The Unitary Plan Wind Tunnel, located at the

NASA Ames Research Center The Ames Research Center (ARC), also known as NASA Ames, is a major NASA research center at Moffett Federal Airfield in California's Silicon Valley. It was founded in 1939 as the second National Advisory Committee for Aeronautics (NACA) laborat ...

Moffett Federal Airfield Moffett Federal Airfield , also known as Moffett Field, is a joint civil-military airport located in an unincorporated part of Santa Clara County, California, United States, between northern Mountain View and northern Sunnyvale. On November ...

Mountain View, California Mountain View is a city in Santa Clara County, California, United States, part of the San Francisco Bay Area. Named for its views of the Santa Cruz Mountains, the population was 82,376 at the 2020 United States census, 2020 census. Mountain V ...

, United States, is a research facility used extensively to design and test new generations of

aircraft An aircraft ( aircraft) is a vehicle that is able to flight, fly by gaining support from the Atmosphere of Earth, air. It counters the force of gravity by using either Buoyancy, static lift or the Lift (force), dynamic lift of an airfoil, or, i ...

, both

commercial Commercial may refer to: * (adjective for) commerce, a system of voluntary exchange of products and services ** (adjective for) trade, the trading of something of economic value such as goods, services, information or money * a dose of advertising ...

and

military A military, also known collectively as armed forces, is a heavily armed, highly organized force primarily intended for warfare. Militaries are typically authorized and maintained by a sovereign state, with their members identifiable by a d ...

, as well as

NASA The National Aeronautics and Space Administration (NASA ) is an independent agencies of the United States government, independent agency of the federal government of the United States, US federal government responsible for the United States ...

space vehicles, including the

Space Shuttle The Space Shuttle is a retired, partially reusable launch system, reusable low Earth orbital spacecraft system operated from 1981 to 2011 by the U.S. National Aeronautics and Space Administration (NASA) as part of the Space Shuttle program. ...

. 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 The Variable Density Tunnel (VDT) was the second wind tunnel at the National Advisory Committee for Aeronautics (NACA) Langley Research Center. Proposed by German aerospace engineer, Max Munk, student of Ludwig Prandtl, it was the world's first v ...

at Langley in 1921, the

National Advisory Committee for Aeronautics The National Advisory Committee for Aeronautics (NACA) was a United States federal agency that was founded on March 3, 1915, to undertake, promote, and institutionalize aeronautical research. On October 1, 1958, the agency was dissolved and its ...

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 A missile is an airborne ranged weapon capable of self-propelled flight aided usually by a propellant, jet engine or rocket motor. Historically, 'missile' referred to any projectile that is thrown, shot or propelled towards a target; this ...

s and

jet aircraft A jet aircraft (or simply jet) is an aircraft (nearly always a fixed-wing aircraft) propelled by one or more jet engines. Whereas the engines in Propeller (aircraft), propeller-powered aircraft generally achieve their maximum efficiency at much ...

indicated a lag in American aeronautical research. In 1949,

Congress A congress is a formal meeting of the representatives of different countries, constituent states, organizations, trade unions, political parties, or other groups. The term originated in Late Middle English to denote an encounter (meeting of ...

passed the Unitary Plan Act, under which the

Federal government A federation (also called a federal state) is an entity characterized by a political union, union of partially federated state, self-governing provinces, states, or other regions under a #Federal governments, federal government (federalism) ...

coordinated a national plan of facility construction encompassing NACA, as well as the

Air Force An air force in the broadest sense is the national military branch that primarily conducts aerial warfare. More specifically, it is the branch of a nation's armed services that is responsible for aerial warfare as distinct from an army aviati ...

, 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

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

transonic Transonic (or transsonic) flow is air flowing around an object at a speed that generates regions of both subsonic and Supersonic speed, supersonic airflow around that object. The exact range of speeds depends on the object's critical Mach numb ...

test section spanned 11 by 11 feet (3.3 x 3.3 m), while the two

supersonic Supersonic speed is the speed of an object that exceeds the speed of sound (Mach 1). For objects traveling in dry air of a temperature of 20 °C (68 °F) at sea level, this speed is approximately . Speeds greater than five times ...

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 The Mach number (M or Ma), often only Mach, (; ) is a dimensionless quantity in fluid dynamics representing the ratio of flow velocity past a Boundary (thermodynamic), boundary to the local speed of sound. It is named after the Austrian physi ...

range of 0.20 to 1.45. * 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 A National Historic Landmark (NHL) is a National Register of Historic Places property types, building, district, object, site, or structure that is officially recognized by the Federal government of the United States, United States government f ...

in 1985. and

History

The American West Coast aircraft industry quickly capitalized on the Ames Unitary Plan Wind Tunnel Complex. The famed

Boeing The Boeing Company, or simply Boeing (), is an American multinational corporation that designs, manufactures, and sells airplanes, rotorcraft, rockets, satellites, and missiles worldwide. The company also provides leasing and product support s ...

fleet of commercial transports and the

Douglas DC-8 The Douglas DC-8 (sometimes McDonnell Douglas DC-8) is an early long-range Narrow-body aircraft, narrow-body jetliner designed and produced by the American Douglas Aircraft Company. Work began in 1952 towards the United States Air Force's (USA ...

DC-9 The McDonnell Douglas DC-9 is an American five-abreast, single-aisle aircraft designed by the Douglas Aircraft Company. It was initially produced as the Douglas DC-9 prior to August 1967, after which point the company had merged with McDonnell A ...

, and

DC-10 The McDonnell Douglas DC-10 is an American trijet wide-body aircraft manufactured by McDonnell Douglas. The DC-10 was intended to succeed the DC-8 for long-range flights. It first flew on August 29, 1970; it was introduced on August 5, 1971 ...

were all tested here; as well as military aircraft such as the

F-111 The General Dynamics F-111 Aardvark is a retired supersonic, medium-range, multirole combat aircraft. Production models of the F-111 had roles that included attack (e.g. interdiction), strategic bombing (including nuclear weapons capabilit ...

fighter, the C-5A Galaxy transport and the

B-1 Lancer The Rockwell B-1 Lancer is a supersonic variable-sweep wing, heavy bomber used by the United States Air Force. It has been nicknamed the "Bone" (from "B-One"). , it is one of the United States Air Force's three strategic bombers, along with th ...

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 Horsepower (hp) is a unit of measurement of power, or the rate at which work is done, usually in reference to the output of engines or motors. There are many different standards and types of horsepower. Two common definitions used today are t ...

and 7200

volts The volt (symbol: V) is the unit of electric potential, electric potential difference (voltage), and electromotive force in the International System of Units (SI). Definition One volt is defined as the electric potential between two point ...

. Combined, the main drive system can produce up to 260,000 horsepower. Drive speed is currently controlled by a

liquid rheostat A liquid rheostat or water rheostat or salt water rheostat is a type of variable resistor. This may be used as a dummy load or as a starting resistor for large slip ring motors. In the simplest form it consists of a tank containing brine or ...

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 Supersonic speed is the speed of an object that exceeds the speed of sound (Mach 1). For objects traveling in dry air of a temperature of 20 °C (68 °F) at sea level, this speed is approximately . Speeds greater than five times ...

conditions are achieved by moving a symmetric flexible wall in a

nozzle A nozzle is a device designed to control the direction or characteristics of a fluid flow (specially to increase velocity) as it exits (or enters) an enclosed chamber or pipe (material), pipe. A nozzle is often a pipe or tube of varying cross ...

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

AOA Aoa, AOA, or AoA may refer to: Government * Agreement on Agriculture, a World Trade Organization treaty * Administration on Aging, a health agency of the United States * Angolan kwanza, the currency of Angola * Auxiliary Organizations Associatio ...

and 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 Shadowgraph is an optical method that reveals non-uniformities in transparent media like air, water, or glass. It is related to, but simpler than, the schlieren and schlieren photography methods that perform a similar function. Shadowgraph is a ...

(which is closely related to

Schlieren Schlieren ( ; , ) are optical inhomogeneities in transparent media that are not necessarily visible to the human eye. Schlieren physics developed out of the need to produce high-quality lenses devoid of such inhomogeneities. These inhomogeneit ...

Infrared Thermography Infrared thermography (IRT), thermal video or thermal imaging, is a process where a thermal camera captures and creates an image of an object by using infrared radiation emitted from the object in a process, which are examples of infrared im ...

, Model Deformation and

Pressure-sensitive paint Pressure-sensitive paint (PSP) is a method for measuring air pressure or local oxygen concentration, usually in aerodynamic settings. PSP is paint-like coating which fluoresces under a specific illumination wavelength in differing intensities depen ...

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.

References

External links

NASA Ames Research Center Wind Tunnels web siteAviation: From Sand Dunes to Sonic Booms, a National Park Service ''Discover Our Shared Heritage'' Travel Itinerary
{{Spaceflight landmarks Infrastructure completed in 1955 Ames Research Center National Historic Landmarks in the San Francisco Bay Area Wind tunnels Buildings and structures in Mountain View, California Government buildings on the National Register of Historic Places in California National Register of Historic Places in Santa Clara County, California Air transportation buildings and structures on the National Register of Historic Places 1955 establishments in California