Software Faulted In Failed Hypersonic Test
Jan 8, 2009
By Guy Norris
ORLANDO, Fla. - Preliminary findings of an investigation into the August 2008 loss of NASA's HyBoLT (hypersonic boundary layer transition) rocket-boosted experimental project suggest a software fault was to blame.
HyBoLT was aimed at gathering data on transition flow physics - one of the fundamental areas of mystery in the high-speed atmospheric flight regime - but was cut short 20 seconds after liftoff from NASA's Wallops Island, Va., test site when the ATK-provided ALV X-1 booster went out of control (Aerospace DAILY, Aug. 25, 2008).
The vehicle was intended to boost a wedge-shaped copper forebody dubbed SOAREX (suborbital aerodynamics and re-entry experiments) to gather data on hypersonic re-entry shapes during the descent. "But it was destroyed after liftoff when it veered sharply," said Seokkwan Yoon, NASA Ames hypersonic aeronautics research scientist.
He added that initial results from the investigation show the likely cause was a "simple software error."
Despite the failure, NASA remains determined to continue with its quest to develop a physics-based predictive capability for both access to space and Earth descent and landing - a movement originally sparked by the February 2003 loss of the space shuttle Columbia. Ongoing high-speed research includes tests in the Langley Research Center's Mach 3.5 "quiet" wind tunnel, as well as the upcoming HiFire (hypersonic international flight research experiments).
The initial HiFire test is on track for May 2009 and is the first of 10 tests that, over the next five years, will gather a "world-class data set" on the unexplored reaches of the hypersonic envelope above Mach 5. The five-year, $56 million HiFire effort is led by the U.S. Air Force Research Laboratory and Australia's Defence Science and Technology Organization. The first test, launched from Australia's Woomera range, will collect re-entry data at Mach 7.2.
Speaking recently at the American Institute of Aeronautics and Astronautics aerospace sciences meeting here, Yoon says NASA's most immediate hypersonic research priority is now the shuttle boundary layer transition flight, an experiment due to take place in February with the upcoming launch of STS-119. For this experiment, a section of the belly of the orbiter has been fitted with discrete protuberances representing artificial tile gap fillers. Fitted with thermocouples, the devices protrude a quarter of an inch and will be monitored by remote infrared imaging systems to detect boundary layer onset at around Mach 15. A second test, to be conducted on another shuttle flight later in 2009, will collect similar data on transition conditions at Mach 18 using devices 0.35 inches high.
HyBoLT model test photo: NASA
