7

Summary

OVERALL ASSESSMENT OF VOLUME II OF THE NATIONAL FACILITIES STUDY REPORT

Volume II of the NFS report is the result of an impressive team effort by numerous personnel from government and industry. Although the report appears to be complete within its guidelines, it does not provide a detailed technical evaluation and analysis of the work that supported the aeronautics portion of the NFS. The conclusions and recommendations of the NFS seem to be supported by factual material wherever it was available, although in some cases they are based on the best judgement of the study participants.

The federal agencies involved in the NFS approved the study terms of reference (see Appendix A and Appendix C). Early deliberations by the NFS Task Group on Aeronautical R&D Facilities resulted in a decision to focus on ground test facilities related to aerodynamic and propulsion testing. As a result, the NFS did not investigate specific requirements in areas such as flight testing, computational facilities, vertical flow spin tunnels, facility instrumentation technologies, or structural test facilities. As discussed in Chapter 6, the ASEB recommends augmenting the NFS to develop a more comprehensive view of future requirements for all aeronautical test facilities. In addition, the NFS report mentions very little about military needs for new facilities, although participants in the NFS and a recent survey by the Air Force Materiel Command endorse the ability of the proposed new tunnels to provide value added to the development of future military aircraft (Leaf, 1994).

RECAP OF THE FINDINGS AND RECOMMENDATIONS OF THE NATIONAL AERONAUTICAL TEST FACILITIES STUDY

The decision to build high Reynolds number subsonic and transonic tunnels must balance the need for more-capable facilities with specific performance parameters, the costs of building and operating new facilities, and the economic benefits that are likely to result. Based on the analyses conducted by the NFS; other factors discussed in this report; and the benefits that the United States could derive from the tunnels in terms of balance of trade, employment, and economic activity, the ASEB recommends proceeding with the design and development of new subsonic and transonic facilities while more fully exploring the items recommended herein for further study. Furthermore, the ASEB has determined that the key thrusts of the NFS are justified. These key points are as follows:

  • Significant aerodynamic performance improvements are achievable, and the nation that excels in the development of these improvements has the opportunity to lead in the global market for commercial and military aircraft.

  • New high Reynolds number ground test facilities are needed for development testing in both the low speed and transonic regimes to assure the competitiveness of future commercial and military aircraft produced in the United States.

  • Along with the procurement of new facilities, selected upgrades to existing



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Assessing the National Plan for Aeronautical Ground Test Facilities 7 Summary OVERALL ASSESSMENT OF VOLUME II OF THE NATIONAL FACILITIES STUDY REPORT Volume II of the NFS report is the result of an impressive team effort by numerous personnel from government and industry. Although the report appears to be complete within its guidelines, it does not provide a detailed technical evaluation and analysis of the work that supported the aeronautics portion of the NFS. The conclusions and recommendations of the NFS seem to be supported by factual material wherever it was available, although in some cases they are based on the best judgement of the study participants. The federal agencies involved in the NFS approved the study terms of reference (see Appendix A and Appendix C). Early deliberations by the NFS Task Group on Aeronautical R&D Facilities resulted in a decision to focus on ground test facilities related to aerodynamic and propulsion testing. As a result, the NFS did not investigate specific requirements in areas such as flight testing, computational facilities, vertical flow spin tunnels, facility instrumentation technologies, or structural test facilities. As discussed in Chapter 6, the ASEB recommends augmenting the NFS to develop a more comprehensive view of future requirements for all aeronautical test facilities. In addition, the NFS report mentions very little about military needs for new facilities, although participants in the NFS and a recent survey by the Air Force Materiel Command endorse the ability of the proposed new tunnels to provide value added to the development of future military aircraft (Leaf, 1994). RECAP OF THE FINDINGS AND RECOMMENDATIONS OF THE NATIONAL AERONAUTICAL TEST FACILITIES STUDY The decision to build high Reynolds number subsonic and transonic tunnels must balance the need for more-capable facilities with specific performance parameters, the costs of building and operating new facilities, and the economic benefits that are likely to result. Based on the analyses conducted by the NFS; other factors discussed in this report; and the benefits that the United States could derive from the tunnels in terms of balance of trade, employment, and economic activity, the ASEB recommends proceeding with the design and development of new subsonic and transonic facilities while more fully exploring the items recommended herein for further study. Furthermore, the ASEB has determined that the key thrusts of the NFS are justified. These key points are as follows: Significant aerodynamic performance improvements are achievable, and the nation that excels in the development of these improvements has the opportunity to lead in the global market for commercial and military aircraft. New high Reynolds number ground test facilities are needed for development testing in both the low speed and transonic regimes to assure the competitiveness of future commercial and military aircraft produced in the United States. Along with the procurement of new facilities, selected upgrades to existing

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Assessing the National Plan for Aeronautical Ground Test Facilities facilities are also essential to adequately support future research and development programs. The United States should acquire premier development wind tunnels rather than rely on continued use of European facilities. Additional action is necessary to adequately address future requirements for supersonic, hypersonic, and aeropropulsion test facilities. The ASEB urges taking the additional actions noted below. These actions go beyond the recommendations contained in the NFS report. The Wind Tunnel Program Office should conduct trade studies to evaluate design options associated with the proposed new low speed and transonic wind tunnels (see Recommendation 2-1).26 In addition, the Wind Tunnel Program Office should ensure that the new transonic and low speed facilities will be able to adequately support development of supersonic aircraft such as high speed civil transports by investigating flight characteristics during takeoff, acceleration, transonic flight over land, and landing. NASA and the Department of Defense should continue support for facility research in the subsonic and transonic regimes. NASA and the Department of Defense should expand coordinated efforts that involve aerodynamic test facilities, computational methods, and flight test capabilities. NASA and the Department of Defense should develop a continuing mechanism for long-term planning of aeronautical test and evaluation facilities. A complete listing of the findings and recommendations of the National Aeronautical Test Facilities Study appears below. U.S. Response to Changing Facility Requirements Finding 1-1: The history of aviation offers several lessons learned that are relevant to the current debate on aeronautical ground test facilities. The future of rapidly evolving disciplines and the types of facilities they will require are often uncertain. Advanced aeronautical ground test facilities go hand-in-hand with leadership in aeronautical design and production. Historical precedent exists for special appropriations that provide full government funding of major aeronautical ground test facilities needed by industry to conduct development testing of military and commercial products. Recommendation 1-1: Planning for a new generation of premier aeronautical ground test facilities should consider how the lessons learned from similar past efforts apply to the current situation. Subsonic and Transonic Facilities Finding 2-1. With regard to low speed and transonic facilities, the findings of the Aeronautics and Space Engineering Board are as follows: Significant aerodynamic performance improvements are achievable, and the nation that excels in the development of these improvements has the opportunity to lead in the global market for commercial and military aircraft. New high-Reynolds-number ground test facilities are needed for development testing in both the low speed and transonic regimes to assure the competitiveness of future commercial and military aircraft produced in the United States. These facilities will also contribute to the development testing of supersonic aircraft, such as high speed civil transports, by characterizing flight characteristics during 26   NASA has established a Wind Tunnel Program Office at Lewis Research Center. This office, which reports to the NASA Administrator, is now working with industry to develop an acquisition strategy for building two new low speed and transonic wind tunnels, as recommended by the National Facilities Study.

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Assessing the National Plan for Aeronautical Ground Test Facilities takeoff, acceleration, transonic flight over land, and landing. Facility configuration trade-off studies conducted by the NFS on Reynolds number, productivity, and life cycle cost appear to be sound. Additional configuration studies are needed for both the subsonic and transonic tunnels. Each assessment should take into account the differences in tunnel and model parameters between subsonic and transonic wind tunnel testing. These additional assessments should cover the following topics: using a single tunnel to test both the low speed and transonic speed regimes; making incremental changes to tunnel operating pressures (e.g., from 5 to 5.5 atmospheres) to allow reduction of facility size and cost without sacrificing Reynolds number capability; including within the baseline design the ability to provide future growth in Reynolds number capability through use of higher operating pressures (up to 8 atmospheres), reduced temperatures (down to about -20°F), and/or a heavy test gas (such as SF6); and improving the robustness of the tunnel designs by designing facility components with margin for growth in pressure and operating power to improve component reliability, increase facility lifetime, and facilitate future upgrades. Completion of planned upgrades to existing facilities is an essential complement to the acquisition of new facilities. Facility research on high pressure wind tunnels and other wind tunnel concepts should continue. These efforts should include research related to high pressure wind tunnel models. Scaling methods are essential to current design processes. Even with new facilities, scaling of ground test results will still be necessary to accommodate full-scale simulation of very large or innovative aircraft designs that may be developed in the future. Coordinated efforts to develop improved scaling methods that use wind tunnel testing, computational methods, and flight tests should be expanded. New facilities offer potential benefits to the U.S. economy and the global environment that are large compared with the investments required. Recommendation 2-1. The ASEB recommends the following: NASA's Wind Tunnel Program Office should proceed with the design and development of new subsonic and transonic facilities while conducting the four design trade studies noted in Finding 2-1c during the design phase of the wind tunnel program. 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 jet-engine flows, low speed testing of supersonic aircraft, and testing of military aircraft and systems. NASA should complete planned upgrades to existing facilities as soon as possible. NASA and the Department of Defense should continue facility research on high pressure wind tunnels and other concepts. NASA and the Department of Defense should expand efforts to develop advanced scaling methods that involve wind tunnel testing, computational methods, and flight tests. Supersonic Facilities Finding 3-1: U.S. supersonic wind tunnels adequately satisfy most current and potential test requirements. Shortfalls exist in productivity, reliability, maintainability, and laminar flow test capabilities. Recommendation 3-1: The Aeronautics and Space Engineering Board recommends upgrading the 16S facility at Arnold Engineering Development Center to include continued improvements in the 16S/16T motor drive and compressor systems. Research to define test requirements and develop practical facility concepts for supersonic laminar flow technology should be continued.

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Assessing the National Plan for Aeronautical Ground Test Facilities Propulsion Facilities Finding 4-1: Current propulsion facilities in the United States are world class and adequate to meet current and near-term test requirements. Recommendation 4-1: Communication between the government agencies that operate national aeropropulsion facilities and industry should be continued to assure propulsion facility readiness relative to future requirements. In particular, the ASEB concurs that the study proposed by the NFS should be conducted. Hypersonic Facilities Finding 5-1: The National Facilities Study report is consistent with prior studies of hypersonic test capabilities. Recommendation 5-1: To address the hypersonic ground test deficiencies identified in previous studies, the ASEB endorses the objectives of the two-phase program recommended in the National Facilities Study report. Additional Considerations and Future Directions PRICING POLICY & FACILITY USAGE Finding 6-1: Pricing policy can have a significant impact on user fees. The size of user fees, in turn, is likely to influence user demand, which is an important factor in planning the construction of new facilities. Recommendation 6-1: The government should make pricing policy an integral part of the decision-making process that it uses for major new ground test facilities. The government should carefully consider any subsequent changes in pricing policy to ensure that they do not compromise the economic viability of its facilities. FACILITY MANAGEMENT Finding 6-2: Management structure, including agency sponsorship, can materially impact the ability of large acquisition programs to meet their cost and schedule goals. Management structures that feature oversight or sponsorship by multiple agencies or organizations tend to increase schedule and cost risk, especially for expensive, long-term programs. Recommendation 6-2: The government should select a facility management structure that minimizes cost, schedule, and programmatic risk. ACQUISITION STRATEGY Finding 6-3: Construction of new facilities using an acquisition process unimpaired by the full weight of federal acquisition regulations would reduce cost and schedule requirements. Recommendation 6-3: The proposed low speed and transonic wind tunnels should be acquired using the most efficient combination of federal and commercial acquisition practices. SITE SELECTION Finding 6-4: For facilities such as the proposed low speed and transonic wind tunnels, which will require large technical staffs and huge amounts of energy, selection of a less-than-optimum site has the potential to degrade the efficiency and increase the cost of facility construction and operation, particularly if power availability restricts wind tunnel operating hours. Recommendation 6-4: If a decision is made to build the proposed tunnels, the site selection process should proceed in a timely fashion. In order to optimize the cost-effectiveness of the proposed new wind tunnels, the process should focus on objective criteria—such as those contained in Volume II-A of the NFS final report—that are directly related to the mission of the proposed facilities. OVERALL PRIORITIES Recommendation 6-5: The ASEB recommends acquisition of new transonic and subsonic wind tunnels as the number one priority in the area of development wind tunnels. If both facilities are not acquired in parallel, then the transonic facility should lead the subsonic facility. Research related to subsonic, transonic, supersonic, and hypersonic facilities should be prioritized and executed as coordinated efforts that involve other related research programs conducted by

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Assessing the National Plan for Aeronautical Ground Test Facilities NASA and the Department of Defense. A study of future propulsion facility requirements should be pursued independently of these other activities. SCOPE OF CURRENT STUDIES Finding 6-6: The National Facilities Study and this National Research Council study have not analyzed requirements for many types of important aeronautical test facilities, such as vertical flow spin tunnels, rotorcraft whirl towers, computational facilities, and flight test facilities. Recommendation 6-6: The results of the National Facilities Study and this National Research Council study should not be used to assert that types of facilities that were outside the scope of their deliberations are unimportant to the future of the U.S. aeronautics industry, even though such facilities are not discussed in the resulting reports. The work of the NFS Task Group on Aeronautical R&D Facilities should be augmented to develop a comprehensive view of future requirements for aeronautical ground test facilities. Furthermore, any effort to develop new wind tunnels should be structured to take maximum advantage of the synergy that exists between ongoing advances in the technologies associated with ground, flight, and computational facilities. INTEGRATED TEST AND EVALUATION METHODOLOGIES Finding 6-7: Judicious use of more-effective test and evaluation methodologies can maximize the impact of new and upgraded facilities on the competitiveness of the aeronautics industry. Recommendation 6-7: Facility development efforts should ensure that new and improved physical assets are designed to accommodate foreseeable advances in test methodologies and other disciplines that will affect facility effectiveness. This will require coordinating advances in ground test capabilities with planned improvements in computational and flight test capabilities. NON-TECHNICAL AERONAUTICAL FACILITY ISSUES Finding 6-8: The service life of major new facilities could easily extend to the middle of the next century. Furthermore, the need for long-range planning of facility needs is a recurrent theme in past studies of aeronautical ground test facilities. Assigning the responsibility to study future requirements and conduct long-range planning to a permanently established body would provide greater continuity than the current process of relying on intermittent, ad hoc committees. Delegating this responsibility to an existing body would achieve the desired goal without adding to the number of government advisory panels. Recommendation 6-8: Long-range planning of future requirements for national aeronautical ground test facilities should be carried out on a continuing basis by a permanently established body such as an interagency advisory group or standing committee. The designated body should work with relevant government agencies and industrial groups to resolve policy and procedural issues that diminish the effectiveness of current and future facilities. REFERENCES Leaf, H. 1994 . Future Military Requirements Relative to Aeronautical Test Facilities . Briefing by Lt Gen Howard Leaf, Headquarters, U.S. Air Force Test and Evaluation, presented to the Aeronautics and Space Engineering Board, National Aeronautical Test Facilities Workshop, at the National Research Council, May 17, 1994 .

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