Bell X-1

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Bell X-1
X-1 #46-062, nicknamed "Glamorous Glennis"
Type	rocket plane
Manufacturer	Bell Aircraft Corporation
Maiden flight	1946-01-19
Status	Retired
Primary users	USAF NACA

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. It was 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.

Contents 1 XS-1 1.1 Program History 1.2 Disposition 1.3 Legacy 1.4 Controversies 1.5 Specification 2 X-1A 3 X-1B 4 X-1C 5 X-1D 6 X-1E 6.1 Operational History 6.2 Disposition 7 X-1B 8 References 9 External links 10 See also

[edit] XS-1

[edit] Program History

On 16 March 1946 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.^[1] The XS-1 was the first high-speed aircraft built purely for aviation research purposes and was never intended for production.

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.^[2] Following Woolams' death on 30 August 1946, Chalmers "Slick" Goodlin was the primary Bell Aircraft test pilot of X-1-1. He made twenty-six 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 $150,000 bonus for breaking the sound barrier.^[3][4][5] Flight tests of the X-1-2 (serial number 46-063) would be conducted by NACA to provide design data for later production high-performance aircraft.

On October 14, 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 belly 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 peak speed; however, Yeager and many other personnel record the possibility that Flight #49 (also with Yeager piloting), which reached a top recorded speed of Mach 0.997, may have in fact passed the Sound Barrier. (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 Aviation Association voted its 1948 Collier Trophy to be shared by the three main participants in the program. Honored at the White House by President Truman were Larry Bell for Bell Aircraft, Captain Yeager for piloting the flights, and John Stack of NACA for the NACA contributions. Years later, Yeager reported that his father, a staunch Republican, refused to shake hands with President Truman (a Democrat).

[edit] Disposition

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. Aircraft #46-064 was destroyed 9 November, 1951, in a ground fire following a captive flight test, after completing only a single glide flight (20 July, 1951.^[6]

[edit] 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.

It should be noted that the intentions of the X-1 experiments were not to exceed the speed of sound in of itself, but to determine if, and then demonstrate that, controlled, sustained flight was possible at supersonic speeds. In earlier claims, the sound barrier was supposedly breached by diving aircraft and it would be impossible there to determine if aerodynamic lift could be maintained at those speeds.

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.

[edit] Controversies

Some claims have been voiced that the overall design of the X-1 was heavily based on the British Miles M.52 jet-powered design. All technical data from the project (including the importance of an all moving tail plane (Brain, Z. 2004)) was transferred to America in 1944, under an agreement that America would then share all of its high speed flight data. The Americans then backed out of the deal, and later made the all-moving tail a requirement for what would become the X-1 project. It has been suggested that at the time they had no data to share. The M.52 project was canceled by the British government in 1946, just a few months before the X-1 broke the sound barrier. Rocket tests later demonstrated that 1/3rd scale models of the M.52 were capable of stable flight at Mach 1.5.^[7]

The key difference between the two aircraft was that the M.52 had a turbofan equipped with a reheat-pipe (afterburner), rather than a liquid fuel rocket.

[edit] Specification

General characteristics

• Crew: 1
• Length: 30 ft 11 in (9.4 m)
• Wingspan: 28 ft (8.5 m)
• Height: 10 ft (3.3 m)
• Wing area: 130 ft² (12 m²)
• Empty weight: 7,000 lb (3,175 kg)
• Loaded weight: 12,225 lb (5,545 kg)
• Max takeoff weight: 12,250 lb (5,557 kg)
• Powerplant: 4× Reaction Motors XLR-11-RM3 liquid fuel rocket, 6,000 lbf (26.7 kN) each

Performance

• Maximum speed: 957 mph (1,541 km/h)
• Range: 5 minutes (powered endurance)
• Service ceiling: 71,900 ft (21,900 m)
• Wing loading: 94 lb/ft² (463 kg/m²)
• Thrust/weight: 0.49

[edit] 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 and altitudes greater than 90,000 feet, specifically focusing on dynamic stability and air loads. 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. 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.^[8]

Data from ^[9]

General characteristics

• Crew: 1
• Length: 35 ft 8 in ()
• Wingspan: 28 ft ()
• Height: 10 ft 8 in ()
• Wing area: 130 ft² ()
• Empty weight: 7,266 lb ()
• Loaded weight: 16,487 lb ()
• Powerplant: × Reaction Motors XLR11-RM-5 rocket, 6,000 lbf () each

Performance

• Maximum speed: 1,650 mph (2.44 Mach)
• Range: 4 minutes 40 seconds ((powered endurance))
• Service ceiling: 90,000+ ft ()

[edit] X-1B

Data from ^[10]

General characteristics

• Crew: 1
• Length: 35 ft 8 in ()
• Wingspan: 28 ft ()
• Height: 10 ft 8 in ()
• Wing area: 130 ft² ()
• Empty weight: 7,266 lb ()
• Loaded weight: 16,487 lb ()
• Powerplant: 1× Reaction Motors XLR11-RM-5 rocket, 6,000 lbf ()

Performance

• Maximum speed: 1,650 mph (2.44 Mach)
• Range: 4 minutes 40 seconds ((powered endurance))
• Service ceiling: 90,000+ ft ()

[edit] X-1C

The X-1C 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.^[11]

[edit] X-1D

Aircraft number #48-1386 was the first of the second generation of supersonic rocket planes. Flown from EB-50 Superfortress A, number #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 was also some minor changes to the avionics set.

Flight History of the X-1D

On 24 July, with Bell company 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.

Data from ^[12]

General characteristics

• Crew: 1
• Length: 35 ft 8 in ()
• Wingspan: 28 ft ()
• Height: 10 ft 8 in ()
• Wing area: 130 ft² ()
• Empty weight: 7,266 lb ()
• Loaded weight: 16,487 lb ()
• Powerplant: 1× Reaction Motors XLR11-RM-5 rocket, 6,000 lbf ()

Performance

• Maximum speed: 1,650 mph (2.44 Mach)
• Range: 4 minutes 40 seconds ((powered endurance))
• Service ceiling: 90,000+ ft ()

[edit] X-1E

The X-1E resulted from a significant reconstruction of the X-1-2 (s/n 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 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.).^[13]
• 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 facilitated the inclusion of an ejection seat.
• The addition of 200 pressure ports for aerodynamic data, and 343 strain gages to measure structural loads and aerodynamic heating along the wing and fuselage.^[14]

[edit] Operational History

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. NACA research pilot John B. McKay took his place in September 1958, completing five flights in pursuit of Mach 3 before the X-1E was permanently grounded following its 26th overall flight, in November 1958, due to the discovery of structural cracks in the fuel tank wall.

[edit] Disposition

The X-1E is permanently on display in front of the NASA Dryden Flight Research Center headquarters building, at Edwards AFB.

[edit] X-1B

Data from ^[15]

General characteristics

• Crew: 1
• Length: 31 ft ()
• Wingspan: 22 ft 10 in ()
• Height: 10 ft 10 in ()
• Wing area: 115 ft² ()
• Empty weight: 6,850 lb ()
• Loaded weight: 14,750 lb ()
• Powerplant: 1× Reaction Motors RMI LR-8-RM-5 rocket, 6,000 lbf ()

Performance

• Maximum speed: 1,450 mph (2.24 Mach)
• Range: 4 minutes 45 seconds ((powered endurance))
• Service ceiling: 90,000+ ft ()

[edit] References

[edit] 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

[edit] See also

• List of experimental aircraft
• List of rocket planes
• List of X-1 flights - list of XS-1 pilots and flights.
• List of X-1A flights - list of X-1A pilots and flights.
• List of X-1B flights - list of X-1B pilots and flights.
• List of X-1D flights - list of X-1D pilots and flights.
• List of X-1E flights - list of X-1E pilots and flights.
• Mach number
• Miles M.52 - An earlier British design which may have substantially influenced the development of the X-1