8-Foot High Speed Tunnel
|Center:||Langley Research Center|
|Historic Eligibility:||National Historic Landmark|
|Important Tests:||Lockheed P-38 Fighter, A-26B Invader,Development of "area rule"|
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As interest in the field of high-speed aerodynamics increased in the early 1930s, Langley’s existing wind tunnels proved too small and underpowered for effective high-speed aircraft testing. Understanding that a new facility would give U.S. engineers a decided advantage in the aeronautical field, Langley’s director of research George W. Lewis authorized the design and construction of a larger high speed wind tunnel in 1933. Construction of the 8-Foot High Speed Tunnel (HST) was funded by the Public Works Administration (PWA) and completed in 1936 at a cost of $266,000.
Within a short time, the aluminum fan blades suffered from fatigue failure. Retired researcher John Becker remembers that:
About a year later at 3:06 a.m. on October 8, 1937, I was running the tunnel at full power and had just promised the operator at the Hampton generating plant that I would reduce power gradually when, without warning, there was a sickening break in the steady roar of the 550-mph wind. Acrid smoke filled the test chamber as I pushed the red emergency button, no doubt blowing the safety valves in Hampton. On entering the tunnel we found the huge multi-bladed drive fan twisted and broken. The cast aluminum ally blades had failed in fatigue from vibrations induced by their passage through the wakes of the support struts. Operations were suspended until March 1938, and the staff was temporarily dispersed to other sections. (see NASA SP-445).
When Becker was interviewed in 2011, he remembered this accident in detail and added that this was the stimulus to change all wind tunnel propeller blades to wood.
The world’s first large high speed tunnel, the HST proved vital during World War II. Evaluating stability-control problems of the Lockheed P-38 Lightning fighter in the 8-Foot HST, Langley engineers devised the “dive recovery flap,” a wedge-shaped flap on the lower surface of the wings that allowed sufficient lift for a pilot to pull out of steep dives. This ingenious feature subsequently was incorporated in the design of a number of U.S. fighter aircraft, including the YP-38 Lightening, the P-47B Thunderbolt, the A-26B Invader, the P-59 Airacomet (the first U.S. jet aircraft), and the P-80 Shooting Star.
In the postwar years, Langley physicist Ray H. Wright observed that interference from wind tunnel walls could be minimized by placing slots in the test section throat, a concept that came to be known as “slotted throat” or “slotted wall tunnel” design. By the end of 1948, the 8-Foot HST had been retrofitted with the new slotted test section configuration, allowing speeds in excess of Mach 1 (the speed of sound, or approximately 761 mph at sea level). Wright and his team used the tunnel to refine the slotted-throat design, and—after modifications—the facility was re-designated the 8-Foot Transonic Tunnel (TT) in October 1950.
In the mid-1950s, the 8-Foot TT facilitated important research in body/wing design for supersonic aircraft. Langley engineer Richard Whitcomb used the tunnel to develop the revolutionary “area rule” principle that — in practical terms — prompted the use of a compressed, or “wasp-waisted,” fuselage design for supersonic jet fighters, allowing them to break what was popularly known as the “sound barrier.” Subsequent testing of area-rule aircraft designs was conducted in the adjacent tunnel, the 8-Foot Transonic Pressure Tunnel. Whitcomb’s once controversial area rule achieved widespread acclaim in the scientific community and the popular press, and he was awarded the Collier Trophy for the greatest achievement in aviation in 1955.
The TT continued in use until 1961, when it was deactivated by NASA. The facility was kept in operational condition until 1976 when critical parts were sent to Wright-Patterson Air Force Base in Ohio and used in the construction of a new facility. Since then, the 8-Foot TT building has been used as office and storage space. The historical significance of the facility and its many contributions to aerospace technology (first continuous-flow high-speed wind tunnel for large test models and actual plane parts and also the landmark 'slotted-throat' design -see NPS site) were recognized when it was designated a National Historic Landmark in 1985.
The office portion of the structure was remodeled and leased to the Langley Air Force Base in the early 2000s, while the tunnel circuit was left to deteriorate. In 2011, the tunnel circuit was demolished.
1955 Richard Whitcomb with Model
[top] Condition and Demolition (2011)
[top] Technical Reports
High-Speed Wind Tunnel Investigation of the Longitudinal Stability and Control Characteristics of a 1/16-Scale Model of the D-558-2 Research Airplane at High Subsonic Mach Numbers and at a Mach Number of 1.2. 1949.
The High Speed Frontier. John V. Becker. 1980.
From Engineering Science to Big Science. Pamela E. Mack, edit. 1998.