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The X Programs


Source: Draft X-33 Environmental Impact Statement, Table A-1

 

Summary of the X-Plane Program.
Model
Manufacturer
No. of Vehicles Built
Years of Operation
No. of Flights
Primary Testing Facility
Research Goals
Program Achievements
No. of 
Major Accidents
Causes of Accidents
No. of Fatalities
Civilian Involvement
X-1 Bell Aircraft
3
1946-51
157
 Edwards AFB Investigate flight characteristics at greater than sonic velocities. Structural, physiological phenomena within transonic speed envelope First Mach 1+ flight; Maximum altitude of 71,902 ft
1
 Defueling Explosion
0
 None
X-1A Bell Aircraft
1
1953-55
25
 Edwards AFB Continue X-1 goals at higher speeds and altitudes Obtained speed of Mach 2.44; Maximum altitude of 90,440 ft
1
 Explosion during captive flight; vehicle jettisoned
0
 None
X-1B Bell Aircraft
1
1954-58
27
 Edwards AFB Exploratory aerodynamic heating tests; experimental reaction control system First reaction controlled flight
0
 Not applicable Not applicable Not applicable
X-1D Bell Aircraft
1
1951
1
 Edwards AFB Continue X-1 goals at higher speeds and altitudes No major milestones
1
 Explosion during captive flight; vehicle jettisoned
0
 None
X-1E Bell Aircraft, Stanley Aircraft (wings)
1
1955-58
26
 Edwards AFB High-speed wing performance Mach 2.24, altitude 73,458 ft; first flight with ventral fins
0
 Not applicable Not applicable Not applicable
X-2 Bell Aircraft
2
1952-56
20
 Edwards AFB Swept-wing performance; higher speeds and altitude than X-1 New altitude record of 126,200 ft; new speed record of Mach 2.87
2
 Gasket explosion destroys first X-2; second aircraft lost to inertial coupling
3
 None
X-3 Douglas Aircraft
1
1954-56
20
 Edwards AFB High speed aerodynamic phenomenon; titanium construction; take off, land under its own power Led to understanding of inertia coupling
0
 Not applicable Not applicable Not applicable
X-4 Northrop Aircraft
2
1950-53
82
 Edwards AFB Test tailless, semi-tailless configuration at transonic speeds Showed tailless craft not suited for transonic flight
0
 Not applicable Not applicable Not applicable
X-5 Bell Aircraft
2
1952-55
133
 Edwards AFB Investigate aerodynamics of variable-seep-wing design Successful sweep-wing operation
0
 Not applicable Not applicable Not applicable
X-6 Convair Division, General Dynamics
1 shield-test aircraft (modified B-36H)
1955-57
47
 Convair Testing Facility Test feasibility of nuclear propulsion Program terminated before prototypes constructed
0
 Not applicable Not applicable Not applicable
X-7A, X-7A-3, X-7B, X-Q5 (unmanned) Lockheed Missiles
61
1951-60
130
 New Mexico Test viability of ramjet engines for anti-aircraft missiles; modified to testing of powerplants Obtained Mach 4.31, first air-breathing full-scale research aircraft designed as Mach 3 testbed
0
 Not applicable Not applicable Not applicable
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 Upper air research, parachute recovery system Peak altitude of 121 miles
0
 Not applicable Not applicable Not applicable
X-9 (unmanned) Bell Aircraft
31
1949-53
28
 Holloman AFB Test air-to-surface missiles; guidance systems, etc. First chemical warhead test vehicle to test supersonic clusterable dispersion
9 unsuccessful flights
 Servo system failures
0
 Not applicable
X-10 (unmanned) North American Aviation
13
1955-59
15
 Edwards AFB Testbed for cruise missile components Established technology base for remote control; first Mach 2-capable target drone
3 unsuccessful flights
 Communications disruption; miswiring; autopilot malfunction
0
 Not applicable
X-11 (unmanned) Convair Astronautics Division
8
1956-58
8
 Cape Canaveral Provide flight data for Atlas missile First ICBM prototypes
0
 Not applicable Not applicable Not applicable
X-12 (unmanned) Convair Astronautics Division
5
1958
5
 Cape Canaveral Test 1½-propulsion-staging guidance system, nose reentry configuration First intercontinental range mission of 6,325 miles
0
 Not applicable Not applicable Not applicable
X-13 Ryan Aeronautical Company
2
1955-57
Unknown
 Edwards AFB Test pure-jet vertical takeoff and landing First successful VTOL flight on jet thrust alone
0
 Not applicable Not applicable Not applicable
X-14, X-14A, X-14B Bell Aircraft
1
1957-81
Unknown
 Moffet Field Test VTOL technology First VTOL aircraft using jet thrust diverter system for vertical lift
0
 Not applicable Not applicable Not applicable
X-15, X-15A-2 North American Aviation
3
1959-68
199
 X-15 High Range (Wendover, UT, to Edwards AFB) Explore problems of space and atmospheric flight at very high speeds and altitudes First manned hypersonic flight vehicle; altitude of 354,200 ft obtained; Mach 6.33 reached
4
 Mid-flight explosions (2); loss of control (1); collapsed landing gear (1)
1
 Not applicable
X-16 Bell Aircraft
Canceled
None
None
 None High-altitude, long-range reconnaissance aircraft Not applicable
Not applicable
 Not applicable Not applicable Not applicable
X-17 (unmanned) Lockheed Missiles
26
1955-57
26
 Holloman AFB Explore reentry characteristics High Mach effects on reentry vehicles
0
 Not applicable Not applicable Not applicable
X-18 Hiller Aircraft
1
1959-61
20
 Edwards AFB Explore large VTOL vehicles First tilt-wing usage for VTOL
0
 Not applicable Not applicable Not applicable
X-19 Curtiss-Wright
2
1964-65
50
 Caldwell; NAFEC, NJ Test VTOL technology using radial lift Dual-tandem tilt propeller use
1
 Equipment failure
0
 Not applicable
X-20 Boeing
Canceled
None
None
 None Piloted orbital flight Provided heat materials testing
Not applicable
 Not applicable Not applicable Not applicable
X-21A Northrop Corporation
2
1963-64
Unknown
 Edwards AFB Test full-scale boundary control on large aircraft Proved Laminar Flow Control viable
0
 Not applicable Not applicable Not applicable
X-22A Bell Aerospace
2
1966-84
501
 Bell, Calspan Test Facilities Research dual-tandem-ducted propeller configuration; research V/STOL handling using variable stability system design Ducted fan viability, advancement of VTOL technology
1
 hydraulic system failure
0
 None
X-23A (unmanned) Martin Marietta
4
1966-67
3
 Vandenberg AFB/Pacific Ocean Test configurations, control systems, and ablative materials for hypersonic reentry vehicles First maneuverable reentry vehicle
0
 Not applicable Not applicable Not applicable
X-24A, X-24B Martin Marietta
1
1969-75
64
 Edwards AFB Research of aerodynamics, flight characteristics of manned vehicle with FDL-7 configuration Verified theoretical advantages of lifting body configuration for hypersonic transatmospheric aircraft
0
 Not applicable Not applicable Not applicable
X-25, X-25A, X-25B Bensen Aircraft
3
1968
   Raleigh, NC Test discretionary descent vehicle designs Insight on pilot training
0
 Not applicable Not applicable Not applicable
X-26A, X-26B Schweizer Aircraft, Lockheed Missiles
6
1967-88
Unknown
 Vietnam Develop ultra-quiet surveillance aircraft Use as training vehicle; contributions to stealth designs
3
 Training exercises
0
 Not applicable
X-27 Lockheed-California
Canceled
None
None
 None Advanced, lightweight fighter None
Not applicable
 Not applicable Not applicable Not applicable
X-28A George Pereira, Osprey Aircraft
1
1971
Unknown
 Philadelphia Naval Base, PA Explore usefulness of small, single-place seaplane for civil police patrol in Southeast Asia Unique contribution as home-built aircraft in X-Plane program
0
 Not applicable Not applicable Not applicable
X-29A Grumman Aerospace
2
1984-90
Unknown
 Edwards AFB Test forward-swept wing design, advanced composites, other aerodynamic advances First FSW aircraft to fly supersonically in level flight
0
 Not applicable Not applicable Not applicable
X-30 None selected
None
None
None
 None Serve as testbed for sustained hypersonic speeds within atmosphere or as space vehicles for orbital payload delivery Not applicable
Not applicable
 Not applicable Not applicable Not applicable
X-31A Rockwell International, Deutsche Aerospace
2
1990-95
523
 Edwards AFB Break "stall-barrier," examine angles of attack 180 degree turn post-stall maneuver
1
 Failure of the pitot ñ static system: erroneous total pressure data
0
 None
X-33 Lockheed-Martin Skunk Works
None
None
None
 None Develop reusable single-stage-to-orbit transportation vehicle Not applicable
Not applicable
 Not applicable Not applicable Not applicable
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

For more information, please contact Donna Holland