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Experimental aircraft (designation numbering series - US DoD)
X-1.
Rocketdyne Lox/Kerosene rocket engine. 880.440 kN. Booster applications. Gas generator, pump-fed. Thrust from 165,000 to 198,000 lbs.
X-10.
Department of Defence Designation of Navaho X-10 intermediate range cruise missile.
X-11.
Alternate designation for Atlas A test vehicle.
X-12.
Alternate designation for Atlas B test vehicle.
X-15.
X-15 rocket-powered manned aircraft project set records for altitude and speed, and reached the edge of space.
X-15.
American air-launched rocketplane.
X-15.
Family of spacecraft.
Crew: Engle. Maximum Speed - 5522 kph. Maximum Altitude - 85527 m. Astronaut wings flight (USAF definition).
Crew: Engle. Maximum Speed - 5712 kph. Maximum Altitude - 82601 m. Astronaut wings flight (USAF definition).
Crew: McKay. Maximum Speed - 6005 kph. Maximum Altitude - 90099 m. Astronaut wings flight (USAF definition).
Crew: Engle. Maximum Speed - 5718 kph. Maximum Altitude - 81230 m. Astronaut wings flight (USAF definition).
Crew: Dana. Maximum Speed - 6034 kph. Maximum Altitude - 93540 m. Astronaut wings flight (USAF definition).
Crew: Knight. Maximum Speed - 6204 kph. Maximum Altitude - 85500 m. Astronaut wings flight (USAF definition).
Crew: Adams. Fatal accident, aircraft destroyed. After reaching peak altitude, entered spin at Mach 5. Entered dive at 30,000 m, began high frequency pitch oscillations, disintegrated when these reached 15 Gs.Maximum Speed - 5744 kph. Maximum Altitude - 81080 m.
Crew: Dana. Maximum Speed - 5540 kph. Maximum Altitude - 81530 m. Astronaut wings flight (USAF definition).
Crew: White Robert. First rocketplane to reach space (USAF defintion). FAI world altitude record. Maximum Speed - 6166 kph. Maximum Altitude - 95940 m. First astronaut wings flight (USAF definition).
Crew: Walker Joseph. First civilian flight above 80 km. Maximum Speed - 5917 kph. Maximum Altitude - 82810 m. Second astronaut wings flight (USAF definition).
Crew: Rushworth. Maximum Speed - 5511 kph. Maximum Altitude - 86870 m. Third astronaut wings flight (USAF definition).
Crew: Walker Joseph. First rocketplane to reach space (FAI defintion). Maximum Speed - 5969 kph. Maximum Altitude - 106010 m. Astronaut wings flight. 80 cm diameter balloon dragged on 30 m line to measure air density. Fourth astronaut wings flight (USAF definition).
Crew: Walker Joseph. Unofficial world altitude record. Maximum Speed - 6105 kph. Maximum Altitude - 107960 m. Second X-15 astronaut flight (FAI definition); fifth astronaut wings flight (USAF definition).
X-15 Pressure Suit.
Alternate designation for MC-2 space suit.
American air-launched orbital launch vehicle. In March 1962, NASA proposed an orbital launch vehicle using the B-52/X-15 combination. A Blue Scout booster would be fitted to an extendable launch rail on the belly of the X-15. The X-15 would be air-launched from the B-52, and then itself air-launch the Blue Scout well above the earth's atmosphere.
American manned spaceplane. 174 launches, 1959.06.08 (X-15 Flight 1) to 1968.10.24 (X-15 Flight 199). The X-15 was the first USAF and NASA project for manned spaceflight, initiated years before Mercury.
American air-launched rocketplane. Manned hypersonic research rocket aircraft.
Lox/Ammonia propellant rocket stage. Loaded/empty mass 14,184/5,158 kg. Thrust 262.45 kN. Vacuum specific impulse 276 seconds.
American air-launched rocketplane. Manned hypersonic research rocket aircraft. Stretched rebuild of crashed X-15A, with drop tanks. Reached Mach 6.7 and 108 km altitude.
American manned spaceplane. Study 1965. The crash-damaged X-15 number 2 was rebuilt to attain even higher speeds. The body frame was stretched, and two drop tanks were added, increasing propellant load by 75%.
Lox/Ammonia propellant rocket stage. Loaded/empty mass 16,069/7,766 kg. Thrust 262.45 kN. Vacuum specific impulse 276 seconds.
Lox/Ammonia rocket stage. Mass 7,026 kg (15,490 lb).
American manned spaceplane. Cancelled 1962. It had been proposed that X-15 number 3 would be reworked to install a delta wing and designed to reach Mach 8.
American manned spacecraft. Study 1958. North American's proposal for the Air Force initial manned space project was to extend the X-15 program. The X-15B was a 'stripped' X-15A with an empty mass of 4500 kg.
X-17.
Department of Defence Designation of RAM all-solid orbital launch vehicle.
X-17.
USAF X-17 flight test program at Cape Canaveral studied reentry problems by simulating reentry velocities and conditions with a three-stage solid-fuel Lockheed X-17. A total of 26 X-17 flights were conducted until March 1957.
X-17.
American test vehicle. USAF X-17 flight test program at Cape Canaveral studied reentry problems by simulating reentry velocities and conditions with a three-stage solid-fuel Lockheed X-17. A total of 26 X-17 flights were conducted until March 1957.
American test vehicle. Three stage vehicle consisting of 1 x 3-DS-47000 + 3 x NOTS 124-C + 1 x NOTS 124-C
American test vehicle. Three stage vehicle consisting of 1 x 3-DS-47000 + 1 x Dummy stage + 1 x Dummy stage
Rocket stage used on X-17 test vehicle.
Solid propellant rocket stage. Loaded mass 700 kg. Thrust 209.00 kN.
Solid propellant rocket stage. Loaded mass 30 kg.
American test vehicle. Three stage vehicle consisting of 1 x T-40 + 1 x Dummy stage + 1 x Dummy stage
X-1A.
American manned rocketplane. Study 1951. The X-1A, B, and D were essentially identical rocketplanes intended to reach speeds above Mach 2.
X-1B.
American manned rocketplane. Flown 1952. The X-1A, B, and D were essentially identical rocketplanes intended to reach speeds above Mach 2.
X-1D.
American manned rocketplane. Study 1953. The X-1A, B, and D were essentially identical rocketplanes intended to reach speeds above Mach 2.
X-1E.
American manned rocketplane. Study 1954. The X-1E was designed to test an ultra-thin 4% thickness to cord wing for supersonic flight.
X-2.
American manned rocketplane. Design began 1945. X-2 was an AAF/ Bell project that flew three supersonic flight research aircraft, powered by liquid rockets. Originally designated XS-2.
X-20 Glider.
Alternate designation for Dynasoar Glider manned spacecraft module.
X-20A.
Alternate designation for Dynasoar manned spaceplane.
Hercules solid rocket engine. 26 kN.
X-23A.
Article Number of Prime manned spaceplane.
Hercules solid rocket engine. 12.1 kN.
Thiokol solid rocket engine family. Used on Atlas Able, Blue Scout 2, Caleb, Delta, Delta A, Delta B, Delta C. First flight 1959.
Thiokol solid rocket engine. 12.4 kN. Isp=256s. Used on Atlas Able, Blue Scout 2, Caleb, Delta, Delta A, Delta B, Delta C. First flight 1959.
Thiokol solid rocket engine. 13.8 kN. Isp=255s. Used on Scout X-1, Scout X-2, Scout X-3. First flight 1960.
American manned spaceplane. 28 launches, 1969.04.17 to 1971.06.04 . The X-24A was the Martin Corporation's subsonic test version of the US Air Force's preferred manned lifting body configuration.
American manned spaceplane. 36 launches, 1973.08.01 to 1975.11.26 .
American manned spaceplane. Cancelled 1977. Two X-24C NHFRF (National Hypersonic Flight Research Facility) aircraft were to be built under a $ 200 million budget.
Hercules solid rocket engine.
Thiokol solid rocket engine. 60.5 kN. Isp=256s. Used on Blue Scout 1, Blue Scout 2, Blue Scout Junior, Scout X-1. First flight 1960.
Hercules solid rocket engine. 257.5 kN.
Thiokol solid rocket engine. 22.2 kN. Isp=266s. Kick stage motor for Delta D, Scout A, Scout X-4. First flight 1963.
Thiokol solid rocket engine family. Used on Scout A, Scout B, Scout D, Scout F, Scout X-2, Scout X-3, Scout X-4. First flight 1962.
Thiokol solid rocket engine. 93.1 kN. Isp=293s. Used on Scout A, Scout B, Scout D, Scout F, Scout X-2, Scout X-3, Scout X-4. First flight 1962.
Thiokol solid rocket engine. 80.8 kN. Out of production. Isp=295s. Used on Scout G launch vehicle. First flight 1979.
Hercules solid rocket engine.
Hercules solid rocket engine.
Hercules solid rocket engine.
X-30.
American SSTO winged orbital launch vehicle. Air-breathing scramjet single stage to orbit. Second attempt after study of similar proposal in early 1960's. Cancelled due to cost, technical challenges.
X-30.
American manned spaceplane. Study 1990.
X-30.
Scramjet/Slush LH2 propellant rocket stage. Loaded/empty mass 140,000/60,000 kg. Thrust 1,370.00 kN. Specific impulse 1550 seconds.
X-33.
American winged rocketplane. NASA-sponsored suborbital unmanned prototype for a single-stage-to-orbit rocketplane. The Lockheed Martin vehicle would have used a linear aerospike engine, metallic insulation, and other features similar to their Starclipper shuttle proposal of 1971. In 1999 catastrophic failure of the composite fuel tank during static test brought into question the technical feasiblity of the design. The program was cancelled in 2001 before any flight articles were completed and after over $1.2 billion had been expended.
X-33.
Lox/LH2 propellant rocket stage. Loaded/empty mass 123,800/28,600 kg. Thrust 2,284.00 kN. Vacuum specific impulse 439 seconds.
X-34.
American spaceplane. Study 1996.
X-34.
American air-launched orbital launch vehicle. NASA failed to attract industry co-investment to develop the original X-34A air-launched, reusable, low-technology, low-cost orbital launch vehicle concept. So the project was scaled back and NASA contracted with Orbital Sciences on 28 August 1996 to build and fly the X-34 unmanned technology demonstrator. This program in turn developed overruns and was cancelled in 2001 before a test flight was made.
X-34.
NASA failed to attract industry co-investment to develop the original X-34A air-launched, reusable, low-technology, low-cost orbital launch vehicle concept. So the project was scaled back and NASA contracted with Orbital Sciences on 28 August 1996 to build and fly the X-34 unmanned technology demonstrator. This program in turn developed overruns and was cancelled in 2001 before a test flight was made.
X-34.
Lox/Kerosene propellant rocket stage. Loaded/empty mass 21,800/8,200 kg. Thrust 268.93 kN. Vacuum specific impulse 310 seconds. Low cost reusable vehicle technology demonstrator.
American air-launched orbital launch vehicle. The original X-34A was a three-stage vehicle consisting of the Orbital Sciences L-1011; which air-launched the X-34A reusable rocketplane; which space-launched the rocket-powered third stage; which would take a small payload to orbit. Only the third stage would be expendable.
Lox/Kerosene propellant rocket stage. Loaded/empty mass 29,500/6,700 kg. Thrust 386.30 kN. Vacuum specific impulse 316 seconds. Original design for two-stage reusable space launcher. Abandoned in favour of more modest X-34A technology demonstrator after industry refused to make significant investments in the concept.
Lox/Kerosene propellant rocket stage. Loaded/empty mass 4,500/300 kg. Thrust 44.10 kN. Vacuum specific impulse 348 seconds.
Aerojet rocket engine. PB2Y-3 ATO. Launch thrust 26.77 kN. Development begun November 1942.
X-37.
American unmanned spaceplane. The Boeing X-37 Space Maneuver Vehicle began as a subscale version of a proposed USAF manned 21st Century spaceplane. The smaller-scale X-40 tested some technologies prior to completion of the X-37A. The X-37B was the operational reusable space vehicle. Operational, first launch 2010.04.22.
X-38.
American manned spaceplane. 2 launches, 1972.02.16 (HL-10 LB Test?) to 1972.05.20 (HL-10 LB Test?). Lifting body reentry vehicle designed as emergency return spacecraft for International Space Station crew.
X4.
German wire-guided air-to-air missile. 8 kg of pressure-fed Salbei + Tonka 250 propellants provided a thrust that varied from 140 kgf down to 30 kgf over the 17 second burn time. Final velocity was 230 m/s.
X-40.
American spaceplane. Study 2001. Boeing X-40A Experimental Space Maneuver Vehicle was built to test landing technologies for the later X-37.
GE Lox/Kerosene rocket engine. 134.8 kN. Vanguard 1st stage. Isp=270s. First flight 1957.
X-43.
American spaceplane. Study 1997. NASA's X-43 Hyper-X program demonstrated an integrated hypersonic scramjet engine briefly at Mach 10 on its third and final flight.
GE exoticLF2/LH2 rocket engine. 334 kN. Developed 1960's. Very high energy engine developed in early 1960's for future large upper stages. Not flown due to toxicity of propellants.
X45ALD-4000.
Manufacturer's designation of XLR13-AJ-5 Nitric acid-Amine rocket engine.
Aerojet Nitric acid/Amine rocket engine. B-29 ATO. Launch thrust 17.6 kN. Development begun June 1948. Regenerative cooling, nitrogen pressure-fed, droppable but no recoverable. Early version using XLR-13-AJ-1 thrust chamber assembly.
Aerojet Nitric acid/Amine rocket engine. Brake rocket for G-4A. Launch thrust 4.41 kN. Braking rocket for glider. Single uncooled chamber, pressure fed, 13 kg of propellant.
X-51A
Aerojet Nitric acid/Amine rocket engine. P-51 superperformance. Launch thrust 5.78 kN. Development begun January 1945. Superperformance
X60ALD-4000.
Manufacturer's designation of XLR13-AJ-7 Nitric acid-Amine rocket engine.
Aerojet Nitric acid/Amine rocket engine. ATO for XB-45, B-45A. Launch thrust 17.6 kN. Development begun May 1946. Pressurising tank surrounded propellant tanks. Regeneratively cooled. Parachute for dropping and recovery after takeoff.
X-8.
Rocketdyne lox/lh2 rocket engine. Launch thrust 400.1 kN. Booster applications. Gas generator, pump-fed. Thrust and specific impulse values are at sea level.
Aerojet Nitric acid/Amine rocket engine. Launch thrust 264 kN. Development begun April 1947. Unspecified Application, 20,000 Ibf subscale tested, new vertical test facility
Aerojet Nitric acid/aniline rocket engine. 11.6 kN.
Mach 3 rocket launch aircraft. Loaded/empty mass 226,758/68,027 kg. Thrust 520.32 kN. Specific impulse 2084 seconds. N. American Bomber-delta wing. Maximum release conditions: Piggy-back, 27,273 kg (19.1 m length x 6.7 m span) at 3,193 kph at 21,341 m altitude
American surface-to-air drone.
XCAL-200.
Government designation of 300LR-200 Nitric acid-Amine rocket engine.
Aerojet Nitric acid/Amine rocket engine for XP-79 Northrop Flying Wing. Thrust 9.12 kN. Aerotojet, a pair of canted 130 kgf thrust chambers mounted longitudinally on a drive shaft, which drove the turbopumps. Developed 1943-1945; blew up on first test.
Aerojet Nitric acid/Amine rocket engine. Thrust 26.67 kN. Conservative alternate to Aerotojet for XP-79 flying wing rocket fighter. Successfully tested in August 1945, but project cancelled. Regeneratively cooled, 4 thrust chambers, pump-fed.
Aerojet isopropylnitrate monopropellant rocket engine. Lark. Launch thrust 6.66 kN. Development begun March 1945. Turborocket; turbine-pump fed monopropellant, single uncooled thrust chamber. Development unsuccessful, all work terminated.
XCNLT-600/1000/1500.
Manufacturer's designation of XCNLT-1500 Isopropylnitrate rocket engine.
XCOR.
XCOR, USA.
Proposed as propellant for some ion motors.
American manned spaceplane. Study 2016. Suborbital vehicle that XCOR planned to design and build on a commercial basis. Rocket powered, it would take off from a runway, and be capable of high altitude, high speed flight.
American manned rocketplane. Study 1949. The Republic XF-91 Thunderceptor was a mixed-power interceptor, being powered by both a jet engine and by a battery of rocket motors. Although it showed promise, it was not put into production.
XF-99.
Alternate designation for CIM-10A surface-to-air missile.
China's launch site for geosynchronous orbit launches. Xichang Satellite Launch Centre is situated in Xichang, Sichuan Province, south-western China. The launch pad is at 102.0 degrees East and 28.2 degrees North. The head office of the launch centre is located in Xichang City, about 65 kilometers away. Xichang Airport is 50 km away. A dedicated railway and highway lead directly to the launch site.
CZ launch complex. Launch Complex 1
CZ launch complex. Launch Complex 2
Xie Guangxuan Chinese Engineer. Chief designer of Chinese tactical and medium range ballistic missiles, and CZ-3 launch vehicle.
American surface-to-air missile. Land-based version. Full scale development begun in 1954. Project cancelled in 1957.
Hughes electric/xenon rocket engine. 17.8 mN. In Production. Isp=2585s. HS 702 operational communications satellites each employed four of these 0.44 kW xenon ion thrusters.
Hughes electric/xenon rocket engine. 63 mN. Isp=2800s. XIPS-25 program, conducted by Hughes, developed thrusters, BBPPUs, and a feed system pressure regulator for stationkeeping of 2500 kg class communication satellites.
Hughes electric/xenon rocket engine. 165 mN. Isp=3800s. 25 cm diameter xenon engine system for orbital circularization, station-keeping, attitude control, and momentum dumping for its HS 702 spacecraft.
Wright turbojet engine. 48.5 kN. Out of production. Thrust is maximum thrust at cruise altitude. Specific impulse is that at cruise design point. Isp=1800s. Used on Navaho X-10 launch vehicle. First flight 1955.
XLIM-49A.
Department of Defence Designation of Nike Zeus anti-ballistic missile.
Rocketdyne Lox/Kerosene rocket engine. 363.2 kN. Atlas D. Atlas Sustainer. Gas generator, pump-fed. Shared turbopumps for booster engines. Isp=309s. First flight 1958.
Reaction Motors, Thiokol Lox/Alcohol rocket engine. Out of Production. Launch thrust 26.67 kN. Rocket engine developed for X-1 in 1940s to break the sound barrier and used twenty years later to power experimental lifting bodies. Four combustion chambers.
XLR11-RM-1.
Government designation of XLR11 Lox-Alcohol rocket engine.
Rocketdyne N2O4/MMH rocket engine. 16.7 kN. Out of Production. Isp=340s. Pump-fed high performance upper stage engine for perigee/apogee stages. as well as transfer vehicles and lunar and Martian missions. Tested extensively but no production.
XLR13-AJ-1.
Government designation of X60ALD-4000 rocket engine.
XLR13-AJ-3.
Government designation of X45ALD-4000 rocket engine.
Aerojet Nitric acid/Amine rocket engine. B-29 ATO. Launch thrust 17.6 kN. Development begun June 1948. Ceramic chamber and nozzle, nitrogen pressure-fed, droppable but no recoverable.
Aerojet Nitric acid/Amine rocket engine. Launch thrust 17.6 kN. Modification of -AJ-1. Regeneratively cooled by fuel, droppable.
XLR15-AJ-1.
Government designation of XCNLT-1500 Isopropylnitrate rocket engine.
XLR16-AJ-1.
Government designation of LR16 rocket engine.
XLR17-CW-1.
Government designation of LR17 Lox-Gasoline rocket engine.
XLR19-CW-1.
Government designation of LR19 Lox-Gasoline rocket engine.
XLR1-AJ-1.
Government designation of 25AL-1000 Nitric acid-Amine rocket engine.
XLR20-AJ-2.
Government designation of XLR20AJ-2 Nitric acid-Gasoline rocket engine.
Aerojet Nitric acid/Gasoline rocket engine. Lark. Launch thrust 6.66 kN. Development begun January 1946. Blast turbine, three levels of thrust (600/1000/7500 lbf). Replaced NM Lark.
XLR21-CW-1.
Government designation of LR21 Lox-Gasoline rocket engine.
XLR22-RM-1.
Government designation of LR22 rocket engine.
XLR23-AJ-1.
Government designation of X90ALT-60000 Nitric acid-Amine rocket engine.
XLR24-AJ-2.
Government designation of XLR24AJ-2 Nitric acid-Gasoline rocket engine.
Aerojet Nitric acid/Gasoline rocket engine. Lark. Launch thrust 10.7 kN. Development begun January 1946. Blast turbine, 2500 Ibf fixed thrust (both were part of overall R&D contract)
Curtiss-Wright Lox/Alcohol rocket engine. 66.880 kN. Out of Production. First flight 1954. Two chamber engine built for X-2 rocketplane. Engine could be throttled continuously from 1140 kgf to 6820 kgf.
XLR26-RM-1.
Government designation of LR26 rocket engine.
XLR27-CW-1.
Government designation of LR27 rocket engine.
XLR29-CW-1.
Government designation of LR29 rocket engine.
XLR2-RM-1.
Government designation of LR2 rocket engine.
XLR30-RM-2.
Government designation of LR30 Lox-Ammonia rocket engine.
XLR31-K-1.
Government designation of LR31 rocket engine.
XLR32-RM-1.
Government designation of LR32 rocket engine.
XLR33-RM-1.
Government designation of LR33 rocket engine.
XLR35-RM-1.
Government designation of LR35 rocket engine.
XLR37-CW-1.
Government designation of LR37 Lox-Gasoline rocket engine.
XLR39-RM-1.
Government designation of LR39 Lox-Alcohol rocket engine.
XLR3-AJ-1.
Government designation of 25XALD-1000 Nitric acid-Amine rocket engine.
XLR40-RM-1.
Government designation of LR40 H2O2-Kerosene rocket engine.
XLR41-NA-1.
Government designation of LR41 rocket engine.
XLR42-NA-1.
Government designation of LR42 rocket engine.
Rocketdyne Lox/Alcohol rocket engine. 333 kN. Development completed 1951. Mark III American version of single-chamber V-2 engine tested in WW2, but with half mass and 34% more thrust. Starting point for all later Rocketdyne engines.
XLR48-RM-1.
Government designation of LR48 rocket engine.
XLR49-AJ-1.
Government designation of LR49 rocket engine.
XLR51-AJ-1.
Government designation of LR51 rocket engine.
XLR53-AJ-1.
Government designation of XLR53AJ-1 Nitric acid-Amine rocket engine.
Aerojet Nitric acid/Amine rocket engine. F-80. Out of Production. Launch thrust 4.41 kN. Development begun 1949. Superperformance, wing tip mounted, regenerative cooling, pressure fed, 240 sec duration, 1000 Ibf thrust each.
XLR54-NA-1.
Government designation of LR54 H2O2-Kerosene rocket engine.
XLR55-?-1.
Government designation of LR55 rocket engine.
XLR5-AJ-1.
Government designation of 40ALD-3000 Nitric acid-Amine rocket engine.
XLR65-B-1.
Government designation of LR65 rocket engine.
XLR6-RM-1.
Government designation of LR6 rocket engine.
Rocketdyne Lox/Alcohol rocket engine. Development cancelled 1955. Launch thrust 533.7 kN. Planned engine for the booster of the Navaho II test vehicle. Gas generator, pump-fed.
XLR7-AJ-1.
Government designation of XCALT-6000 Nitric acid-Amine rocket engine.
XLR81-BA.
Government designation of Bell 8081 Nitric acid-UDMH rocket engine.
XLR81-BA-13.
Government designation of Bell 8247 Nitric acid-UDMH rocket engine.
Rocketdyne Lox/Kerosene rocket engine. 602 kN. Out of production. Isp=273s. Experimental version of the engine for the booster of the Navaho G-38 intercontinental cruise missile. Flown in the Navaho G-26 booster prototypes. First flight 1956.
Rocketdyne Lox/Kerosene rocket engine. 758.7 kN. Atlas A, B, C. Out of production. Designed for booster applications. Gas generator, pump-fed. Shared turbopumps for booster engines. Isp=282s. First flight 1957.
Rocketdyne Lox/Kerosene rocket engine. 758.7 kN. Atlas D. Designed for booster applications. Gas generator, pump-fed. Shared turbopumps for booster engines. Isp=282s. First flight 1958.
Thiokol Lox/Ammonia rocket engine. 262.4 kN. Out of production. Isp=276s. The first large, man-rated, throttleable, restartable liquid propellant rocket engine, boosted the X-15A. First flight 1959.
XLR9-AJ-1.
Government designation of X4-AL-1000 Nitric acid-Amine rocket engine.
XM.
American agency. XM Radio, USA.
XM-19.
Alternate designation for Journeyman-0 rocket stage.
XM-270.
Alternate designation for MLRS tactical ballistic rocket.
XM-28.
Alternate designation for Davy Crockett XM-29 tactical ballistic rocket.
XM-388.
Alternate designation for Davy Crockett M-28 tactical ballistic rocket.
Hercules solid rocket engine. 772 kN.
Rocket solid engine. 200 kN.
American turbojet engine.
American short range ballistic missile.
XMM.
European x-ray astronomy satellite. One launch, 1999.12.10. ESA's X-ray Multi-Mirror space observatory was the biggest science satellite ever built in Europe. The spacecraft's X-ray optics covered a spectral range of 1-120 nanometers (12keV-0.1keV).
XMM-Newton.
Alternate designation for XMM x-ray astronomy satellite.
X-OP.
Manufacturer's designation for SSX ssto vtovl orbital launch vehicle.
XOV.
Manufacturer's designation for Blackstar manned spaceplane.
American manned rocketplane. Flown in 1945. The XP-79 was Jack Northrop's design for a rocket-propelled flying wing fighter.
American manned delta-wing rocketplane. Never flown with rockets, but flew as a turbojet-powered research aircraft, 1948-1953.
The X-Prize competition was an attempt to promote commercial civilian spaceflight in a manner similar to the prizes handed out in the early days of aviation. Ten million dollars was to go to the first team to fly a vehicle capable of launching three people into space (defined as an altitude of 100 km in a suborbital trajectory), twice in a two-week period. The vehicle had to be 90% reusable by dry mass. For purposes of the two flights, the competition accepted flight by one person and ballast equivalent to two others at 90 kg per passenger.
The X-Prize competition was an attempt to promote commercial civilian spaceflight in a manner similar to the prizes handed out in the early days of aviation. Ten million dollars was to go to the first team to fly a vehicle capable of launching three people into space (defined as an altitude of 100 km in a suborbital trajectory), twice in a two-week period. The vehicle had to be 90% reusable by dry mass. For purposes of the two flights, the competition accepted flight by one person and ballast equivalent to two others at 90 kg per passenger. The flights had to be completed before the end of 2005.
XCOR Nitrous oxide/Alcohol rocket engine. 0.067 kN. First stages. Hardware. Engine was run on oxygen and nitrous oxide oxidizers, with propane, ethane, kerosene, turpentine, and a variety of alcohols.
XCOR Lox/Alcohol rocket engine. 0.700 kN. First stages. Hardware. The XR3A2 700-newton engine was the first XCOR LOX/alcohol engine, accumulating 61 brief runs in the course of injector concept development, which led to later engines.
XCOR Nitrous oxide/Alcohol rocket engine. 0.220 kN. First stages. Hardware. Regeneratively cooled engine using nitrous oxide and isopropyl alcohol as propellants.
XCOR Lox/CH4 rocket engine. 0.223 kN. First stages. Hardware. Methane-fueled engine allowing long-term on-orbit storage, higher density than hydrogen engines. Intended for use in reaction control systems and satellite maneuvering systems
XCOR Lox/Alcohol rocket engine. 1.780 kN. First stages. Fully operational pressure-fed, regeneratively cooled engine. Flown on the EZ-Rocket, a modified Long-EZ aircraft fitted with two engines. First flight 2001.
XCOR Lox/Kerosene rocket engine. 6.670 kN. First stages. Hardware. Built for the Rocket Racing League's first X-Racer. The rocket engine was sized for the best compromise between acceleration and endurance.
XCOR Lox/Kerosene rocket engine. 8 kN. First stages. Hardware. Pump-fed, regeneratively cooled with fuel. Engine could be used to power the prototype Xerus suborbital manned vehicle for initial flight testing.
XCOR Lox/CH4 rocket engine. 22.3 kN. First stages. Conceptual lox/methane rocket engine developed for a DARPA program through layout design phase, but never built.
XCOR Lox/CH4 rocket engine. 33.360 kN. First stages. Hardware. Prototype LOX/methane rocket engine developed as a stepping stone to NASA's original Orion manned spacecraft and return to the moon and manned mission to Mars plans.
Category of spacecraft.
X-ray Multi Mirror.
Code name for XMM x-ray astronomy satellite.
Wright ramjet engine. 33.4 kN. Out of production. Thrust is maximum thrust at cruise altitude. Specific impulse is that at cruise design point. Isp=1200s. Used on Navaho G-26 launch vehicle. First flight 1956.
XRM-89.
Department of Defence Designation of Blue Scout 1 suborbital launch vehicle.
XRM-90.
Department of Defence Designation of Blue Scout 2 all-solid orbital launch vehicle.
XRM-91.
Department of Defence Designation of Blue Scout Junior suborbital launch vehicle.
X-Rocket.
Alternate designation for SSX ssto vtovl orbital launch vehicle.
Rocketdyne lox/lh2 rocket engine. 1192 kN. Development ended 1999. Isp=439s. Linear aerospike engine for X-33 SSTO technology demonstrator. Based on J-2S engine developed for improved Saturn launch vehicles in the 1960's.
XS-1.
American manned rocketplane. Design begun 1943. Also known as the X-1. This rocket plane was the first aircraft to break the sound barrier, and the first in a line of X- aircraft leading to the space shuttle.
XS-2.
Alternate designation for X-2 manned rocketplane.
XSM-64.
Department of Defence Designation of Navaho G-26 intermediate range cruise missile.
XSS.
American rendezvous technology satellite. 2 launches, 2003.01.29 (XSS-10) and 2005.04.11 (USA 165).
XSSM-A-2.
Alternate Designation of Navaho SSM-A-2 intermediate range cruise missile.
XSSM-A-4.
Alternate Designation of Navaho G-26 intermediate range cruise missile.
XTE.
American x-ray astronomy satellite. One launch, 1995.12.30. X-ray Timing Explorer; X-ray astronomy.
Xue Lun Chinese pilot. Head of the first Chinese astronaut group, Unit 714, in 1971. Purged after being accused of involvement in Lin Biao's coup d'etat against Mao Zedong. The group was dissolved soon thereafter.
XUV.
eXtreme UltraViolet