Dr. Rich Roberts, second from right, chief of the Aerodynamics Branch Store Separation Section of Arnold Engineering Development Complex (AEDC), briefs Maj. Gen. Evan Dertien, commander, Air Force Test Center, on the 16-foot transonic wind tunnel during Dertien's visit to Arnold Air Force Base, headquarters of AEDC, Oct. 13, 2021. The transonic tunnel is part of the Aerodynamics Test Branch of AEDC, which provides aerodynamic effects and captive trajectory ground-test capabilities. (U.S. Air Force photo by Jill Pickett) (This image has been altered by obscuring a poster for security reasons.)