AFMC Command News

AEDC Hypervelocity Wind Tunnel 9 reaches 5,000 run mark

  • Published
  • By Bradley Hicks
  • AEDC Public Affairs

The list of milestones and achievements at Arnold Engineering Development Complex Hypervelocity Wind Tunnel 9 recently grew a bit longer.

On April 11, the team at the White Oak, Maryland facility celebrated the successful completion of 5,000 test runs by Tunnel 9 personnel.

”It’s always exciting when we cross these important milestones, and the rate at which they have been occurring shows the importance of Tunnel 9 to the nation,” said Joe Coblish, AEDC White Oak Air Force site director. “The nation’s highest priority efforts on hypersonic system development outlined in the National Defense Strategy are supported each and every day at Tunnel 9. I am very proud of the accomplishments that this team has made in the last few years.”

Tunnel 9 became an Air Force facility in 1997. Its purpose since has been to provide critical aerodynamic and aerothermal ground test simulation environment for the development of hypersonic systems; including critical altitude regimes associated with strategic missile systems, advanced defensive interceptor systems and hypersonic vehicle technologies.

The facility supports developmental testing for Air Force, Navy, Army, Missile Defense Agency, Defense Advanced Research Projects Agency and NASA programs, as well as advancing hypersonic technologies such as waverider-type vehicles, scramjet inlets and transatmospheric space planes that are being worked by our commercial industry and DOD Research Labs partners.

Past testing at Tunnel 9 includes aerodynamic, aerothermal, thermal-structural, fundamental flow physics and computational fluid dynamics validation experiments. In addition, due to its unique test capabilities not available in other U.S. test facilities, fundamental science and technology test programs have been conducted to advance knowledge of hypersonic flow physics and mature CFD capabilities.

Tunnel 9 came online in 1973, around six years after Congress had granted approval for its construction. Initial runs were performed to ensure the facility was customer-ready. In 1976, the first-ever customer test occurred in support of an Air Force system.

At the time, the tunnel was operated by the U.S. Navy as part of the Naval Ordnance Laboratory. It would continue to operate in this manner for the better part of two decades but, in 1995, the Base Realignment and Closure commission closed the Navy White Oak site and threatened to close Tunnel 9.

In the end, however, Tunnel 9 was deemed critical to the nation’s ground test infrastructure and was kept open. It became an Air Force facility in October 1997. Tunnel 9 has since continued to provide renowned capabilities to test hypersonic weapons at speeds as high as 18 times the speed of sound and over a wide range of altitude conditions.

Tunnel 9 is classified as a high-Reynolds number, blow-down hypersonic wind tunnel. This means it does not operate continuously like many of the large engine and wind tunnel facilities of AEDC. Tunnel 9 runs are of short duration, lasting only a few seconds. However, during each run a large quantity of test data is acquired as the test article is often swept through an angle-of-attack orientation while simultaneously collecting static stability and control, surface pressure, and heat transfer data.

The most recent upgrade to Tunnel 9 include the expansion to Mach 18. The Mach 18 capability now available at Tunnel 9 allows for testing at speeds never before realized in an AEDC wind tunnel. Calibration of the Mach 18 system was completed in July 2020 and the first customer runs occurred in August 2020. The Mach 18 capability has been used extensively during almost every customer test conducted since initial operational capability, further highlighting the importance of this new capability to advancing hypersonic system development.

In December 1984, less than a decade after its first test, Tunnel 9 reached 1,000 runs during a Navy test. In September 1989, the wind tunnel reached the 2,000 run milestone. By March 2006, Tunnel 9 reached 3,000 runs. Tunnel 9 hit the 4,000 run mark in January 2015.

In its earlier years, Tunnel 9 completed an average of 100 runs per year. It completed a record number of runs in 1985 and came close to that recently in 2021 as the new demand for hypersonic testing has rapidly expanded.

“We’ve become very efficient in our test process and operations at Tunnel 9 by working closely with our customers to help them focus on critical data requirements, but also we have crossed-trained our personnel to the maximum extent to support surge test operations,” Coblish said. “It has been this flexibility that allowed Tunnel 9 to respond to cyclical test demand in the past, but this operation model is not sustainable.”      

Even with the efficiency improvements, due to the increased testing demand, the Tunnel 9 facility is busier than ever before, with back-to-back customer test entries scheduled.

The projected test capacity needs to approach a significant number of runs per year to meet the demand, Coblish said.

“The good news is that the DOD has identified this need to increase capacity and support capability enhancements in response to the expanding test requirements,” he said. “These critical resources planned across the FYDP [Future Years Defense Program] will go a long way to increase staffing and materials to respond to the increased test operations demand, as well as enhance the Tunnel 9 capability to support our customers as we move advanced hypersonic systems forward to deployment.”