12-Foot Low Speed Tunnel

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Facility 644
Building 644

Center: Langley Research Center
Location: Hampton, Virginia
Year Built: 1939
Historic Eligibility: National Register Eligible
Important Tests: Free Flight Testing, Static Testing, Dynamic Testing

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Virtual Tour of Facility

[top] History

In the late 1930s after successfully advocating for, designing, and initiating operations of the 15-foot vertical spin tunnel, Charles H. Zimmerman conceived and successfully developed another unique wind-tunnel apparatus to study the dynamic stability and control characteristics of an aircraft model in a free-flying condition. A 5-foot-diameter “proof-of-concept” wind tunnel was constructed and suspended from a yoke that permitted it to be rotated about a horizontal axis and tilted from the horizontal position to a nose-down orientation up to angle of 25º. A tunnel operator stood at the side of the test section and controlled the tilt angle of the tunnel as well as the airspeed produced by a fan located at the right rear of the test section. His main function was to adjust the airspeed and tunnel angles so that the model remained stationary in the center of the tunnel during a test. The evaluation pilot was positioned at the rear of the tunnel where he could easily see the lateral motions of the model and provide inputs to the model’s controls via fine wires that were kept slack during the flight.

In a typical free-flight test, the model was placed at the center of a takeoff platform and the elevator or model pitch control was manually adjusted to a desired setting. The tunnel angle was adjusted to the expected glide path of the unpowered model and the airspeed was slowly increased until the model rose from the platform and assumed a flying attitude. The tunnel operator and evaluation pilot coordinated their tasks to permit an assessment of the relative stability and responses of the model to control inputs.

Initial testing in the 5-Foot Free-Flight Tunnel started in 1937 with very encouraging results, including the development of an automatic light-beam-control device to reduce crashes during the learning process. Zimmerman’s team quickly designed and developed a larger free-flight capability for a 12-foot tunnel with an octagonal test section in 1939. Housed in a sphere near the current spin tunnel, the Langley 12-Foot Free-Flight Tunnel (now known as the Langley 12-Foot Low-Speed Tunnel) provides all-weather test capability adjacent to an office building staffed by researchers and support crews. The closed-circuit free-flight tunnel initially operated with a tiltable (hydraulically-driven) test section in a two-operator mode similar to the earlier tunnel. For about 20 years, highly successful studies of radical aircraft configurations were conducted, during which advancements in internal strain-gauge technology permitted not only free-flight evaluations but also measurements of the aerodynamic characteristics of free-flight models during conventional wind-tunnel tests.

In 1958, a slack in the post-war operational schedule of the Langley Full Scale Tunnel permitted exploratory free-flight tests to be conducted in its gigantic 30 by 60 foot test section, providing much more freedom and less risk during flight tests. In addition, the models could be much larger and sophisticated than the simple balsa models used in the free-light tunnel. For these reasons, the free-flight, technique was transferred to the larger wind tunnel. When the technique was transferred, the free-flight tunnel was converted for conventional force-test studies of aerodynamics and its test section was fixed in a horizontal attitude. The tunnel has been used as an exploratory low-cost test facility for over 50 years, and is in continuous use by NASA Langley today for static and dynamic force tests.

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[top] Construction

1938-02-04NACA 14847.1.jpg1938-02-181938-02-251938-03-041938-03-111938-03-181938-03-251938-04-011938-04-161938-04-29NACA 15242.2.jpg1938-05-071938-05-2019381938-06-231938-07-261938-08-051938-08-261938-09-021938-09-091938-11-051938-12-101939-01-06

[top] General Exterior and Interior

Cutaway of 12-Ft Low Speed TunnelDescription and Photos644PhotoCard.jpgFront view1978 Free Spinning Tunnel, 12-Ft Low Speed Tunnel, and 20-Ft Spin Tunnel19841994 Close up viewBuilding 6441939 5-ft Free Flight Tunnel1939 Models for Spin and Free Flight12-Ft Free Flight Tunnel1944-08-03 Propeller in Main TunnelLMAL 39078.jpg1944-08-05 New Propeller Fan1944-08-10 Tunnel Fan17626.jpg

[top] Group Photos and Social Events

1946 Jimmie DoolittleLMAL 49265.jpgsee more on Doolittle's Raid1974

[top] Models

1943 Bell XP-631947-05-13 Composite of Model 66-91947-05-21 16th Gen L InspectionLMAL 53088.jpgLMAL 53089.jpg1954-12-09 Model Test Set-UpLAL 87374.jpg1955-01-29 Tunnel Testing EquipmentLAL 88052.jpgLAL 88053.jpg1984 Advanced Canard in 12 Foot Tunnel1989 Wind Tunnel Testing in the 12 Foot Tunnel19891989 Researcher with Model1998 Hyper-Agility Model1999 Turbulence Spheres1999 Turbulence Spheres.jpg2000 BWB-450 Model19421943-05-06 Model in Test Section1943-07-13 Model in Tunnel (Publicity)LMAL 33718.jpgLMAL 33719.jpgLMAL 33720.jpgLMAL 33721.jpgLMAL 33722.jpgLMAL 33723.jpgLMAL 33724.jpg1943-09-27 Two Models in FlightLMAL 34603.jpgLMAL 34604.jpgLMAL 34605.jpgLMAL 34606.jpgLMAL 34608.jpg1944-09-04 Model in FlightLMAL 39501.jpgLMAL 39502.jpgLMAL 39503.jpgLMAL 39504.jpgLMAL 39505.jpgLMAL 39506.jpg1945-01-30 Model in FlightLMAL 42262.jpg1959-06-22 Aviation Week Photo Early X-151965 Testing Tenth Scale Model of F-111A of Variable Sweep Wings1973-03-29 Model in 12' TunnelL-73-1968.jpgL-73-1969.jpg1973-07-09 Variable Sweep Supersonic1973-09-04 AESO Commands USBL-73-5673.jpgL-73-5674.jpgYankee1978-04-141978-05 Scale Powered ModelL-78-3375.jpg

T-34C Radio-Controlled Model undergoing Force Tests


Model Photos A-M

Model Photos N-Z

Test Log Descriptions and Photos

[top] Repairs and Equipment

1939-01-30 Insulation at Ceiling1939-05-09 Air Conditioning EquipmentNACA 17608.jpgNACA 17609.jpg1944-03-18 Motor and BracketLMAL 36911.jpgLMAL 36912.jpgLMAL 36913.jpg1944-04-04 Propeller DamageLMAL 37122.jpgLMAL 37123.jpgLMAL 37124.jpgLMAL 37125.jpgLMAL 37126.jpg1946-04-23 Insulation FailureLMAL 47798.jpgLMAL 47799.jpg1946-11-22 FFT Swinging GearLMAL 50753.jpgLMAL 50754.jpgLMAL 50755.jpgLMAL 50756.jpgLMAL 50757.jpgLMAL 50758.jpgLMAL 50759.jpgLMAL 50760.jpgLMAL 50761.jpg1948-03-02 Removing PropellerLMAL 55716.jpgLMAL 55717.jpgLMAL 55718.jpg1948-03-11 Monorail InstallationLMAL 55796.jpgLMAL 55797.jpg1948-03-12 Coil InstallationLMAL 57882.jpg1948-03-02 Removing PropellerLMAL 55716.jpgLMAL 55717.jpgLMAL 55718.jpg1948-03-11 Monorail InstallationLMAL 55796.jpgLMAL 55797.jpg1948-03-12 Coil InstallationLMAL 57882.jpg1992-02-09 Control room Before Upgrade92-01074.jpg92-01077.jpg92-01078.jpg92-01079.jpg92-01080.jpg92-01081.jpg17608.jpg17609.jpg

[top] Demolition

2013 Relative location of Smaller Tunnels646first.jpg646second.jpg646third.jpg

[top] Films

NACA-Era: Wright Lecture Film #1
NACA-Era: Tests of Cascade Model in Hovering Flight
NACA-Era: Hovering Flight Tests of a Take-off Model Using Large Flap and Extensible Vanes for Redirecting the Propeller Slip Stream
NACA-Era: Hinged Tip Sequence Tech Film #18
NACA-Era: 1/24-Scale Model and Simulated Action Shots
NACA-Era: Kaiser Hughes Tailless Airplane Tests
NACA-Era: Pitch-up and Directional Divergences as Demonstrated by Free-Flight Model Tests (Catalog #L-85)
NACA-Era: Tests of a 1/10-Scale Model of the Convair F-102A (MX-1554) Airplane
NACA-Era: Stability and Control Tests of a Chance Vought F7U-3 Airplane in Towed Flight
Investigation of Dynamic Stability and Controllability
1940: Tests of Northrop N-1M Tailless Airplane
Final Tests of Northrop N-1M Tailless Airplane
1941: Tests of Northrop XP-56 Tailless Airplane
1944: Consolidated Vultee Tailless Airplane
1944: Consolidated Vultee Tailless Airplane - Part 3
1945: Tow Tests of the Model XFG-1 Airplane
1946: Tour and Description of Free Flight Tunnel
1947: Stability and Control Tests of XF7U-1
1947: Tests of Consolidated Vultee XB-53 Airplane
1947: Stability and Control Tests of a 1/10 Scale Model of the McDonnell XP-88 Airplane
1947: Stability and Control Tests of a 1/12 Scale Model of an XP-92 Mock-up Airplane
1947: Tests of a 1/10 Scale Model of the Douglas XS-3 Airplane
1950s: Tow Test for F84E Airplane (Catalog #L-1)
1948: Investigations of Pilot Escape by Nose Jettisoning
1950 Nose Jettison Tests of 1/50-Scale Models of Douglas D-558 and D-588-2 Airplanes. See also Toward Mach 2: The Douglas D-558 Program. J. D. Hunley, editor. 1999. NASA SP-4222.
1954: Flight Tests of a 0.4 Scale Stand-On Type Vertically Rising Aircraft
Hovering Flight Tests of a Model of a Vertical Take-Off Airplane
1956: Film of Tunnel Radio Control Activities
1960: Departmental Talk by D.E. Hewes
Dynamic Stability Characteristics of Models of Some Aircraft-towed Mine Sweeping Devices
Free-Spinning Tunnel Work
Dynamic Model Test Techniques for Stall/Spin Studies
High Alpha Flight Dynamics on the X-29
HL-10 Model Landing Tests
Exdrone Testing at Plum Tree Insland

[top] Documents

1939: Floorplan Drawing, 1970 Revision

1941: Preliminary Stability and Control Tests in Free-Flight Tunnel

1942: Tunnel Costs and Details

1948 floorplan

1991 Structural Integrity of Wind Tunnel Wooden Fan Blades

1965 Real Property Record

Test Log Tests 1-41

2013 Historic American Building Survey

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