ARNOLD AIR FORCE BASE, TENN. – Image 161011-F-0000U-001: AEDC instrumentation engineer Dan Pruyn works on the Tiltrotor Test Rig in preparation for a test in the 40-foot by-80-foot wind tunnel at the National Full-Scale Aerodynamics Complex, the AEDC wind tunnel testing site located in California. The test of the TTR is a project sponsored by the National Aeronautics and Space Administration. TTR is a horizontal axis rig and rotates on the test section turntable to face the rotor into the wind at high speed, or fly edge-wise at low speed (100 knots), or at any angle in between. It is designed to accommodate a variety of rotors. (U.S. Air Force photo/Jeffrey Johnson)