Graham Warwick/WASHINGTON DC Tim Furniss/LONDON
NASA and Lockheed Martin are discussing follow-on flight testing of the X-33 to further reduce the risk attached to commercial development of the planned VentureStar reusable launch vehicle.
The X-33 technology demonstrator has yet to fly, but talks are under way on an upgraded "X-33B", says NASA programme manager Gene Austin. The X-33B would incorporate upgrades to the propulsion, hot structure and avionics, says Cleon Lacefield, programme manager at Lockheed Mar- tin Skunk Works, where assembly of the X-33 and design of the full-scale VentureStar is taking place.
Lockheed Martin plans to develop the VentureStar commercially, but needs to minimise the risk to attract investors. Follow-on flight testing of an upgraded X-33 would help build the business case, says Lacefield. Plans call for the X-33B to fly in late 2001/early 2002, ahead of the VentureStar critical design review in mid-2002.
NASA's cost-sharing agreement with Lockheed Martin on the X-33 allows for a follow-on phase, says Austin. X-33 upgrades could include modifying the vehicle to use the "densified" propellants planned for the VentureStar, adds Lacefield.
The Skunk Works plans to roll out the X-33 in the first quarter of next year, while the first flight from Edwards AFB, California, has slipped to the third quarter. Fifteen suborbital flights are planned. NASA will decide by the end of 2000 on which reusable launch vehicle option to pursue for International Space Station resupply missions, says Austin.
The X-33 programme is progressing, meanwhile, with major elements entering validation testing. The aluminium liquid oxygen tanks have undergone structural testing, while tests on the first composite liquid hydrogen tank are about to begin.
The first test firings of the XRS-2200 linear aerospike engine of the X-33 will begin this month. Four Boeing Rocketdyne engines - two test engines and two flight engines - will be tested. Initial tests will focus on engine ignition and start sequence development, followed by verification of engine performance at various mixture ratios and power levels, and thrust vector control.
Next January, a dual engine arrangement assembled in flight configuration will be tested for 2,646s. In flight tests from June, the X-33's two linear aerospike engines will run for up to 195s.
• The US Government's General Accounting Office (GAO) says the X-33 "will not meet its original cost and performance objectives". The first flight has been delayed from March to next June, the required top speed has been reduced by 10% and important technology demonstrations for the proposed follow-on VentureStar single-stage to orbit vehicle have been eliminated, says the GAO.
NASA's "approach to developing next generation launch vehicles isn't working", the GAO adds.
Source: Flight International
