Below are the first 10 and last 10 pages of uncorrected machine-read text (when available) of this chapter, followed by the top 30 algorithmically extracted key phrases from the chapter as a whole.
Intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text on the opening pages of each chapter. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.
Do not use for reproduction, copying, pasting, or reading; exclusively for search engines.
OCR for page 68
Materials Needs and R&D Strategy for Future Military Aerospace Propulsion Systems 3 Materials Development Assessment The availability of critical materials for propulsion systems and innovative manufacturing processes and capacity have been key elements in creating and maintaining U.S. preeminence in military aircraft capabilities and have contributed significantly to the U.S. engine manufacturers’ competitiveness in the global market.1 The first six sections of this chapter provide assessments of the following: Section 3.1, the materials development process used for structural materials research and development (R&D); Section 3.2, the organizations in the Air Force Research Laboratory (AFRL) addressing materials R&D; Section 3.3, materials research and databases; Section 3.4, the importance of materials to the three types of propulsion needed for U.S. Air Force (USAF) missions; Section 3.5, the current global activities in propulsion structural materials; and Section 3.6, the past, present, and planned activities of the AFRL in propulsion structural materials. Sections 3.7 and 3.8 present, respectively, the findings and recommendations of the committee related to its materials development assessments. 3.1 DEVELOPMENT PROCESS FOR STRUCTURAL MATERIALS RESEARCH AND DEVELOPMENT The Air Force’s science and technology (S&T) process is illustrated in Figure 3.1. Basic research (6.1), applied research (6.2), and advanced technology 1 National Research Council. 2006. A Review of United States Air Force and Department of Defense Aerospace Propulsion Needs. Washington, D.C.: The National Academies Press.
OCR for page 69
Materials Needs and R&D Strategy for Future Military Aerospace Propulsion Systems FIGURE 3.1 Air Force science and technology program. NOTE: Acronyms are defined in Appendix F. development (6.3) constitute the parts of the S&T program that are managed by the AFRL. The S&T program seeks new ways of accomplishing tasks of military value and developing the underlying scientific and engineering principles involved. Individual S&T projects are not directed at developing new operational weapons systems, although they may support such development by solving specific problems. The 6.3 Manufacturing Technology (ManTech) element is the program of the Air Force that anticipates and closes gaps in manufacturing capabilities for the affordable, timely, and low-risk development, production, and sustainment of defense systems. The elements above 6.3 are the Air Force’s Acquisition Program, managed by the system program offices. Within the S&T program, basic research (6.1) is the systematic study directed toward greater knowledge or understanding in science and engineering of the fundamental aspects of phenomena and/or observable facts consistent with the Air Force missions, but without practical application of that knowledge and understanding. Applied research (6.2) is systematic study to gain the knowledge or understanding necessary to determine the means by which a recognized and specific need may be met; these efforts attempt to determine and exploit the potential
OCR for page 70
Materials Needs and R&D Strategy for Future Military Aerospace Propulsion Systems of scientific discoveries or improvements in technology such as new materials, devices, methods, and processes. Advanced technology development (6.3) includes all efforts that have moved into the development and integration of hardware for large-scale or field experiments and tests. Advanced technology development demonstrates the viability of applying existing technology to new products and processes in a general way. If a new material followed the exact path illustrated in Figure 3.1, a 6.1 program would last on average about 3 to 5 years, a 6.2 program would last about 3 to 5 years, and a 6.3 advanced technology development program would last about 3 years. The total S&T effort would thus be around 9 to 13 years. This time period assumes that no major issues would result in program delays; such issues could easily add several years to the process. If a ManTech program were factored into the process, the total time could easily reach 14 to 18 years or longer. It is possible that the Air Force S&T steps shown in the figure could be skipped altogether if a strong industry development effort completed the technology base work with internal funds. The nature of the work would remain the same, but would be funded by industry. For noncritical components, materials that have already transitioned into a system and are subsequently modified typically require much less time for reinsertion than for the original development effort. In general, the 6.1 step is eliminated for reinsertion. The “tweaked” material may start at the late 6.2 or early 6.3 stage. In such a case, the time to transition into a system may be as short as 3 to 5 years. For critical components, materials that have already transitioned into a system and are subsequently modified would also likely see the 6.1 step eliminated. The modified material may also start at the late 6.2 or early 6.3 stage. The 6.3 stage could be longer for critical than for noncritical applications owing to additional testing. In such a case, the time to transition may be as short as 5 years of S&T or as long as 8 years, especially if requalification is required. Figure 3.1 is useful for illustrating the various elements of the S&T program and their relationships to the system customer (the three program elements in the upper-right-hand corner) and the various TRLs for each stage. However, a material’s transition path, in which a new composition or process transitions sequentially from one totally isolated or independent element to another, as shown in Figure 3.1, does not represent the actual technology transition path that most materials and processes follow. There is no consistent formal path for a material’s transition from basic research to applied research to system development to ManTech. For a new material, the S&T elements represented in Figure 3.1 could be working on complementary, parallel paths, with multiple programs in each. As the maturity level increases, including in production, work at an earlier stage may be necessary to address an unforeseen issue. This cyclical nature of materials transition is not unusual and in many cases is a known element of risk for high-performance applications. Modification of an existing material could require that multiple pro-
OCR for page 71
Materials Needs and R&D Strategy for Future Military Aerospace Propulsion Systems gram elements (upper right, Figure 3.1) also be pursuing parallel, complementary paths. In all cases, continuous interaction among the program elements must take place for the transition to be timely and successful. 3.2 ORGANIZATIONAL ENTITIES OF THE AIR FORCE RESEARCH LABORATORY The Air Force Office of Scientific Research (AFOSR), the Materials and Manufacturing Directorate, and the Propulsion and Power Directorate are the organizational entities that handle the development of new materials and their introduction into propulsion systems. The AFOSR manages the basic research investment (6.1 in Figure 3.1) and is a part of the AFRL. The AFOSR fosters and funds basic research within the AFRL, domestic universities, and industry laboratories to support USAF needs. Research managers seek to create revolutionary scientific breakthroughs, enabling the Air Force and industry to produce world-class, militarily significant, and commercially valuable products using technical guidance from the AFRL and requirements of the Air Force; research managers also ensure the transition of research results to support USAF needs. The Materials and Manufacturing Directorate performs comprehensive research and development activities to provide the Air Force with new and improved materials, processes, and manufacturing technologies. Its activities span 6.1, 6.2, and 6.3. The directorate receives 6.1 funds from the AFOSR for intramural research and has its own 6.2 and 6.3 budget elements for materials R&D and manufacturing technology. The directorate explores new materials, processes, and manufacturing technologies for use in aerospace applications, including aircraft, spacecraft, missiles, rockets, and ground-based systems, along with their structural, electronic, and optical components. Areas of expertise in this directorate include thermal protection materials, metallic and nonmetallic structural materials, nondestructive inspection, materials used in aerospace propulsion systems, electromagnetic and electronic materials, and laser-hardened materials. The directorate provides real-time materials operating problem solutions and failure analysis, along with support to Air Force weapons system acquisition offices and maintenance depots, to solve materials-related concerns and problems. The directorate plans, executes, and integrates advanced manufacturing technology programs and affordability initiatives that address manufacturing process technologies, computer-integrated manufacturing, and excellence through design for producibility, quality, cost, and the use of commercial processes and practices for military needs. The Air Expeditionary Forces Technologies Division, located at Tyndall Air Force Base (AFB), Florida, addresses environmental issues and provides materials expertise for airbase assets such as runways and infrastructure. The directorate also manages the Air Force Corrosion Control Program Office at Robins AFB, Georgia; the Air Force
OCR for page 72
Materials Needs and R&D Strategy for Future Military Aerospace Propulsion Systems Nondestructive Inspection Office at Tinker AFB, Oklahoma; and the Air Force Advanced Composites Office at Hill AFB, Utah. The Propulsion and Power Directorate provides a complete spectrum of advanced propulsion technologies for the nation’s military services. The directorate has its own 6.2 and 6.3 budget elements. Its 6.3 funds are the principal source of funding for transitioning new materials to promote application of these technologies to military systems for an aerospace force for advanced aircraft, weapons, and space electrical power system technologies and to advance concepts for advanced air-breathing, rocket, and space propulsion. In addition, the directorate designs and analyzes advanced propulsion concepts and promotes the application of advanced propulsion science and technology to military and commercial systems; assists operational commands and air logistics centers in resolving field problems; and coordinates and participates in joint propulsion science and technology programs with other Air Force Materiel Command, USAF, and Department of Defense (DOD) organizations, NASA, other government agencies, other countries, industry, and academia.2 The following sections describe the current and planned approaches and activities of the major contributors addressing Air Force needs in the materials area. 3.2.1 Research Funding and Directions at AFRL The Air Force Research Laboratory exists to eliminate gaps in technology in order to address today’s needs and to reshape tomorrow’s Air Force. The longer-term focus is on the future needs of the Air Force. The AFRL consists of 10 technical directorates, including the AFOSR: AFOSR, located in Arlington, Virginia; Air Vehicles Directorate, at Wright-Patterson AFB, Ohio; Directed Energy Directorate, at Kirtland AFB, New Mexico; Human Effectiveness Directorate, at Wright-Patterson AFB, Ohio; Information Directorate, at the Rome Research Site, New York; Materials and Manufacturing Directorate, at Wright-Patterson AFB, Ohio, and Tyndall AFB, Florida; Munitions Directorate, at Eglin AFB, Florida; Propulsion and Power Directorate, at Wright-Patterson AFB, Ohio, and Edwards AFB, California; Sensors Directorate, at Wright-Patterson AFB, Ohio; and Space Vehicles Directorate, at Kirtland AFB, New Mexico; 2 See http://www.wpafb.af.mil/afrl/rz/. Accessed September 11, 2009.
OCR for page 73
Materials Needs and R&D Strategy for Future Military Aerospace Propulsion Systems Funding of the directorates is divided between short- and long-term needs, with the emphasis on the long term: 80 percent of funding is for long-term activities.3 The AFRL responds to the immediate needs of the warfighter by moving staff around as needed to solve short-term issues. Funding priorities and levels have changed over the years with the changes in the geopolitical world, the economy, and the mission and vision for the AFRL. For example, engineering funding for USAF was cut by approximately 70 percent in the late 1980s and by a further 20 percent in the early 1990s, resulting in a considerable loss of capabilities. The AFRL directorates have not been subject to the same level of engineering reductions as other Air Force functions;4 however, these reductions have resulted in some increased workloads within the laboratories, as the product centers in the Air Force now look to the AFRL or to the engine contractors or suppliers for solutions. Research and development at the AFRL is organized in Focused Long Term Challenges (FLTCs),5 described in Chapter 2 of this report, and 70 to 75 percent of the funding is for tasks held within the FLTCs. The remainder of the funding at the laboratories is for “discovery,” or low technology readiness level, less-directed work aimed at longer-term issues. Discovery does include 6.1, low 6.2, and some engineering research. Discovery includes the 6.1 funding received from the AFOSR; generally, approximately 20 percent of AFOSR’s funding goes to the AFRL and constitutes approximately 50 percent of the discovery budget.6 Most of the remainder of the discovery budget is early 6.2 funding and comes from the directorate budgets. The splits and focus of the discovery money vary by directorate and are set by the priorities of the directorate. In addition to the above sources, there is a special Laboratory Director’s fund of approximately $1 million per year. There is an open competition throughout the AFRL for grassroots ideas, with awards of between approximately $50,000 and $100,000 per year for selected projects. Technology pull comes from the FLTC roadmaps and associated plans. Technology push comes mainly from the discovery activities and Laboratory Director’s funding; an example is the modeling of materials and materials behavior that is being explored with discovery funding. 3 Information presented to the committee by J. Arnold, K. Stevens, Col. W. Hack, C. Stevens, and C. Ward at Wright-Patterson AFB, May 27, 2009. 4 Information received during presentations to the committee at Wright-Patterson AFB, Ohio, May 27, 2009. 5 The committee recognizes that the Materials and Manufacturing Directorate’s approach to FLTCs is evolving and dynamic at this time and that some changes in the approach are forthcoming. 6 Information received during presentations to the committee at Wright-Patterson AFB, Ohio, May 27, 2009.
OCR for page 74
Materials Needs and R&D Strategy for Future Military Aerospace Propulsion Systems The FLTCs are divided into near-, mid-, and far-term research and development. The customers and technology providers are intertwined in defining the FLTC goals. Management is done by a matrix method, with each FLTC being assigned to a directorate, which pulls in expertise from other relevant directorates to flesh out priorities and build roadmaps. A single directorate may thus support six to eight FLTCs. Materials, especially high-temperature materials, are important in a number of the FLTCs, and the Materials and Manufacturing Directorate is involved with nearly all of the FLTCs to some degree. The Materials and Manufacturing Directorate has management responsibility for the sustainment FLTC. The sustainment FLTC has a focus on long-term operation and evolutionary progress.7 The Materials and Manufacturing and the Propulsion and Power Directorates work quite closely together on common interests. The use of a joint workshop to set the priorities and provide input to the roadmaps is discussed elsewhere in this report. One of the materials and propulsion workshop sessions led to approximately 25 new ideas for materials. Some priority was given to these ideas, and efforts have been made to obtain the required funding. Each FLTC may have many roadmaps for individual elements of the particular challenge. Roadmaps have “owners” and often include unfunded programs; however, nothing can be added or subtracted without the permission of the owner. These unfunded lines are for technology developments that are identified as being necessary to meet long-term goals but for which there is no funding identified. In general, the FLTCs are ambitious and are underfunded, although they provide a driving force and an interdependent, long-term plan. FLTCs are reviewed regularly and changed as appropriate. Recently, the AFRL has been presenting the FLTCs to industry groups to educate them and to identify areas for collaboration. There is a balance in research efforts between the AFRL and industry. The situation has changed over the years, with the large prime contractors becoming increasingly more reliant on the suppliers to do research and development. The prime contractors act as integrators, passing some of the materials development work to their suppliers, which puts financial stress on the supplier. Often the result is that incremental changes are possible but revolutionary changes are difficult. The importance for a project of reaching Milestone B or TRL 6 needs to be emphasized. The milestone is difficult to define exactly, but the focus is on the demonstration of process maturity and component development. Milestone B generally marks the end of 6.3 programs, which start at TRL 4 or 5. The engineering acquisition major review at Milestone B is aimed at managing risk for future development; the effect of this setup is that materials must be selected early in the 7 As noted above, the committee recognizes that the Materials and Manufacturing Directorate’s approach to FLTCs is evolving and dynamic at this time and that some changes in the approach are forthcoming.
OCR for page 75
Materials Needs and R&D Strategy for Future Military Aerospace Propulsion Systems process, because the use of new materials may require new designs and increase risk later in the process. Further discussion of risk and the associated valley of death is presented in Chapters 2, 4, and 5, but these topics are mentioned here as they are integral to the FLTC and planning process. 3.2.2 Air Force Office of Scientific Research Basic research investments for USAF are managed by the AFOSR. As a part of the AFRL, AFOSR’s technical experts foster and fund research within the AFRL, universities, and industry laboratories to ensure the transition of research results to support USAF needs. Following are five general focus areas: Aero-structure interactions and control; Energy, power, and propulsion; Complex materials and structures; Space architecture and protection; and Thermal control. The current AFOSR basic research program is divided into three directorates. Research on aerospace propulsion materials is funded primarily through the Aerospace, Chemical, and Materials Science Directorate under 12 topical areas.8 The area most relevant to propulsion systems is topical area (7): High Temperature Aerospace Materials (HTAM). As stated in an Air Force BAA, “The objective of basic research in HTAM is to provide the fundamental knowledge required to enable revolutionary advances in future Air Force technologies through the discovery and characterization of high-temperature materials (nominally temperatures above 1000ºC), including ceramics, metals, [and] hybrid systems including composites.” Current research under HTAM includes fundamental research on high-temperature materials, focused on understanding combined mechanical behaviors such as strength and toughness as a function of thermal and acoustic loads. For example, the program includes exploratory research on refractory materials systems such as molybdenum and niobium silicides, borides, and boro-silicides that includes studies of phase equilibria, thermal stability, coating methodology, oxidation, corrosion, and mechanical behavior. These types of programs represent long-term, high-risk investments in the development of revolutionary high-temperature materials for propulsion, which are likely to lead to “revolutionary” as opposed to “incremental” advances in the temperature limits of engine operation. Although the AFOSR has a broad portfolio that is relevant to future propulsion needs, further analysis of the AFOSR portfolio could be useful in order to 8 See http://www.wpafb.af.mil/AFRL/afosr/. Accessed May 6, 2009.
OCR for page 76
Materials Needs and R&D Strategy for Future Military Aerospace Propulsion Systems determine its topical breakdown with respect to the development of new materials at the lower TRLs and how to best coordinate activities with the Materials and Manufacturing and the Propulsion and Power Directorates and obtain inputs from the warfighter. The analysis could consider whether the research portfolio is sufficiently broad to build the desired knowledge base and to train the number of future scientists and engineers needed to address the challenges that lie ahead. In addition, the further analysis should consider the internal investment in materials research through the AFRL and potential interactions with efforts funded by other agencies such as the Office of Naval Research (ONR) and NASA. 3.2.3 Materials Lab: Materials and Manufacturing Directorate The Materials and Manufacturing Directorate, or the Materials Lab as it is often called, is one of the AFRL’s 10 directorates. It performs comprehensive research and development activities to provide new or improved materials, processes, and manufacturing technologies for USAF. The directorate integrates industry requirements with an execution program providing advanced manufacturing processes, techniques, and systems for the timely, reliable, high-quality, economical production and sustainment of Air Force systems. The directorate’s areas of expertise include thermal protection materials, metallic and nonmetallic structural materials, nondestructive inspection, materials for aerospace propulsion systems, electro magnetic and electronic materials, and laser-hardened materials. Figure 3.2 presents the directorate’s organizational chart. The directorate addresses the sustained need for metals development currently and into the future, through the Metals Branch of the Metals, Ceramics and NDE [Nondestructive Evaluation] Division. The primary focus of the research is on high-temperature metals; it is aimed at service temperatures in the range from 650ºC to 1500ºC. The most general objective of the Metals Branch is to establish and maintain leadership in metals technologies for Air Force systems. For the foreseeable future, the group is focused on research in the following areas: Materials damage prediction for turbine engine materials, Computational tool development, Advanced turbine disk materials, and Thin gage/honeycomb structure for thermal protection systems. The objective of the Metals Branch is to understand, develop, and transition metallic materials with high specific strength and stiffness along with other functional properties for use in existing, advanced, and conceptual aerospace systems for USAF. The technical program is implemented through an integrated extramural and intramural program. The extramural program is conducted through contrac-
OCR for page 77
Materials Needs and R&D Strategy for Future Military Aerospace Propulsion Systems FIGURE 3.2 Organizational chart of the Air Force Research Laboratory’s Materials and Manufacturing Directorate (AFRL/RX). SOURCE: From http://www.ml.afrl.af.mil/orgchart.html. tual arrangements with aerospace companies and academic institutions. The intramural program is conducted in the facilities of the Materials and Manufacturing Directorate. Technical collaborations with other organizations in the United States and abroad are also pursued. The technical program consists of efforts in four areas: materials damage prediction for turbine engine materials, computational tool devel opment, advanced turbine disk materials, and thin gage/honeycomb structure for thermal protection systems. The Materials and Manufacturing Directorate receives some 6.1 funds from the AFOSR for intramural research. Within the directorate’s own 6.2 and 6.3 budget elements, its scientists and engineers explore new materials, processes, and manufacturing technologies. With a host of modern material analysis laboratories, the directorate performs research on thermal protection materials, metallic and nonmetallic structural materials, nondestructive inspection, materials used in aerospace propulsion systems, electromagnetic and electronic materials, and laser-hardened materials. It also provides real-time operating problem solutions and failure analysis, along with support to Air Force weapons system acquisition offices and maintenance depots, including work on advanced manufacturing technology programs and affordability initiatives. Materials Lab activities address environmental issues, and lab activities through the Air Expeditionary Forces Technologies
OCR for page 78
Materials Needs and R&D Strategy for Future Military Aerospace Propulsion Systems Division, located at Tyndall AFB, Florida, provide materials expertise for air base assets such as runways. The Materials Lab also manages the Air Force Corrosion Control Program Office at Robins AFB, Georgia; the Air Force Nondestructive Inspection Office at Tinker AFB, Oklahoma; and the Air Force Advanced Composites Office at Hill AFB, Utah. The historic model described in Figure 3.1 continues to frame the current approach for Air Force propulsion materials development.9 Several organizational and programmatic changes over the past few years have changed the materials development environment, resulting in changes in this decade compared with the previous several decades. These changes include a significant reduction in applied research in other agencies working on propulsion materials technology, and a contract focus for the materials work on the Integrated High Performance Turbine Engine Technology (IHPTET) Program (and the Versatile Affordable Advanced Turbine Engine [VAATE] Program that has replaced it).10 Also, the level of funding available for propulsion has been reduced as a result of a diffusion of focus due to the increased diversity of the Air Force mission(s) in recent years.11 The historic model has also been modified to some extent on the contractor’s side in recent years. The current business model gives suppliers more responsibility for component manufacturing process development and more involvement in the details of the design. Several of the engine manufacturers have reported a deterioration in some of the supplier base with respect to addressing propulsion materials as the pressures for more short-term profitability have increased in the supplier base.12 The propulsion industry has undergone some restructuring in recent years that has had an effect on materials development in the United States. Pratt and Whitney has consolidated its material activities from its Florida R&D facility into the East Hartford, Connecticut, operation,13 resulting in a reduction of the total number of materials scientists and engineers. The Rolls-Royce acquisition of Allison Engine Company generated the Liberty Works that is focused exclusively on military technology, while Honeywell has purchased the parent company of Allied Signal Propulsion. The committee could not make an assessment of the impact of these changes relative to meeting U.S. military needs, although the changes are significant enough to be noted here. 9 J. Arnold, K. Stevens, Col. W. Hack, C. Stevens, and C. Ward, Wright-Patterson AFB, presentations to the committee, May 27, 2009. 10 Chart: “Funding History for Propulsion Materials: (6.2) Funding—Applied Research,” C. Ward, presentation to the committee, Irvine California, January 29, 2009. 11 National Research Council. 2006. A Review of United States Air Force and Department of Defense Aerospace Propulsion Needs. Washington, D.C.: The National Academies Press. 12 Malcolm Thomas, Rolls-Royce North America; Frank Preli, Pratt and Whitney; Art Temmesfeld, Air Force Research Laboratory; presentations to the committee, Washington, D.C., March 23, 2009. 13 Jack Schirra, Pratt and Whitney, briefing to the committee, Washington, D.C., July 20, 2009.
OCR for page 107
Materials Needs and R&D Strategy for Future Military Aerospace Propulsion Systems Russia The All-Russian Scientific Research Institute of Aviation Materials (VIAM) conducts the majority of aeronautical materials research in Russia. Its research includes casting superalloys for turbine blades. VIAM claims significant benefits of its intermetallic alloys over Ni-based alloys in service life and cost. It also has applications related to cobalt aluminate surface treatments to improve blade performance and durability. VIAM also developed a vacuum plasma high energy technology method for coating and providing surface treatment of ME-Cr-Al-Y alloys. AIAA-published papers address ramjet and scramjet research for hypersonic (Mach 6 range) applications and general research on pulse-detonation propulsion concepts by the Russian Academy of Sciences and the Central Institute of Aviation. Within the Russian Federation, NPO Energomash has a long history of success in designing and manufacturing liquid-fuel rocket engines. These engines are used in other international launch vehicles such as the United Launch Alliance (U.S.) Atlas V, the SeaLaunch (U.S.-led joint venture) Zenit, and the South Korean Naro-1. Ukraine Pratt and Whitney Division of United Technologies Corporation has established a collaborative research venture with the Paton Research Institute in Kiev. The research is focused on developing new materials using electron-beam deposition processing. Conclusion Although the results of the literature and patent searches referred to at the beginning of Section 3.5.2 do not allow a complete assessment of the state of the art of international propulsion and materials development, they do indicate significant activity and investment. In particular, the focus on advanced ceramics in Japan and the focus on intermetallics and metal-ceramic composites by the European Union will certainly create centers of excellence with the capability to rival or exceed U.S. capability. The EU approach of requiring a consortia of government, industry, and academia to pursue EU funding brings together the best talent and resources, and it may be an operating model for consideration for some areas of future U.S. materials development. The EuMaT vision is to establish the leading global position in materials technology and to have Europe emerge by 2020 as a leader in the development and utilization of advanced material solutions and manufacturing processes.
OCR for page 108
Materials Needs and R&D Strategy for Future Military Aerospace Propulsion Systems 3.6 THE PLAN Discussions with personnel in the Materials and Manufacturing and the Propulsion and Power Directorates of the AFRL indicate that the directorates address three broad categories of military needs in the area of materials research: (1) near-term needs: rapidly deliver technical innovation, driven by warfighter emergencies; (2) intermediate-term needs: develop technology options that meet the needs of capability developers; and (3) far-term needs: conduct long-term research, driven by a bold technology goal. These categories align with the Focused Long Term Challenges approach to capability planning currently employed by the USAF. It was reported that 80 percent of the Materials and Manufacturing Directorate’s funding is directed toward the long term. The immediate needs of the warfighter are addressed by committing staff as needed to solve short-term issues. As materials in propulsion systems become more mature and reach high TRLs or MRLs (moving from 6.2 programs to 6.3 or 6.4 activities), the requirements are driven by the Propulsion and Power Directorate or specific program offices. Directorate funds for the nearest-term requirements were estimated to be approximately 3 percent of the materials R&D budget,42 since the majority of these costs are in the fielded-systems operational budgets. In addition, there is a special Laboratory Director’s fund of approximately $1 million per year, as noted in Section 3.2.1, to support new material systems or new processes. A portion of the directorate’s budget is used to address fielded-system support issues; however, the majority of this type of directorate work that addresses problems arising in fielded propulsion systems is funded by the specific program offices or other organizations. 3.6.1 Review of Relevant Focused Long Term Challenges and Roadmaps In assessing propulsion material technology needs, the committee reviewed a wide range of Air Force requirements and planning and implementation activity. One of the difficulties in assessing the relative adequacy of the propulsion materials program(s) in comparison to the successes and failures of the past results from the changing mission requirements and evolving technologies in the area. This complexity is well stated in a report summarizing a group of materials and propulsion technology workshops held at Wright-Patterson AFB in 2008.43 The USAF is entering a period of rapidly evolving new technologies. In propulsion, the new programs in air and space propulsion and power are producing war-winning concepts, 42 J. Arnold, K. Stevens, Col. W. Hack, C. Stevens, and C. Ward, presentations to the committee, Wright-Patterson AFB, Ohio, May 27, 2009. 43 AFRL, Materials for Advanced Aerospace Propulsion and Power Systems, AFRL/RZ and AFRL/RX Workshop, AFRL-RZ-WP-TM-2008-2127, 2008.
OCR for page 109
Materials Needs and R&D Strategy for Future Military Aerospace Propulsion Systems which will enable enhanced vehicle payload, range, and loiter capability. There are also emerging totally new weapon classes, such as hypersonic vehicles with very high heat loads, and directed energy weapons with escalating demands for very high power, each requiring advanced components and a closely integrated thermal management system strategy. In addition, both legacy and pipeline systems must be sustained and retrofitted with improved capability and robustness. The degree of complexity of evolving requirements and technologies is further reinforced when one reviews the Focused Long Term Challenges (FLTCs) approach44 to defining capabilities needed to address the Air Force current and future missions that include strategic needs for the following: Global strike; Homeland security; Global mobility; Space and command, control, communications, computers, intelligence, surveillance, and reconnaissance; Nuclear response; and Global persistent attack. Meeting these needs is further complicated when the integration challenges are associated with addressing and implementing solutions in the following areas: Air vehicles, Sensors, Information acquisition and management, Directed energy, Human effectiveness, Space vehicles, Materials and manufacturing, Munitions, and Propulsion. The Air Force has segmented these needs by time periods that impose the added requirements of operating with a high degree of both urgency and vision. The segments are defined in terms of the following: The near term. Rapidly deliver technical innovation, driven by warfighter emergencies—reshape today’s battles (Today). 44 Leo Rose, AFRL, “Focused Long Term Challenges (FLTC),” presentation, March 18, 2008.
OCR for page 110
Materials Needs and R&D Strategy for Future Military Aerospace Propulsion Systems The intermediate term. Develop technology options that meet the needs of capability developers—shape today’s Air Force (4 years plus). The far term. Conduct long-term research, driven by a bold technology goal—shape the future Air Force (12 years plus). Eight Focused Long Term Challenges are represented in the Air Force plans: Anticipatory Command, Control, and Intelligence (C2I); Unprecedented Proactive Intelligence, Surveillance, and Reconnaissance; Dominant Difficult Surface Target Engagement/Defeat; Persistent and Responsive Precision Engagement; Assured Operations in High Threat Environment; Dominant Offensive Cyber Engagement; On-Demand Force Projection, Anywhere; and Affordable Mission Generation and Sustainment. Examining the FLTC document45 provides insight into the weapons system requirements and in turn the propulsion system figures of merit and the resulting leverage that propulsion materials technology will have on a mission. FLTC 1 (Anticipatory Command, Control, and Intelligence) requires battlespace awareness and the synchronized management of battlespace effects that require the discovery of threatening systems and objects and fully effective C2I operations. This implies a range of surveillance aircraft from small to large high-altitude unmanned aerial vehicles (UAVs) and manned subsonic platforms in addition to satellite assets. FLTC 2 (Unprecedented Proactive Intelligence, Surveillance, and Reconnaissance) dictates effective surveillance capability with real-time high-performance networking with persistence. The weapons systems to meet a portion of this challenge are the same as those of FLTC 1; however, in addition, a requirement for large manned aircraft with persistence and large electrical power requirements is defined. FLTC 3 (Dominant Difficult Surface Target Engagement/Defeat) introduces the emergence of the requirement for the micro-UAV that can enter complex urban environments and help direct scalable kinetic and nonkinetic effect to difficult targets, including chemical, biological, radiological, nuclear, and explosives (CBRNE) threats. FLTC 4 (Persistent and Responsive Precision Engagement) addresses the more traditional Air Force role of responsive precision engagement with the requirement for global delivery of the full spectrum of nonkinetic and kinetic effects. 45 AFRL, Materials for Advanced Aerospace Propulsion and Power Systems, AFRL/RZ and AFRL/RX Workshop, AFRL-RZ-WP-TM-2008-2127, 2008.
OCR for page 111
Materials Needs and R&D Strategy for Future Military Aerospace Propulsion Systems The resulting systems include both stealthy and high-Mach-number manned or unmanned vehicles. FLTC 5 (Assured Operations in High Threat Environment) puts further emphasis on stealth and information gathering and management. In addition, it introduces the possible use of unmanned combat air vehicles (UCAVs) in both traditional battlespaces and urban environments. FLTC 6 (Dominant Offensive Cyber Engagement) puts emphasis on electronic systems, and it also defines requirements for a variety of both large and small surveillance platforms and the early warning aircraft of the future. FLTC 7 (On-Demand Force Projection, Anywhere) identifies weapons systems at two ends of the flight spectrum. The more traditional role of global projection of ground forces and materiel anywhere in the world in any weather falls to the large air transport vehicles, while the requirement for rapid response and access to space defines a need for very-high-Mach-number or hypersonic systems. FLTC 8 (Affordable Mission Generation and Sustainment) addresses affordability and sustainment of all missions and addresses an area that for propulsion materials and operating systems is considered a key element for successful implementation of materials systems and robustness of the final product. The related qualification and support systems for propulsion are necessitated by this requirement, with the challenge being quantification. The committee’s review of the generation of specific propulsion-materials-related requirements included briefings by personnel from both the Materials Lab and the Propulsion and Power Lab, briefings by the three U.S. engine manufacturers, a briefing on ONR activities in the area, a visit by a committee subgroup to the Materials and Manufacturing Directorate at Wright-Patterson Air Force Base, a series of USAF reports on the subject dating back to 2002, and historic data dating back to the early 1990s. Product taxonomy has been used to reduce the capabilities defined in the FLTCs to attributes and to propulsion “products” that in turn define materials requirements for significant advances in capabilities. These products are identified as turbine engines, both liquid-fueled rocket engines and solid rocket motors, and scramjets. For each of these product areas, requirements have been identified for the focus of materials research and development. In the case of turbine engines, these include hybrid disk systems, SiC/SiC CMCs, fluids and lubricants, and preventive maintenance checks and services. The materials requirements for liquid-fueled rocket engines include high-pressure oxygen-compatible Ni-based super alloys, high-stiffness Al alloys, and SiC/SiC CMCs. The solid rocket motor material requirements defined by this process include advanced cyanate ester composites, advanced refractory carbides, and carbon-carbon composites. The scramjet analysis yielded material requirements in the areas of advanced thin-gauge metals, SiC/SiC and C-SiC CMCs, and carbon-carbon composites.
OCR for page 112
Materials Needs and R&D Strategy for Future Military Aerospace Propulsion Systems The turbine engine material requirements have been clearly articulated through the VAATE Program, which builds on the institutionalized process developed under the past IHPTET Program that was led by the DOD Office of DDR&E and featured the Air Force as the major participant.46 This program addressed large turbine engines and identified the requirements for increased capabilities as follows: The main barriers to increased performance: Compressor pressure ratio (Compressor exit temperature) turbine temperature component efficiencies and cooling flow These are in turn stated in terms of materials: Material limitations constrain pressure ratio and turbine temperature This program provides a direct linkage between the capabilities, the propulsion requirements, and the materials development activities within the Air Force and the manufacturing community. In the case of the liquid-fueled rocket engines, the materials programs recognized a series of materials advances as noted above; however, the linkage to new systems’ requirements47 was not as clear as that noted in the turbine engine work. One requirement noted in the liquid rocket engine review was that there be a continental United States (CONUS) source for high-temperature composites, since the primary source for these materials is currently Japan, and the government of Japan places export restrictions on the use of these materials for certain weapons systems. The committee could not find propulsion requirements for the small or micro-UAV that address the capabilities of FLTC 2 in the area of effective surveillance capability with real-time high-performance networking in the urban battlespace. 3.6.2 Overview of the Plan The Materials and Manufacturing Directorate and the Propulsion and Power Directorate of the Air Force Research Laboratory have a history of working together to formulate coordinated materials development and applications planning. The current effort in this area was brought into focus through a series of workshops 46 Charles W. Stevens, Chief, Turbine Branch, AFRL/RZTT, “Versatile Affordable Advanced Engine Program (VAATE),” briefing to the committee, July 20, 2008. 47 Drew DeGeorge, Edwards AFB, “Rockets,” briefing to the committee, July 22, 2008.
OCR for page 113
Materials Needs and R&D Strategy for Future Military Aerospace Propulsion Systems that incorporated the Air Force Future Long Term Challenges into this planning and generated a set of agreed-on responses for the two directorates addressing a range of notional future platforms. The approach is an interactive examination of capabilities, concepts, advanced propulsion and power (options), and materials. The interactive nature of the process entails iterations between each of these elements of the AFRL directorates’ capabilities and their charters within the 6.1, 6.2, and 6.3 funding categories. The planning process recognizes that USAF is entering a period of rapidly evolving new technologies and that there are also emerging totally new weapons classes, such as hypersonic vehicles with very high heat loads, and directed-energy weapons with escalating demands for very high power. The planning also recognizes that the product of the planning would have to fit within constrained budgets dictated by the current R&D funding environment. In this context the group authoring the plan identified 18 key technology areas extending across the spectrum of air-breathing propulsion. Materials research and development investments needed for USAF to maintain leadership in propulsion and power were identified; these investments would advance the state of the art in the 18 key areas to readiness levels needed for component development. Specific funding recommendations to address the critical materials limitations were made, and the allocation to each of the 18 areas was recommended, as was timing of the funding. The planning also recognized several issues concerning U.S. military access to critical technologies in the global marketplace: for example, battery mate rials, magnetic materials, energetic materials, high-strength fibers, and refractory alloys. It was noted by the committee that the AFOSR could play a significant role in bringing these technologies to a higher level of readiness through further joint activities; however, it was noted that the workshops did not include representatives from the warfighter, the system program office organization, or the AFOSR. The committee thinks that the inclusion of these groups is essential to formulating a successful materials strategic plan. The plan does not address alternative techniques for coping with the realities of current and future budget pressures on materials development funding—techniques such as encouraging collaboration among domestic competitors, among competitors and suppliers, among universities, among universities and companies, and among international entities. The committee’s assessment of this planning was based on the Air Force document Materials for Advanced Aerospace Propulsion and Power Systems48 and was conducted as a review and evaluation of the USAF strategic plan for materials research and development to support future propulsion and power needs of the USAF. No other sources were consulted. Some of the material in the plan reviewed 48 AFRL, Materials for Advanced Aerospace Propulsion and Power Systems, AFRL/RZ and AFRL/RX Workshop, AFRL-RZ-WP-TM-2008-2127, 2008.
OCR for page 114
Materials Needs and R&D Strategy for Future Military Aerospace Propulsion Systems by the committee is ITAR-controlled, and the details of the committee’s assessment are provided in the ITAR-restricted text of Appendix D. Only a brief, unrestricted summary of the assessment process is included here. 3.6.3 Assessment of the Plan The committee’s assessment used seven questions employed in evaluations of strategic plans. Following is a brief (unrestricted) summary of the committee’s evaluation of the plan with respect to each of the seven questions: Is there a logical process that defines the development of the strategic plan? The approach used in the workshops followed a well-developed roadmapping technique that provides a logical, well-defined, iterative process that guided the development of the strategic plan. The process is wholly contained within the Materials and Manufacturing Directorate and the Propulsion and Power Directorate of the AFRL and collaboration between the two directorates, but did not include the warfighter, representatives of system program offices, or the AFOSR. Is the strategic plan based on reliable, documentable data and information? The critical input data and information based on USAF needs have been interpreted and expressed as a set of eight FLTCs. There is no evidence that the USAF major commands have been directly consulted to determine USAF needs other than through their participation in the original definition of the FLTCs. Does the strategic plan contain realistic risk assessments? The strategic plan lists relative assessments of payoff, technical competency, technical risk, resource risk, transition opportunity, and FLTC relevance for each of 18 development opportunities. Specificity with respect to how various risks are determined is lacking. Does the strategic plan contain milestones and resource allocations? The strategic plan contains detailed roadmaps, goals, milestones, and associated resource needs for each of the 18 development opportunities and system payoffs that are defined. The linkage to resource (fiscal) needs is less well defined. Does the strategic plan contain an implementation component? The strategic plan does address implementation of the plan using very high level roadmaps. A role for industry is clearly mentioned but left undefined in the strategic plan. Implementation duties and responsibilities for government and academia are not offered as should be done in a well-structured strategy. Does the strategic plan contain an assessment component? The strategic plan does not present the formal section on assessment that is usually found in plans of this type. An oversight advisory board charged with guidance of
OCR for page 115
Materials Needs and R&D Strategy for Future Military Aerospace Propulsion Systems the initiatives recommended in the strategic plan is not discussed in the document. Will the strategic plan accomplish its goals, if properly implemented? The detailed roadmaps do not address the complexity and interconnectedness of the development opportunities and the FLTCs. The plan lacks sufficient recognition of the inadequacy of the flow of new technologies from the AFOSR and other sources. The goals are attainable within the strategic plan as written, but there is a risk of loss of efficiency and the variability of funding and the recognition of opportunities for domestic and global collaboration. 3.6.4 Summary The Air Force has in place a development process and organization that have been used for structural materials R&D in the past and that have produced a series of successful propulsion systems and excellent weapons platforms. Some excellent work is currently under way in both the basic and applied materials R&D areas and in planning; however, these areas address only a small part of the propulsion spectrum. The reduced national emphasis on this technology area is exemplified by a reduction in the budgets of the Materials and Manufacturing and the Propulsion and Power Directorates and by the number of competitive demonstrator engines used to transition advanced materials to new and existing systems and does not appear to be adequate to meet future Air Force needs. The deficiency in meeting the needs is compounded by this reduction in emphasis on propulsion and related materials, the increased requirements generated by the broader missions being defined by the Focused Long Term Challenges, and the growing competitive global systems capabilities resulting from other nations’ focused investments in propulsion materials technology. Of specific concern are areas such as composite-fiber manufacturing in which the United States is entirely dependent on foreign sources for materials for future weapons systems. 3.7 FINDINGS The Materials and Manufacturing Directorate and the Propulsion and Power Directorate of the Air Force Research Laboratory and the AFOSR have cooperated in the past through the institutionalized 6.1, 6.2, and 6.3 funding categories and formal programs such as the IHPTET Program to provide USAF and the U.S. industry a global competitive advantage in propulsion technology and fielded systems; however, the current VAATE Program does not have the same level of industrial competition and funded materials support as in the past, and indications are that future 6.3 demonstrator programs will see further reductions in these areas.
OCR for page 116
Materials Needs and R&D Strategy for Future Military Aerospace Propulsion Systems Finding: Current and future AFRL engine programs will have a decreased level of industrial-base cooperation and materials funding. The transition from basic research to applied research to advanced development to manufacturing technology is not characterized by an executable process but rather is conducted on an ad hoc basis responding to “user pull” and competitive imperatives. Finding: The Air Force has had a formal process for the transition from basic to applied research that may not be directly applicable to the current budget and broadened mission environment. The current planning process of the AFRL Materials and Manufacturing Directorate and Propulsion and Power Directorate recognizes the need for activities in the near term, intermediate term, and far term to address the full spectrum of the Air Force mission, but the expanded scope has put significant pressure on the materials propulsion funding profile. Finding: The current planning process of the AFRL Materials and Manufacturing Directorate and Propulsion and Power Directorate is evolving to address the FLTC approach. The reduction in the number of technology demonstrators has significantly reduced the number of opportunities to demonstrate advanced materials and processes prior to insertion in existing and emerging propulsion systems. Although the number of new systems planned is decreasing, advanced materials are critical in improving existing and emerging propulsion systems. Finding: Advanced materials are critical to further improving existing systems and in developing new systems. Specifically, high-temperature materials are required to increase the compressor exit and turbine inlet temperatures for improved fuel efficiency and high-Mach-number capabilities as identified in the joint planning of the Materials and Manufacturing and the Propulsion and Power Directorates. Finding: The United States has lost its competitive advantage in the areas of attachment of compressor and fan blades using advanced welding processes, super-plastically formed diffusion-bonded hollow fan blades, and some areas of ceramic-matrix composites.
OCR for page 117
Materials Needs and R&D Strategy for Future Military Aerospace Propulsion Systems 3.8 RECOMMENDATIONS Recommendation: The Air Force Research Laboratory’s Materials and Manufacturing Directorate and Propulsion and Power Directorate need to develop a strategy to maintain or regain U.S. preeminence in propulsion materials. The strategy should include the regular review and updating of the directorates’ propulsion materials plan, with an emphasis on the consequences of unfunded items, the changing external environment, and maintaining a balance for the near-, mid-, and far-term activities in response to the Focused Long Term Challenges and funding commitment. Recommendation: The AFRL Materials and Manufacturing Directorate and Propulsion and Power Directorate should increase their communication and collaboration with the AFOSR, system program offices, industry, and academia relative to propulsion materials needs, advances, technology readiness, and the potential systems payoffs of technology insertion. Recommendation: To maintain or regain the U.S. military competitive advantage in the areas of propulsion materials and to keep the United States on the leading edge of propulsion technology, there is a need for advocacy within the Office of the Secretary of Defense/Director, Defense Research and Engineering, to increase activities in new materials development and competitive 6.2 component and 6.3 demonstrator programs. Additional detailed findings and recommendations that are related to the ITAR-controlled plan are provided in restricted Appendix D, the text of which is not releasable to the public.