Lockheed Martin X-33

The Lockheed Martin X-33 was a proposed uncrewed, sub-scale suborbital spaceplane built to demonstrate technologies for VentureStar, a planned single-stage-to-orbit reusable launch vehicle. NASA selected Lockheed Martin Skunk Works over proposals from Rockwell International and McDonnell Douglas on 2 July 1996. The craft was to test metallic thermal protection, composite cryogenic fuel tanks for liquid hydrogen, an aerospike engine and a lifting body shape, launching upright like a rocket and landing horizontally on a runway. After the composite hydrogen tank failed in testing in November 1999, NASA ended support and the program was cancelled in February 2001 with about 85 percent of the prototype assembled.