NASA says replacing the failed composite liquid hydrogen tank in the Lockheed Martin X-33 will delay the first flight of the reusable launch vehicle (RLV) technology demonstrator by at least of two years.
The space agency released the long-delayed failure investigation report last week, but says an agreement with Lockheed Martin on restructuring the X-33 programme is still a "few weeks" away.
The tank failed last November during ground testing. The composite structure withstood flight loads, but failed as it warmed after the cryogenic fuel was drained, the outer skin and core separating from the inner skin.
NASA says debonding was caused by microcracks in the inner and outer skins which allowed hydrogen from inside the tank and nitrogen from outside (used for inerting) to enter the core and force the structure apart.
NASA and Lockheed Martin have decided to replace the composite tank with an aluminium unit, as the manufacturer had already decided to use an aluminium fuel tank in the full-scale VentureStar single-stage-to-orbit RLV. Protracted negotiations on funding for a restructured X-33 demonstration programme, which held up release of the failure report, are also delaying the start of work on the new tank.
The X-33 is a cost-sharing programme, but NASA's share is capped while industry's has increased. Negotiations on funding have taken longer than expected, NASA admits, and could still further delay the first flight.
NASA, meanwhile, has awarded the first tranche of contracts under its second-generation RLV risk reduction programme, its successor to the X-33 effort.
Definition study contracts totalling $15 million have been awarded to Andrews Space & Technology, Boeing, Boeing's Rocket dyne division, Futron, Kelly Space & Technology, Lockheed Martin, Orbital Sciences, Pratt & Whitney and Space Access.
Source: Flight International
