The designers of the 16-foot supersonic wind tunnel at Arnold Air Force Base recognized when their work began in the 1950s that continuous improvements to the test facility would eventually be needed to keep pace with advancements in technology that were sure to transpire over the ensuing decades.
The first operational run in the wind tunnel, otherwise referred to as 16S, occurred in 1960, and 16S did not originally have a flow-straightening device installed. However, the facility was built so that it could accommodate an airflow-straightening “honeycomb” structure and, just as the designers foresaw, technological progression and the need for better flow quality ultimately necessitated the installation of a large honeycomb structure in 16S.
After years of planning and months of installation, the structure is now in place, and some of those involved in the project were joined by Arnold Engineering Development Complex leadership to mark the occasion with a ribbon cutting ceremony Nov. 6 in front of the completed honeycomb at Arnold AFB, headquarters of AEDC.
“This honeycomb will improve flow quality and the efficiency of our testing when combined with the precision of modern test instrumentation,” said Lt. Col. James Gresham, commander of the 716th Test Squadron at AEDC.
Gresham added that, as far as those involved in the project are aware, the 16S honeycomb is the largest such structure in the world.
The honeycomb is a single-piece structure measuring 55 feet in diameter and weighing more than 67 tons, and it is made up of thousands of stainless steel 1-inch hexagonal honeycomb tubes. If all of the metal that comprises the 4-foot-thick structure was to be rolled out flat, it would cover around 11 acres.
It was during the late 1990s when AEDC Fellow Mike Mills, an aerospace engineering and wind tunnel expert, began advocating for the installation of the honeycomb screen to improve flow quality in 16S. A prototype section of the tunnel was fabricated, and flow quality improvements were demonstrated by the team.
The success of the demonstration effort combined with the advocacy for a planned restoration of 16S garnered enough support that, eventually, a completed upgrade to the 16S facility was approved.
Return-to-service efforts began in 2013 with the multi-year project to restore 16S and end its dormancy, culminating in a successful air-on test run in January 2021. A standard model was used to validate the operational capability of 16S.
Before the ribbon was cut to signify completion of the honeycomb, Gresham expressed his appreciate to those involved in the undertaking, calling the process a “fantastic team effort across the board.”
“It’s great to stand here in front of the team and be able to witness this, knowing that next week we’re going to blow air through this tunnel and actually get to leverage something that’s been over 70 years in the making,” he said.