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The Aerodynamic Wind Tunnel 4T, situated in the Propulsion Wind Tunnel Facility, is a versatile mid-size test unit which has a 4-ft by 4-ft by 12.5-ft long test section. The "T for transonic" designation indicates its primary utility for testing at near-sonic airspeeds. However, its Mach number capability extends from less than 0.2 to 2.0, which is roughly equivalent to an airspeed range from 160 to 1,600 miles per hour. 

Tunnel 4T is a continuous-flow wind tunnel that can simulate altitudes from sea level to 98,000 feet.  In addition, it can provide Reynolds numbers up to 7.1 million per foot.  

Although Tunnel 4T is primarily used to conduct small-scale aerodynamic and store separation testing, a variety of test types -- many of which can be applied simultaneously during a single test entry -- are available.  Specialized testing, such as material testing, has occurred in Tunnel 4T.  However, Arnold Engineering Development Center engineers can develop specialized test techniques to meet the unique test needs of customers. 

Supporting systems include modern, state-of-the-art, steady-state, and high-speed data acquisition systems with automated test process controls for high test productivity similar to Propulsion Wind Tunnel 16T.  Other test types include:

 -- Stability and Control  -- Captive Loads
 -- Acoustics  -- Static and Dynamic Pressures
 -- Pressure-Sensitive Paint  -- Oil Flow
 -- Freestream  -- Aerodynamic Grid
 -- Flow-Field Probe  -- Captive Trajectory
 -- Flow Visualization
       - Shadowgraph
       - Laser Vapor Sheet
       - Doppler Global Velocimetry
       - Particle Image Velocimetry

Tunnel 4T has supported almost every major national flight vehicle development program.  Recently, 4T was used for weapons integration testing on several fighters such as multi-service F-35 Lightning II, F-22A Raptor, F/A-18C Hornet, F-14 Tomcat, F-15 Eagle, and F-16 Fighting Falcon.  The tunnel has also been used to test large vehicles such as the B-1 Lancer and has provided Space Shuttle material testing.  Customers include Department of Defense organizations, NASA, domestic and foreign private industry, and academia.