Orion Testing in World Class Facility
By: Emily Outen
Langley's National Transonic Facility has been used for investigating models of the space shuttle, the blended-wing body aircraft, a C-17 cargo plane and even a submarine. Research in this world-class wind tunnel is no less important now with testing underway on a model of the Constellation Program’s Orion Launch Abort Vehicle.
Researchers are using the unique capabilities of this wind tunnel to see how a 6 percent scale model of the Launch Abort Vehicle, which includes the Orion crew module and the Launch Abort System, will behave at flight-like conditions.
“This model configuration is the launch abort vehicle,” said Greg Brauckmann, lead research engineer. “When Orion launches off the pad and is ascending through the atmosphere, the launch abort vehicle can pull the crew module to safety if there is an emergency.”
During this testing researchers are looking for flight or near-flight Reynolds Numbers, which are indicators of turbulent air flow. High Reynolds Numbers create flight-like conditions, representing the environment Orion will face. At these flight-like conditions, researchers can better predict how the vehicle will perform.
The high Reynolds Number data are difficult to obtain, which is a major reason why the researchers are taking advantage of the National Transonic Facility.
“One of the things that is unique about this wind tunnel is the cryogenic capability,” Brauckmann said.
“We can inject liquid nitrogen into the tunnel and cool it to about minus 250 degrees Fahrenheit. Because we're at such a low temperature, which decreases the viscosity and increases the density, we can get the high Reynolds Numbers,” he said.
Only one other wind tunnel in the world comes close to the National Transonic Facility's capability of obtaining near-flight Reynolds Numbers, which is invaluable as a tool in predicting behavior at flight conditions.
“By going down to minus-250 degrees Fahrenheit, we're able to match the number of particles flowing over the surface of wing on the flight vehicle,” said Josh Revenaugh, test engineer at the National Transonic Facility.
Not only do engineers test in “cryogenic mode,” they can also test in “air mode.”
“In air mode, we can run at 120 degrees Fahrenheit,” test engineer Ashley Dittberner said. “With air, you can get the same data but just at lower Reynolds Numbers.”
Researchers use the lower Reynolds Numbers testing to compare to data received from testing at other tunnels that cannot obtain the near-flight Reynolds Numbers.
“We hope past results will correlate with the data that we have gotten from this testing, and if it does that, then we can reduce our uncertainties,” Brauckmann said.
During a test run, engineers will move the model up through the angle of attack as well as pitch and roll the model. From the movement, they will acquire and analyze aerodynamic data for the simulated launch abort vehicle and provide the results to the Constellation Program.
While Constellation testing is a relatively new opportunity for the National Transonic Facility, it is a welcomed one.
“Seeing the Constellation Program come to this facility and being a part of the testing is a great experience,” Dittberner said.
"They only build a new manned spacecraft once in a lifetime, so it's exciting to be a part of it," Revenaugh said.
NASA Langley Research Center
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