ARNOLD AIR FORCE BASE, Tenn. -- On Oct. 21, 1952, supersonic airflow was first achieved at, what was then known as Arnold Engineering Development Center, when the first wind tunnel was placed in operation.
The tunnel, known as Transonic Wind Tunnel 1T, provided the Arnold Engineering Development Complex with a 1-foot transonic test capability at Arnold Air Force Base.
Reaching this 70-year milestone, AEDC team members, and especially those with the 716th Test Squadron, reflected on the historical contributions of 1T, also referred to as “PeeWee.”
“Tunnel 1T was a 1/16th scale copy of the test leg of the larger 16-foot transonic tunnel that was under construction at the time,” said Mike Mills, an AEDC Fellow and subject matter expert for the 716 TS.
The construction of 1T, which began February 1952, was initially justified to confirm design decisions made for the 16-foot transonic wind tunnel 16T and to serve as a test unit for training operating crews. Parts of 1T were shipped to Arnold from Germany after World War II, while other parts of the tunnel were fabricated on base.
According to a 2017 report by Mills and AEDC team members Wesley Brueland and William Stevens, the results obtained in the tunnel “have left their mark on AEDC and wind tunnels around the world.”
“However, its value beyond the initial intent was quickly recognized, and in the 43 years of operation, tunnel 1T made major contributions to AEDC and wind tunnel technology in general,” the paper states. “Most notable was the use of the tunnel 1T to develop and refine the transonic porous wall configuration still used today, not only at AEDC but in wind tunnels around the world.”
Additionally, research on sting support interference and vibration, large blockage model studies, and experimental and high-risk setup verification were accomplished using 1T.
Tunnel 1T was used as a relatively inexpensive tool to identify problems and develop a solution. In the 1980s, aerodynamic configurations of the tunnel 16T High-Angle Automated Sting and Captive Trajectory System were both developed in tunnel 1T. Modifications to the 16T diffuser and scavenging system were developed by testing in 1T.
“The modifications to 16T resulted in an estimated 8% reduction in energy consumption of 16T in fiscal year ’84 alone,” Mills said. “This benefit has continued to accrue over the 37 years since the modifications were made.”
From initial operations in 1952 until 1995, an estimated 400 tests were run in the facility. The Joint Army-Navy-NASA-Air Force, or JANNAF, plume research in 1995 was the last test in 1T.
Other notable program development entries in 1T include testing for the Atlas program, Mercury capsule testing, NASA Saturn V testing, F-111 flow field studies and B1 engine inlet testing.
The wind tunnel has been out of service since 1995, but over the years there has been a push to restore the 1-foot by 1-foot test section. In 2005 and 2013, studies were conducted to assess the cost and feasibility of reactivating the tunnel.
Though still not operational today, Mills added that it was a valuable asset to AEDC and aerodynamic ground test facilities everywhere.
“1T was an excellent training ground for young engineers,” he said. “I was fortunate to run two tests in 1T within three years of beginning my AEDC career. I learned how to plan and lead a test team in a low stress environment before leading tests in tunnels 16T and 16S.”
Lt. Col. James Gresham, commander, 716 TS, noted that the aerodynamic capabilities at Arnold today are a direct result of the research conducted in 1T.
“Much like the Air Force builds and tests technology demonstrators and prototypes to reduce programmatic risk for operational combat aircraft, at AEDC we used the same concept when developing our world-class wind tunnels,” he said. “We learned an incredible amount with tunnel 1T which was critical to developing and maturing the amazing data collection capabilities we have today with tunnel 16T. Now, 16T is the busiest, high-fidelity, production wind tunnel in the nation and supports development and modernization efforts for the highest priority programs in the National Defense Strategy. We continue to stand on the shoulders of the giants who established AEDC as a ground test facility second to none."
Ed Tucker, AEDC senior technical director, also commented how the tests conducted in 1T helped to first lead the complex in its support of the warfighter.
“Just over a year after President Harry Truman dedicated AEDC, the 1T wind tunnel became operational, launching what would become the first of many world-class aerospace test capabilities at AEDC,” Tucker said. “Similar to the mandate championed by Gen. Henry ‘Hap’ Arnold after World War II, AEDC is once again leading the charge to answer the urgent call for new advanced test and evaluation capabilities needed to develop game-changing weapon systems. Now, 70 years after technicians and engineers first initiated airflow in 1T, we are still using the methods and lessons learned from that historical event as we develop and operate a new generation of T&E [test and evaluation] capabilities for the nation.”