WASHINGTON (States News Service) - With its X 33 program slipping ever farther behind schedule, Lockheed Martin VentureStar is now considering replacing the troublesome composite fuel tanks on the futuristic vehicle with aluminum ones.
A company official on Friday said that no final decision on the tanks will come until the NASA-Lockheed investigation into the failure of the composite tanks is complete.
But preliminary design work on aluminum tanks began in December at Lockheed Martin Michoud Space Systems in New Orleans.
The X 33 is a half-size prototype of the proposed VentureStar reusable launch vehicle. Already a year behind schedule, the project was further delayed last November when one of the hydrogen fuel tanks built from a lightweight carbon composite burst during testing. It was the second failure of a fuel tank since assembly on the vehicle began in early 1999.
The investigation was to be completed by the end of last year but NASA now says the probe could go until February.
"It was a combination of the (Christmas) holiday, and they took their time moving the tank," from the testing stand to a different building, said NASA spokesman Dave Drachlis. "And that took longer than expected."
Meanwhile, engine and software testing continues on the X 33 program, as does design work on the full-sized VentureStar.
The $1.3-billion X 33 program is governed by a cost-sharing agreement between NASA and Lockheed. Original costs were to be shared but Lockheed would have footed the bill for any additional costs.
The company has agreed to put an extra $100 million into the X 33 over the next two years as long as NASA does not terminate the program. That money will go to the repair or replacement of the failed fuel tank.
Although the X 33 was conceived as a near-identical half-size version of the VentureStar, the larger vehicle's design has morphed over the last year. There now are significant differences, including an external payload bay; vertical fins on the wings instead of the body, and aluminum rather than composite fuel tanks.
Some critics have questioned whether or not the X 33 will still serve a useful purpose given how different it will be from the VentureStar.
The move to aluminum tanks for the X 33 would push its design closer to that of the VentureStar. The metal tanks would be heavier and thus reduce the vehicle's top speed and altitude.
Drachlis said he did not think the X 33 team felt "any discouragement at all" over the delays.
"Sometimes you make an estimate for how long something will take, but it's not until you get into it that you have a clear idea," he said. "That's just the way it is."
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