The Langley Full Scale Tunnel (LFST) is located within Building 643 on the East side of Langley Air Force Base (AFB), Hampton, Virginia, adjacent to the NASA Langley Research Center. Langley AFB is a secure installation with controlled access. The LFST is strategically positioned within the mid-Atlantic business and industrial corridor, and is easily accessible by all transportation modes. (See Getting Here for Maps, and more information).
The Wind Tunnel
The tunnel test section is nominally 30-ft. (9.1 m) high, 60-ft. (18.3 m) wide, with a quasi-elliptical cross-section, 56-ft. long. It is a closed-circuit, three-quarter open-jet, double-return, continuous flow design which operates at atmospheric pressure. The airflow from the dual fans mounted within the collector cone is split right and left into two equal streams, each doubling back between the test section and the building walls to the entrance cone, reuniting prior to the contraction section upstream of the test section. The contraction section and collector cones are constructed of 2 inch wood planking, attached to a steel frame and covered on the inside with galvanized sheet metal.
Contraction Section - The contraction is 75-ft. in length and in this distance the cross section changes from a rectangle of 72-ft. by 110-ft. to a 30-ft. by 60-ft. quasi-elliptical section. The area reduction in the contraction is very slightly below 5:1. The shape of the section was chosen to give a constant acceleration to the air stream and to retain a 9-ft. length of nozzle for directing the flow.
Test Section - The plenum chamber, which surrounds the working section of the jet, is 80-ft. long, 122-ft. wide and 72 ft. high. Its size and the open-jet design make the tunnel ideal for low-speed testing of large, high drag and/or high blockage test articles.
Two 20-ft. by 40-ft. doors in the walls of the return passage are located on the west side of the test chamber to provide access. A 15,000 pound overhead crane is available for lifting automobiles, aircraft or other models into the test section. Personnel access to the test section is by stairs on the west side, or by an elevator located on the east side. The top and both sides of the jet are open while the bottom has a groundboard that extends 2-feet 5-inches above the lower lip of the nozzle. Observation of tests is normally via remotely controlled video cameras. High intensity lights can be used for photography, filming or video needs. Direct observation can be done from Room 300 which is elevated on the east side of the test section. Exhaust fans are located in the ceiling for expulsion of exhaust gases. Air-exchange doors are also located in the north end of the circuit for rapid purging of the circuit.
Fan and Drive Motors - The tunnel is powered by two-4,000-hp wound-rotor, slip-ring induction electric motors, each driving a four-blade 35.5-ft (10.6 m) laminated wood propeller. The motors are mounted with rotor shafts centered within the exit cone passages. Rotational speed is varied by a solid state control system. The motors and supporting structure are enclosed in fairings to minimize resistance to air flow. Motors are normally started at approximately 80-RPM and can be adjusted in increments of 1, 10, or 100, to a current maximum 210-RPM. The control panel for monitoring RPM is located in the control room, and includes a trim control to synchronize the two motors. For specialized purposes, the motor winding configuration can switched to a "low speed" range, permitting steady RPMs from around 20 to above 100. The resulting test section speed range is approximately 5 mph to 80 mph.
Collector Section - Forward of the fans and located on the center line of the tunnel is a smooth fairing which transforms the quasi-elliptic section of the single passage into two circular passages at the fans. From the fans aft, the exit cone is divided into two passages and each transforms from a 35-foot 6 1/2-inch circular section to a 46-foot square in 132-feet. The included angle between the sides of each passage is approximately 6 degrees.
Guide Vanes - The air is turned at the four corners of each passage by guide vanes. These vanes are of the curved-airfoil type formed by two intersecting arcs with a rounded nose. The arcs were carefully chosen to give a practically constant area through the vanes.
Full Scale Model Support/Balance/Scale House - The full scale model support, balance, and scale house are located directly below the groundboard. It contains the six component balance from which the readings are fed into the control room. The scales are capable of handling loads up to 20,000-lbs.
Data system - Multiple PC-based data systems have been developed using LabView software. The primary system acquires data from the trapeze automotive balance, internal strain gage balances, or full-scale balance, with reduced data accessible in real-time via a Local Area Network (LAN). Secondary systems are employed for acquisition of pressure and vane anemometer data.
Pressure Measurements - The LFST is equipped with a PSI-8400 electronically scanned pressure transducer (ESP) system. The ESP system consists of a data acquisition and calibration unit, a pressure control unit, and remote pressure-measuring modules. Currently, one 48-port module is available. By adding modules, simultaneous measurements of up to several hundred pressures are possible. The ESP modules are normally mounted in the test vehicle for best results.
Computational Fluid Dynamics Facilities
The Department of Aerospace Engineering offers computational calculation of whole body aerodynamics as well as partial geometries and parametric designs. Fluid flow and heat transfer computations are mainly conducted on a 64-CPU Sun HPC 10000 Sunfire Supercomputer. ODU Aerospace Engineering Website
Ground Vehicle Simulations - Surface pressure and velocity flowfield and force data components (drag, lift and side force) are calculated. Wake flow analysis, computational visualization and component based drag and lift analysis are also conducted.
The Building
The overall size of this facility is enormous, with the building itself being 434-feet long, 222-feet wide, and reaching a maximum height of 97-feet. It covers approximately 2 1/2-acres and encloses approximately 8,000,000-cubic feet. Within this cavernous structure are located the wind tunnel, hangar, office space, and machine shop.
Control Room - Located on the north wall of the test section, the control room contains the controls for the drive motors, survey carriage, data systems, compressed air, and full scale model support. Multiple video feeds allow the viewing of the groundboard, test vehicle and fans.
The Groundboard and Turntable - The 1/4 inch smooth steel groundboard is 42-feet 6-inches in width, 52-feet 9- inches in length and is elevated 21 feet 4 inches above the ground. Ample space is available under the groundboard for running power cables and air supply lines. Four 120V receptacles are located on each side of the ground plane. A hydraulically driven turntable, 28.5 feet in diameter, can be rotated 360 degrees to create sideslip on the test article.
Automotive Test Capability
A full-scale automotive force balance, known locally as a "trapeze" balance, became operational early in 1998. The trapeze balance provides accurate measurements of total vehicle drag, plus downforce at each wheel. The vehicle is supported on four small tire contact plates, separated from the surrounding non-metric groundboard. The groundboard configuration provides a fresh boundary layer roughly 15 feet ahead of the vehicle. An active secondary boundary layer control system is also available when required, installed just ahead of the test vehicle. For larger vehicles, the tire contact plates are connected to the external 6-component balance, as described more fully below. By this means, vehicles up to 20,000 pound deadweight can be tested, such as Class-8 tractors.
Struts can be extended 14-feet above the groundboard to either hold a full size general aviation aircraft, or a sting and internal balance on a T-bar for smaller test articles. A hydraulic ram makes it possible to achieve an angle of attack range from approximately “10 to 70 degrees with the T-bar. The struts can also have aerodynamic fairings installed to nearly eliminate tare-drag loads when using the external balance for measurements. A wide variety of test articles can be accommodated with this balance system.
Survey Carriage - Attached to the test section roof trusses is a 55-foot steel structural bridge and car which can be rolled across the full width, length and depth of the test chamber. Suspended below the car is a retractable survey boom, which can carry a variety of survey probes, rakes and even aircraft models.
Angle-of-Attack Measurements - Model angle-of-attack is measured using Lucas Schaevitz sensors within ± 0.05 degrees. In most cases the sensors are mounted inside the test model.
Turbine Anemometers - 6 turbine-type anemometers are available for radiator through-flow measurements.
Hangar - On the south side of the LFST is an adjoining hangar that can be used for the staging and storage of large test models, general aviation aircraft or automobiles. It has a width of 62-feet, length of 75-feet, and offers 30-feet of usable height. A 3-ton overhead crane is available.
Offices - Within the building are 5,000- sq. ft. dedicated to office space and a conference room which are located under the return passages on the south end of the tunnel. "Secret rooms" are available for proprietary projects.
Machine Shop - Also housed within the building is a 7,000-sq. ft. sheet metal and machine shop that is equipped with lathes, mills, drill presses, band saws, metal forming equipment, grinders/sanders and other related equipment. Wood working tools include a tablesaw, bandsaw, drill press, router and handsaws as well as a state of the art Shopbot CNC controlled router. The router may be used for rapid prototyping models from foam or wood.
Other Supporting Capabilities
Also available to support testing are compressed air and DC power sources, as well as a smoke generator for flow visualization.
