Arnold overcomes hurdles to complete test

  • Published
  • By Philip Lorenz III
  • AEDC/PA
ARNOLD AIR FORCE BASE, Tenn. --  Aero thermal testing in the Arnold Engineering Development Center's von Karman Facility Hypersonic Wind Tunnel C has evaluated the performance of newer Thermal Protection System materials used on the large main fuel tank under simulated flight conditions it would be subjected to during the space shuttle's ascent. 

The purpose of the thermal protection system is to maintain the propellant quality inside the external tank and preclude ice or frost formation prior to launch and during ascent. 

"The recently completed aero thermal testing provided a quantitative assessment of several TSP materials reformulated by NCFI (North Carolina Foam Industries)," said John Hopf, lead Aerospace Testing Alliance project engineer at AEDC. "The data will be compared with historical ascent recession rates as part of a recertification process conducted by Lockheed Martin." 

The testing was a milestone event, but more for what went on behind the scenes. 

Testing on TPS foam samples began in March, but was interrupted when one of the requested test conditions was unattainable because of problems with the tunnel's cooling system. 

"Our ground testing facilities are very complex and if any aspect, from power to cooling to airflow, isn't working perfectly, testing can suffer," said Gregory Fox, AEDC's ATA project lead with the test operations group. "We formed five core teams to tackle this challenge -- it wasn't long before this team totaled more than 200 of our people, including machinists, pipe fitters, boilermakers, welders and mechanical designers - and they pulled it off in time to meet our customer's schedule -- no small feat." 

Philip Kopfinger, Lockheed Martin's lead engineer for the materials testing, admitted he was getting a bit nervous about acquiring the data critical to certifying the new TPS materials by NASA's tight deadline. 

"We had to get this test done on time to support the qualification of these materials so we could start spraying foam on the production tanks that were starting in mid August," he said. "The test data acquired during the recent entry is absolutely critical to the safety and success of upcoming Space Shuttle missions." 

Arnold has been critical to NASA's success, Mr. Kopfinger said. 

"AEDC has unique ground testing facilities - with world-class capabilities you can't find anywhere else," he said. "These facilities have been used to test literally every one of NASA's manned spacecraft, orbiters, etc."