ARNOLD AFB, Tenn. – Lt. Col. David Hoffman, right, becomes director of the Flight Systems Combined Test Force (TSTW) during a Change of Directorship ceremony July 21 inside the Model Installation Building, part of the Propulsion Wind Tunnel Test Facility, at Arnold Air Force Base, Tennessee. Col. Timothy West, (left) chief of the AEDC Test Operations Division, passes the TSTW guidon to Hoffman as 1st Lt. Roy Fisher, looks on. The Flight Systems CTF provides aerodynamic ground-test capabilities from low subsonic to hypersonic speeds in various wind tunnels and supports Department of Defense, U.S. industry and international aerospace programs. (U.S. Air Force photo/Rick Goodfriend)