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            using lower power levels can also be uriven from standard   alistic data with the models out of the wind tunnel wall
            110 and 440 v systems in the facility, d-c motors can be   boundary layer, a special ground board.is employed. This
            powered from variable power supply equipment adjustable   simulated ground plane shields all of the model supports
            from 0-30 v. A full scale vehicle, for instance, could have   which are level pads coincident with the ground plane. This
            its fan driven and also its wheels rotated, if desired, with   shielding prevents impingement of the mainstream on the
            the available electrical power equipment.           model supports, and thus eliminates large tare loads. To
              SUPPORT EQUIPMENT - In addition to the normal sup­  reduce the boundary layer at the model to a minimum, there
            port equipment used at the wind tunnel for testing aircraft   is suction just aft of the ground plane lip so that only a small
            models, there is also equipment designed to support testing   boundary thickness exists at the model. A moving belt ground
            of automobiles. Automotive support is permitted using ad­  plane is planned for this facility. When that capability ex­
            justable pads which can be varied in wheelbase from 75-   ists, an automobile must be supported by a string attached
            154 in., with a tread variation from 45-68 in. This full   to a balance within the model. This type of support system
            scale system can be installed in either of the two test sec­  will create an additional correction for base pressure effects.
            tions. There is also a support system designed to a 3/8 scale   ENVIRONMENTAL CONDITIONS - Environmental condi­
            of the above tread and wheelbase variations.        tions existing in the test section would not affect hard sur­
              Full scale vehicles, assuming a frontal area of 25 sq ft,   face models, but there may be some damage to modeling
            can be tested very satisfactorily in the forward (large) test   clay or soft models. The humidity is essentially that of the
            section, but in the rear (smaller) section the data may be   ambient air, and the temperatures range from below freez­
            questionable. In this case the blockage is about 6.5% of   ing early on winter mornings to about 120 F maximum in
            the test section area, and anything over 5% could create   the summertime with tunnel shell cooling. This, however,
            a deleterious pressure loss. Yaw runs to moderate angles   is not unique in an aerodynamic low speed tunnel, where
            could be conducted in the large section.            design inputs do not include close control or environmental
              For the purpose of obtaining interference effects, anothei   conditions.
           vehicle can be located near the test vehicle in any direc­
                                                                CONCLUSION
            tion with the reduced scale models and at any practical
           displacement. Test data could be measured and recorded   Since the wind tunnel is designed for aerodynamic testing
           on the one vehicle attached to the balance. Full scale dual   it has a good cross sectional velocity distribution with low
           vehicle testing can be accomplished on in line close prox­  turbulence flow, and accurate steady state data can be ob­
            imity tests. This type of testing could help considerably   tained. Because of the overall size and speed capability and
           in understanding the interference phenomena of passing ve­  also because of the dual test sections, considerable data
           hicles particularly between cars and trucks.         can be obtained in the area of scaling effects. In this area,
              All of the automotive support systems are attached to   this facility can provide an opportunity not available to
           the balance and are near the tunnel floor. To obtain re­  the automotive industry in any other wind tunnel.






























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