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Pathfinder composite liquid oxygen tank

07 September 2001

A joint effort between NASA and Lockheed Martin has resulted in the development and successful initial testing of the first sub-scale cryogenic tank built of a composite material that is compatible with liquid oxygen.

Lockheed Martin designed and built the composite tank, and NASA is testing it at the Marshall Space Flight Center in Huntsville, Ala. The tank has successfully completed the initial cycles of cryogenic, or very low temperature, proof testing in liquid oxygen. In testing, the tank is enduring thermal and pressure environments that simulate flight conditions a liquid oxygen tank would experience on a space launch vehicle. The tank also will undergo life cycle testing at Marshall Center to demonstrate mission life capabilities.

"This marks a real advance in space technology," said Michael Phipps, NASA project manager for this material characteristics development unit. "No approved standards for composite pressure vessels exist; there has not been enough information on them to write standards. So the technical data we are getting from this effort is very valuable." Using state-of-the-art cryogenic composite tank analysis, fabrication, and inspection techniques, the Lockheed Martin/NASA team designed and constructed the tank at both the Marshall Center and the NASA Michoud Assembly Facility in New Orleans. The composite tank is approximately nine feet (2.7 meters) in length and four feet (1.2 meters) in diameter and weighs less than 500 pounds (225 kilograms), which represents an 18 percent weight savings over a metal tank of similar construction.

Composites are seen as one of the key components in the drive by NASA and the aerospace industry to decrease the weight of future launch vehicles as a means of reducing the cost of launching payloads into orbit from the current $10,000 per pound to $1,000 per pound. That is one of the goals of NASA's Second Generation Reusable Launch Vehicle (RLV) program, a research and technology development effort that also aims to substantially improve safety and reliability. The Marshall Center manages that program for NASA.

NASA at the Marshall Center and at the White Sands Test Facility in New Mexico has worked together with Lockheed Martin since 1997 to develop the approach and test methods for demonstrating composite liquid oxygen tanks. NASA and Lockheed Martin tested the material extensively following a building-block approach. This approach began with coupon testing, progressing to panels, then to specific tank type interfaces and joints, scaling up to small bottles, and finally to this sub-scale tank.





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