraftThe Bell Aircraft Corporation was an aircraft manufacturer of the United States, a builder of several types of fighter aircraft for World War II but most famous for the Bell X-1, the first supersonic aircraft, and for the development and production of many important civilian and military helicopters...
to build three XS-1 (for "Experimental, Supersonic", later X-1) aircraft to obtain flight data on conditions in the transonic speed range. 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-caliberThe .50 Browning Machine Gun or .50 BMG is a cartridge developed for the Browning .50 Caliber machine gun in the late 1910s. Entering service officially in 1921, the round is based on a greatly scaled-up .30-06 cartridge...
(12.7 mm) machine gun bullet that was known to be stable in supersonic flight. The pattern shape was followed to the point of seating the pilot 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
tailplaneA tailplane, also known as horizontal stabilizer, is a small lifting surface located behind the main lifting surfaces of a fixed-wing aircraft as well as other non-fixed wing aircraft such as helicopters and gyroplanes...
. An all-moving tail was developed by the British for the
Miles M.52The Miles M.52 was a British supersonic research aircraft project which was undertaken in top secret between 1942 and 1945. The Air Ministry later cancelled the project for reasons that remain controversial to this day.-Design and development:...
, and first saw actual transonic flight on the Bell X-1; ] that allowed 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. It burned ethyl alcohol diluted with water and liquid oxygen. The thrust could be changed in 1500 lbf increments by firing one or more of the chambers. The fuel and oxygen tanks for the first two X-1 engines were pressurized with nitrogen and the rest with steam-driven turbopumps. The all-important fuel turbopumps, necessary to raise the chamber pressure and thrust, while lightening the engine, were built by Robert Goddard who was under Navy contract to provide jet-assisted takeoff rockets.
Operational history
Bell Aircraft Chief
Test PilotA test pilot is an aviator who flies new and modified aircraft in specific maneuvers, allowing the results to be measured and the design to be evaluated.Test pilots may work for military organizations or private, companies...
,
Jack WoolamsJack Woolams attended the University of Chicago for two years before joining the United States Army Air Corps. He served on active duty for approximately eighteen months, after which he returned to the University of Chicago and graduated with a degree in economics in June 1941.-Career and Flight...
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 BaseEdwards Air Force Base is a United States Air Force base located on the border of Kern County, Los Angeles County, and San Bernardino County, California, in the Antelope Valley. It is southwest of the central business district of North Edwards, California and due east of Rosamond. It is named in...
) in California. Following Woolams' death on 30 August 1946,
Chalmers "Slick" GoodlinChalmers H. "Slick" Goodlin was the second test pilot of the Bell X-1 supersonic rocket plane, and the first to operate the craft in powered flight...
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. 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 ForceThe United States Air Force is the aerial warfare branch of the U.S. armed forces and one of the American uniformed services. Initially part of the United States Army, the USAF was formed as a separate branch of the military on 18 September 1947 under the National Security Act of 1947 - 80 P.L....
had been created as a separate service, the tests culminated in the first manned supersonic flight, piloted by Air Force Captain
Charles "Chuck" YeagerCharles Elwood "Chuck" Yeager is a retired General in the United States Air Force and noted test pilot. He is widely considered to be the first pilot to travel faster than sound...
in aircraft #46-062, which he had christened ‘
Glamorous Glennis’, after his wife. The
rocketA rocket or rocket vehicle is a missile, spacecraft, aircraft or other vehicle which obtains thrust by the reaction of the rocket to the ejection of a jet of fast moving fluid exhaust from a rocket engine. Chemical rockets create their exhaust by the combustion of rocket propellant...
-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. (The measurements were not accurate to three significant figures and no
sonic boomThe term sonic boom is commonly used to refer to the shocks caused by the supersonic flight of an aircraft. Sonic booms generate enormous amounts of sound energy, sounding much like an explosion...
was recorded for that flight.)
As a result of the X-1's initial supersonic flight, the National Aeronautics Association voted its 1948
Collier TrophyThe Collier Trophy is an annual aviation award administered by the U.S. National Aeronautics Association , presented to those who have made "the greatest achievement in aeronautics or astronautics in America, with respect to improving the performance, efficiency, and safety of air or space...
to be shared by the three main participants in the program. Honored at the
White HouseThe White House is the official residence and principal workplace of the President of the United States. Located at 1600 Pennsylvania Avenue NW in Washington, D.C., it was built between 1792 and 1800 of white-painted Aquia sandstone in the late Georgian style and has been the residence of every...
by President
Harry S. TrumanHarry S. Truman was the 33rd President of the United States . As President Franklin D. Roosevelt's third vice-president and the 34th Vice President of the United States, he succeeded to the presidency on April 12, 1945, when President Roosevelt died less than three months after beginning his...
were
Larry BellLarry Bell may refer to:*Lawrence Dale Bell , American industrialist and founder of Bell Aircraft Corporation*Larry Bell , contemporary artist based in Los Angeles, California and Taos, New Mexico*Larry Bell, founder of Bell's Brewery...
for Bell Aircraft, Captain Yeager for piloting the flights, and
John StackJohn Stack was an American x-ray engineer, competition rower and Olympic champion. He won a gold medal in coxed eights at the 1948 Summer Olympics with the American team....
for the NACA contributions.
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 provided a basis for American aviation supremacy in the latter half of the 20th century.
Disposition
Aircraft #46-062 is currently on display in the Milestones of Flight gallery of the
National Air and Space MuseumThe National Air and Space Museum of the Smithsonian Institution is a museum in Washington, D.C., United States, and is the most popular of the Smithsonian museums. It maintains the largest collection of aircraft and spacecraft in the world...
in Washington, DC, alongside the
Spirit of St. LouisThe Spirit of St. Louis is the custom-built single engine, single seat monoplane that was flown solo by Charles Lindbergh on May 20–21, 1927, on the first non-stop flight from New York to Paris for which Lindbergh won the $25,000 Orteig Prize.Lindbergh took off in the Spirit from Roosevelt...
and SpaceShipOne. Aircraft #46-063, now the X-1E, is on display in front of the
NASAThe National Aeronautics and Space Administration is an agency of the United States government, responsible for the nation's public space program. NASA was established by the National Aeronautics and Space Act on July 29, 1958, replacing its predecessor, the National Advisory Committee for...
Dryden Flight Research CenterThe Dryden Flight Research Center , located inside Edwards Air Force Base, is an aeronautical research center operated by NASA. On March 26, 1976 it was named in honor of the late Hugh L. Dryden, a prominent aeronautical engineer who at the time of his death in 1965 was NASA's deputy administrator...
headquarters building.
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 couplingInertia coupling is a potentially lethal phenomenon of high-speed flight in which the inertia of the heavier fuselage overpowers the aerodynamic stabilizing forces of the wing and empennage...
. Only Yeager's skills as an aviator prevented him from dying that day; later Mel Apt would die testing the
Bell X-2The Bell X-2 "Starbuster" was a research aircraft built to investigate flight characteristics in the Mach 2-3 range.-Design and development:...
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 Ziegler.
After
NACANACA may refer to:*NACA , a human gene*National Association of Consumer Advocates, an organization of consumer lawyers*National Advisory Committee for Aeronautics, the forerunner of the U.S...
started its high-speed testing with the
Douglas SkyrocketThe Douglas Skyrocket was a rocket and jet-powered supersonic research aircraft built by the Douglas Aircraft Company for the United States Navy...
, 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 YeagerCharles Elwood "Chuck" Yeager is a retired General in the United States Air Force and noted test pilot. He is widely considered to be the first pilot to travel faster than sound...
, 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 aircraft spun out of control, due to the then not yet understood phenomenon of
inertia couplingInertia coupling is a potentially lethal phenomenon of high-speed flight in which the inertia of the heavier fuselage overpowers the aerodynamic stabilizing forces of the wing and empennage...
. The X-1 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.
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 heatingAerodynamic heating is the heating of a solid body produced by the passage of fluid over a body such as a meteor, missile, or airplane. It is a form of forced convection in that the flow field is created by forces beyond those associated with the thermal processes...
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 at the
National Museum of the United States Air ForceThe National Museum of the United States Air Force is the official National Museum of the United States Air Force and is located at Wright-Patterson Air Force Base, near Dayton, Ohio. The NMUSAF is the world's largest and oldest military aviation museum. More than 400 aircraft and missiles are on...
,
Wright-Patterson Air Force BaseWright-Patterson Air Force Base is a United States Air Force base located in Greene and Montgomery counties, eight miles northeast of the central business district of Dayton, Ohio, United States. Part of the base is located along the city limits of Riverside and is also adjacent to Fairborn and...
at
Dayton, OhioDayton is a city in and the county seat of Montgomery County, Ohio, United States, in the southwestern part of the state. The population was 166,179 at the 2000 census. The Dayton Metropolitan Statistical Area had a population of 848,153 in the 2000 census. Dayton is the fourth largest...
, where it is displayed in the Museum's Research & Development Hanger.
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 SabreThe North American Aviation F-86 Sabre was a transonic jet fighter aircraft. The Sabre is best known for its Korean War role where it was pitted against the Soviet MiG-15 and obtained UN air superiority...
and the North American
F-100 Super SabreThe North American F-100 Super Sabre was a jet fighter aircraft that served with the United States Air Force from 1954 to 1971 and with the Air National Guard until 1979. As the first of the Century Series collection of USAF jet fighters, it was capable of supersonic speed in level flight...
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-50AThe Boeing B-50 Superfortress was a post-World War II revision of the wartime United States B-29 Superfortress with larger Pratt & Whitney R-4360 radial engines, a taller vertical stabilizer, and other improvements.-Design and development:...
(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 LakeRogers Dry Lake is an endorheic desert salt pan in the Mojave Desert of Kern County, California. The lake derives its name from the anglicisation from the Spanish name, Rodriguez Dry Lake. It is the central part of Edwards Air Force Base as its hard playa surface provides a natural extension to...
, 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 phosphateTricresyl phosphate, abbreviated TCP, is an organophosphate compound. It is a derived from cresol and phosphoric acid. This viscous liquid is colourless when pure, but commercial samples are typically yellow. It is nonflammable and virtually insoluble in water...
(TCP), a leather treatment, which was used in the
liquid oxygenLiquid oxygen is a form of the element oxygen. It has a pale blue color and is strongly paramagnetic and can be suspended between the poles of a powerful horse shoe magnet...
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:
- 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.)
- A re-profiled super-thin wing ( inches at the root
A root is the part of a plant that is below ground.Root may also refer to:In computing:*Root directory, the first or top-most directory in a hierarchy*Root node, the node in a tree data structure from which every other node is accessible...
), based on the X-3 StilettoThe Douglas X-3 Stiletto was a 1950s United States experimental jet aircraft with a slender fuselage and a long tapered nose, manufactured by the Douglas Aircraft Company. Its primary mission was to investigate the design features of an aircraft suitable for sustained supersonic speeds, which...
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 WalkerJoseph Albert "Joe" Walker was an American test pilot and a NASA astronaut.In 1963, Walker made two X-15 flights beyond 100 kilometers - the edge of space. These were the only powered spaceplane flights past that threshold until SpaceShipOne in 2004. These flights qualified him as an astronaut...
. 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. McKayJohn B. McKay was one of the first pilots assigned to the X-15 flight research program at NASA's Flight Research Center, Edwards Air Force Base, California. As a civilian research pilot and aeronautical engineer, he made 30 flights in X-15s from October 28, 1960, until September 8, 1966...
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.
Specification (Bell X-1)
Specification (Bell X-1E)
See also
External links