View source for Unitary Plan Wind Tunnel (Mountain View, California)

{{for|NASA's Unitary Plan Wind Tunnel in Langley|Langley Research Center}}
{{more citations needed|date=April 2020}}
{{Infobox NRHP
| name                 = Unitary Plan Wind Tunnel
| nrhp_type            = nhl
| image                = Unitary Plan Wind Tunnel aerial.jpeg
| caption              = Aerial view of the Unitary Plan Wind Tunnel complex, 1974
| location             = [[Mountain View, California]]
| coordinates          = {{coord|37|25|0.9|N|122|3|37.71|W|display=inline,title}}
| locmapin             = United States San Jose#California#USA
| area                 =
| built                = 1955
| designated_nrhp_type = October 3, 1985<ref name="nhlsum">{{cite web|url=http://tps.cr.nps.gov/nhl/detail.cfm?ResourceId=1917&ResourceType=Structure|title=Unitary Plan Wind Tunnel|access-date=2008-04-12|work=National Historic Landmark summary listing|publisher=National Park Service|archive-date=2008-05-04|archive-url=https://web.archive.org/web/20080504003103/http://tps.cr.nps.gov/nhl/detail.cfm?ResourceId=1917&ResourceType=Structure|url-status=dead}}</ref>
| added                = October 3, 1985<ref name="nris">{{NRISref|2006a}}</ref>
| refnum               = 85002799
}}
The '''Unitary Plan Wind Tunnel''', located at the [[NASA Ames Research Center]] in [[Moffett Federal Airfield]], [[Mountain View, California]], United States, is a research facility used extensively to design and test new generations of [[aircraft]], both [[airliner|commercial]] and [[military aircraft|military]], as well as [[National Aeronautics and Space Administration|NASA]] space vehicles, including the [[Space Shuttle]]. The facility was completed in 1955 and is one of five facilities created after the 1949 [[Unitary Plan Act]] supporting aeronautics research.
==Background==
After the construction of the [[Variable Density Tunnel]] at [[Langley, Virginia|Langley]] in 1921,<ref name="unitary">{{cite web | url=http://www.cr.nps.gov/nr/travel/santaclara/uni.htm | title=Unitary Plan Wind Tunnel | work=California's Historic Silicon Valley | publisher=[[National Park Service]] | access-date=2007-03-12 | archive-date=2007-02-06 | archive-url=https://web.archive.org/web/20070206181558/http://www.cr.nps.gov/nr/travel/santaclara/uni.htm | url-status=dead }}</ref> the [[National Advisory Committee for Aeronautics]] built a variety of technical research facilities upon which the American aircraft industry was based. These facilities enabled the American aircraft industry to dominate the skies in both commercial and military aviation. By 1945, America's lead in the field of aviation seemed to be evaporating. The technological achievements of the German [[missile]]s and [[jet aircraft]] indicated a lag in American aeronautical research.
In 1949, [[United States Congress|Congress]] passed the [[Unitary Plan Act]], under which the [[Federal Government of the United States|Federal government]] coordinated a national plan of facility construction encompassing NACA, as well as the [[United States Air Force|Air Force]], private industry, and universities. The Unitary Plan resulted in the construction of a new series of wind tunnel complexes to support the American aircraft industry, including the Ames Unitary Plan Wind Tunnel Complex.
==Construction==
[[File:Unitary Plan Wind Tunnel.JPG|thumb|Portion of the Unitary Plan Wind Tunnel in 2014]]
Construction of this facility began in 1950-1951 and continued until 1955. Because no one wind tunnel could meet all the demands for additional research facilities simulating the entire range of aircraft and missile flight, NACA chose to build the Ames tunnel with three separate test sections drawing power from a common centralized power plant. The [[Subsonic and transonic wind tunnel|transonic]] test section spanned 11 by 11 feet (3.3 x 3.3 m), while the two [[supersonic wind tunnel|supersonic]] sections were smaller: nine by seven feet (2.7 x 2.1 m) and eight by seven feet (2.4 x 2.1 m). Giant valves 20 feet (6 m) in diameter supplied air from one supersonic leg to another.
The Unitary Plan Wind Tunnel has three closed-loop wind tunnels, each with its own model test section, but all sharing the same drive motors. The drive motors power compressors to propel the air within the wind tunnel circuit. Because of this shared layout, only one UPWT test section can be used at a time. The three wind tunnels that are part of this system are:
* 11-by 11-foot Transonic Test Section.  A closed-return, variable-density tunnel with a fixed-geometry, ventilated test section with a flexible wall nozzle with a [[Mach number|Mach]] range of 0.20 to 1.45.<ref>{{cite web| url=https://www.loc.gov/rr/frd/pdf-files/Western_Hemisphere_Wind_Tunnels.pdf | title=Wind tunnels of the Western Hemisphere | archive-url=https://web.archive.org/web/20091206161057/https://www.loc.gov/rr/frd/pdf-files/Western_Hemisphere_Wind_Tunnels.pdf | archive-date=2009-12-06}}</ref>
* 9-by 7-foot Supersonic Test Section.  A closed circuit, single return, variable density, continuous flow wind tunnel with a Mach range of 1.55 to 2.55.
* 8-by 7-foot Supersonic Test Section. A closed circuit, single return, variable density, continuous flow wind tunnel with a Mach range of 2.55 to 3.5. (The 8x7 was decommissioned in the early 90's and is considered "mothballed").
The Unitary Plan Wind Tunnel was declared a [[National Historic Landmark]] in 1985.<ref name="nhlsum"/><ref name="nrhpinv2">{{Cite web|title=National Register of Historic Places Inventory-Nomination: Unitary Plan Wind Tunnel / Unitary Plan Facility|url={{NHLS url|id=85002799}} |date=May 15, 1984 |author=Harry A. Butowsky |publisher=National Park Service}} and {{NHLS url|id=85002799|title=''Accompanying photo, aerial, from 1984''|photos=y}}&nbsp;{{small|(32&nbsp;KB)}}</ref>
==History==
[[Image:Unitary Plan Wind Tunnel Modification Project 1996.jpeg|thumb|Crew working on the diffuser and contraction vanes, 1996]]
[[Image:Ames Wind Tunnel NAN8-55.jpg|thumb|Aerial view of the Wind Tunnel with construction going on in the mid-1950s]]
The American West Coast aircraft industry quickly capitalized on the Ames Unitary Plan Wind Tunnel Complex. The famed [[Boeing]] fleet of commercial transports and the [[Douglas DC-8]], [[McDonnell Douglas DC-9|DC-9]], and [[McDonnell Douglas DC-10|DC-10]] were all tested here; as well as military aircraft such as the [[General Dynamics F-111|F-111]] fighter, the [[C-5A Galaxy]] transport and the [[B-1 Lancer]] bomber. In addition to aircraft, in the 1960s and 1970s all NASA crewed space vehicles including the Space Shuttle and SLS have been tested in the Ames Unitary Plan Wind tunnel complex.
==Drive system==
The major element of the tunnel complex is its main drive system. The main drive consists of four wound-rotor-type induction electric motors connected in tandem.
Each motor is rated to produce up to 65,000 [[Horsepower]] and 7200 [[volts]]. Combined, the main drive system can produce up to 260,000 horsepower. Drive speed is currently controlled by a [[liquid rheostat]] system.
==11ft transonic wind tunnel==
The Transonic wind tunnel is a closed-return, variable density tunnel with a fixed test section geometry. The 11-ft is capable of speeds from Mach 0.25 to Mach 1.4. Airflow is produced by a three-stage, axial-flow compressor. [[Supersonic]] conditions are achieved by moving a symmetric flexible wall in a [[De Laval nozzle|nozzle]] configuration.
Typical models in the 11-ft are either a full span (sting mounted), or half span (floor mounted) configuration.
A sting-mounted model support is capable of moving the test article to various [[Angle of attack|AOA]] and [[Angle of sideslip|AOS]] setpoints within at 15 degree cone.
Typical model measurements acquired may include: Forces and Moments, Steady-State Pressures, Temperatures.
Multiple optical test techniques are offered which include: [[Shadowgraph]] (which is closely related to [[Schlieren Photography|Schlieren]]), [[Infrared Thermography]], Model Deformation and [[Pressure-sensitive paint]].
[[File:NASA Ames SUGAR wind tunnel tests-front.jpg|thumb|SUGAR/ TBW Full-Span Model in the UPWT 11-ft Test Section]]
[[File:Unitary Plan Wind Tunnel (9413320773).jpg|thumb|Half Span model of Boeing 777 in the 11-ft Test Section]]
==9x7ft supersonic wind tunnel==
[[File:Escape System in Wind Tunnel GPN-2000-001573.jpg|thumb|Apollo Launch Escape Tower Test in the 9x7ft Supersonic Wind Tunnel]]
The 9x7ft Supersonic Wind tunnel is capable of speeds from Mach 1.55 to Mach 2.5. Mach number is set by moving an asymmetric, sliding nozzle block. Airflow is produced by an 11-stage, axial-flow compressor that weighs over 450 tons.
==See also==
* [[Wind tunnel]]
* [[List of wind tunnels]]
==References==
{{Reflist}}
==External links==
{{commons category|Unitary Plan Wind Tunnel}}
*[https://web.archive.org/web/19981212034119/http://www.windtunnels.arc.nasa.gov/ NASA Ames Research Center Wind Tunnels web site]
*[http://www.nps.gov/history/nr/travel/aviation/ Aviation: From Sand Dunes to Sonic Booms, a National Park Service ''Discover Our Shared Heritage'' Travel Itinerary]
{{Spaceflight landmarks}}
[[Category:Infrastructure completed in 1955]]
[[Category:Ames Research Center]]
[[Category:National Historic Landmarks in the San Francisco Bay Area]]
[[Category:Wind tunnels]]
[[Category:Buildings and structures in Mountain View, California]]
[[Category:Government buildings on the National Register of Historic Places in California]]
[[Category:National Register of Historic Places in Santa Clara County, California]]
[[Category:Air transportation buildings and structures on the National Register of Historic Places]]
[[Category:1955 establishments in California]]