NASA Aeronautics Research: An Assessment (2008)

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Appendix C Validating the Ranking of the Research and Technology Challenges from the Decadal Survey This appendix investigates whether the selection of the 51 highest-priority research and technology (R&T) challenges in the Decadal Survey of Civil Aeronautics (NRC, 2006) remains valid in light of the National Aeronautics Research and Development Policy (NSTC, 2006) and the National Plan for Aeronautics Research and Development and Related Infrastructure (NSTC, 2007). The Decadal Survey ranks 89 R&T challenges according to their ability to accomplish strategic objectives for U.S. aeronautics research. At the time that study was conducted, the federal government had yet to define what those strategic objectives should be. Therefore, in order to conduct the ranking, the steering committee that oversaw the Decadal Survey identified and defined six strategic objectives that, in its estimation, should motivate and guide the next decade of civil aeronautics research in the United States, pending the release of a national research and development (R&D) plan for aeronautics. After the National Research Council published the Decadal Survey of Civil Aeronautics, the National S ­ cience and Technology Council released the National Aeronautics Research and Development Policy and the more detailed National Plan. As shown in Table C-1, there is excellent correlation between the strategic objectives of the Decadal Survey and the key principles of the National Policy and the National Plan. The only exceptions are “support for the space program” (which appears in the Decadal Survey) and “world-class aeronautics workforce” (which appears in the National Policy and the National Plan, although the National Plan includes no research goals or objectives related to this principle).  To assess how the list of the top 51 R&T challenges might have looked if the National Policy and the National Plan had predated the Decadal Survey of Civil Aeronautics, the committee for the present study considered the following factors: 1. In the process of ranking the R&T challenges, the Decadal Survey of Civil Aeronautics uses dif- ferent weightings for different strategic objectives. A weighting of 5 was given to capacity and to The National Plan for Aeronautics Research and Development and Related Infrastructure notes that “aerospace workforce issues are being explored by the Aerospace Revitalization Task Force led by the Department of Labor pursuant to Public Law 109-420” (NSTC, 2007, p. 2). 101 

102 NASA AERONAUTICS RESEARCH—AN ASSESSMENT TABLE C-1  Comparison of the Strategic Objectives from the Decadal Survey of Civil Aeronautics with the Principles from the National Aeronautics Research and Development Policy and the National Plan for Aeronautics Research and Development and Related Infrastructure Strategic Objectives: Decadal Surveya Principles: National Policyb and National Planc • Increase capacity. • Mobility through the air is vital to economic stability, growth, and security as a nation. • Improve safety and reliability. • Aviation safety is paramount. • Increase efficiency and performance. • Assuring energy availability and efficiency is central to the growth of the aeronautics enterprise. • Reduce energy consumption and • The environment must be protected while sustaining growth in air environmental impact. transportation. • Take advantage of synergies with • Aviation is vital to national security and homeland defense. national and homeland security. • Security of and within the aeronautics enterprise must be maintained. • Support the space program. • The United States should continue to possess, rely on, and develop its world-class aeronautics workforce. aNRC (2006), p. 1. bNSTC (2006), pp. 7-8. cNSTC (2007), pp. 1-2. safety and reliability, 3 was given to efficiency and performance and to energy consumption and environmental impact, and 1 was given to synergies with national and homeland security and to support for the space program. The National Policy and the National Plan, however, treat all the principles as equally important. 2. In the National Plan, the principles concerning (a) energy availability and efficiency and (b) the environment have been combined. 3. Support to the space program is not included as a principle of the National Policy, and the National Plan includes no R&D goals or objectives related to space except with regard to the demonstration of sustained, controlled hypersonic flight in support of national defense and homeland security (including space launch applications). 4. NASA is directed elsewhere in the National Policy to maintain its core competencies, including core competencies “that support NASA’s human and robotic space activities” (NSTC, 2006, p. 9). Accordingly, the committee for this study reranked the R&T challenges of the Decadal Survey by changing the weightings as follows: 1. As a result of factor 1, above, all strategic objectives were assigned the same value (1.0), except that: 2. As a result of factor 2, the strategic objectives corresponding to (1) energy availability and effi- ciency and (2) the environment were combined by giving them combined weighting of 1.0 (i.e., a weighting of 0.5 each), and 

APPENDIX C 103 3. As a result of factors 3 and 4, the strategic objective for support to space was also given a smaller weighting (0.5). Factor 3 implied the value should be smaller than the value assigned to the other strategic objectives, and factor 4 implied the value should be greater than zero. In other words, the priorities of the 89 R&T challenges from the Decadal Survey of Civil Aeronautics were recalculated using the following weightings: Weighting Strategic Objective 1.0 Increase capacity 1.0 Improve safety and reliability 0.5 Increase efficiency and performance 0.5 Reduce energy consumption and environmental impact 1.0 Take advantage of synergies with national and homeland security 0.5 Support the space program Using this different weighting scheme, only four R&T challenges not previously ranked among the top 51 moved into the top 51. Those challenges are as follows: • A12. Accurate predictions of thermal balance and techniques for the reduction of heat transfer to hypersonic vehicles • A14. Efficient control authority of advanced configurations to permit robust operations at hyper- sonic speeds and for access-to-space vehicles • B12. Hypersonic hydrocarbon-fueled scramjet • E12. Autonomous flight monitoring of manned and unmanned aircraft  The committee for this study does not assert that these four R&T challenges should be considered among NASA’s highest-priority challenges, in part because the ranking of challenges by the Decadal Survey was much more than a mathematical exercise. Rather, the committee concludes that this exercise confirms the validity of rankings in the Decadal Survey, because it seems clear that even if the National Policy and the National Plan had been issued prior to the Decadal Survey, the rankings in the Decadal Survey would be essentially the same, with perhaps just a few R&T challenges near the cut-off point changing sides. This study determined how effectively NASA is addressing the four R&T challenges identified above. This information is provided with the caveat that shortcomings in addressing these challenges are not nec- essarily shortcomings in NASA’s aeronautics research program, given that, unlike the challenges discussed in ­Chapter 2, these challenges do not appear among the highest-priority R&T challenges in the Decadal Survey of Civil Aeronautics. The assessment of these four challenges uses the same color-coded grading scheme that is described in detail at the beginning of Chapter 2. Briefly stated, a green grade means that the project will sub- stantively advance the state of the art with no significant shortcomings. A yellow grade means that the This reranking would displace the following R&T challenges out of the top 51: • A7b. Accuracy of wake vortex prediction, and vortex detection and mitigation techniques • A11. Robust and efficient multidisciplinary design tools • B9. High-reliability, high-performance, and high-power-density aircraft electric power systems •  Adaptive ATM techniques to minimize the impact of weather by taking better advantage of improved probabilistic E7. forecasts 

104 NASA AERONAUTICS RESEARCH—AN ASSESSMENT project contains minor shortcomings, which are recoverable within the current overall project concept. A black grade means that the project contains major shortcomings, which would be difficult to recover from within the current overall project concept. White means that the challenge is not relevant. A12  Accurate predictions of thermal balance and techniques for the reduction of heat transfer to hypersonic vehicles SFW SRW Supersonics Hypersonics Airportal Airspace IVHM IIFD IRAC Aging A/C        Y         This R&T challenge has the following milestones: • Improve models for predicting the effects of ablation on heat transfer. • Develop a high-fidelity model for radiating shock layers. • Develop turbulence models validated against experimental data for highly cooled walls. The Aerodynamics, Aerothermodynamics, and Plasmadynamics element of the Hypersonics Project includes tasks for developing high-fidelity thermal radiation models. The same element also includes a small activity on ablation modeling. The Hypersonics Project does not address turbulence modeling for highly cooled walls. A14  Efficient control authority of advanced configurations to permit robust operations at hypersonic speeds and for access-to-space vehicles SFW SRW Supersonics Hypersonics Airportal Airspace IVHM IIFD IRAC Aging A/C        black         This R&T challenge has the following milestones: • Develop techniques to accurately predict flow-control authority in shock-dominated flows and in transitional flows. • Demonstrate novel flow-control techniques applicable to hypersonic vehicles. • Develop novel ground- and flight-test instrumentation techniques for validation of analytical and computational models. The Hypersonics Project includes little substantive work related to the above milestones. Only one task in the Aerodynamics, Aerothermodynamics, and Plasmadynamics element mentions flow-control demonstration—and it is mentioned as just one of several milestones associated with that task. Milestones for each R&T challenge are defined in Appendixes A through E of the Decadal Survey of Civil Aeronautics (NRC, 2006). 

APPENDIX C 105 B12  Hypersonic hydrocarbon-fueled scramjet SFW SRW Supersonics Hypersonics Airportal Airspace IVHM IIFD IRAC Aging A/C       Y         This R&T challenge has the following milestones: • Develop advanced instrumentation capable of measuring time-averaged and time-resolved flow parameters to validate design tools. • Complete unit experiments based on generic inlets, isolators, combustors, and nozzles to provide to provide benchmark data sets for model validation. • Conduct experiments on mode transition for validation of unsteady models. • Assist DoD flight demonstration programs that are currently in progress. The Propulsion and Experimental Capabilities elements of the Hypersonics Project include several tasks devoted to supporting the DoD’s X-51 Program, which is developing and testing hydrocarbon scramjet tech­nology. The Hypersonics Project also includes diagnostics research related to this challenge that is being conducted alongside the X-51 tests. E12  Autonomous flight monitoring of manned and unmanned aircraft SFW SRW Supersonics Hypersonics Airportal Airspace IVHM IIFD IRAC Aging A/C           Y     This R&T challenge has the following milestones: • Produce a detailed set of requirements and design specification for flight monitoring systems deployed on manned and unmanned aircraft. • Demonstrate algorithms and knowledge to enable a flight monitoring system that accurately anticipates, detects, and diagnoses flight plan deviations. • Demonstrate the ability to more accurately project the near-term results of manipulating aircraft controls and inform pilots of likely consequences in terms of aircraft motion, potential collisions, airspace violations, etc. • Design protocols for disseminating information from flight monitoring systems locally and throughout the air transportation system. • Specify corrective actions appropriate for manned and unmanned aircraft in response to unplanned deviations detected by a flight monitoring system. The Integrated Intelligent Flight Deck Project is supporting substantial research related to manned aircraft, but it is not dealing with unmanned aircraft. REFERENCES NRC (National Research Council). 2006. Decadal Survey of Civil Aeronautics: Foundation for the Future. Washington, D.C.: The National Academies Press. Available online at <http://www.nap.edu/catalog.php?record_id=11664>. NSTC (National Science and Technology Council). 2006. National Aeronautics Research and Development Policy. Washington, D.C.: Office of Science and Technology Policy. Available online at <www.ostp.gov/html/NationalAeroR&DPolicy12-19-06.pdf>. NSTC. 2007. National Plan for Aeronautics Research and Development and Related Infrastructure. Washington, D.C.: Office of Science and Technology Policy. Available online at <www.aeronautics.nasa.gov/releases/12_21_07_release.htm>.