X-# Builder Manned 1st Flt Purpose
X-1. Bell Y Jan. 1946 Rocket powered plane, developed to investigate
supersonic flight regime. It broke the sound
barrier in 1947 with Chuck Yeager piloting.
X-2. Bell Y Aug. 1955 Rocket powered plane, 1st Mach 3 flight,
this was a swept wing X-1.
X-3. Douglas Y Oct. 1952 Jet powered supersonic plane (couldn't fly
supersonic in level flight) Stiletto
X-4. Northrop Y Dec. 1948 Jet powered tailless transonic airplane
X-5. Bell Y June 1951 First successful variable sweep airplane
X-6. Convair Y - This aircraft was to have been nuclear powered
(never built) NB-36 did fly with a reactor
X-7. Lockheed N Apr. 1951 Supersonic/Hypersonic ramjet testbed missile.
X-8. Aerojet N Nov. 1947 Upper atmosphere research rocket
(became the "Aerobee")
X-9. Bell N May 1950 Missile test bed (Mach 2 aerodynamics), results
used for the development of the "Rascal"
X-10. North American N Oct. 1953 2nd phase of the R&D for the "Navaho" - later
became target drones.
X-11. Convair N July 1948 Rocket to test ICBM concepts (smaller than V-2's),
precursor to the Atlas missile program.
X-12. Convair N - A jet powered version of the X-11
(program canceled).
X-13. Ryan Y Dec. 1956 A pure jet "tailsitter" VTOL aircraft
X-14. Bell Y Feb. 1957 A deflected jet VTOL aircraft
X-15. North American Y June 1959 Rocket powered hypersonic research airplane
X-16. Bell Y - Proposed high altitude photo-recon plane
(X designation a coverup; lost competition
to Lockheed U-2).
X-17. Lockheed N Sept 1956 3 stage solid propellant rocket built for re-entry
testing of warhead configurations.
X-18. Hiller Y Nov. 1959 A tilt-wing VTOL aircraft (never made the
transition from hover to flight or vice versa)
X-19. Curtis-Wright Y Oct. 1963 A tilt-propeller VTOL aircraft (plane had seats
for 4 passengers)
X-20. Boeing Y - A manned-recoverable orbital vehicle concept;
the "Dyna-Soar" (program canceled)
X-21. Northrop Y Apr. 1963 Laminar flow control demonstration aircraft
X-22. Bell Y Mar. 1966 A tilt-ducted propeller V/STOL aircraft
(wing tips also rotated)
X-23. Martin N 1967 Unmanned lifting body concept demonstrator
(unpowered).
X-24. Martin Y Apr. 1969 Rocket powered manned lifting body
X-25. Bensen Y 1967 Government designation for the Bensen gyrocopter
X-26. Lockheed Y July 1967 Quiet-Recon; the Lockheed Q-Star
X-27. Lockheed Y - High performance fighter engine test bed
(Lockheed's "Lancer"), program canceled
X-28. Osprey Y Aug. 1970 Government designation of the homebuilt
"Osprey 1"; a small single engine flying boat.
X-29. Grumman Y 14 Dec. 1984 Forward swept wing demonstrator
X-30. Rockwell/etc. Y - NASP (never built)
X-31. Rockwell/MBB Y 11 Oct. 1990 Post-Stall Maneuver demonstrator
X-32 Boeing Y - This is the Boeing JSF
(Joint Strike Fighter) concept vehicle
X-33 Lockheed N next generation reusable launch system
Martin awarded in 1996
X-34. Orbital Sci. N new small payload launch system
Phase 1, Mar. 1995
X-35 Lockheed Y - This is the Lockheed Martin JSF
Martin (Joint Strike Fighter) concept vehicle
X-36 McDonnell N 17 May 1997 Tailless (vertical) Aircraft Research UAV
(now Boeing)
X-38 Scaled N Fall 1997 Experimental Crew Return Vehicle
Composites to be droppped from a B-52 (X-24A derivative)
For further reading:
Jay Miller, The X-Planes, Specialty Press, 1983 (more recent editions available).
Ben Guenther, Jay Miller, and Terri Panopalis, North American X-15/X-15A-2, Aerofax Datagraph 2.
-, Proceedings of the X-15 First Flight 30th Anniversary Celebration, NASA CP 3105, June 8, 1989, published: 1991.
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direct comments and suggestions to W.H. Mason, mason@apollo.aoe.vt.edu