Feb. 22, 2005
Dryden Flight Research Center
P.O. Box 273
Edwards, California 93523
Phone 661/276-3449
FAX 661/276-3566
Gray Creech
NASA Dryden Flight Research Center
Phone: 661/276-2662
gray.creech@dfrc.nasa.gov
RELEASE: 05-06
SPACE SHUTTLE RETURN TO FLIGHT GETS A "LIFT" FROM NASA DRYDEN F-15B
To help the Space Shuttle safely return to flight, NASA engineers are
acquiring data on how insulating foam debris or "divots" behave when
these small pieces are shed from the Shuttle's external fuel tank
during launch.
NASA's Dryden Flight Research Center at Edwards Air Force Base,
Calif., is conducting 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 is using 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.
Image Right: All six divots of thermal insulation foam have been
ejected from the flight test fixture on NASA's F-15B testbed as it
returns from a LIFT experiment flight. NASA Photo EC05-0028-18 by
Carla Thomas.
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.
LIFT project manager Stephen Corda said objectives of the current
flight tests on the F-15B include determining divot structural
survivability and stability in flight and quantifying divot
trajectories using videography. The flight data of divot trajectories
may also be used for Computational Fluid Dynamic code validation.
"We're using the unique capabilities of the supersonic F-15B aircraft
and the aerodynamic flight test fixture to provide a means to eject
these debris or divots from the fixture, and then photograph them
with a high-speed digital video system, where we're able to video
these divots in flight at up to 10,000 frames per second," Corda
noted.
NASA' s Space Shuttle Systems Engineering and Integration office at
the Johnson Space Center (JSC) in Houston, Texas, is funding the LIFT
flight tests at NASA Dryden as part of the Space Shuttle
Return-to-Flight effort. JSC aeroscience engineer Ricardo Machin said
the current LIFT flight tests will help them validate the models that
they use for debris transport analysis.
"In particular, it's going to help us understand whether the divots
break up once they come off the external tank, and secondly whether
they will trim and begin to fly, or if they'll tumble. The difference
between trimming and flying makes a huge difference in the amount of
kinetic energy that this piece of debris can impart to the shuttle,"
Machin said.
Image Left: A post-flight inspection of the panels on the F-15B's
flight test fixture shows all six divots of TPS foam were
successfully ejected during the LIFT experiment. NASA Photo
EC05-0030-04 by Tony Landis.
The LIFT flight test requires 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.
-NASA-
TELEVISION EDITORS: Interview segments and B-roll footage to support
this release will be aired during the Video File feeds on NASA TV
beginning on Feb. 22. NASA TV is available on the Web and via
satellite in the continental U.S. on AMC-6, at 72 degrees west
longitude, transponder 9, 3880 MHz, vertical polarization, audio at
6.8 MHz. In Alaska and Hawaii, NASA TV is available on AMC-7, at 137
degrees west longitude, transponder 18, at 4060 MHz, vertical
polarization, audio at 6.8 MHz. For NASA TV information and schedules
on the Internet, visit: http://www.nasa.gov/ntv.
PHOTO EDITORS: Still photos to support this release are available in
high resolution at:
http://www1.dfrc.nasa.gov/Gallery/Photo/F-15B/index.html.
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