r I I 2 00/Z20/03 NASA/TM-2001-210564 S 5lf'<f5 LCfj ( I I ~ Innovative Airbreathing Propulsion Concepts for Access to Space Woodrow Whitlow, Jr., Richard A. Blech, and Isaiah M. Blankson Glenn Research Center, Cleveland, Ohio I i :::::J October 2001 The NASA STI Program Office ... in Profile Since its founding, NASA has been dedicated to • CONFERENCE PUBLICATION. Collected the advancement of aeronautics and space papers from scientific and technical science. The NASA Scientific and Technical conferences, symposia, seminars, or other Information (STI) Program Office plays a key part meetings sponsored or cosponsored by in helping NASA maintain this important role. NASA The NASA STI Program Office is operated by • SPECIAL PUBLICATION. Scientific, Langley Research Center, the Lead Center for technical, or historical information from NASA's scientific and technical information. 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Blankson Glerul Research Center, Cleveland, Ohio Prepared for the Novel Aero Propulsion Systems International Symposium sponsored by the Institution of Mechanical Engineers London, England, September 3-4, 2000 National Aeronautics and Space Administration GlelU1 Research Center October 2001 This report contains preliminary findings, subject to revision as analysis proceeds. Trade names or manufacturers' names are used in this report for identification only. This usage does not constitute an official endorsement, either expressed or implied, by the National Aeronautics and Space Administration. Available from NASA Center for Aerospace Information National Technical Information Service 7121 Standard Drive 5285 Port Royal Road Hanover, MD 21076 Springfield, VA 22100 Available electronically at http: //gltrs.grc.nasa.gov I GLTRS Innovative Airbreathing Propulsion Concepts for Access to Space Woodrow Whitlow Jr.,* ruchard A. Blech, and Isaiah M . Blankson National Aeronautics and Space Administration Glenn Research Center Cleveland, Ohio 44135 Abstract The National Aeronautics and Space Administration (NASA) Glenn Research Center (GRC) is actively involved in the research of new air-breathing propulsion systems for access to space. The rationale for using air-breathing propulsion is discussed. Several categories of propulsion systems are described, including rocket-based and turbine-based combined cycles. CUlTent research in these areas at GRC is highlighted. Introduction The current cost to launch payloads to low earth orbit (LEO) is approximately 10000 U.S. dollars ($) per pound ($22000 per kilogram). This high cost limits our ability to pursue space science and hinders the development of new markets and a productive space enterplise. This enterprise includes NASA's space launch needs and those of industry, universities, the military, and other U.S. government agencies. NASA's Advanced Space Transportation Program (ASTP) proposes a vision of the future l where space travel is as routine as in today's commercial air transportation systems. Dramatically lower launch costs will be required to make this vision a reality. In order to provide more affordable access to space, NASA has established new goals in its Aeronautics and Space Transportation plan. These goals target a reduction in the cost of launching payloads to LEO to $1000 per pound ($2200 per kilogram) by 2007 and to $lOO 's per pound by 20252 while increasing safety by orders of magnitude. Several programs within NASA are addressing innovative propulsion systems that offer potential for reducing launch costs. Various air-breathing propulsion systems currently are being investigated under these programs. The NASA Aerospace Propulsion and Power Base Research and Technology Program supports long-term fundamental research and is managed at GRC. Currently funded areas relevant to space transportation include hybrid hyperspeed propulsion (HHP) and pulse detonation engine (PDE) research. The HHP Program currently is addressing rocket-based combined cycle and turbine-based combined cycle systems. The PDE research program has the goal of demonstrating the feasibility of PDE-based hybrid-cycle and combined cycle propulsion systems that meet NASA's aviation and access-to-space goals. The ASTP also is part of the Base Research and Technology Program and is managed at the Marshall Space Flight Center. As technologies developed under the Aerospace Propulsion and Power Base Research and Technology Program mature, they are incorporated into ASTP. One example of this is rocket-based combined cycle systems that are being considered as part of ASTP. NASAlTM-2001-210564 J The NASA Ultra Efficient Engine Technology (UEET) Program has the goal of developing propulsion system component technology that is relevant to a wide range of vehicle missions. In addition to subsonic and supersonic speed regimes, it includes the hypersonic speed regime. More specifically, component technologies for turbine-based combined cycle engines are being developed as patt of UEET. Airbreathing Propulsion for Launch Vehicles The use of air-breathing propulsion for launch vehicles can result in significant weight savings. This is due to the fact that oxygen from the atmosphere is utilized to reduce the amount of oxidizer that the vehicle must CatTy. The oxidizer weight savings then can be reinvested in a more robust vehicle structure and increased payload capacity. It should be emphasized that the propulsion system itself should be as robust as possible, since reusability is a key requirement for reducing space transportation costs. Figure I shows the performances of various propulsion systems as a function of Mach number. The performance parameter is specific impulse, which is defined as the propellant weight flow specific thrust. Note that air-breathing propulsion systems (i.e., turbojet, ramjet, scratnjet) generally perform better than pure rocket systems. 5000 RAMJETS (VARIABLE , / . GEOMElRY) 4000 -==. ··'·i" :. 3000 SPECIFI C IMPULSE, sec 2000 1000 HYDROGEN HYDROCARBON o 2 4 6 8 10 12 MACH NUMBER Figure 1. Performance vs. mach number for various propulsion systems. The Orbital Sciences Corporation already is using an air-breathing propulsion system in its Pegasus launch vehicle. The Pegasus is a winged, three-stage, solid rocket booster that is deployed from a L-lOll jetliner. Thus, the jet engines of the L-IOll provide air-breathing propulsion for the first part of the Pegasus trajectory (about Mach 0.8 and 39,000 feet). It would be more efficient, however, if the airbreathing propulsion system were more closely integrated with the launch vehicle. A highly integrated airframe-propulsion system also is required if the air-breathing propulsion system is utilized at higher Mach numbers. NASAfTM-2001-210564 2 ---------------- - --- ------ There are many airbreathing propulsion cycles that can be considered for a reusable launch vehicle. Extensive system studies have been performed by NASA Langley to evaluate several candidates.3 The design and evaluation of a particular cycle must be done in conjunction with the airframe design, and an iterative design and analysis process is required as shown in Figure 2. The process starts from the left with a preliminary vehicle and propulsion definition that is based on the mission requirements. Various analysis steps follow, including a full evaluation of perfOlmance over the complete flight trajectory. Analysis then is