Wright Brothers Wind Tunnel

For more than 80 years, MIT’s Wright Brothers Wind Tunnel has been a powerful testing tool for aviation and space flight innovation, advancing research for industry leaders as well as MIT. Its high wind capabilities have been used to assess the aerodynamics properties of everything from motorcycles, aircraft, and drones to Olympic ski gear, space suits, and potential building structures. In 2017, the MIT Department of Aeronautics and Astronautics (AeroAstro) announced it would replace the tunnel with a brand-new facility thanks to a lead funding commitment from Boeing with Mark Drela, the Terry J. Kohler Professor and director of the Wright Brothers Wind Tunnel, at the helm.

Today, MIT is home to the most advanced academic wind tunnel in the country, capable of reaching wind speeds up to 230 miles per hour (mph), with the largest test section in U.S. academia. The Wright Brothers Wind Tunnel expects to reach full operational capacity by midsummer of 2022. At that time, the Wright Brothers Wind Tunnel will be open to the outside world for industry testing, scheduled tours, and more. For more information, email aa-wbwt-contact@mit.edu.

Specifications

Characteristics
Airspeed range15 mph – 230 mph
Dynamic pressure range0.5 psf – 135 psf
Flow conditioning8:1 contraction ratio

4 anti-turbulence screens

Honeycomb + screen in fourth-corner vanes

Flow-circuit heat exchanger
Drive2500 hp motor, VFD control to 600 rpm max

16 ft diameter fan, 17 blades, BLI design

Leaned + swept stator, 7 cambered vanes
Test sectionDimensions: 12 x 7.75 x 18 ft

Corner fillets, tapering 14…10 in

At nearly ambient pressure

All-glass side walls, 5 windows in ceiling
Model mounting (on external balance)Metric post and pitch pushrod inside non-metric aero fairing, allowing +/- 30 deg pitch and +/-30 deg yaw

OR

Metric flange just under floor, allowing +/- 30 deg yaw
Model mounting (on floor turntable)Non-metric floor turntable, allowing +/- 45 deg yaw
EquipmentBuilt-in y, z traverse, reaching entire test section

Portable 2-axis traverse, 3 x 4 ft reach

Pitot-static probes

3-hole and 5-hole probes

Pitot rakes

Electronic pressure scanning sensors, up to 1 psid

1-axis and 2-axis inclinometers
MATLAB-based test control softwareCan control and drive nearly all tunnel functions via GUI  and/or custom high-level MATLAB scripts

Can interrogate tunnel airflow instruments, main balance, and any custom user instrument output

Automates wind-off tares

Allows real-time data viewing

Logs all data with time stamps

Allows data export in a wide variety of formats
External Balance Load Limits (Moment reference point is at center of test section)
Lift+1500 lb / -500 lb
Drag+/- 225 lb
Sideforce+/- 750 lb
Pitching moment+/-500 ft-lb
Yawing moment+/-500 ft-lb
Rolling moment (strut mount)+/-500 ft-lb
Rolling moment (flange mount)+/- 1500 ft-lb
This diagram shows the key components of the Wright Brothers Wind Tunnel from a top-down view. When the tunnel is activated, air circulates counterclockwise around the closed circuit. The unique shape of the fan blades was explicitly designed to work with the boundary layer (noted in blue), a natural phenomenon that occurs whenever air interacts with an object’s surface.
Image: Mark Drela

Eight things to know about the newly-upgraded Wright Brothers Wind Tunnel

Read on MIT Spectrum

A History of MIT Wind Tunnels

The Wright Brothers Wind Tunnel was dedicated on September 12, 1938, at the 5th International Congress of Applied Mechanics. It was named after Orville and Wilbur Wright to commemorate and perpetuate the methods of research and controlled experimentation used in the development of the first successful airplane. Initially, the tunnel was used for aerodynamic research on scale models of aircraft and their components, but later research was conducted on scale models of architectural structures as well. MIT built the Wright Brothers Wind Tunnel to replace the existing 4-foot, 5-foot, and 7.5-foot diameter wind tunnels which had become virtually obsolete due to advances in the speed and size of aircraft. The Wright Brothers Wind Tunnel was utilized primarily by the aircraft manufacturing industry, which until the post-World War II period possessed few adequate wind tunnel facilities.

When the Wright Brothers Wind Tunnel was built in 1938-1939 it was the state of the art in wind tunnel design and construction. It was a closed-return, variable-density wind tunnel equipped with a 7.5-foot by 10-foot diameter elliptical test section. During the next 15 years, similar wind tunnels were built in the U.S., and aircraft design methods were developed which eliminated much of the need for wind tunnel testing. Simultaneously, with the advent of jet propulsion, there developed a need to test for the aerodynamic characteristics of jet aircraft as they approached, and then surpassed, the speed of sound. To fill this void the Wright Brothers Wind Tunnel staff designed the Blowdown Wind Tunnel, which was in use from 1952 to 1959. Using interchangeable test sections, and the Wright Brothers Wind Tunnel as a pressure reservoir, the Blowdown Wind Tunnel was capable of being run as either a transonic or supersonic wind tunnel. The aircraft industry and government agencies began to request testing time in the new facilities. Among those who made use of MIT’s “new” wind tunnel facility was the Office of Air Research, United States Air Force, which contracted for an investigation of aerodynamics, aeroelastic and stability problems in the transonic speed range.

Although used primarily for aerodynamic tests of aircraft, the Wright Brothers Wind Tunnel was used for other purposes as well. Beginning in the late 1950’s, numerous studies of the effects of winds on architectural structures and their environment were conducted in the tunnel. Among the structures tested were the Associated Universities, Inc.’s proposed radio telescope (1957), the Millstone Hill parabolic scanner (1957), the Green Building in MIT’s Eastman Court (1965), MIT’s Center for Advanced Engineering Studies (1966), and the Northeast Radio Observatory Corporation’s proposed radome (1966).

In the early 1960’s, as U.S. government agencies and the aircraft manufacturing industry developed their own wind tunnel facilities, use of the Wright Brothers Wind Tunnel for aerodynamic research declined. Since then, it has been used primarily for studies of architectural structures and MIT Department of Aeronautics and Astronautics student research projects.

In 1896, as part of his Mechanical Engineering thesis, Albert J. Wells built the first wind tunnel at MIT, a 3-foot diameter square wind tunnel. Eighteen years later, in 1914, Jerome C. Hunsaker of MIT’s Department of Naval Architecture and Marine Engineering built a 4-foot diameter square wind tunnel. The wind tunnel was located on Vassar Street in Cambridge. As the main MIT campus did not move to Cambridge from Boston until 1916, the wind tunnel preceded the “new MIT” by two years. The wind tunnel and wind tunnel tests formed the basis for a graduate course in aeronautical engineering in the Department of Naval Architecture and Marine Engineering until 1920.

In 1917, following the entrance of the United States into World War I, the U.S. War Department, Air Service, Engineering Division, McCook Field, Dayton, Ohio, leased the wind tunnel. Among the engineers assigned to the wind tunnel at various times during the lease period were Edward P. Warner, Shatswell Ober, and John R. Markham. Ober and Markham remained involved with MIT’s wind tunnels, in one capacity or another, until 1960. In 1921 the lease agreement was terminated though the Air Service continued to support wind tunnel testing at MIT until 1926 with annual grants.

The increase in size and speed of airplanes during the 1920’s and 1930’s required the building of a larger, more effective wind tunnel. By the fall of 1933 several tunnels were available for instruction and development testing. Hunsaker was named to head the Department of Mechanical Engineering and placed in charge of its “course” in aeronautical engineering. A major step towards a new and substantial tunnel was made in 1935 upon crystallization of a design. The new tunnel would be a closed single return circuit with a closed elliptical operating test section seven and one-half by ten feet, enclosed within an outer steel shell that would allow pressurized tunnel operations and thus achieve a variable Reynolds number capability. The driver was a 2,000 horsepower, pole changing induction motor and controllable pitch thirteen foot diameter fan. Measurements of forces and moments over adjustable pitch and yaw ranges were to be made with a rigid pyramidal support balance with remotely indicating, self-balancing, mechanical beams.

A proposal for the construction of the Wright Brothers Wind Tunnel was received by the MIT Corporation in 1936, and approved the following year. Funds, totaling approximately $230,000, were obtained from the MIT Corporation, airplane manufacturers, friends of Wilbur Wright, and other groups of interested individuals. During the early years of its operation the Wright Brothers Wind Tunnel was used extensively by the aircraft manufacturing industry to test scale models of their latest aircraft. In 1940, with the addition of equipment donated by the Curtiss-Wright and United Aircraft Corporations, it became possible to test for the aerodynamic characteristics of powered models, an important advance that produced more accurate test results. During World War II the tunnel was in use 24 hours a day testing military airplanes designed by commercial manufacturers for the allied war effort. To meet the needs of continuous operation, a formal Wright Brothers Wind Tunnel staff, consisting of project engineers and shift leaders, was organized under the supervision of Shatswell Ober, Joseph Bicknell, and John R. Markham.

The 7.5-foot wind tunnel, made obsolete by the Wright Brothers Wind Tunnel, was dismantled in 1941 and the 4-foot wind tunnel was used sparingly. In l948 the 5-foot wind tunnel, which used too much power and took up too much space, was closed. Simultaneously, students in course 16.62 (Aerodynamic Laboratory) were required to perform one laboratory exercise using the Wright Brothers Wind Tunnel. To free the tunnel for commercial research a new student wind tunnel was designed and built by the Wright Brothers Wind Tunnel staff. The new student wind tunnel had a 4.5-foot by 6-foot diameter test section, a six-component aerodynamic balance, and special equipment for testing powered models. The wind tunnel was located at the site of the old student wind tunnel in the Daniel Guggenheim Aeronautical Laboratory. It was constructed in 1948 and used until 1961.

In the late 1960s it was decided to broaden the match of the tunnel’s capabilities to the needs of the civil engineering and architectural communities. Beginning in 1972 the facility took on the major undertaking of both wind tunnel simulations and onsite measurements to explain the infamous window failures in the then new John Hancock Tower in Boston. A design evaluation assignment was awarded to establish the wind effects on the facade and at ground level for the Sears Tower in Chicago, and this occupied the latter years of the 1970s, along with a number of other ground studies (radome housings, the Battery Park and World Trade Center Towers area at the southern tip of Manhattan, antenna configurations, galloping power transmission lines, and tall structures in Cincinnati, Columbus, Orlando, Toledo and Boston).
 
Special lectures and demonstrations of wind tunnel practice were conducted each semester for the MIT School of Architecture, the presence of graduate Research Assistants from Civil Engineering became a regular feature, and smokestack plume pollution research studies for the Mechanical Engineering Department were conducted. Helicopter rotor studies were conducted, and a unique gust generating system for general wind tunnel applications was devised. A particularly interesting project was a series of tests on acoustical sensing.
 
In 1979, as interest in aeronautics increased, a growth in airplane testing took place alongside the ongoing industrial studies. The Fairchild Republic Company became a major user of the facility and successively developed a number of aircraft including the Saab/Fairchild SF340 twin-engine transport, the USAF T46A Next Generation Trainer, a drone vehicle, a forward swept wing fighter prototype, and several advanced preliminary design configurations. The Digital Equipment Corporation provided a new computation system for automated data acquisition, and with special support grants from Fairchild, the facility acquired a new test control console, a complete reconfiguration of the original balance system allowing installation of modern strain gage sensors for all six components, computation system peripherals, and encouragement to pursue recertification for pressurized operations with either air or a heavy gas. In 1984, during development testing of a joint Boeing/Fairchild model, pressure operations over the range from 0.5 to 1.5 atmospheres were carried out for the first time in three decades to examine Reynolds number effects, and the maximum pressure has since been extended to 2.0 atmospheres.

In more recent years, faculty research interests generated long range studies of unsteady airfoil flow fields, jet engine inlet-vortex behavior, aeroelastic tests of unducted propeller fans, and panel methods for tunnel wall interaction effects. Industrial testing has ranged over auxiliary propulsion burner units, helicopter antenna pods, and in-flight trailing cables, as well as new concepts for roofing attachments, a variety of stationary and vehicle mounted ground antenna configurations, the aeroelastic dynamics of airport control tower configurations for the Federal Aviation Authority, and the less anticipated live tests in Olympic ski gear, astronauts’ space suits for tare evaluations related to underwater simulations of weightless space activity, racing bicycles, subway station entrances, and Olympic rowing shells for oarlock system drag comparisons. In more than a half century of operations, Wright Brothers Wind Tunnel work has been recorded in several hundred theses and more than one thousand technical reports.