List of X-planes

Template:Short description Template:About Template:Use dmy dates Template:Use American English

Bell X-1-2

The X-planes are a series of experimental United States aircraft and rockets, used to test and evaluate new technologies and aerodynamic concepts. They have an X designator within the US system of aircraft designations, which denotes the experimental research mission.

Not all US experimental aircraft have been designated as X-planes; some received US Navy designations before 1962,<ref>"D-558-I" NASA Dryden Fact Sheets. NASA. Accessed May 8, 2010.</ref> while others have been known only by manufacturers' designations,<ref group="N">For example, the Piasecki PA-97</ref> non-'X'-series designations,<ref group="N">For example, the NASA AD-1 and Bell XV-15</ref> or classified codenames.<ref group="N">For example, the Northrop Tacit Blue</ref> This list only includes the designated X-planes.

HistoryEdit

The X-planes concept officially came into being in 1944, as a joint programme involving the National Advisory Committee for Aeronautics (NACA), the US Navy (USN) and the US Army Air Forces (USAAF), in order to pursue research into high-speed aircraft.<ref name="Miller 1983, p.9">Miller 1983, p.9.</ref> NACA later became the National Aeronautics and Space Administration (NASA) and the USAAF became the United States Air Force (USAF). Other organizations such as the Defence Advanced Research Projects Agency (DARPA) and the US Marine Corps (USMC) have also since sponsored X-plane projects.

The first experimental aircraft specification, for a transonic rocket plane, was placed in 1945, and the first operational flight of an X-plane took place when the Bell X-1 made its first powered flight nearly three years later at Muroc Air Force Base, California, now known as Edwards Air Force Base.<ref>Miller 1983, pp.15-17.</ref> The majority of X-plane testing has since taken place there.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>

X-planes have since accomplished many aviation "firsts" including breaking speed and altitude barriers, varying wing sweep in flight, implementing exotic alloys and propulsion innovations, and many more.<ref name="Miller 1983, p.9"/>

New X-planes appeared fairly regularly for many years until the flow temporarily stopped in the early 1970s. A series of experimental hypersonic projects, including an advanced version of the Martin Marietta X-24 lifting body, were turned down. Eventually issues with the Rockwell HiMAT advanced UAV led to a crewed X-plane with forward sweep, the Grumman X-29, which flew in 1984.<ref>Miller 1983, p.13.</ref>

Some of the X-planes have been well publicized, while others, such as the X-16, have been developed in secrecy.<ref>Miller 2001, p. 209</ref> The first, the Bell X-1, became well known in 1947 after it became the first aircraft to break the sound barrier in level flight.<ref name = "X-1">Template:Citation.</ref> 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.Template:Citation needed X-planes 8, 9, 11, 12, and 17 were actually missiles Template:Sfn used to test new types of engines, and some other vehicles were unoccupied or UAVs (some were remotely flown, some were partially or fully autonomous).

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 Lightning II.<ref name="MartinBaker">Template:Citation.</ref>

ListEdit

In the list, the date is that of the first flight, or of cancellation if it never flew.

List of X-planes
Image	Type	Manufacturer	Agency	Date	Role	Notes
File:Bell X-1 46-062 (in flight).jpg	X-1	Bell	USAF, NACA	1946	High-speed and high-altitude flight	First aircraft to break the sound barrier in level flight. Proved aerodynamic viability of thin wing sections.Template:Sfn
File:Bell X-1A.jpg	X-1A X-1B X-1C X-1D	Bell	USAF, NACA	1951	High-speed and high-altitude flight
File:Joe Walker X-1E.jpg	X-1E	Bell	USAF, NACA	1955	High-speed and high-altitude flight
File:X-2 After Drop from B-50 Mothership - GPN-2000-000396.jpg	X-2	Bell	USAF	1952	High-speed and high-altitude flight	First aircraft to exceed Mach 3.Template:Sfn
File:Douglas X-3 NASA E-17348.jpg	X-3 Stiletto	Douglas	USAF, NACA	1952	Highly loaded trapezoidal wing	Titanium alloy construction; Underpowered, but provided insights into inertia coupling.Template:Sfn
File:Northrop-X4-Bantam.jpg	X-4 Bantam	Northrop	USAF, NACA	1948	Transonic tailless aircraft Template:Sfn
File:Bell-X5-Multiple.jpg	X-5	Bell	USAF, NACA	1951	variable geometry	First aircraft to fly with variable wing sweep.Template:Sfn
File:NB-36H producing contrails in flight.jpg	X-6	Convair	USAF, AEC	1957	Nuclear Propulsion	Not built. The Convair NB-36H experiment, a B-36 modified to carry (but not powered by) a nuclear reactor, flew from 1955 to 1957.Template:Sfn<ref>Miller 1983.</ref>
File:X-7 USAF.jpg	X-7	Lockheed	USAF, USA, USN	1951	Ramjet engines.Template:Sfn
File:AerojetX8.jpg	X-8 Aerobee	Aerojet	NACA, USAF, USN	1949	Upper air researchTemplate:Sfn	Later models used as sounding rockets.
File:Bell X-9 trailer.jpg	X-9 Shrike	Bell	USAF	1949	Guidance and propulsion technology	Assisted development of GAM-63 Rascal missile.Template:Sfn
File:North American X-10 runway.jpg	X-10	North American	USAF	1953	SM-64 Navajo missile testbed.Template:Sfn
	X-11	Convair	USAF	1953	Proposed SM-65 Atlas missile testbed.Template:Sfn
	X-12	Convair	USAF	1953	Proposed SM-65 Atlas missile testbed.Template:Sfn
File:Ryan X-13.jpg	X-13 Vertijet	Ryan	USAF, USN	1955	Vertical takeoff and landing (VTOL)	tailsitting VTOL flight.Template:Sfn
File:Bell X-14 colour ground.jpg	X-14	Bell	USAF, NASA	1957	VTOL	Vectored thrust configuration for VTOL flight.Template:Sfn
File:X-15 in flight.jpg	X-15	North American	USAF, NASA	1959	Hypersonic, high-altitude flight	First crewed hypersonic aircraft; capable of suborbital spaceflight.Template:Sfn
File:X-15A2 NB-52B 3.jpg	X-15A-2	North American	USAF, NASA	1964	Hypersonic, high-altitude flight	Major Pete Knight flew the X-15A-2 to a Mach 6.70, making it the fastest piloted flight of the X-plane program.
File:Bell X-16.jpg	X-16	Bell	USAF	1954	High-altitude reconnaissance Template:Sfn	"X-16" designation used to hide true purpose.<ref>"X-16". Global security, accessed 11 May 2010.</ref> Canceled and never flew.
File:Lockheed X-17 horizontal.jpg	X-17	Lockheed	USAF, USN	1956	High Mach number reentry.Template:Sfn
File:Hiller X-18 testplatformLarge.jpg	X-18	Hiller	USAF, USN	1959	Vertical and/or short take-off and landing (V/STOL)	Evaluated the tiltwing concept for VTOL flight.Template:Sfn
File:Curtiss-Wright X-19 flying.jpg	X-19	Curtiss-Wright	Tri-service	1963	Tandem tiltrotor VTOLTemplate:Sfn	XC-143 designation requested but turned down.<ref name="DSMMDS" />
File:NASA Color Dyna Soar.jpg	X-20 Dyna-Soar	Boeing	USAF	1963	Reusable spaceplane	Intended for military missions.Template:Sfn Canceled and never built.
File:X21A.jpg	X-21A	Northrop	USAF	1963	Boundary layer control Template:Sfn
File:X-22a onground bw.jpg	X-22	Bell	Tri-service	1966	Quad ducted fan tiltrotor STOVLTemplate:Sfn
File:X23 PRIME.JPG	X-23 PRIME	Martin Marietta	USAF	1966	Maneuvering atmospheric reentry Template:Sfn	Designation never officially assigned.<ref name="DSMMDS">Parsch 2024, "Missing Designations"</ref>
File:X24.jpg	X-24A	Martin Marietta	USAF, NASA	1969	Low-speed lifting body Template:Sfn
File:X-24b-flying.jpg	X-24B	Martin Marietta	USAF, NASA	1973	Low-speed lifting body Template:Sfn
File:X-25.jpg	X-25	Bensen	USAF	1955	Commercial light autogyro for downed pilots.Template:Sfn
File:X-26 sailplane.jpg File:QT-2PCs in STAAF, RVN Hangar c1968.jpg	X-26 Frigate	Schweizer	DARPA, US Army, USN	1967	Training glider for yaw-roll coupling Quiet observation aircraft Template:Sfn
File:X-27 mockup.jpg	X-27	Lockheed	None	1971	high-performance research aircraft. High-performance fighterTemplate:Sfn	Proposed development of Lockheed CL-1200 Lancer. Canceled and never flew.
File:X-28 on ground.jpg	X-28 Sea Skimmer	Osprey	USN	1970	Low-cost aerial policing seaplaneTemplate:Sfn
File:Grumman-X29-InFlight.jpg	X-29	Grumman	DARPA, USAF, NASA	1984	Forward-swept wing Template:Sfn
File:X-30 NASP 2.jpg	X-30 NASP	Rockwell	NASA, DARPA, USAF	1993	Single-stage-to-orbit spaceplane Template:Sfn	Canceled and never built.
File:Rockwell-MBB X-31 landing.JPG	X-31	Rockwell-MBB	DARPA, USAF, BdV	1990	Thrust vectoring supermaneuverability Template:Sfn
File:USAF X32B 250.jpg	X-32A	Boeing	USAF, USN, USMC, RAF	2000	Joint Strike Fighter Template:Sfn
File:USAF X32B 250.jpg	X-32B	Boeing	USAF, USN, USMC, RAF	2001	Joint Strike Fighter Template:Sfn
File:X-33 Venture Star in Orbit.jpg	X-33	Lockheed Martin	NASA	2001	Half-scale reusable launch vehicle prototype.Template:Sfn	Prototype never completed.
File:Orbital Sciences X34.jpg	X-34	Orbital Sciences	NASA	2001	Reusable pilotless spaceplane.Template:Sfn	Never flew.
File:X-35.jpg	X-35A	Lockheed Martin	USAF, USN, USMC, RAF	2000	Joint Strike Fighter Template:Sfn
File:X-35B Steven F. Udvar-Hazy Center.tif	X-35B			2001		First in family to use VTOL. Also used unconventional mode of lift engine (lift fan).
File:Lockheed F-35 Joint Strike Fighter.jpg	X-35C			2000
File:Boeing-X36-InFlight.jpg	X-36	McDonnell Douglas	NASA	1997	28% scale tailless fighter Template:Sfn
File:Boeing X-37B inside payload fairing before launch.jpg	X-37	Boeing	USAF, USSF, NASA	2010	Reusable orbital spaceplane Template:Sfn	Drop test performed in 2006. Seven flights to space since 22 April 2010
File:ISS Crew Return Vehicle.jpg	X-38	Scaled Composites	NASA	1998	Lifting body Crew Return Vehicle Template:Sfn
	X-39	Unknown	USAF		Future Aircraft Technology Enhancements (FATE) program.Template:Sfn	Designation never officially assigned.<ref name="DSMMDS" />
File:Boeing X40A.jpg	X-40A	Boeing	USAF, NASA	1998	80% scale Space Maneuver Vehicle X-37 prototype.Template:Sfn
File:Early CAV concept 1997-98 NSSRM.jpg	X-41	Unknown	USAF		Maneuvering re-entry vehicle.Template:Sfn
	X-42 Template:Anchor	Unknown	USAF		Expendable liquid propellant upper-stage rocket.Template:Sfn
File:X-43 NASA.jpg	X-43 Hyper-X	Micro-Craft	NASA	2001	Hypersonic Scramjet Template:Sfn
File:X-44 Manta artistic impression.JPG	X-44 MANTA	Lockheed Martin	USAF, NASA	2000	F-22-based Multi-Axis No-Tail Aircraft thrust vectoringTemplate:Sfn	Canceled, never flew.
File:Boeing X-45A UCAV.jpg	X-45	Boeing	DARPA, USAF	2002	Unmanned combat air vehicle (UCAV)Template:Sfn
File:X46.jpg	X-46	Boeing	DARPA, USN	2003	Unmanned combat air vehicle (UCAV).Template:Sfn	Naval use. Canceled, never flew.
File:X-47A rollout.jpg	X-47A Pegasus	Northrop Grumman	DARPA, USN	2003	Unmanned combat air vehicle (UCAV)Template:Sfn	Naval use.
File:X-47B operating in the Atlantic Test Range (modified).jpg	X-47B	Northrop Grumman	DARPA, USN	2011	UCAV	Naval use.
	X-47C	Northrop Grumman	USAF		Manned bomber	Proposal for a new-generation strategic bomber. Design only.
File:ED06-0198-62.jpg	X-48	Boeing	NASA	2007	Blended Wing Body (BWB)Template:Sfn
File:Piasecki X-49A.jpg	X-49 SpeedHawk	Piasecki	US Army	2007	Compound helicopter Vectored Thrust Ducted Propeller (VTDP) testbed.<ref name="412015-L">Parsch 2024, "DOD 4120.15-L"</ref>
	X-50 Dragonfly	Boeing	DARPA	2003	Canard Rotor/Wing Template:Sfn
File:X51waverider.jpg	X-51 Waverider	Boeing	USAF	citation	CitationClass=web }}</ref>	Hypersonic scramjet<ref>"X-51 Scramjet Engine Demonstrator - WaveRider" globalsecurity.org. Accessed 2010-05-11.</ref>
—	X-52	—	—	—	—	Number skipped to avoid confusion with Boeing B-52 Stratofortress.<ref name="DSMMDS"/>
File:X-53 Active Aeroelastic Wing NASA test aircraft EC03-0039-1.jpg	X-53	Boeing	NASA, USAF	2002	Active Aeroelastic Wing<ref>Jordan 2006</ref>
	X-54	Gulfstream	NASA		Low-noise supersonic transport<ref>412015-L</ref> in development.
File:Lockheed Martin X-55 ACCA 001.jpg	X-55	Lockheed Martin	USAF	2009	Advanced Composite Cargo Aircraft (ACCA)<ref>Kaufman 2009</ref>
File:Lockheed Martin X-56A.jpg	X-56	Lockheed Martin	USAF/NASA	2013	Active flutter suppression and gust load alleviation	Part of the high-altitude, long-endurance (HALE) reconnaissance aircraft program.<ref>Norris 2012</ref>
File:X57-Maxwell-CGI.jpg	X-57 Maxwell	ESAero/Tecnam	NASA	2023	citation	CitationClass=web }}</ref>	Part of NASA's Scalable Convergent Electric Propulsion Technology Operations Research project<ref name=Harrington/> (SCEPTOR). Cancelled in 2023, never flew.
—	X-58	—	—	—	—	Number skipped; slot apparently assigned to Kratos XQ-58 Valkyrie.<ref>The Air Force Valkyrie Drone, a Sidekick for Human-Piloted Planes, Will Fly This Year</ref>
File:NASA’s X-59 Sits on Ramp (AFRC2023-0198-03).jpg	X-59 Quesst	Lockheed Martin	NASA	2024	Prototype quiet supersonic transport aircraft<ref name="Banke">{{#invoke:citation/CS1\|citation	CitationClass=web }}</ref>
	X-60	Generation Orbit Launch Services	USAF		Air-launched rocket for hypersonic flight research<ref>{{#invoke:citation/CS1\|citation	CitationClass=web }}</ref>
File:GremlinsFlightTestNovember2019.jpg	X-61 Gremlins	Dynetics	DARPA	2020	Air-launched and air-recoverable reconnaissance unmanned air vehicle (UAV)<ref>Template:Cite journal</ref><ref>Template:Cite journal</ref>
File:X-62 VISTA.jpg	X-62 VISTA	Lockheed Martin/Calspan	USAF	2021	Variable In-flight Simulator Test Aircraft.	First flew in 1993 as the NF-16D (for the MATV program). Designated the X-62A during a major research system upgrade in 2021. Assigned to the USAF Test Pilot School.<ref name=x62a>Giancarlo Casem (30 Jul 2021) NF-16D VISTA becomes X-62A, paves way for Skyborg autonomous flight tests</ref>
—	X-63	ABL Space Systems	AFRL	2023	Modular aerospike engine launch vehicle testbed based on RS1. <ref name="AFRL">{{#invoke:citation/CS1\|citation	CitationClass=web }}</ref>	The RS1 launch vehicle first flew on Jan 10, 2023. The launch ended in failure. <ref>Template:Cite news</ref>
—	X-64	Invocon Inc.	AFRL	—	Modular aerospike engine launch vehicle testbed<ref name="AFRL"></ref>
File:X-65 by DARPA.jpg	X-65 CRANE	Aurora Flight Sciences	DARPA	2025	citation	CitationClass=web }}</ref>
File:NASA Boeing X-66A Sustainable Flight Demonstrator side.jpg	X-66	Boeing	NASA	2028	citation	CitationClass=web }}</ref>