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Aviation: the History of the X Series of Aircraft |
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| Aircraft X Number | Manufacturer | Total Number Built | Operating Time Span | No. of Flights | Primary Testing Facility | Achievement Highlights | Notes |
| X- 1 | Bell Aircraft | 3 | 1946- 51 | 157 | Edwards AFB | First Mach 1+ flight; Maximum altitude of 71,902 ft | |
| X- 1A | Bell Aircraft | 1 | 1953- 55 | 25 | Edwards AFB | Obtained speed of Mach 2.44; Maximum altitude of 90,440 ft | |
| X- 1B | Bell Aircraft | 1 | 1954- 58 | 27 | Edwards AFB | First reaction controlled flight | |
| X- 1D | Bell Aircraft | 1 | 1951 | 1 | Edwards AFB | No major ahcievments, Explosion during captive flight; vehicle jettisoned | |
| X- 1E | Bell Aircraft, Stanley Aircraft (wings) | 1 | 1955- 58 | 26 | Edwards AFB | Mach 2.24, altitude 73,458 ft; first flight with ventral fins | |
| X- 2 | Bell Aircraft | 2 | 1952- 56 | 20 | Edwards AFB | New altitude record
of 126,200 ft; new speed record of Mach 2.87 Gasket explosion destroyed first X- 2; second aircraft lost to inertial coupling |
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| X- 3 | Douglas Aircraft | 1 | 1954- 56 | 20 | Edwards AFB | Led to understanding of inertia coupling | |
| X- 4 | Northrop Aircraft | 2 | 1950- 53 | 82 | Edwards AFB | Showed tailless craft not suited for transonic flight | |
| X- 5 | Bell Aircraft | 2 | 1952- 55 | 133 | Edwards AFB | Successful sweep- wing operation | |
| X- 6 | Convair Division, General Dynamics | 1 shield- test aircraft (modified B- 36H) | 1955- 57 | 47 | Convair Testing Facility | Program terminated before prototypes constructed | |
| X- 7A, X- 7A- 3, X- 7B, X- Q5 (unmanned) |
Lockheed Missiles | 61 | 1951- 60 | 130 | New Mexico | Obtained Mach 4.31, first air- breathing full- scale research aircraft designed as Mach 3 testbed | |
| X- 8A, X- 8B, X- 8C, X- 8D Aerobees (unmanned) |
Aerojet Engineering | 108 (X- 8 designation) 800+ Aerobees |
1947- 56 | Unknown | White Sands, Holloman AFB | Peak altitude of 121 miles | |
| X- 9 (unmanned) | Bell Aircraft | 31 | 1949- 53 | 28 | Holloman AFB | First chemical warhead
test vehicle to test supersonic clusterable dispersion 9 unsuccessful flights |
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| X- 10 (unmanned) | North American Aviation | 13 | 1955- 59 | 15 | Edwards AFB | Established technology
base for remote control; first Mach 2- capable target drone 3 unsuccessful flights Communications disruption; miswiring; autopilot malfunction |
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| X- 11 (unmanned) | Convair Astronautics Division | 8 | 1956- 58 | 8 | Cape Canaveral | First ICBM prototypes | |
| X- 12 (unmanned) | Convair Astronautics Division | 5 | 1958 | 5 | Cape Canaveral | First intercontinental range mission of 6,325 miles | |
| X- 13 | Ryan Aeronautical Company | 2 | 1955- 57 | Unknown | Edwards AFB | First successful VTOL flight on jet thrust alone | |
| X- 14, X- 14A, X- 14B |
Bell Aircraft | 1 | 1957- 81 | Unknown | Moffet Field | First VTOL aircraft using jet thrust diverter system for vertical lift | |
| X-
15, X- 15A- 2 |
North American Aviation | 3 | 1959- 68 | 199 | X- 15 High Range (Wendover, UT, to Edwards AFB) | First manned hyper- sonic flight vehicle; altitude of 354,200 ft obtained; Mach 6.7 reached 4 Mid- flight explosions (2); loss of control (1); collapsed landing gear (1) | |
| X- 16 | Bell Aircraft Canceled | None | None | None | None | ||
| X- 17 (unmanned) | Lockheed Missiles | 26 | 1955- 57 | 26 | Holloman AFB | High Mach effects on reentry vehicles | |
| X- 18 | Hiller Aircraft | 1 | 1959- 61 | 20 | Edwards AFB | First tilt- wing usage for VTOL | |
| X- 19 | Curtiss- Wright | 2 | 1964- 65 | 50 | Caldwell; NAFEC, NJ | Dual- tandem tilt propeller use One Equipment failure | |
| X- 20 | Boeing | Canceled | None | None | None | ||
| X- 21A | Northrop Corporation | 2 | 1963- 64 | Unknown | Edwards AFB | Proved Laminar Flow Control viable | |
| X- 22A | Bell Aerospace | 2 | 1966- 84 | 501 | Bell, Calspan Test Facilities | Ducted fan viability, advancement of VTOL technology; One hydraulic system failure | |
| X- 23A (unmanned) | Martin Marietta | 4 | 1966- 67 | 3 | Vandenberg AFB/ Pacific Ocean | First maneuverable reentry vehicle | |
| X-
24A, X- 24B |
Martin Marietta | 1 | 1969- 75 | 64 | Edwards AFB | Verified theoretical advantages of lifting body configuration for hypersonic trans- atmospheric aircraft | |
| X- 25, X- 25A, X- 25B |
Bensen Aircraft | 3 | 1968 | None | Raleigh, NC | Insight on pilot training | |
| X- 26A, X- 26B |
Schweizer Aircraft, Lockheed Missiles | 6 | 1967- 88 | Unknown | Vietnam | Use as training vehicle; contributions to stealth designs | |
| X- 27 | Lockheed- California | Canceled | None | None | None | ||
| X- 28A | George Pereira, Osprey Aircraft | 1 | 1971 | Unknown | Philadelphia Naval Base, PA | Unique contribution as home- built aircraft in X- Plane program | |
| X- 29A | Grumman Aerospace | 2 | 1984- 90 | Unknown | Edwards AFB | First Forsard Swept Wing (FSW) aircraft to fly supersonically in level flight | |
| X- 30 | None selected | None | None | None | None | ||
| X- 31A | Rockwell International, Deutsche Aerospace | 2 | 1990- 95 | 523 | Edwards AFB | 180 degree turn post- stall maneuver Failure of the pitot static system: erroneous total pressure data | |
| X-32 | |||||||
| X-33 | Lockheed- Martin Skunk Works | 1 | 1999-2000 | 15 | Edwards AFB | ||
| X-34 | Speeds up to Mach 8 and altitudes of 250,000 feet. The project has a goal of reaching $500K/flight recurring cost and demonstrating a rate of 24 flights in 12 months while maintaining a small work force. | The X-34 is a reusable technology testbed vehicle that is designed to demonstrate technologies that are essential to lowering the cost of access to space. The vehicle structure is an all-composite with a one piece delta wing design 58 feet in length and 28 feet wide. | |||||
| X-35 | |||||||
| X-36 | |||||||
| X-37 | Designed to be modular to allow for rapid insertion of technologies and experiments | The X-37 is 27.5eet long - abouthalf the length of the Shuttle payload bay and weighs about 6 tons. Its wingspan is about 15 feet, nd it contains an experiment bay 7 eet long and 4 feet in diameter. | |||||
| X-38 | |||||||
| X-39 | |||||||
| X-40 | |||||||
| X-41 | |||||||
| X-42 | |||||||
| X-43 | |||||||
| DC-X | McDonnell Douglas | 1994-96 | White Sands NM | Incorporate new advanced technologies for demonstrating the feasibility of single stage to orbit flight | The DC-X is designed both to take off and land in a vertical attitude | ||
Key to Acronyms: AFB = Air Force Base FDL- 7 = Flight Dynamics Laboratory- 7 (a prototype test craft of the Air Force's Flight Dynamics Laboratory, a predecessor to the X- 24B). FSW = forward swept wing ICBM = intercontinental ballistic missile V/ STOL = vertical/ short takeoff and landing VTOL = vertical takeoff and landing |
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