Lockheed Martin X-33
Encyclopedia
The Lockheed Martin X-33 was an unmanned, sub-scale technology demonstrator suborbital spaceplane
developed in the 1990s under the U.S. government-funded Space Launch Initiative
program. The X-33 was a technology demonstrator for the VentureStar
orbital spaceplane, which was planned to be a next-generation, commercially operated reusable launch vehicle
. The X-33 would flight-test a range of technologies that NASA believed it needed for single-stage-to-orbit
reusable launch vehicles (SSTO RLVs), such as metallic thermal protection systems, composite
cryogenic fuel tanks for liquid hydrogen, the aerospike engine
, autonomous (unmanned) flight control, rapid flight turn-around times through streamlined operations, and its lifting body
aerodynamics.
Failures led to the cancellation of the program as a federal program in 2001, but Lockheed Martin has conducted related testing, and has had successes as recently as 2009.
and Lockheed Martin
hoped to test fly a craft that would demonstrate the viability of a single-stage-to-orbit
(SSTO) design. An SSTO craft would not require external fuel tanks or boosters to reach low-earth orbit. Doing away with the need for "staging" with launch vehicles, such as with the Shuttle and the Apollo rockets, would lead to an inherently more reliable and safer space launch vehicle. While the X-33 would not approach airplane-like safety, the X-33 would attempt to demonstrate that 0.997 reliability, or 3 mishaps out of 1,000 launches, which would be an order of magnitude more reliable than the Space Shuttle system, was achievable. The 15 planned experimental X-33 flights could only begin this statistical evaluation.
The unmanned craft would have been launched vertically from a specially designed facility constructed on Edwards Air Force Base, and landed horizontally (VTHL) on a runway at the end of its mission. Initial sub-orbital test flights were planned from Edwards AFB to Dugway Proving Grounds southwest of Salt Lake City, Utah
.
Once those test flights were completed, further flight tests were to be conducted from Edwards AFB to Malmstrom AFB in Great Falls, Montana
, to gather more complete data on aircraft heating and engine performance at higher speeds and altitudes.
On July 2, 1996, NASA selected Lockheed Martin Skunk Works
of Palmdale, California
, to design, build, and test the X-33 experimental vehicle for the RLV program. Lockheed Martin's design concept for the X-33 was selected over competing designs from Boeing
and McDonnell Douglas
. Boeing featured a Space Shuttle
-derived design, and McDonnell Douglas featured a design based on its vertical takeoff and landing (VTVL
) DC-XA test vehicle.
The X-33 was never intended to fly higher than an altitude of 100 km, nor faster than one-half of orbital velocity. Had any successful tests occurred, extrapolation would have been necessary to apply the results to a proposed orbital vehicle.
hoped to make the business case for a full-scale SSTO RLV, called VentureStar
, that would be developed and operated through commercial means. The intention was that rather than operate space transport systems as it has with the Space Shuttle
, NASA would instead look to private industry to operate the reusable launch vehicle and NASA would purchase launch services from the commercial launch provider. Thus, the X-33 was not only about honing space flight technologies, but also about successfully demonstrating the technology required to make a commercial reusable launch vehicle possible.
The VentureStar was to be the first commercial aircraft to fly into space. The unmanned X-33 was slated to fly 15 suborbital hops to near 75.8 km altitude. It was to be launched upright like a rocket and rather than having a straight flight path it would fly diagonally up for half the flight, reaching extremely high altitudes, and then back down for the rest of the flight. The VentureStar was intended for long inter-continental flights and supposed to be in service by 2012, but this project was never funded or begun.
The decision to design and build the X-33 grew out of an internal NASA study titled "Access to Space". Unlike other space transport studies, "Access to Space" was to result in the design and construction of a vehicle.
.
In particular, the composite liquid hydrogen fuel tank failed during testing in November 1999. The tank was constructed of honeycomb composite walls and internal structures to reduce its weight. A lighter tank was needed for the craft to demonstrate necessary technologies for single-stage-to-orbit operations. A hydrogen fueled SSTO craft's mass fraction requires that the weight of the vehicle without fuel be 10% of the fully fueled weight. This would allow for a vehicle to fly to low earth orbit without the need for the sort of external boosters and fuel tanks used by the Space Shuttle. But, after the composite tank failed on the test stand during fueling and pressure tests, NASA came to the conclusion that the technology of the time was simply not advanced enough for such a design. While the composite tank walls themselves were lighter, the odd hydrogen tank shape resulted in complex joints increasing the total mass of the composite tank to above that of an aluminum-based tank.
NASA had invested $922 million in the project before cancellation and Lockheed Martin a further $357 million. Due to changes in the space launch business—including the challenges faced by companies such as Globalstar
, Teledesic
, and Iridium and the resulting drop in the number of anticipated commercial satellite launches per year—Lockheed Martin deemed that continuing development of the X-33 privately without government support would not be profitable.
On September 7, 2004, Northrop Grumman and NASA engineers unveiled a liquid hydrogen tank made of carbon fiber composite material that had demonstrated the ability for repeated fuelings and simulated launch cycles. Northrop Grumman concluded that these successful tests have enabled the development and refinement of new manufacturing processes that will allow the company to build large composite tanks without an autoclave; and design and engineering development of conformal fuel tanks appropriate for use on a single-stage-to-orbit vehicle.
Lockheed Martin has been testing a new and different 1/5 scale rocket described to be similar in capabilities and design, known now simply as a "Space Reusable Launch Vehicle". Two tests were conducted secretly at the Spaceport America
in New Mexico. The first on December 19, 2007 was billed as a complete success, while the August 12, 2008 launch ended in an irreparable crash after 12.5 seconds of flight. A third test on October 10, 2009, was another success.
Spaceplane
A spaceplane is a vehicle that operates as an aircraft in Earth's atmosphere, as well as a spacecraft when it is in space. It combines features of an aircraft and a spacecraft, which can be thought of as an aircraft that can endure and maneuver in the vacuum of space or likewise a spacecraft that...
developed in the 1990s under the U.S. government-funded Space Launch Initiative
Space Launch Initiative
The Space Launch Initiative was a NASA and U.S. Department of Defense joint research and technology project to determine the requirements to meet all the nation’s hypersonics, space launch and space technology needs...
program. The X-33 was a technology demonstrator for the VentureStar
VentureStar
VentureStar was a proposed spaceplane design for a single-stage-to-orbit reusable launch system by Lockheed Martin. The program's primary goal as a United States federally funded program was to develop a reusable unmanned spaceplane for launching satellites into orbit at a fraction of the cost of...
orbital spaceplane, which was planned to be a next-generation, commercially operated reusable launch vehicle
Reusable launch system
A reusable launch system is a launch system which is capable of launching a launch vehicle into space more than once. This contrasts with expendable launch systems, where each launch vehicle is launched once and then discarded.No true orbital reusable launch system is currently in use. The...
. The X-33 would flight-test a range of technologies that NASA believed it needed for single-stage-to-orbit
Single-stage-to-orbit
A single-stage-to-orbit vehicle reaches orbit from the surface of a body without jettisoning hardware, expending only propellants and fluids. The term usually, but not exclusively, refers to reusable vehicles....
reusable launch vehicles (SSTO RLVs), such as metallic thermal protection systems, composite
Composite material
Composite materials, often shortened to composites or called composition materials, are engineered or naturally occurring materials made from two or more constituent materials with significantly different physical or chemical properties which remain separate and distinct at the macroscopic or...
cryogenic fuel tanks for liquid hydrogen, the aerospike engine
Aerospike engine
The aerospike engine is a type of rocket engine that maintains its aerodynamic efficiency across a wide range of altitudes through the use of an aerospike nozzle. It is a member of the class of altitude compensating nozzle engines. A vehicle with an aerospike engine uses 25–30% less fuel at low...
, autonomous (unmanned) flight control, rapid flight turn-around times through streamlined operations, and its lifting body
Lifting body
A lifting body is a fixed-wing aircraft configuration in which the body itself produces lift. In contrast to a flying wing, which is a wing with minimal or no conventional fuselage, a lifting body can be thought of as a fuselage with little or no conventional wing...
aerodynamics.
Failures led to the cancellation of the program as a federal program in 2001, but Lockheed Martin has conducted related testing, and has had successes as recently as 2009.
Design and development
Through the use of the lifting body shape, composite liquid fuel tanks, and the aerospike engine, NASANASA
The National Aeronautics and Space Administration is the agency of the United States government that is responsible for the nation's civilian space program and for aeronautics and aerospace research...
and Lockheed Martin
Lockheed Martin
Lockheed Martin is an American global aerospace, defense, security, and advanced technology company with worldwide interests. It was formed by the merger of Lockheed Corporation with Martin Marietta in March 1995. It is headquartered in Bethesda, Maryland, in the Washington Metropolitan Area....
hoped to test fly a craft that would demonstrate the viability of a single-stage-to-orbit
Single-stage-to-orbit
A single-stage-to-orbit vehicle reaches orbit from the surface of a body without jettisoning hardware, expending only propellants and fluids. The term usually, but not exclusively, refers to reusable vehicles....
(SSTO) design. An SSTO craft would not require external fuel tanks or boosters to reach low-earth orbit. Doing away with the need for "staging" with launch vehicles, such as with the Shuttle and the Apollo rockets, would lead to an inherently more reliable and safer space launch vehicle. While the X-33 would not approach airplane-like safety, the X-33 would attempt to demonstrate that 0.997 reliability, or 3 mishaps out of 1,000 launches, which would be an order of magnitude more reliable than the Space Shuttle system, was achievable. The 15 planned experimental X-33 flights could only begin this statistical evaluation.
The unmanned craft would have been launched vertically from a specially designed facility constructed on Edwards Air Force Base, and landed horizontally (VTHL) on a runway at the end of its mission. Initial sub-orbital test flights were planned from Edwards AFB to Dugway Proving Grounds southwest of Salt Lake City, Utah
Salt Lake City, Utah
Salt Lake City is the capital and the most populous city of the U.S. state of Utah. The name of the city is often shortened to Salt Lake or SLC. With a population of 186,440 as of the 2010 Census, the city lies in the Salt Lake City metropolitan area, which has a total population of 1,124,197...
.
Once those test flights were completed, further flight tests were to be conducted from Edwards AFB to Malmstrom AFB in Great Falls, Montana
Great Falls, Montana
Great Falls is a city in and the county seat of Cascade County, Montana, United States. The population was 58,505 at the 2010 census. It is the principal city of the Great Falls, Montana Metropolitan Statistical Area, which encompasses all of Cascade County...
, to gather more complete data on aircraft heating and engine performance at higher speeds and altitudes.
On July 2, 1996, NASA selected Lockheed Martin Skunk Works
Skunk works
Skunk Works is an official alias for Lockheed Martin’s Advanced Development Programs , formerly called Lockheed Advanced Development Projects. Skunk Works is responsible for a number of famous aircraft designs, including the U-2, the SR-71 Blackbird, the F-117 Nighthawk, and the F-22 Raptor...
of Palmdale, California
Palmdale, California
Palmdale is a city located in the center of northern Los Angeles County, California, United States.Palmdale was the first community within the Antelope Valley to incorporate as a city on August 24, 1962; 47 years later, voters approved creating a charter city in November, 2009. Palmdale is...
, to design, build, and test the X-33 experimental vehicle for the RLV program. Lockheed Martin's design concept for the X-33 was selected over competing designs from Boeing
Boeing
The Boeing Company is an American multinational aerospace and defense corporation, founded in 1916 by William E. Boeing in Seattle, Washington. Boeing has expanded over the years, merging with McDonnell Douglas in 1997. Boeing Corporate headquarters has been in Chicago, Illinois since 2001...
and McDonnell Douglas
McDonnell Douglas
McDonnell Douglas was a major American aerospace manufacturer and defense contractor, producing a number of famous commercial and military aircraft. It formed from a merger of McDonnell Aircraft and Douglas Aircraft in 1967. McDonnell Douglas was based at Lambert-St. Louis International Airport...
. Boeing featured a Space Shuttle
Space Shuttle
The Space Shuttle was a manned orbital rocket and spacecraft system operated by NASA on 135 missions from 1981 to 2011. The system combined rocket launch, orbital spacecraft, and re-entry spaceplane with modular add-ons...
-derived design, and McDonnell Douglas featured a design based on its vertical takeoff and landing (VTVL
VTVL
Vertical takeoff, vertical landing is a form of takeoff and landing using rockets . Multiple VTVL craft have flown. , at least five VTVL rocket vehicles are currently under development at four different aerospace companies...
) DC-XA test vehicle.
The X-33 was never intended to fly higher than an altitude of 100 km, nor faster than one-half of orbital velocity. Had any successful tests occurred, extrapolation would have been necessary to apply the results to a proposed orbital vehicle.
Commercial spaceflight
Based on the X-33 experience shared with NASA, Lockheed MartinLockheed Martin
Lockheed Martin is an American global aerospace, defense, security, and advanced technology company with worldwide interests. It was formed by the merger of Lockheed Corporation with Martin Marietta in March 1995. It is headquartered in Bethesda, Maryland, in the Washington Metropolitan Area....
hoped to make the business case for a full-scale SSTO RLV, called VentureStar
VentureStar
VentureStar was a proposed spaceplane design for a single-stage-to-orbit reusable launch system by Lockheed Martin. The program's primary goal as a United States federally funded program was to develop a reusable unmanned spaceplane for launching satellites into orbit at a fraction of the cost of...
, that would be developed and operated through commercial means. The intention was that rather than operate space transport systems as it has with the Space Shuttle
Space Shuttle
The Space Shuttle was a manned orbital rocket and spacecraft system operated by NASA on 135 missions from 1981 to 2011. The system combined rocket launch, orbital spacecraft, and re-entry spaceplane with modular add-ons...
, NASA would instead look to private industry to operate the reusable launch vehicle and NASA would purchase launch services from the commercial launch provider. Thus, the X-33 was not only about honing space flight technologies, but also about successfully demonstrating the technology required to make a commercial reusable launch vehicle possible.
The VentureStar was to be the first commercial aircraft to fly into space. The unmanned X-33 was slated to fly 15 suborbital hops to near 75.8 km altitude. It was to be launched upright like a rocket and rather than having a straight flight path it would fly diagonally up for half the flight, reaching extremely high altitudes, and then back down for the rest of the flight. The VentureStar was intended for long inter-continental flights and supposed to be in service by 2012, but this project was never funded or begun.
The decision to design and build the X-33 grew out of an internal NASA study titled "Access to Space". Unlike other space transport studies, "Access to Space" was to result in the design and construction of a vehicle.
NASA cancellation
Construction of the prototype was some 85% assembled with 96% of the parts and the launch facility 100% complete when the program was canceled by NASA in 2001, after a long series of technical difficulties including flight instability and excess weightWeight
In science and engineering, the weight of an object is the force on the object due to gravity. Its magnitude , often denoted by an italic letter W, is the product of the mass m of the object and the magnitude of the local gravitational acceleration g; thus:...
.
In particular, the composite liquid hydrogen fuel tank failed during testing in November 1999. The tank was constructed of honeycomb composite walls and internal structures to reduce its weight. A lighter tank was needed for the craft to demonstrate necessary technologies for single-stage-to-orbit operations. A hydrogen fueled SSTO craft's mass fraction requires that the weight of the vehicle without fuel be 10% of the fully fueled weight. This would allow for a vehicle to fly to low earth orbit without the need for the sort of external boosters and fuel tanks used by the Space Shuttle. But, after the composite tank failed on the test stand during fueling and pressure tests, NASA came to the conclusion that the technology of the time was simply not advanced enough for such a design. While the composite tank walls themselves were lighter, the odd hydrogen tank shape resulted in complex joints increasing the total mass of the composite tank to above that of an aluminum-based tank.
NASA had invested $922 million in the project before cancellation and Lockheed Martin a further $357 million. Due to changes in the space launch business—including the challenges faced by companies such as Globalstar
Globalstar
Globalstar is a low Earth orbit satellite constellation for satellite phone and low-speed data communications, somewhat similar to the Iridium satellite constellation and Orbcomm satellite systems.-History:...
, Teledesic
Teledesic
Teledesic was a company founded in the 1990s to build a commercial broadband satellite constellation for Internet services. Using low-earth orbiting satellites small antennas could be used to provide uplinks of as much as 100 Mbit/second and downlinks of up to 720 Mbit/second...
, and Iridium and the resulting drop in the number of anticipated commercial satellite launches per year—Lockheed Martin deemed that continuing development of the X-33 privately without government support would not be profitable.
Continued research
After the cancellation in 2001, engineers were able to make a working liquid oxygen tank out of carbon fiber composite.On September 7, 2004, Northrop Grumman and NASA engineers unveiled a liquid hydrogen tank made of carbon fiber composite material that had demonstrated the ability for repeated fuelings and simulated launch cycles. Northrop Grumman concluded that these successful tests have enabled the development and refinement of new manufacturing processes that will allow the company to build large composite tanks without an autoclave; and design and engineering development of conformal fuel tanks appropriate for use on a single-stage-to-orbit vehicle.
Lockheed Martin has been testing a new and different 1/5 scale rocket described to be similar in capabilities and design, known now simply as a "Space Reusable Launch Vehicle". Two tests were conducted secretly at the Spaceport America
Spaceport America
Spaceport America is a spaceport located in the Jornada del Muerto desert basin in New Mexico, United States. It lies north of El Paso, north of Las Cruces, east of Truth or Consequences...
in New Mexico. The first on December 19, 2007 was billed as a complete success, while the August 12, 2008 launch ended in an irreparable crash after 12.5 seconds of flight. A third test on October 10, 2009, was another success.
External links
- X-33 History Project page on NASA.gov
- X-33 project article on Nasaspaceflight.com
- Federation of American Scientists, GAO, August 1999.
- [ftp://ftp.hq.nasa.gov/pub/pao/pressrel/2001/01-031.txt X-33 cancellation press release], NASA, March 1, 2001.