B

NASA’s Aeronautics Programs

OVERVIEW OF THE FUNDAMENTAL AERONAUTICS PROGRAM

The Fundamental Aeronautics Program is a major part of the Aeronautics Research Mission Directorate (ARMD). The Fundamental Aeronautics Program’s overarching goal is:

To achieve technological capabilities necessary to overcome national challenges in air transportation including reduced noise, emissions, and fuel consumption, increased mobility through a faster means of transportation, and the ability to ascend/descend at very high speeds through atmospheres.1

The National Aeronautics Research and Development Policy of December 2006 and Plan of December 2007 and February 2010 emphasized the importance of air transportation in the United States. A large undertaking in this area has been the Next Generation (NextGen) Air Transportation System by the Joint Planning Development Office (JPDO).

In terms of national defense, the fundamental aeronautics program is concentrated on four additional goals. Two that demand strong focus are to improve rotorcraft and sustained hypersonic flight. The remaining two are supporting roles and are aimed to reduce engine specific fuel consumption and to increase cruise lift to drag. Three goals have been laid out relating to energy and the environment as well. One is to reduce environmental impact, and a second is to increase energy efficiency. The third goal is to determine alternative fuels.2

There are four main divisions of the program. The first is the Subsonic Fixed Wing project, which improves subsonic/transonic transport aircraft in the areas of energy efficiency and the reduction of emissions and noise. The Subsonic Rotary Wing project focuses on increasing the speed, range, and payload of rotary wing vehicles while also reducing noise, vibrations, and emissions in order to improve the transportation system. A third group of the Fundamental Aeronautics Program is the supersonics project, designed to improve cruise efficiency, noise, emissions, performance, and boom acceptability for supersonic vehicles. Hypersonics is the final project of the

________________

1 NASA Fundamental Aeronautics Program, presentation to the National Research Council Committee on NASA’s Aeronautics Flight Research Capabilities, April 20, 2011, Slide 9.

2 NASA, NASA FY2012 Budget Estimate for Aeronautics Research, available at http://www.nasa.gov/pdf/516642main_NASAFY12_Budget_Estimates-Aero-508.pdf, p. 25.



The National Academies | 500 Fifth St. N.W. | Washington, D.C. 20001
Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement



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 75
B NASA's Aeronautics Programs OVERVIEW OF THE FUNDAMENTAL AERONAUTICS PROGRAM The Fundamental Aeronautics Program is a major part of the Aeronautics Research Mission Directorate (ARMD). The Fundamental Aeronautics Program's overarching goal is: To achieve technological capabilities necessary to overcome national challenges in air transportation including re- duced noise, emissions, and fuel consumption, increased mobility through a faster means of transportation, and the ability to ascend/descend at very high speeds through atmospheres. 1 The National Aeronautics Research and Development Policy of December 2006 and Plan of December 2007 and February 2010 emphasized the importance of air transportation in the United States. A large undertaking in this area has been the Next Generation (NextGen) Air Transportation System by the Joint Planning Development Office (JPDO). In terms of national defense, the fundamental aeronautics program is concentrated on four additional goals. Two that demand strong focus are to improve rotorcraft and sustained hypersonic flight. The remaining two are supporting roles and are aimed to reduce engine specific fuel consumption and to increase cruise lift to drag. Three goals have been laid out relating to energy and the environment as well. One is to reduce environmental impact, and a second is to increase energy efficiency. The third goal is to determine alternative fuels. 2 There are four main divisions of the program. The first is the Subsonic Fixed Wing project, which improves subsonic/transonic transport aircraft in the areas of energy efficiency and the reduction of emissions and noise. The Subsonic Rotary Wing project focuses on increasing the speed, range, and payload of rotary wing vehicles while also reducing noise, vibrations, and emissions in order to improve the transportation system. A third group of the Fundamental Aeronautics Program is the supersonics project, designed to improve cruise efficiency, noise, emissions, performance, and boom acceptability for supersonic vehicles. Hypersonics is the final project of the 1 NASA Fundamental Aeronautics Program, presentation to the National Research Council Committee on NASA's Aeronautics Flight Research Capabilities, April 20, 2011, Slide 9. 2 NASA, NASA FY2012 Budget Estimate for Aeronautics Research, available at http://www.nasa.gov/pdf/516642main_NASAFY12_ Budget_Estimates-Aero-508.pdf, p. 25. 75

OCR for page 75
76 RECAPTURING NASA'S AERONAUTICS FLIGHT RESEARCH CAPABILITIES Fundamental Aeronautics Program. The goal of this group is to create technologies and tools needed for air- breathing access to space and other planetary atmospheres. 3 Subsonic Fixed Wing Project The Subsonic Fixed Wing project is the largest project by funding within the Fundamental Aeronautics Program. It has logged millions of flight hours while focusing on two main objectives: (1) to develop prediction and analysis tools in order to reduce uncertainty and (2) to create concepts and technologies to improve noise, emissions, and the performance of the aircraft. These objectives are significant in that they can address demands from NextGen and also improve subsonic air transportation. There are currently 300+ in-house and contracted personnel for the project, with 55+ NASA Research Announcements (NRAs) to academia and businesses as well as various partnerships.4 The stated technical challenge of the Subsonic Fixed Wing project is to explore and develop tools, technolo- gies, and concepts for improved energy efficiency and environmental compatibility for the sustained growth of commercial aviation.5 The environmental challenges include reducing perceived noise and reducing harmful emis- sions. The efficiency challenges include reducing drag through efficient aerodynamics, reducing weight through new lightweight aircraft structures and propulsion systems, and increasing propulsion system efficiencies. Inherent in all of these challenges is the need to improve tools and analysis techniques. Tools being developed under the Subsonic Fixed Wing project such as the Fiber Optic Sensing System will advance the ability to determine the health of new lightweight structures, which will improve overall vehicle per- formance. This capability will be applicable to all flight regimes; however, it has been assigned to the Subsonic Fixed Wing project because it has the greatest opportunity to proceed to flight test under this project. The planned testing of alternative fuels is also a part of the Subsonic Fixed Wing project even though the new fuels should be usable in rotorcraft and supersonic vehicles. Inter-program collaboration with NASA's Aviation Safety Program has been conducted in pursuit of new and more robust control system development. The Subsonic Fixed Wing project is also advocating the Planned Cargo Aircraft Precision Formations for Increased Range and Efficiency program. This project is a collaboration with the Defense Advanced Research Projects Agency Formation Flight Program. Subsonic Rotary Wing Project Helicopters have been used extensively in the military, and now are being used increasingly in civil operations that include medical evacuation, off-seashore exploration, disaster evacuation, and emergency relief operations. A major inhibition for widespread use of helicopters in the civil market is their life-cycle cost (an order of magni- tude higher than that of fixed wing aircraft), which stems from low rotor and propulsion efficiency, high vibratory loads, and unacceptable noise signatures. To increase the structural, aerodynamic, and propulsion efficiencies of the integrated systems, enhancements in rotor aeromechanics in conjunction with variable-speed propulsion system are being explored. A key challenge is to develop robust comprehensive design tools using high-fidelity prediction methodologies.6 The Subsonic Rotary Wing project currently conducts research in support of the Next Generation Air Trans- portation System and the civil sector. In terms of research, three main areas are currently focused on: efficiency, 3 NASA Fundamental Aeronautics Program, presentation to the National Research Council Committee on NASA's Aeronautics Flight Research Capabilities, April 20, 2011, Slide 9. 4 NASA Fundamental Aeronautics Program, presentation to the National Research Council Committee on NASA's Aeronautics Flight Re- search Capabilities, April 20, 2011, Slides 18-19. 5 NASA Dryden Research Center, "Overview," presentation to the National Research Council Committee on NASA's Aeronautics Flight Research Capabilities, April 20, 2011, Slide 116. 6 NASA Fundamental Aeronautics Program, presentation to the National Research Council Committee on NASA's Aeronautics Flight Research Capabilities, April 20, 2011, Slides 20-21.

OCR for page 75
APPENDIX B 77 productivity, and environmental acceptance.7 Efficiency incorporates the structural weight of the rotorcraft as well as the aerodynamics. Productivity includes capabilities for maneuverability, long ranges, large payloads, and high speeds. Finally, environmental acceptance concentrates on noise reduction, among other factors. According to the 2012 Budget Estimate by NASA,8 Fundamental Aeronautics Program leadership has set several specific goals to develop various technologies. One goal is to create variable speed rotor concepts while maintaining propulsion efficiency. This capability will allow the rotorcraft to become more competitive with fixed wing aircraft for short- and medium-duration missions. In order to accomplish this, advanced modeling and concept tools such as oil-free engine gearbox systems, wide-operability engine systems, and efficient, multi/variable-speed drive systems must be generated. A second goal is noise reduction, specifically to reduce internal noise to less than 77 dB and confine external noise to the landing area. The third goal focuses on higher speeds. A 100-knot increase in cruise speed for any rotary wing configuration has been proposed while also maintaining low vibration and low noise. Other goals include technology development for crashworthiness, icing conditions, and a range of maintenance methods. A final objective is to develop rotorcraft analysis and tools based on first-principles modeling instead of empirical methods. This will be done to enable design tools that can be used on any hardware platform as well as on com- parable future developments, which ultimately will lower design cycle costs. A program commitment has been made to validate concepts for reducing internal noise in large, advanced rotorcraft by 2018. Supersonics Project The focus for the Supersonics project is to develop technology to allow for more practical civil supersonic airliners. There are several environmental and efficiency challenges that arise with this goal. One large issue that must be addressed is the supersonic boom noise over land as well as maintaining acceptable noise levels for air- ports. Emissions are also important to reduce in addition to improving fuel burn. A plan must also be produced to integrate supersonic aircraft into existing airspace traffic. 9 A more detailed examination of the Supersonics project is included in the case studies in Chapter 2 of this report. Hypersonics Project The Hypersonics project encompasses a two-fold focus. First is the air-breathing access to space, which incor- porates air-breathing propulsion from Mach 0 to orbit, a reusable, lightweight structure, and integrated vehicle design tools. Second are the entry, descent, and landing in other planetary atmospheres. Required are improved aerothermodynamic tools and the accompanying technologies and concepts associated with this challenge. 10 A more detailed examination of the Hypersonics project is included in the case studies in Chapter 2 of this report. Fundamental Aeronautics Program Flight Research Activities When conducting flight research, the Fundamental Aeronautics Program follows the ARMD guidelines regard- ing external collaborations. These partnerships are crucial to conducting flight research. When key technical chal- lenges are examined that represent significant capabilities for the vehicle flight regimes, a number of questions are posed in order to focus and prioritize the portfolios. The main research tools utilized are analytical/numerical tools that consist of computational fluid dynamics, finite element methods, and high-fidelity simulations; ground testing 7 NASA Fundamental Aeronautics Program, Subsonic Rotary Wing Project, available at http://www.aeronautics.nasa.gov/fap/srw_project.html. 8 NASA, NASA 2012 Budget Estimate, Aeronautics Research: Fundamental Aeronautics Program, available at http://www.nasa.gov/ pdf/516642main_NASAFY12_Budget_Estimates-Aero-508.pdf. 9 NASA Fundamental Aeronautics Program, presentation to the National Research Council Committee on NASA's Aeronautics Flight Research Capabilities, April 20, 2011, Slides 22-23. 10 NASA Fundamental Aeronautics Program, presentation to the National Research Council Committee on NASA's Aeronautics Flight Research Capabilities, April 20, 2011, Slides 24-25.

OCR for page 75
78 RECAPTURING NASA'S AERONAUTICS FLIGHT RESEARCH CAPABILITIES TABLE B.1 Current Projects Under Way Completed Ongoing Planned Subsonic Fixed Wing (SFW) 7 1 2 (FY2005-FY2011) (FY2011) (FY2012+) Subsonic Rotary Wing (SRW) 5 1 1 (FY2007-FY2011) (FY2011) (FY2012+) Supersonics (SUP) 7 10 1 (FY2007-FY2011) (FY2011) Hypersonics (HYP) 2 completed, 1 3 1 launch vehicle loss (FY2011) (FY2008-FY2010) using facilities such as wind tunnels; and flight testing. Flight testing is used to generate knowledge, create and validate tools, and produce quality data that other methods are not capable of producing. Table B.1 summarizes the flight research flight test campaigns.11 Examples of current projects include the testing of sonic booms on large structures, flight testing of the X-51 to demonstrate hypersonic air-breathing-powered flight, rotary wing acoustic flight research, and fixed wing emis- sions flight research. Fundamental Aeronautics Research Budget The FY2012 president's budget allocates $186.33 million to the Fundamental Aeronautics Program; $90.12 million of this amount will support the Subsonic Fixed Wing project, and $43.12 million will go to Supersonics, $28.07 million to Subsonic Rotary Wing, and $25.02 million to Hypersonics. Of the FY2011 resources, 53 percent went to labor, and 18 percent went to each of the categories NRAs and work year equivalent labor. The remaining resources were allocated to discretionary procurements and travel. 12 OVERVIEW OF THE INTEGRATED SYSTEMS RESEARCH PROGRAM The Integrated Systems Research Program is responsible for taking emerging technologies and testing them in an operationally relevant environment. The program's goal is to make the technologies useful to key avia- tion stakeholders. Currently two projects are being operated within the Integrated Systems Research Program, the Environmentally Responsible Aviation project and the Uninhabited Aerial Systems in the National Airspace System project. Environmentally Responsible Aviation Project The Environmentally Responsible Aviation project is made up of three sub-projects: Airframe Technology, Propulsion Technology, and Vehicle System Integration.13 Specific goals have been established to reduce fuel consumption, noise, and specific harmful emissions. The projects goals are time based to field technologies in the 2020 time frame. Additional information on and analysis of the current program are presented as a case study in Chapter 2. 11 NASA Fundamental Aeronautics Program, presentation to the National Research Council Committee on NASA's Aeronautics Flight Research Capabilities, April 20, 2011, Slides 29-30. 12 NASA Fundamental Aeronautics Program, presentation to the National Research Council Committee on NASA's Aeronautics Flight Research Capabilities, April 20, 2011, Slides 14-15. 13 NASA Aeronautics Research Mission Directorate, "NASA Integrated Systems Research Program," available at http://www.aeronautics. nasa.gov/programs_isrp.htm.

OCR for page 75
APPENDIX B 79 Unmanned Air Vehicles in the National Airspace Project Most of the technological issues of the operation of unpiloted aircraft have been overcome. The military and other agencies are using unpiloted vehicles for a number of purposes. Capabilities for performing remote sensing without putting human life at risk are becoming ever more vital. Currently these unpiloted vehicles are flown in restricted airspace or under specific certificates of authorization. The current laws set forth in the Federal Aviation Regulations presume that a human operator will be present in the vehicle to "see and avoid" other aircraft. This project's goal is to demonstrate an integrated system in a relevant environment that will allow for safe operation of an unpiloted vehicle. This demonstration and other experiments will be the basis for updating the regulations to allow for routine operation of unpiloted vehicles in the national airspace. Integrated Systems Research Program Flight Test Activities The two major flight test efforts within the Integrated Systems Research Program are (1) the flight test- ing of the X-48 Blended Wing Body aircraft under the Environmentally Responsible Aviation project and (2) the planned live, virtual and constructive test demonstration of the Uninhabited Aerial Systems in the National Airspace project planned to begin in 2012. Other efforts are being conducted within the other projects that feed into these two efforts. The G-III aircraft being modified to perform distributed roughness elements is currently being modified for flight testing by the Aeronautics Test Program and will test the fundamental understanding obtained from the subsonic fixed wing aircraft project. Additional details are presented in the ERA project case study in Chapter 2. Integrated Systems Research Program Budget The budget of the Integrated Systems Research Program in fiscal year (FY) 2010 was $56.9 million, which funded the Environmentally Responsible Aviation project. The presidential budget request for FY2012 is $104.2 million. This amount is split into the two major projects, with $73.6 million for the Environmentally Responsible Aviation project and $30.6 million for the Unmanned Air Vehicles in the National Air Space project. 14 OVERVIEW OF THE AVIATION SAFETY PROGRAM NASA's Aviation Safety Program has the goal to proactively identify risk and develop new ways of achiev- ing increased safety. The program is conducting foundational research and developing technologies to address an increasingly crowded airspace system and the introduction of new systems like NextGen. Working with industry, academia, and other government agencies to achieve this goal, the program investigates improvements to aircraft systems, including automation and human machine interaction, aircraft structural integrity, environmental haz- ards, and NextGen systems. Within the Aviation Safety Program there are three specific projects: the Atmospheric Environmental Safety Technologies project, the System-wide Safety and Assurance Technologies project, and the Vehicle Systems Safety Technologies project. The long-term scheduling and planning that ARMD must do to remain within tight budgets require that NASA not chase fleeting causes and events. Aviation safety should be the exception to this rule. One of the primary goals of the Aviation Safety Program is to identify risk and work to provide increased safety. The Royal Aeronautics Society, along with the American Institute of Aeronautics and Astronautics, multiple government agencies (the Federal Aviation Administration and National Transportation Safety Board), international agencies, industry, and academic institutions, has teamed to address the number of Loss of ControlIn Flight (LOC-I) accidents such as Air France's Flight 447. ARMD is uniquely capable of supporting efforts such as this because of its world-class simulation capabilities and flight assets. 14 NASA, NASA FY2012 Budget Estimates for Aeronautics Research, available at http://www1gtm.nasa.gov.speedera.net/pdf/516642main_ NASA_FY12_Budget_Estimates-Aeronautics.pdf.

OCR for page 75
80 RECAPTURING NASA'S AERONAUTICS FLIGHT RESEARCH CAPABILITIES Vehicle Systems Safety Technologies The Vehicle Systems Safety Technologies project is focused on safety improvements related to vehicle sys- tems. This goal is achieved through the development of advanced systems and structural prognostics and health monitoring as well as methods to prevent and recover from unsafe flight conditions. The effort to prevent and recover from unsafe flight conditions includes new cockpit design to promote better man-machine interaction and automated recovery systems. System-wide Safety and Assurance Technologies The System-wide Safety and Assurance Technologies project is tasked with the analysis of the entire aviation system, not just a single aircraft. The project studies data from previous incident and mishaps and looks for root causes or other systemic problems. These data are used to predict other possible failures within the system. This includes the increased level of reliance on automated systems and protections, the human element such as fatigue, system and component failure prediction, and enhanced methods of disseminating safety information to stakeholders. Atmospheric Environment Safety Technologies The Atmospheric Environment Safety Technologies project investigates risks inherent in the atmospheric environment that vehicles must operate in, and it develops technologies to fly safe. The majority of this work is focused on the effects of icing on airframes and propulsion systems. Additional research is being conducted on methods to sense and avoid these hazardous conditions. As aeronautics moves to higher speeds and altitudes, the Atmospheric Environment Safety Technologies project can help support the body of knowledge for the environment above 60,000 feet. Industry and other govern- ment agencies need to understand the atmosphere through the diurnal cycle as well as winds and turbulence. The chemical environment is also of interest. The safety of vehicles operating in this region will also be dependent on systems' ability to recover from single-event upsets. Aviation Safety Program Flight Test Activities The majority of flight research within the Aviation Safety Program has been focused on vehicle systems safety and more specifically flight controls technologies. This flight research on flight controls has been performed in two venues--small simple unpiloted aircraft for basic work, and piloted and very complex F/A-18 aircraft. Additional flight research is being conducted within the Atmospheric Environment Safety Technologies project. Aviation Safety Program Budget The Aviation Safety Program budget for FY2010 was $74.0 million. The presidential budget request for FY2012 is $79.6 million. No specific budget allocation between the three projects was presented. A significant number of cost-sharing partners are also contributing to the work being performed under the Aviation Safety Program.15 OVERVIEW OF THE AIRSPACE SYSTEMS PROGRAM Working to make air travel as efficient as possible, the Airspace Systems Program is helping to develop and implement NextGen. As with most NASA programs the work is conducted with industry, academia, and domestic and international government agencies. The goals of the Airspace Systems Program are to reduce aircraft fuel 15 NASA, NASA FY2012 Budget Estimates for Aeronautics Research, available at http://www1gtm.nasa.gov.speedera.net/pdf/516642main_ NASA_FY12_Budget_Estimates-Aeronautics.pdf.

OCR for page 75
APPENDIX B 81 consumption, noise, and emissions; accommodate projected growth in air traffic while preserving and enhancing safety; and maximize flexibility and effectiveness in the use of airports, airspace, and aircraft. 16 NextGen Concept and Technologies Development The NextGen Concept and Technologies Development project is devising methods to increase the efficiency and capacity of the National Airspace System. The project is studying new methods to optimize in-route flight plans and departure and arrival procedures. These new methods must also account for the effects of weather and other dynamic changes to the airspace. Concepts are also being developed to improve the efficiency and safety of surface operations. NextGen Systems Analysis, Integration and Evaluation The NextGen Systems Analysis, Integration and Evaluation project is an independent test organization for solu- tions proposed by the NextGen Concept and Technologies Development project. The project uses systems analysis and simulation techniques to demonstrate the viability of NextGen concepts. This project is also responsible for the eventual flight demonstrations and evaluations of these systems. Airspace Systems Program Flight Test Activities Flight research within the Airspace Systems Program is limited. The majority of the work is being conducted in sophisticated simulation facilities. As work progresses there are flight activities to verify and validate the new technologies developed. The Airspace Systems Program is planning an integrated test utilizing many aircraft per- forming normal operations within the national airspace. To do this the program is looking to partner with one or more air carriers that have already equipped their aircraft fleet with Automatic Dependent Surveillance-Broadcast equipment. Airspace Systems Program Budget The FY2010 budget for the Airspace Systems Program was $79.0 million. The budget requested in FY2012 is increased to $92.7 million. The projected budget in the years FY2013 to FY2016 shows a steady decline. 17 It is surprising that this budget decease would occur during the period that is expected to include flight testing activities. This decline will require that partners provide the majority of funds for the flight research activities. OVERVIEW OF THE AERONAUTICS TEST PROGRAM The Aeronautics Test Program (ATP) does not conduct flight research; however, it does make it possible for the other programs within ARMD to conduct both ground and flight testing. ATP is largely responsible for the operations and maintenance of ground test facilities such as wind tunnels but is also charged with providing ground-based mission control rooms for flight test activities. This program is responsible for the maintenance of the fleet of NASA aircraft; as such its responsibility is in large part to provide support to mission directorates within NASA. ATP is also involved in the preparation of aircraft for flight test. For example, ATP is currently modifying newly acquired F-15Ds to replace the NASA F-15Bs. ATP also operates flight simulators for pilot training and 16NASA Aeronautics Research Mission Directorate, "Airspace Systems Program," available at http://www.aeronautics.nasa.gov/ programs_asp.htm. 17 NASA, NASA FY2012 Budget Estimates for Aeronautics Research, available at http://www1gtm.nasa.gov.speedera.net/pdf/516642main_ NASA_FY12_Budget_Estimates-Aeronautics.pdf.

OCR for page 75
82 RECAPTURING NASA'S AERONAUTICS FLIGHT RESEARCH CAPABILITIES rehearsals and the flight loads laboratories, which are used to test aircraft structures and structural instrumentation prior to flight testing. Flight Operations and Test Infrastructure ATP is the major support organization for all of ARMD and also contributes its test and operations capa- bilities to other NASA mission directorates. ATP is responsible for the operation of ground support capabilities such as simulation facilities, wind tunnels, flight loads labs, and the flight test mission control centers. ATP also provides the mission support fleet of aircraft to meet customer needs, and research aircraft support. Aeronautics Test Program Flight Test Activities Although the primary objective of ATP is to operate ground test facilities, it also is involved in flight activi- ties. These flight activities are located primarily at the Dryden Flight Research Center and include the operation of the Western Aeronautical Test Range, and numerous support and testbed aircraft. Used to provide safety chase and video and photo documentation, the support aircraft fleet includes F/A-18, T-38, T-34C, B200 King Air, and other aircraft. The testbed aircraft fleet includes F/A-18, F-15B, ER-2, G III, Global Hawks, and other aircraft. A more detailed list of NASA aircraft is presented in Appendix A. Aeronautics Test Program Budget The Aeronautics Test Program has a proposed budget for FY2012 of $79.4 million of ARMD's $569.4 mil- lion.18 ATP's FY2010 budget was $65.6 million. 18 NASA, NASA FY2012 Budget Estimates for Aeronautics Research, available at http://www1gtm.nasa.gov.speedera.net/pdf/516642main_ NASA_FY12_Budget_Estimates-Aeronautics.pdf.