F-15B #836 Research Testbed. NASA public domain image colelction.

Project Description Before the Space Shuttle could safely return to flight, engineers needed data on how insulating foam debris or "divots" behaved when these small pieces were shed from the Shuttle's external fuel tank during launch. NASA's Dryden Flight Research Center conducted a series of flight tests of the divots as part of the Return to Flight team effort. The Lifting Insulating Foam Trajectory (LIFT) flight test series at Dryden used the center's F-15B Research Testbed aircraft to test these "divots" in a real flight environment at speeds up to about Mach 2, or twice the speed of sound. Small-scale divoting occurs when the adhesive on the external tank thermal protection system (TPS) foam fails. This occurs as a result of decreasing atmospheric pressure combined with increased heating during Shuttle ascent causing air trapped beneath the TPS to expand. Objectives of the LIFT flight tests on the F-15B included determining divot structural survivability and stability in flight and quantifying divot trajectories using videography. The flight data of divot trajectories could also be used for Computational Fluid Dynamic code validation. NASA's Space Shuttle Systems Engineering and Integration office at the Johnson Space Center (JSC) in Houston, Texas, funded the LIFT flight tests at NASA Dryden as part of the Space Shuttle Return-to-Flight effort. The LIFT flight test required two new capabilities: an in-flight foam divot ejection system, and a high-speed video system to track and record the trajectories of the divots in flight. Both capabilities were developed by Dryden engineers in just over two months. Dryden's LIFT team designed, fabricated, and ground-tested four different divot ejection systems, completing 70 ground tests to determine and refine the best approach. NASA Dryden engineers also designed and procured the very high-speed digital video equipment, including development of a system to synchronize the cameras with the divot ejection system. In addition, they developed videography analysis techniques in order to quantify divot trajectories. Photo Description Two panels of Space Shuttle TPS insulation were mounted on the flight test fixture underneath NASA's F-15B during the Lifting Foam Trajectory flight test series. February 16, 2005 Nasa Photo / Jim Ross EC05-0030-12

NASA Identifier: 276244main_EC05-0030-12_full