Lockheed Martin X-33

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The X-33 was a sub scale technology demonstrator for the VentureStar, 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.

Contents 1 Design 2 Commercial spaceflight 3 Cancellation 4 The X-33 in fiction 5 See also 6 External links

[edit] Design

Most importantly, through the use of the lifting body shape, composite liquid fuel tanks, and the aerospike engine, NASA 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 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.

The unmanned craft would have been launched vertically (from a specially designed facility constructed on Edwards Air Force Base), and have landed horizontally 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 would 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 DC-XA test vehicle.

[edit] Commercial spaceflight

Based on the X-33 experience shared with NASA, Lockheed Martin 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 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.

[edit] Cancellation

Construction of the prototype was some 85% complete when the program was canceled by NASA in 2001, after a long series of technical difficulties including flight instability and excess weight. 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 be light enough in order for the craft to demonstrate necessary technologies for single-stage-to-orbit operations. A hydrogen fueled SSTO craft's mass fraction requires that weight of the vehicle without fuel to be 10% of the fully-fueled weight. This would allow for a vehicle to fly to low earth orbit without the need for external boosters and fuel tanks, as currently used with the Space Shuttle. But, after the composite tank's failure 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.

NASA had invested $912M in the project before cancellation and Lockheed Martin a further $357M. 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 the business case to continue development privately without government support was unviable.

After the cancellation, engineers were able to make a working liquid oxygen tank out of carbon fiber composite. [1]

[edit] The X-33 in fiction

• A Boeing X-33 [sic] is mentioned in Dan Brown's Angels & Demons where it is owned by CERN, the nuclear physics research laboratory, and is able to go at Mach 15, flying from Boston to Switzerland in less than an hour. CERN does not actually own an X-33, nor would such a craft be usable for intercontinental travel.
• The PC game Nexus: the Jupiter Incident depicts an X-33 in orbital flight during the opening movie.
• During the opening credits of the television series "Star Trek: Enterprise", an X-33 style shuttle is shown in orbit during a sequence showing the advancing engineering progress of launch vehicles. It is sandwiched between the space shuttle with the ISS, and the fictional first flight to achieve warp speed.
• In the animated mini-series Invasion America the protagonists hijacked an X-33 style craft to fly to the Moon to reach the staging area of an alien invasion. This would be an impossible task for the real X-33, which would not have been capable of inter-planetary flight.
• The 1987 toy line for G.I. Joe included a playset for the Space Shuttle Defiant, which bears a large resemblance to the X-33. This playset included a mobile crawler/gantry and a booster as well. The mold for the shuttle was re-used in 1987 for the Crusader shuttle toy as well.

[edit] See also

• VentureStar
• Space Shuttle program
• NASA

[edit] External links

• NASA press release on cancellation
• The X-33 History Project Home Page
• Nasaspaceflight.com article on the X-33 project