16-Foot Transonic Dynamics Tunnel
|Center:||Langley Research Center|
|Historic Eligibility:||National Register Eligible|
|Important Tests:||A-209, B-32, Boeing C-17, F-8U, Lockheed Electra, F-15, Space Shuttle, HiMAT|
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The 16-Foot Transonic Dynamics Tunnel (TDT) was not always 16-ft. When constructed in 1939, the tunnel was known as the 19-Foot Pressure Tunnel. The tunnel was made form approximately 5,000 tons of steel. An 8,000-horsepower electric motor and a 34.5-ft propeller were installed. These materials allowed the tunnel to be set at 2.5 atmospheres pressure and to create a 300-mph velocity at the test section. The tunnel also had a decompression chamber which made it unique. Operators would have to enter and exit through the chamber like a deep-sea diver does when training.
The purpose behind the 19-ft Pressure Tunnel was to answer questions about scale effects. Researchers were not confident that the conclusions drawn from other tunnel tests were one hundred percent applicable. Some tunnels like the small Variable Density Tunnel fulfilled this need but in order to reach full-scale Reynolds number, a larger high pressure tunnel was needed. The 19-ft Pressure Tunnel became the first attempt to combine large scale with high pressure in one tunnel. The tunnel ran tests for the A-20, the B-32, and the F-8U and other various World War II military aircraft.
Eventually, the technology and construction behind variable density tunnels became more sophisticated. As a result, the 19-ft Pressure Tunnel focused on different tests like aeroelasticity and flutter at high speeds. In 1954, the tunnel underwent major modifications to become the 16-ft TDT and by 1960 the tunnel was ready for its first tests. Some of the modifications included reducing the old circular test section to 16 X 16 feet. Slotted walls were added for transonic capabilities and a 20,000-horsepower electric drive motor was installed. Designers and researchers wanted to get the tunnel to reach Mach 1.2 speeds, but they knew these modifications would not do that. To get the desired speed, they replaced the test medium, air, with freon. Freon worked well as it allowed tunnel to reach the right speeds but it also increased Reynolds number capabilities too.
One of the major models to be tested in the TDT was the Lockheed Electra. In 1959, an Electra disintegrated in the air leaving no survivors. The reason for the crash was unclear as causes like metal fatigue were ruled out. The reason became apparent when another Electra crashed 6 months later. Violent flutter was ripping the wings of the planes. The Electra was hurriedly tested as 130 were still in operation. The research completed in the TDT solved the problem, and all the Electras were repaired. Other flutter tests the TDT performed were for the C-141 military transport, the F-15 fighter, ad the F-16 fighter. The TDT is still in use today and has continued to do tests for the Navy and NASA programs like the Space Shuttle and Highly Maneuverable Aircraft Technology (HiMAT). For more on this, see Researcher News Article.
19-Foot Pressure Tunnel
19-Foot Pressure Tunnel Modification
Test Section in 1946
Computing in 1947 with the Bell Relay Computer Processor Table
Test in the 19-Foot Tunnel
Rotary balance testing of a B-58 model in 1960. See also Project 391: B-58 in building 645.
[top] C-17 Flutter Winglet
C-17 model tested in December 1983 for flutter
[top] Hexagonal Wing Model
[top] 1/9 Scale Model of Prop Fan Test
[top] Other Models
1983-01-26 F-16 Stores Flutter Test
[top] Group Photos and Social Events
East Area Computers in Front of 19-Foot
Below is a partial listing of films from the TDT Film Archives. To see additional films, see the Transonic Dynamics Tunnel playlist on the Cultural Resources Channel of YouTube.
History of the Transonic Dynamics Tunnel. Lecture by Bob Doggett given in 2010.
[top] Wing Configuration and Stall Studies
[top] Other Models
Brief Description of Langley's Transonic Dynamics Tunnel. 1965. TM X-1130.
Subsonic and Transonic Flutter and Flow Investigations of the T-Tail of a Large Multijet Cargo Airplane. Maynard C. Sandford, Charles L. Rublin, and E. Carson Yates, Jr. 1968. TN D-4316.
The Langley Transonic Dynamics Tunnel. 1969. Aeroelasticity Branch Staff. LWP-799.
Wind-Tunnel Study of Deflected-Elevator Flutter Encountered on a T-Tail Airplane. Maynard C. Sandford and Charles L. Rublin. 1969. TN D-5024.
Flutter Studies to Determine Nacelle Aerodynamic Effects of a Fan-Jet Transport Model for Two Mount Systems and Two Wind Tunnels. Moses G. Farmer. 1970. TN D-6003.
Experimental Parametric Studies of Transonic T-Tail Flutter. CharlesL. Rublin and Laynard C. Sandford. 1975. TN D-8066.
Modification to the Langley Research Center Transonic Dynamics Tunnel to Increase Density Capability, Reduce Freon Usage, and Provide Model Deformation Measurement and Flow Visualization Capabilities. 1980 C of F Identity N. 80-4.
Aeroelasticity Matters: Some Reflections on Two Decades of Testing in the NASA Langley Transonic Dynamics Tunnel. Wilmer H. Reed III. Presented at the International Symposium on Aeroelasticity, Nuremberg, Germany. October 1981.
Major Airplane Flutter Investigations in TDT. 1994. Richard Layman.
Contributions of Transonic Dynamics Tunnel Testing to Airplane Flutter Clearance. Jose A. Rivera and James R. Florance. 2000. AIAA 2000-1768.