NASA Aeronautics Research: An Assessment (2008)

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4 Bridging the Gaps This chapter identifies key gaps that must be eliminated for NASA’s aeronautics program to meet key goals in terms of the research and technology (R&T) challenges from the Decadal Survey of Civil Aero- nautics (NRC, 2006) as well as internal NASA requirements for aeronautics research and the require- ments that NASA is expected to satisfy in support of aeronautics research by other federal agencies. One of the federal government’s goals for its aeronautics research and development (R&D) is to “cultivate a research and development environment that enables a globally competitive U.S. aeronautics enterprise, and encourages industry investment and academic participation” (NSTC, 2006, p. 4). One of NASA’s objectives is to preserve “the role of the United States as a leader in aeronautical and space science and technology and in the application thereof to the conduct of peaceful activities within and outside the atmosphere,” in part through “research into, and the solution of, problems of flight within and outside the Earth’s atmosphere, the development, construction, testing, and operation for research purposes of aeronautical and space vehicles” (National Aeronautics and Space Act of 1958, Public Law No. 85-568, as amended). Consistent with the above, the Decadal Survey of Civil Aeronautics recom- mends that the federal government take action to ensure U.S. leadership in civil aeronautics. The current approach used by NASA’s Aeronautics Research Mission Directorate (ARMD) for achieving agency goals related to aeronautics is embodied in the following principles (Porter, 2007, p. 9): • We will dedicate ourselves to the mastery and intellectual stewardship of the core competencies of aero- nautics for the nation in all flight regimes. • We will focus our research in areas that are appropriate to NASA’s unique capabilities. • We will directly address the fundamental research needs of the Next Generation Air Transportation System (NGATS/NextGen) in partnership with the member agencies of the Joint Planning and Development Office (JPDO). Next Generation Air Transportation System, formerly known by the abbreviation NGATS, is now more commonly referred to as NextGen. 82 

BRIDGING THE GAPS 83 As noted in the statement of task for this study, NASA uses the term fundamental research to include continued long-term, scientific study in areas such as physics, chemistry, materials, experimental tech- niques, and computational techniques that leads to a furthering of the understanding of the underlying principles that form the foundation of the core aeronautics disciplines, as well as that research that integrates the knowledge gained in these core areas to significantly enhance NASA’s capabilities, tools, and technologies at the disciplinary (e.g., aerodynamics, combustion, trajectory prediction uncertainty) and multidisciplinary (e.g., airframe design, engine design, airspace modeling and simulation) levels. To effectively support U.S. efforts to maintain a position of aeronautics leadership and competitive- ness, NASA research at all levels must be carefully structured in terms of work content, performance expectations, and tech­nology transfer to external and internal users of NASA aeronautics research, which include U.S. industry, the Federal Aviation Administration (FAA), Department of Defense (DoD), academia, and the NASA space program. Foundational research that addresses underlying principles will tend to be earlier in the technology maturity continuum, and it will be more scientific in nature, which makes it more difficult to schedule meaningful milestones and to point this research in a direction that is sure to enhance U.S. competitiveness and meet user needs. On the other hand, more advanced research with a clear path to application will likely have a heightened sense of urgency and purpose. The ideal plan would have a combination of both foundational and applied research in appropriate areas, with management systems appropriate for each. For example, integration of multidisciplinary research related to the health of vehicle systems and vehicles as a whole (see R&T challenge D5) would be more effective if managed through an overarching and formal organizational entity that relies on system engineering disciplines. Maintaining a position of leadership requires staying ahead of the pack, by being the first to bridge each new gap into the future. This is a challenging task; were it not so, others would have overtaken the leader to set a faster pace. The statement of task for this study directs the committee to consider whether there are gaps, and “if gaps are found, what steps should be taken by the federal government to eliminate them.” Looking to the future of NASA’s aeronautics research, the following gaps will require special attention to ensure that the nation’s civil aeronautics research program, executed through NASA, achieves its goals. GAP BETWEEN RESEARCH RESULTS AND APPLICATION The Decadal Survey of Civil Aeronautics evaluates R&T challenges based on their potential to achieve six strategic objectives: • Increase the capacity of the air transportation system. • Improve the safety and reliability of the air transportation system. • Increase the efficiency and performance of aircraft, facilities, and so on to maximize utilization of the air transportation system. • Reduce energy consumption and the negative environmental impact of air transportation. • Take advantage of synergies when specific aeronautical research helps to achieve the first four objectives while also helping to achieve the goals of the DoD and the Department of Homeland Security. • Support the space program. Maintaining core competencies, especially in areas that resonate with NASA’s unique capabilities, is an appropriate part of NASA’s strategy for maintaining a U.S. position of leadership in aeronau- 

84 NASA AERONAUTICS RESEARCH—AN ASSESSMENT tics. However, NASA does not manufacture, own, or operate the aircraft and ground systems that comprise the air transportation system. Thus, for NASA research to provide value to its stakehold- ers and/or achieve the performance-enhancing goals of the Decadal Survey of Civil Aeronautics, its research results must ultimately be transferred to industry, the FAA, and the other organizations that do manufacture, own, and operate key elements of the air transportation system. For example, the projects that are working on R&T challenges related to the air transportation system should articulate, at some level, how research results are tied to capability improvements as well as a transition path that will help guide researchers in planning and conducting research in such a way that it is likely to be of value to external users. Furthermore, projects that are developing modeling and analysis tools should have a plan for validating the tools in particular applications of interest, such as investigating the performance of one or more notional aircraft. Technology transfer issues are especially critical given that NASA’s current approach to aeronautics research will not mature technology as far as in the past, and this will require users, such as the FAA and industry, to adjust their expectations and processes accordingly. NASA’s legislative charter (the National Aeronautics and Space Act of 1958, as amended) establishes “the preservation of the role of the United States as a leader in aeronautical and space science and tech- nology” as one of NASA’s objectives. In addition, the National Aeronautics Research and Development Policy (NSTC, 2006) confirms that “a continued strong U.S. government role in aeronautics R&D is needed to . . . create an environment in which U.S. industry remains innovative and competitive.” As noted above, ARMD has dedicated itself to the mastery and intellectual stewardship of core competen- cies in all flight regimes. Yet this is only a means to an end, and the larger purpose is NASA’s legislative mandate to ensure continued U.S. leadership in aeronautics. NASA’s ability to fulfill this mandate would be jeopardized if NASA were to view itself as the ultimate beneficiary of its own aeronautics research. This outcome will be avoided if NASA’s efforts to maintain core competencies are structured to achieve the larger goals of (1) maintaining U.S. leadership and industrial competitiveness, (2) accomplishing the strategic objectives of the Decadal Survey of Civil Aeronautics, and (3) fulfilling the principles described in the National Aeronautics Research and Development Policy (NSTC, 2006) and the National Plan for Aeronautics Research and Development and Related Infrastructure (NSTC, 2007). This difficult task would be facilitated if the principal investigators (PIs) for NASA’s aeronautics research projects identify and connect with the organizations that will bridge the gap between NASA research results, user needs, and implementation of the larger goals. In addition, for technology intended to enhance the competitive- ness of U.S. industry, U.S. leadership would be enhanced by a technology transfer process that does not necessarily include immediate, public dissemination of results to potential foreign competitors, so that the U.S. industrial base has a head start in absorbing the fruits of this research. This is not necessary for noncompetitive research, such as investigating the impact that aviation plays on the environment, or other research that NASA may conduct as part of international collaborations. In addition, the quality of NASA’s research would be enhanced by technology transfer processes designed to (1) accommodate external peer review as much as possible and (2) avoid locking academia out of the NASA aeronautics program (given academia’s understandable interest in open publication of results by its researchers). A closer connection between NASA aeronautics PIs and some potential users of their research would also facilitate the formation of a coordinated set of research goals and milestones that are timed to anticipate user needs. A closer examination of NASA’s research into airspace issues serves to illustrate this point. The mostly likely path for research by the NGATS Air Traffic Management (ATM)-Airportal and ATM-Airspace Projects to have a real-world impact is by supporting the JPDO’s goals for Next- Gen. Establishing a close link between the plans for these two projects and the needs of the JPDO was complicated by the fact that a NextGen R&D requirements document was not available when NASA’s 

BRIDGING THE GAPS 85 project plans were being prepared. Even so, initial planning of the NGATS ATM-Airportal and ATM- Airspace Projects represented a good-faith effort to meet the expected NextGen requirements in both content and timing. Key officials at the U.S. Air Force, the Defense Advanced Research Projects Agency, and the NASA space program seem well connected with and satisfied that the PIs responsible for research related to their areas of concern are aware of their interests and provide necessary and timely support. In addition, the JPDO provides a multiagency forum for improving connections between researchers and users. Finding. Maintaining technical expertise and core competence in appropriate areas is necessary to maintaining leadership, but it is not sufficient. Close contact with potential users is also necessary, to facilitate research planning and the transfer of research results from NASA to users. Recommendation. The NASA Aeronautics Research Mission Directorate should bridge the gap between research and application—and thereby increase the likelihood that this research will be of value to the intended users—as follows: • Foster closer connections between NASA principal investigators and the potential external and internal users of their research, which include U.S. industry, the Federal Aviation Administration, the Department of Defense, academia, and the NASA space program. • Improve research planning to ensure that the results are likely to be available in time to meet the future needs of the nation. • Consistently articulate during the course of project planning and execution how research results are tied to capability improvements and how results will be transferred to users. • For technology intended to enhance the competitiveness of U.S. industry, establish a more direct link between NASA and U.S. industry to provide for technology transfer in a way that does not necessarily include the immediate, public dissemination of results to potential foreign competitors. As part of the effort to implement this recommendation, NASA should ensure that the NGATS ATM- Airportal and ATM-Airspace Projects meet the R&D needs defined by the NextGen JPDO for NASA. GAP BETWEEN RESEARCH SCOPE AND RESOURCES As noted in Chapter 2, NASA is doing a mixed job in responding to the R&T challenges from the Decadal Survey. The committee found no significant shortcomings in NASA’s efforts to address 4 R&T challenges, and 8 challenges were uniformly evaluated as demonstrating minor shortcomings. For 7 other R&T challenges, NASA is making little or no progress or, even if planned research is successful, it is highly unlikely to make a significant difference in a time frame of interest to users of the research results. For the 32 other R&T challenges, NASA is effectively addressing some areas, but not others, and the overall assessment of these challenges is best described as “mixed.” This is not surprising, given that the Decadal Survey was not chartered to quantify the cost of achieving the highest-priority R&T challenges, individually or as a whole, nor was it tasked with assessing how those costs might compare to NASA’s likely budget for aeronautics research. As a result, NASA simply doesn’t have the resources to address all of the 51 highest-priority R&T challenges simultaneously, and attempting to do so would reduce the effectiveness of NASA’s aeronautics research. Without additional resources, the value added by the NASA aeronautics program would be enhanced by redefining the scope and priorities of the program, 

86 NASA AERONAUTICS RESEARCH—AN ASSESSMENT even if all of the 51 highest-priority R&T challenges from the Decadal Survey of Civil Aeronautics are not addressed simultaneously. Decisions about which research tasks to pursue in the near term should be guided by the ability of proposed research to meet specified metrics, such as those used in the Decadal Survey to identify which challenges were most appropriate for NASA. Those metrics are as follows: • Supporting infrastructure, which refers to whether NASA already possesses the necessary facili- ties, resources, and expertise to conduct proposed research. • Mission alignment, which refers to whether the proposed research falls under NASA’s charter, as defined in the National Aeronautics and Space Act of 1958 (as amended). • Lack of alternative sponsors, which refers to whether other sponsors are able and willing to per- form the necessary research. NASA should not be repeating research that is (or should be) done by industry, other federal agencies, or other organizations. • Appropriate level of risk, which refers to whether the level of risk associated with a research task is appropriate for a NASA research project. For example, NASA should not pursue incremental research that is of such low risk that industry could easily complete the research. Nor should NASA pursue research of great theoretical promise if the scientific and technical hurdles are so high that it has very little chance of success. The NASA aeronautics program includes little in the way of substantial flight tests.  Many research tasks focus on tool development, and not on tool validation and/or the use of validated tools to develop new system concepts. This is, in large part, an unavoidable consequence of trying to address a wide range of R&T challenges with resources that are inadequate to the task. The current approach is very broad, but it is not very deep. In addition, although NASA is conducting valuable aeronautics research, in many cases comparable work and capabilities also exist elsewhere. As a result, too much of NASA’s aeronautics research has limited potential to advance the state of the art far enough and with enough urgency to make a substantial difference in meeting individual R&T challenges or the larger goal of achieving the strategic objectives of the Decadal Survey of Civil Aeronautics. Furthermore, a research strategy that focuses on maintaining core competencies in areas where exper- tise already exists may be a reasonable approach to a tightly constrained fiscal environment. However, this approach could also trap NASA into conducting some research that is obsolete or low-priority simply because the research makes use of current expertise and capabilities. This approach also limits NASA’s ability to take a leading position in new fields where it might be appropriate for the NASA of the future to possess new core competencies and new unique capabilities. For example, unmanned air vehicles (UAVs) are an emerging presence in civil aviation, and NASA should develop new capabilities related to UAV operations, safety, and control in civil airspace (see R&T challenges D10, E2, and E3). Finding. The NASA aeronautics program has the technical ability to address each of the highest-prior- ity R&T challenges from the Decadal Survey of Civil Aeronautics individually (via in-house research and/or partnerships with external research organizations). However, a substantial increase in the ARMD budget would be necessary to address all 51 challenges in a thorough and comprehensive manner. In addition, NASA’s aeronautics research program faces many constraints (in terms of overall budget, the existing set of NASA centers, limitations on the ability to transfer staff positions among centers, and A notable exception concerns work related to R&T challenge A4a, Aerodynamic designs and flow-control schemes to reduce aircraft and rotor noise. NASA is planning to initiate a new phase of the Quiet Technology Demonstrator Program that involved NASA, manufacturers, and airlines in flight testing of advanced noise control techniques for subsonic fixed-wing aircraft. This is an important example of collaboration to facilitate technology transition to in-flight use. 

BRIDGING THE GAPS 87 limitations on the ability to compete with the private sector in terms of financial compensation in some critical fields), and attempting to address too many research objectives will severely limit the ability to advance the state of the art or develop new core competencies and unique capabilities that may be vital to the future of U.S. aeronautics. Recommendation. The NASA Aeronautics Research Mission Directorate should ensure that its research p ­ rogram substantively advances the state of the art and makes a significant difference in a time frame of interest to users of the research results by (1) making a concerted effort to identify the potential users of ongoing research and how that research relates to those needs and (2) prioritizing potential research opportunities according to an accepted set of metrics. In addition, absent a substantial increase in funding and/or a substantial reduction in other constraints that NASA faces in conducting aeronautics research (such as facilities, workforce composition, and federal ­policies), NASA, in consultation with the aeronautics research community and others as appropriate, should redefine the scope and priorities within the aeronautics research program to be consistent with available resources and the priorities identified in (2) above (even if all 51 highest-priority R&T challenges from the Decadal Survey of Civil Aeronautics are not addressed simultaneously). This would improve the value of the research that the aeronautics program is able to perform, and it would make resources available to facilitate the develop- ment of new core competencies and unique capabilities that may be essential to the nation and to the NASA aeronautics program of the future. GAP BETWEEN PROJECT REFERENCE DOCUMENTS AND PROJECT STRUCTURE NASA has developed a reference document for each of its 10 aeronautics research projects. The reference documents are intended to define the rationale, scope, and detailed content of a comprehen- sive research effort to address each project area, but NASA does not consider them to be completed research plans. The reference documents diagram projects in terms of a four-level hierarchy, as follows: Level 1. Foundational physics and modeling. Level 2. Discipline-level capabilities. Level 3. Multidisciplinary capabilities. Level 4. System design. For example, the diagrams for the Subsonic Fixed Wing Project and Supersonics Project appear in Figures 4-1 and 4-2, respectively. Knowledge and capabilities are expected to flow up, from Level 1 to Level 4 (as shown), while requirements and needs are expected to flow down, from Level 4 to Level 1 (not shown). The four-level diagrams and the reference documents as a whole provide a conceptual description of the ­projects, but in some cases they are difficult to correlate to the manner in which the projects are being implemented. In most cases, each project is divided into research task areas, each of which is managed by an associate principal investigator (API). In some cases, there is a good correlation between the project management structure and the project level diagram. For example, the Subsonic Fixed Wing Project has 10 Level 2 areas, and an API has been appointed for each of these areas (except for power, because work in that area has been deferred), as shown in Table 4-1. In many cases, however, it is difficult to map significant areas of research (as indicated by the API areas of responsibility) into the level diagram for the corresponding project. For example, the Superson- ics Project has 7 Level 2 areas and 10 APIs (see Table 4-2). The areas of responsibility for many APIs 

88 NASA AERONAUTICS RESEARCH—AN ASSESSMENT SUBSONICS: FIXED WING Level 4 Validated Physics-based MDAO Tools Integrated with Technology Development Including virtual access to the flight envelope, and virtual expeditions through design space that enable system-level design of a wide class of subsonic fixed wing vehicles Level 3 Propulsion/Power Vehicle Systems Integration & Analysis Airframe Systems Systems for Systems Experimental Validation Level 2 Materials Controls System Analysis, Experimental Power Acoustics Design, & & Structures/ and Capabilities Mechanical Dynamics Aeroelasticity Optimization Components Combustion Aerodynamics Aerothermodynamics Level 1 Fundamental Materials Power Modeling & Control Methods Acoustics Physics Fundamental New Science Simulation and Strategies Experimental Aeroelasticity Approaches Mechanics of Materials Reacting Flow Dynamic and Structures Physics/CFD Modeling & Application & Computational Methods Enhancement of Simulation (Research & Implementing) Current Experimental Mechanical Components Techniques Fluid Dynamics & Heat Transfer (Understanding & Modeling) FIGURE 4-1  Subsonic Fixed Wing Project Level 1 to Level 4 integration diagram (topics shown with black back- ground are currently deferred). Note: MDAO, Multidisciplinary Design, Analysis, and Optimization; CFD, computa- tional fluid dynamics. SOURCE: NASA (2006a). 4-1 TABLE 4-1  Associate Principal Investigator (API) Areas of Responsibility for Level 2 Research Areas for the Subsonic Fixed Wing Project Subsonic Fixed Wing Project: API Areas of Responsibility Level 2 Areas Materials and Structures Materials and Structures/Mechanical Components Combustion Combustion Controls and Dynamics Controls and Dynamics Acoustics Acoustics Aeroelasticity Aeroelasticity Aerodynamics Aerodynamics Aerothermodynamics Aerothermodynamics Systems Analysis, Design, and Optimization System Analysis, Design, and Optimization Experimental Capabilities Experimental Capabilities N/A Power 

BRIDGING THE GAPS 89 SUPERSONICS Level 4 4.01 Multidisciplinary Physics-based Predictive Design, Analysis, & Optimization Capabilities for a Wide Class of Vehicles Operating in the Supersonic Flight Regime, with Quantified Uncertainties and Known Sensitivities Level 3 3.01 Propulsion/Power Systems 3.03 Airframe Systems 3.04 Systems for Experimental Validation Level 2 2.01 2.03 2.05 2.02 2.07 2.09 Propulsion & Power Acoustics Materials & Structures Airframe & Propulsion Aerodynamics Experimental Aerothermodynamics Aero-Propulso-Servo- Capabilities 2.04 Elasticity Sonic Boom Level 1 1.03 Fluid Dynamics/ 1.05 Acoustics 1.01 Materials & 1.07 Unsteady, Flexible 1.10 Actuation/Sensors/ Heat Transfer Physics Structures Modeling Dynamics & Control Electronics 1.04 Reacting Flow Physics 1.06 Computational 1.12 Experimental & Methods & Strategies Measurement Techniques FIGURE 4-2  Supersonics Project Level 1 to Level 4 integration diagram. SOURCE: NASA (2006b). 4-2 TABLE 4-2  Associate Principal Investigator (API) Areas of Responsibility for Level 2 Research Areas for the Supersonics Project Supersonics Project: API Areas of Responsibility Level 2 Areas Cruise Efficiency—Propulsion Propulsion and Power Aerothermodynamics Cruise Efficiency—Airframe Aerodynamics Airport Noise Acoustics Sonic Boom Modeling Sonic Boom Lightweight and Durability at High Temperature Materials and Structures Aero-propulso-servo-elasticity (APSE) Airframe and Propulsion APSE Experimental Validations and Capabilities Experimental Capabilities Systems Integration and Assessment N/A High-Altitude Emissions N/A Entry, Descent, and Landing (of spacecraft) N/A 

90 NASA AERONAUTICS RESEARCH—AN ASSESSMENT do not seem to cleanly map into the level diagram, and in many cases the scope of many Level 2 areas is broader than that of the closest matching API areas of responsibility. Recommendation. As reference documents and project plans are revised and updated, NASA should continue to improve the correlation between (1) the reference documents that describe project rationale and scope and (2) the project plans and actual implementation of each project. LOOKING FORWARD NASA has a critical part to play in preserving the role of the United States as a leader in aeronautics. NASA research facilities and expertise support research by other federal agencies and industry, and the results of research conducted and/or sponsored by NASA are embodied in key elements of the U.S. air transportation system, military aviation, and space program. NASA aeronautics research will carry on this tradition as long as its research is properly prioritized and research tasks are executed with enough depth and vigor to produce meaningful results in a timely fashion. REFERENCES NASA (National Aeronautics and Space Administration). 2006a. Fundamental Aeronautics Program, Subsonic Fixed Wing Project Reference Document. Washington, D.C.: NASA Headquarters, Aeronautics Research Mission Directorate. Available online at <www.aeronautics. nasa.gov/nra_pdf/sfw_proposal_c1.pdf>. NASA. 2006b. Fundamental Aeronautics Program, Supersonics Project Reference Document. Washington, D.C.: NASA Headquarters, Aero- nautics Research Mission Directorate. Available online at <www.aeronautics.nasa.gov/nra_pdf/sup_proposal_c1.pdf>. 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>. Porter, Lisa. 2007. Aeronautics Research Mission Directorate Briefing to the National Research Council. Dr. Lisa Porter, Associate Adminis- trator for Aeronautics. April 16.