United Launch Alliance conducts test of the Orion Crew Exploration Vehicle in AEDC's 16 foot transonic wind tunnel

  • Published
  • By Philip Lorenz III
  • AEDC/PA
ARNOLD AIR FORCE BASE, Tenn. --  A team of engineers, technicians and outside machinists at AEDC played a key role in conducting transonic wind tunnel testing in support of NASA's upcoming Exploration Flight Test-1 (EFT-1), the first planned, flight test of the Orion Multi-Purpose Vehicle without a crew.

A United Launch Alliance (ULA) team, led by Mike Schoonmaker, was at AEDC's 16-foot transonic wind tunnel to gather dynamic pressure, and steady state pressure data for the 5.9 percent scale modeled Orion crew capsule mounted on a Delta IV booster.

EFT-1, which is scheduled for launch in 2014, will take Orion to an altitude of approximately 3,600 miles above the Earth's surface, more than 15 times farther than the International Space Station's orbital position. This mission will see Orion traveling farther into space than any manned spacecraft has gone in more than 40 years.

"The 'Orion' Multi-Purpose Crew Vehicle (MPCV) is a beyond-low-earth-orbit manned spacecraft that is being built by Lockheed Martin for NASA," Schoonmaker said. "With the retirement of the Space Shuttles, Orion will provide the U.S. with manned access to space.

"Prior to flying a manned mission, an unmanned Orion will fly on a Delta IV to demonstrate both flight and reentry performance parameters. The testing at AEDC supports the first flight test, EFT-1, of Orion."

Schoonmaker said the test article his team installed in AEDC's 16T wind tunnel is the entire three-body configuration of the Delta IV Heavy with the Orion, the Orion Service Module, and the Orion Launch abort system on the front end.

Nathan Payne, the Aerospace Testing Alliance project engineer on the ULA Orion entry test at AEDC, said, "This was a buffet/acoustic test in our 16T wind tunnel facility. The Orion's test objectives were to gather dynamic pressure data over the entire model's surfaces. ULA can then use this data to provide vehicle forcing function for axial, pitch, yaw and their respective moments.

"We were defining the surface acoustics and vibrational environment on the model to support a component that will be used on the full scale vehicle."

Payne added, "We gathered static pressure data over selected areas of the vehicle's surface and obtained [Background-Oriented] Schlieren images of shock interaction between the payload and the strap on liquid rocket nose cone geometries."

The wind tunnel testing at AEDC supports buffet environment definitions and provides whole vehicle buffet forcing functions.

"The Delta IV Heavy vehicle is a flight-tested configuration, but every time a new geometry is put on the front end, ULA must verify flight margins," Schoonmaker said. "The new element in this case, Orion, has not flown yet, but Orion models have been tested in other wind tunnels; thus, these new data are really to support whole vehicle buffet modeling and response predictions. This data supports the first engineering test flight of Orion on Delta IV, EFT-1."

Schoonmaker said AEDC's 16T wind tunnel facility is the test site of choice for an entry like the ULA Orion configuration.

"AEDC was chosen because the previous Atlas V Heavy test was conducted at AEDC and reuse of those elements for a cost and schedule savings required a tunnel of the size of AEDC," he said. "The AEDC tunnel is comparatively quiet with known tunnel tones and I can interface with the AEDC tunnel operation computer to use the tunnel optimally.

"Since everything is under computer control, I can acquire 1,000 test points in a bit less than seven hours of air-on operation. With appropriate planning and support from AEDC, I find 16T to be both very efficient and cost effective for large test matrices."

Schoonmaker also enjoys the professional and personal camaraderie that comes from years of collaboration and working closely with his counterparts at AEDC.

"I am always impressed with the friendly atmosphere and professionalism. The facilities are truly impressive, but, having spent many days and nights in the control room for other tests, I don't really pay too much attention to the hardware anymore. My focus is on the people and the clear communication of test requirements and goals. My focus is on the team that will help me meet my goals."

Buffet testing requires considerable instrumentation of the model. For the test, more than 500 pressure transducer signals were acquired from the model for each test point. The initial challenge involved with this level of instrumentation was the packaging and verification of all the transducers and cables within the model. The second challenge was to maintain functionality of all signals for the duration of the test despite the vibration environment.

Schoonmaker said, "All channels are monitored real time and any channel loss is immediately assessed as to channel criticality, how long it would take to fix that channel, and what risk is added to the test if the model is opened."

Schoonmaker was quick to add, "You will note that I don't list the AEDC test conditions as a challenge. My test conditions are well within the AEDC operational envelope. The overall challenge was always to ensure that all test goals were met and the data support the analytical buffet response assessment."