The Arnold Engineering Development Center's Hypervelocity Wind Tunnel 9, located near Silver Spring, Md., recently completed its 3,000th test-run as the facility approaches 30 years of operation. The first test, ironically in support of an Air Force system, occurred in 1976 when the facility was operated by the U.S. Navy as part of the Naval Ordnance Laboratory.

In its early years of operation, Tunnel 9 completed an average of 100 runs per year, with a record 281 runs in 1985. But technology advancements in more recent years have enabled the team to test more proficiently with fewer runs, saving customers' time and money and providing better data than ever before.

"Today, through the use of powerful computational methods, far fewer, yet highly accurate and more complex, test runs are needed to validate computational fluid dynamics codes," said AEDC White Oak Site Director Dan Marren.

"With today's more efficient operations, Tunnel 9's expert staff can support about 60 to 80 runs per year, focusing on unique physics-based challenges. This year, Tunnel 9 is running at near maximum capacity for the U.S. Air Force, DARPA, NASA, U.S. Navy and the Missile Defense Agency, and fiscal year 2007 is looking just as productive," he said.

A typical test in Tunnel 9 acquires about one to two seconds of data.

"In a single second, Tunnel 9 can obtain surface pressures, heat transfer data and characterize the forces acting on a test article while simultaneously changing the model's altitude," Mr. Marren said.

Other facilities attempting to replicate this extreme test environment operate for 1/1,000 of a second making Tunnel 9 unique in its ability to obtain design information.

Thirty years of testing has produced approximately one hour of data when all of the test runs are added together. Tunnel 9 has been, and continues to be, critical in the development of accurate strategic reentry systems; in aiding successful earth reentry for NASA's space shuttle; in enabling direct hit missile defense interceptors at closing speeds approaching 10,000 mph; and in advancing understanding of complex aerodynamics and aerothermodynamic phenomenon of high-speed propulsion systems.

"When you are used to continuous wind tunnels operating at less severe environments, you tend to think that one air-on hour is short," Mr. Marren said. "But consider what system advances Tunnel 9 has enabled in a single hour."

(Courtesy of Air Force Materiel Command News Service)