NASA Web Site! Wind Tunnel Enterprise

National Transonic Facility

NASA Langley Research Center
Since 1982, The Langley National Transonic Facility (NTF) has provided the highest quality flight Reynolds
number aeronautical data to the research, industry, and DoD communities.
Test Section and Performance
 National Transonic Facility Characteristics
The Langley National Transonic Facility (NTF) is a high pressure, cryogenic, closed circuit wind tunnel. The test section has 12 slots and 14 reentry flaps in the ceiling and floor to prevent the near-sonic flow "choking" effect. To ensure minimal energy consumption, the interior of the pressure shell is thermally insulated. The drive system consists of a fan with variable inlet guide vanes for responsive Mach number control. The fan is powered by a 100-MW motor.

The tunnel has two modes of cooling. In the variable temperature cryogenic mode, nitrogen is the test gas. Liquid nitrogen is sprayed into the circuit. The heat of vaporization and latent heat cools the tunnel structure while removing the fan heat. In this mode, the NTF tunnel provides full-scale flight Reynolds numbers without an increase in model size.

In the ambient temperature air mode, air is the test gas. Water flows through the cooling coil to remove fan heat.
Mach number 0.1 to 1.2
Reynolds number, per foot 4x106 to 145x106
Pressure, psia 15 to 130
Temperature, degrees F -250 to 150
Test gases Nitrogen, Air
Test section size, feet 8.2 x 8.2
Length, feet 25
Area, square feet 66.8
Contraction area ratio 14.95:1
Circuit length, feet 497
Drive power, horsepower 135,000



circuit arrangement
NTF tunnel circuit arrangement. Dimensions in feet.
Pathfinder II model
Pathfinder II model. 		Model Observation
The NTF video measurements system consists of electronic imaging cameras, processors, and display hardware used for model flow visualization; boundary layer transition detection; and wing deformation and optical angle-of-attack measurements.
Instrumentation
The NTF can accommodate various types of internal 6-component strain gage balances. Typical corrections to the balance are interactions, temperature effects, attitude tares, axes orientation, and pressure and momentum (flow) tares.

Onboard angle-of-attack (AOA) accelerometers are available that include thermal conditioning systems for cryogenic operation.

The electronically scanned pressure (ESP) system provides high accuracy measurement of model and facility pressures at rates up to 500 samples per sec. The modules are available in differential pressures of 2.5, 5, 15, 3O, and 45 psi. 		Data Acquisition and Processing
The NTF data acquisition system accepts analog, digital, and frequency (pulse-train) inputs and is controlled by a UNIX computer. The capacity of the system is 256 channels of analog data, 32 channels of digital data, and 1 frequency channel. A 14-track FM tape recorder for dynamic data acquisition is also available. Final data are reduced on a separate UNIX workstation. For data analysis, the NTF provides UNIX and Macintosh computers. Customer supplied computers can be networked to the data reduction system if desired. Secure data links are available for classified projects. 		Facilities Available to Users
Three model buildup bays are provided at the facility for buildup of models. A calibration area provides the instrumentation systems for further calibrations that may be required to quantify deflection constants and weight tares.

Safety and Design Criteria
Langley?s LHB 1710.15 Wind Tunnel Model System Criteria is the guideline for model design and fabrication. Model installation and any exceptions to this document must have the approval of the NTF Safety Head on a case-by-case basis to assure personnel and tunnel hardware are not exposed to risk.
Model Supports
 Test Techniques
The model support system is a circular arc sector that provides an angle-of-attack range of -11.5? to 19.0? at a rate of up to 4? per sec. The strut incorporates a roll drive with a range of -90? to 180? which, in conjunction with the pitch of the strut, is able to provide pitch and yaw data. The normal force load capacity of the strut is 27,000 lbs. Several sting and strut combinations are available for testing of aerodynamic models. Several flow visualization techniques are available to investigate transition or separation locations on the model. Ultraviolet (UV) lighting is also available for fluorescent minitufts. A video model deformation system is available to optically ascertain deflection and rotation values of model components. Temperature sensitive paint (TSP) and pressure sensitive paint (PSP) techniques are currently being developed to acquire boundary layer transition and global surface pressure measurements.
767
Boeing 767 model in tunnel.
 Pathfinder II Model
Pathfinder II model in tunnel.
Type of Testing
 Test Request Procedures

Alpha Jet model.		 The NTF provides testing in support of stability and control, cruise performance, stall buffet onset, and configuration aerodynamics validation for both full-span and half-span models. The NTF staff can model the customer?s test objectives and test priorities utilizing a computerized test process simulator to design the most efficient test plan strategy with respect to cost, duration, and consumables. The first step of the test process is to submit a test request form. The form can be filled out electronically or printed for mailing at the NASA Langley aero Compass website. A posttest questionnaire is also available at this site. Our customers are encouraged to provide feedback to the facility for our continuous improvement process.
Document Version 1.0
Trademark Disclaimer:
The use of trademarks or names of manufacturers in this report is for accurate reporting and does not constitute an official endorsement, either expressed or implied, of such products or manufacturers by the National Aeronautics and Space Administration.
For more information contact:
The National Transonic Facility Manager -- NASA Langley Research Center -- Hampton, Virginia 23681-2199
phone: 757 ° 864 ° 5033 | fax: 757 ° 864 ° 7892 | e-mail: wte+fm_ntf@larc.nasa.gov
NASA Official Responsible For Content:
Pete Jacobs		 Page Curator: CONITS Development Team Date Last Updated:11/17/2005