List of X-planes

Bell X-1-2

The X-planes are a series of experimental United States airplanes and helicopters (and some rockets) used to test and evaluate new technologies and aerodynamic concepts. Most of the X-planes have been operated by the National Advisory Committee for Aeronautics (NACA) or, later, the National Aeronautics and Space Administration (NASA), often in conjunction with the United States Air Force. The majority of X-plane testing has occurred at Edwards Air Force Base.^[1]

Some of the X-planes have been well publicized, while others, such as the X-16, have been developed in secrecy.^[2] The first, the Bell X-1, became well known after it became, in 1947, the first aircraft to break the sound barrier in level flight.^[3] Later X-planes supported important research in a multitude of aerodynamic and technical fields, but only the North American X-15 rocket plane of the early 1960s achieved comparable fame to that of the X-1. X-planes 7 through 12 were actually missiles^[4] (used to test new types of engines), and some other vehicles were un-piloted (some were remotely flown, some were full-on drones).

Most X-planes are not expected to go into full-scale production; one exception was the Lockheed Martin X-35, which competed against the Boeing X-32 during the Joint Strike Fighter Program, and has entered production as the F-35.^[5]

Not all US experimental aircraft have been designated as X-planes; some received US Navy designations before 1962,^[6] while others have been known only by manufacturers' designations,^{[N 1]} non-'X'-series designations,^{[N 2]} or classified codenames.^{[N 3]}

Name	Manufacturer Agency	Image	Maiden flight	Purpose and Notes
X-1	Bell Aircraft USAF, NACA		January 19, 1946	High-speed and high-altitude testing. First aircraft to break the sound barrier in level flight. Proved aerodynamic viability of thin wing sections.[7]
X-2 "Starbuster"	Bell Aircraft USAF		June 27, 1952	High-speed and high-altitude testing. First aircraft to exceed Mach 3.[8]
X-3 Stiletto	Douglas Aircraft USAF, NACA		October 27, 1952	Titanium alloy construction; low aspect ratio wings. Planned to test long-duration high-speed flight. Incapable of reaching design speed, but provided insights into inertia coupling.[9]
X-4 Bantam	Northrop USAF, NACA		December 15, 1948	Evaluated handling characteristics of tailless aircraft in the transonic speed region.[10]
X-5	Bell Aircraft USAF, NACA		June 20, 1951	First aircraft to fly with variable geometry wings.[11]
X-6	Convair USAF, AEC		Not flown	Modified Convair B-36 for study of Aircraft Nuclear Propulsion; not built. NB-36H testbed tested reactor.[12]
X-7 "Flying Stove Pipe"	Lockheed Tri-service		April 1951	High-speed testbed for ramjet engines.[13]
X-8 Aerobee	Aerojet NACA, USAF, USN			Upper air research vehicle and sounding rocket.[14]
X-9 Shrike	Bell Aircraft USAF		April 1949	Guidance and propulsion technology testbed. Assisted development of GAM-63 Rascal missile.[15]
X-10	North American Aviation USAF		October 13, 1953	Testbed for SM-64 Navajo missile.[16]
X-11	Convair USAF		June 11, 1957	Testbed for SM-65 Atlas missile.[17]
X-12	Convair USAF		July, 1958	Advanced testbed for SM-65 Atlas missile.[18]
X-13 Vertijet	Ryan Aeronautical USAF, USN		December 10, 1955	Vertical takeoff and landing (VTOL) testbed. Evaluated tailsitting configuration for VTOL flight.[19]
X-14	Bell Aircraft USAF, NASA		February 19, 1957	VTOL testbed. Examined the vectored thrust configuration for VTOL flight.[20]
X-15	North American Aviation USAF, NASA		June 8, 1959	Hypersonic (Mach 6.7), high-altitude (350,000 feet (110,000 m)) testing. First manned hypersonic aircraft; capable of suborbital spaceflight.[21]
X-16	Bell Aircraft USAF		Never flew	High-altitude reconnaissance aircraft project.[22] "X-16" designation used as cover story.[23]
X-17	Lockheed USAF, USN		April 1956	Tested the effects of high Mach number reentry.[24]
X-18	Hiller Aircraft USAF, USN		November 24, 1959	VTOL/Short take-off and vertical landing (STOVL) testbed. Evaluated the tiltwing concept for VTOL flight.[25]
X-19	Curtiss-Wright Tri-service		November 1963	Tandem tiltrotor VTOL transport testbed.[26] XC-143 designation proposed.[27]
X-20 Dyna-Soar	Boeing USAF		Never built	Reusable spaceplane for military missions.[28]
X-21	Northrop USAF		April 18, 1963	Boundary layer control testbed.[29]
X-22	Bell Aircraft Tri-service		March 17, 1966	Quad ducted fan tiltrotor STOVL testbed.[30]
X-23 PRIME	Martin Marietta USAF		December 21, 1966	Maneuvering atmospheric reentry effects testbed.[31] Designation never officially assigned.[32]
X-24	Martin Marietta USAF, NASA		August 1, 1973	Low-speed lifting body handling testbed. Lifting body aerodynamic shape trials.[33]
X-25	Benson USAF		December 6, 1955	Light autogyro for emergency use by downed pilots.[34]
X-26 Frigate	Schweizer DARPA, US Army, USN		1967	Training glider for yaw-roll coupling Quiet observation aircraft testbed.[35]
X-27	Lockheed		Never flew	High performance fighter prototype.[36]
X-28 Sea Skimmer	Osprey Aircraft USN		August 12, 1970	Inexpensive aerial policing seaplane testbed.[37]
X-29	Grumman DARPA, USAF, NASA		1984	Forward-swept wing testbed.[38]
X-30 NASP	Rockwell NASA, DARPA, USAF		Never built	Single stage to orbit spaceplane prototype.[39]
X-31	Rockwell DARPA, USAF, BdV		1990	Thrust vectoring supermaneuverability testbed. ESTOL testbed.[40]
X-32	Boeing USAF, USN, RAF		September 2000	Joint Strike Fighter prototype.[41]
X-33 Venture Star	Lockheed Martin NASA		Prototype never completed	Half-scale reusable launch vehicle prototype.[42]
X-34	Orbital Sciences NASA		Never flew	Reusable unmanned spaceplane testbed.[43]
X-35	Lockheed Martin USAF, USN, RAF		2000	Joint Strike Fighter prototype.[44]
X-36	McDonnell Douglas/Boeing NASA		May 17, 1997	28% scale tailless fighter testbed.[45]
X-37	Boeing USAF, NASA		April 7, 2006 (drop test) April 22, 2010 (orbital flight)	Reusable orbital spaceplane.[46]
X-38	Scaled Composites NASA		1999	Lifting body Crew Return Vehicle demonstrator.[47]
X-39	Unknown USAF	Classified	Unknown	Future Aircraft Technology Enhancements (FATE) program.[48] Designation never officially assigned.[32]
X-40	Boeing USAF, NASA		August 11, 1998	80% scale Space Maneuver Vehicle testbed. X-37 prototype.[49]
X-41	Unknown USAF	Classified	Unknown	Maneuvering re-entry vehicle.[50]
X-42	Unknown USAF	Classified	Unknown	Expendable liquid propellant upper-stage rocket.[51]
X-43 Hyper-X	Micro Craft NASA		June 2, 2001	Scramjet hypersonic testbed (Mach 9.68) (110,000 ft).[52]
X-44 MANTA	Lockheed Martin USAF, NASA		Cancelled	F-22-based Multi-Axis No-Tail Aircraft thrust vectoring testbed.[53]
X-45	Boeing DARPA, USAF		May 22, 2002	Unmanned combat air vehicle (UCAV) demonstrator.[54]
X-46	Boeing DARPA, USN		Cancelled	Naval UCAV demonstrator.[55]
X-47A Pegasus X-47B	Northrop Grumman DARPA, USN		February 23, 2003	Naval UCAV demonstrator.[56]
X-48	Boeing NASA		July 20, 2007	Blended Wing Body (BWB) testbed.[57]
X-49 Speedhawk	Piasecki Aircraft US Army		July 29, 2007	Compound helicopter Vectored Thrust Ducted Propeller (VTDP) testbed.[58]
X-50 Dragonfly	Boeing DARPA		24 November 2003	Canard Rotor/Wing testbed.[59]
X-51 Waverider	Boeing USAF		26 May 2010[60]	Hypersonic scramjet demonstrator.[61]
X-52	Number skipped to avoid confusion with B-52.[32]
X-53	Boeing Phantom Works NASA, USAF		November 2002	Active Aeroelastic Wing testbed.[62]
X-54	Gulfstream Aerospace NASA		Future	Supersonic transport testbed.[58]
X-55	Lockheed Martin Skunk Works USAF		June 2, 2009	Advanced Composite Cargo Aircraft (ACCA). Molded composite fuselage and empennage testbed.[63]
X-56	Lockheed Martin Skunk Works USAF/NASA		2012	Active flutter suppression and gust load alleviation technology for potential use in future high-altitude, long-endurance (HALE) reconnaissance aircraft.[64]

See also

• Experimental aircraft
• List of experimental aircraft
• List of military aircraft of the United States

References

Notes

Citations

Bibliography

External links

Wikimedia Commons has media related to X-planes.

• Early X-planes
• X-15 Videos by NASA