Trey Glenn, an outside machinist, rotates a wheel truck on a transfer cart carrying a test cart from the Model Installation Building to the 16-foot supersonic wind tunnel, Jan. 12, 2021, at Arnold Air Force Base, Tenn. The transfer cart rides on rails, and in order to make a turn the cart is jacked up, then the wheel trucks are rotated 90 degrees. (U.S. Air Force photo by Jill Pickett) (This image has been altered by obscuring a badge for security purposes.)