Aeronautical Facilities Assessing the National Plan for Aeronautical Ground Test Facilities (1994) / Chapter Skim
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2 Subsonic and Transonic Facilities
2 Subsonic and Transonic Facilities
Pages 13-26
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From page 13... ...
In contrast, European industry has a new government-funded transonic facility coming on-line during 1994 that is expected to significantly outperform any transonic development facilities in the United States in terms of Reynolds number capability. More-capable wind tunnels will facilitate improvements in aircraft performance and i3NASA's National Transonic Facility can test at much higher Reynolds numbers than the new European Transonic Wind Tunnel (ETW)
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From page 14... ...
An analogous situation exists for military aircraft-flight Reynolds numbers for current aircraft are as high as 60 rrullion for the C-S and considerably higher for the B-2. IMPORTANCE OF GROUND BASED FACILITIES Ground test facilities are important, because they allow new aircraft designs to be Tithe NFS initially established a Reynolds number test capability of approximately 30 million as a goal for both the low speed and transonic wind tunnels.
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From page 15... ...
Thus, designers would not be able to use low Reynolds number tests such as these to fully and accurately determine flight performance. Development testing in new wind tunnels with the capability to simulate flight Reynolds numbers would overcome this problem.
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From page 16... ...
Building better ground test facilities is a cost-effective way to avoid problems in the flight testing phase and ensure that new designs will perform as expected. COMPUTATIONAL SIMULATION Computational methods such as computational fluid dynamics are used during the aircraft design process to analyze and predict aerodynamic characteristics in all speed regimes.
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From page 17... ...
Use of higher pressures is likely to be more feasible for subsonic wind tunnels than for transonic 17 wind tunnels because of the differences in full-scale flight dynamic pressure. WIND TUNNELS IN THE DEVELOPMENT PROCESS Wind tunnel data are used to confirm or modify aircraft designs in an iterative manner until flight tests verify performance and handling characteristics.
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From page 18... ...
Continued funding of appropriate research is an essential precursor to the development of future generations of ground test facilities, and it is also likely to directly contribute to future upgrades of existing and planned facilities. INFLUENCE OF FASTER DESIGN/TEST CYCLE When aircraft designers prepare to introduce a new product, they must decide how far to push available technology before selecting the final design.
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From page 19... ...
Other tunnel requirements concerning turbulence, noise, wall boundary interference effects, simulation of jet-engine inlet and exhaust flows, and interactions of engine flows with external aerodynamic flows are acknowledged by the NFS, and the ASEB anticipates that tunnel design solutions win be further refined during the detailed design phase. The design phase also should ensure that features necessary to adequately accommodate development testing of military aircraft, including stores separation testing, are incorporated into the design of the new wind tunnels as appropriate.
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From page 20... ...
These utilization rates, which appear to be reasonable, should be verified as part of the proposed assessment of using a single facility for both subsonic and transonic testing. As previously stated, the ASEB agrees that the proposed Reynolds number capabilities for the low speed and transonic wind tunnels seem appropriate.
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From page 21... ...
One of the FSO's major tasks was to assess the costs, schedule, and technical merit of alternative concepts for new subsonic and transonic wind tunnels under consideration by the NFS. The work of the hyphen the test gas is not air, the test data must be interpreted to account for the impact of differences in the specific heat constant.
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From page 22... ...
ECONOMIC AND ENVIRONMENTAL FACTORS The ASEB agrees with the NFS that development of the proposed high Reynolds number subsonic and transonic wind tunnels can provide economic benefits through: · competitive advantages associated with significant improvements in aircraft maximum lift capability and cruise efficiency, which are sensitive to Reynolds number effects; · reduced aircraft operating cost and structural weight; · higher payload and range; · increased sales of commercial transports and improved market share; and · higher gross domestic product, a more positive trade balance, and increased domestic employment. Table 2-3 illustrates the performance gains that might be obtained by projected improvements in new aircraft (Boeing, 19941.
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From page 23... ...
Finding 2-~. With regard to low speed and transonic facilities, the findings of the Aeronautics and Space Engineering Board are as follows: a.
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From page 24... ...
It should also ensure that the detailed designs of the proposed new wind tunnels will adequately support requirements related" to factors such as noise, turbulence, simulation of jetengine f lows, low speeds testing of supersonic aircraft, and testing of military aircraft and systems.
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From page 25... ...
Briefing by Lt Gen Howard Leaf, 25 Headquarters, U.S. Air Force Test and Evaluation, to the Aeronautics and Space Engineering Board National Aeronautical Test Facilities Workshop, National Research Council, Washington, D.C., May 1~18, 1994.
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