NASA - National Aeronautics and Space Administration

Specifications

> Capability
> Operating Characteristics
> Test Section Dimensions
> Model Installation Diagram
> Forces and Moments
> Turntable Model Support
> Semispan Testing
> Installation and Personnel Access
> Flow Visualization
> High Pressure Air The 11-by 11-foot Transonic Wind Tunnel (11-foot TWT) Facility is part of the Unitary Plan Wind Tunnel (UPWT) complex at NASA's Ames Research Center at Moffett Field, California, where generations of commercial and military aircraft and NASA space vehicles, including the space shuttle, have been designed and tested.

The 11-foot TWT is a closed-return, variable-density tunnel with a fixed-geometry, ventilated test section with a flexible wall nozzle. It is one of three separate test sections powered by a common drive system. A three-stage, axial-flow compressor powered by four wound-rotor, variable-speed induction motors, produces airflow. Interchangeability of models among the UPWT test sections allows testing across a wide range of conditions.

The 11-foot TWT has been instrumental in the development of virtually every domestically produced commercial transport and military fixed-wing airframe since the 1960s. The facility is used extensively for airframe testing and aerodynamic studies and has played a vital role in every manned space flight program.


A model of f-18 is tested in the NASA Ames 11-by 11-foot transonic wind tunnel. Image credit: NASA Ames Research Center

	ATP 11-by 11-ft Brochure.pdf

Capability

Mach range = 0.20 to 1.45

Rn = 0.30 to 9.6 million per foot

Stagnation pressure = 3.0 to 32.0 psia

Maximum stagnation temperature = 150°F. Typical temperature variation over the course of a test = 20°F

Closed circuit, single return, variable density, continuous flow wind tunnel

Interchangeability of models between Unitary Plan Wind Tunnel (UPWT) test sections allows testing across a wide range of conditions

Internal strain-gage sting mount, model component and floor balances are used for measuring forces and moments. NASA Ames and NASA Langley inventories typically available

Full support of DTC psi module capability

Support strut has simultaneously variable pitch and yaw capability (± 15°)

Two controllable 3000 psi auxiliary air systems capable of flow rates up to 40 lb/sec each. One line can be controlled up to 80°F and the other up to 400°F

User interaction will be X-terminal based

Full internal and external network capability. PCs and Macs available to customers as needed

Typical two weeks of model build up and instrument preparation included in the facility occupancy charge

Click image to enlarge

Operating Characteristics

Mach number (continuously variable)	0.30 to 1.50
Stagnation pressure	3.0 to 32.0 psia
Reynolds number	0.3 x 106 to 9.6 x 106 /ft
Maximum stagnation temperature	600°R
Strut angle of attack	range nominally ± 15°

Test Section Dimensions

Height	11.0 ft
Width	11.0 ft
Length	22.0 ft
Access hatch, top:	7.0 x 22.0 ft
Side doors:	3.0 x 4.9 ft

Click image to enlarge

Test Section Dimensions Plan View AutoCAD Files:

	Version 2000i AutoCAD file (.dwg)

Translation files:

	Version 2000 Drawing Exchange file (.dxf)
	Initial Graphics Exchange Specification file(.igs)

*Note: Right click (PC) / control click (Mac) and "Save As..." to download files. To open, use "Import" function in drawing program.

Free Drawing Viewer from AutoDesk (a free, downloadable application that lets you view and print basic design drawing formats; Windows OS only)

Free Drawing Viewer from eDrawings (a free, downloadable application that lets you view and print basic design drawing formats; Windows and Mac)

Test Section Dimensions Elevation View AutoCAD Files:

Click image to enlarge

	Version 2000i AutoCAD file (.dwg)

Translation files:

	Version 2000 Drawing Exchange file (.dxf)
	Initial Graphics Exchange Specification file (.igs)

*Note: Right click (PC) / control click (Mac) and "Save As..." to download files. To open, use "Import" function in drawing program.

Free Drawing Viewer from AutoDesk (a free, downloadable application that lets you view and print basic design drawing formats; Windows OS only)

Free Drawing Viewer from eDrawings (a free, downloadable application that lets you view and print basic design drawing formats; Windows and Mac)

Model Installation Diagram

This diagram shows a sting installed with a 40-inch extension presented in the image below.

*Click image to enlarge

Forces and Moments

A traversing strut downstream of the test section can be programmed to translate vertically to maintain a desired point of model-pitch rotation throughout the vertical plane angle-range. The model support center-of-rotation in the horizontal plane is 4.8 inches aft of the strut leading edge. These angles are continuously variable and are determined by the relative positions of a knuckle and sleeve inside the support body.

The model support system can position the model at attitudes circumscribed by a 15-degree half-angle cone. Bent primary adapters of 5, 10, 12.5, and 20 degrees are available to alter the range of model angles. Forces and moments resolved at the model support center of rotation are limited to:

Vertical	± 8,000 lbs
Lateral	± 4,000 lbs
Axial	± 3,000 lbs
Rolling Moment	± 104,000 in-lbs
Combined Vertical and Lateral Bending Moment	± 800,000 in-lbs

Link to NASA Ames Balance Inventory website

Turntable Model Support

A subfloor-mounted turntable model support, used primarily for semispan model testing, is located at tunnel station 106. This support system can be rotated ± 180 degrees and forces and moments are limited to:

Lateral force (at a height of up to 24 inches above the floor:	± 50,000 lbs
Torque (about axis of turntable):	± 500,000 in-lbs

Semispan Testing

Provisions are available for sealing the slots in the test section floor to provide a solid image plane for semispan testing.

NASA Ames SemiSpan Balances and Load Ranges
EZ #	NEMS	INV #	Size/Model	NF lbs	PM in-lbs	AF lbs	YM in-lbs	RM in-lbs
71	1809091		6K, MC-6.0-27.5	6000	3000	1200	6000	30000
69	1809090		15K, MC-150-27.5	15000	10000	3000	15016	75088
70			40K, MC-400-27.5	40000	20000	8000	40000	200000

Semispan model installed in the 11-by 11-foot Transonic Wind Tunnel

Installation and Personnel Access

Models can be installed through a hatch in the top of the test section. Personnel gain access to the test section through doors in the diffuser sidewalls downstream of the model support strut.

11-by 11-foot Transonic Wind Tunnel Hatch Access

Hatch Dimensions: 7.0 x 22.0 ft

*Click image to enlarge

Flow Visualization

Flow visualization techniques are available through multiple, optical-quality windows in the tunnel sidewalls. Optical-quality windows are also available in the test section ceiling and floor.

High-Pressure Air

High-pressure air (3,000 psi) is available at weight flows to 80 pounds per second through dual, independently regulated lines ending within the support strut. A one-megawatt, moveable heater can preheat air from one of these lines. Preheated air at 60 pounds per second is available at the turntable.