Future Air Force Needs for Survivability (2006) / Chapter Skim
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3 Technological Setting
3 Technological Setting
Pages 32-57
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. It also indicates R&D needed for longer-term opportunities and programs for air vehicles in the 2025 IOC time frame and beyond.
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The F-22 uniquely combines high degrees of stealth, supercruise, situation awareness, and maneuverability for survivability. near-term technology needs Higher flight speeds add complexity to the design process because of the need to increase the high-speed aerodynamic efficiency of the platform while still meeting signature requirements.
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Application of the morphing materials and concepts to a swing-wing design may provide the strike aircraft designer with the best of both worlds -- a wing that can assume the low-sweep aerodynamics desired for takeoff, landing, cruise, and maximum persistence, as well as sweep-back to create the long continuous lines desired for a stealth design combined with efficient supersonic cruise that further enhances survivability. Evolving operational requirements demand the careful consideration of proven variable-aerodynamic design techniques to address future threat scenarios effectively.
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Sensor performance requirements for range, resolution, and processing speed can also be significantly increased by increasing speed. In addition to onboard sensors, future aircraft systems will require the reception of Global Positioning System signals and continuous communications capabilities.
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The hot section will operate for extended periods at near-maximum flow-path temperature, meaning not only that oxidation and/or erosion will be a limiting factor, but also that component creep will become a more prevalent design consideration. Air vehicle thermal management is a challenge for today's advanced aircraft systems and will be even more so for the next generation of long-range strike aircraft.
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An alternative approach to a ramjet or scramjet system is an all-rocket propulsion system, which can be either single-stage or multiple-stage. Solid rocket propulsion technology is highly mature and little development risk exists, but the limited specific impulse of solid rocket systems results in shorter ranges for volumeconstrained systems compared with air-breathing systems.
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Meeting future aircraft range and loiter requirements will require engines with much improved fuel-consumption characteristics. Improved component aerodynamics and sealing to reduce parasitic leakage will be
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While this issue is not specific to the question of speed and stealth, future aircraft systems will be
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If an engine can be built to fully utilize the efficiency gains of the constant volume cycle, relatively large gains in propulsion system efficiency and performance, which are application-dependent, can be realized. Expendable PDEs for supersonic missiles have the potential to operate at speeds approaching hypersonic, and they integrate well into small, space-constrained high-speed weapons currently under evaluation by the Air Force and the Navy.
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3-1 specified mission leads to larger air vehicles, larger propulsion systems, and increased signatures. Alternatively, a high-speed missile hosted on a standoff air platform may handle the same mission as a gravity weapon dropped from a stealthy air vehicle that is capable of persisting in a high-threat environment.
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has been investigating high-speed missile technologies to enable a 5National Research Council, Review and Evaluation of the Air Force Hypersonic technology Program, National Academy Press, Washington, D.C., 1998. 6United States Air Force Scientific Advisory Board, why and whither Hypersonics Research in the US Air Force, SAB-TR-00-03, HQ USAF/SB, Washington, D.C., December 2000.
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: Lockheed Martin Corporation. broader range of options, as illustrated in Figure 3-2.
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Technology gaps currently exist in improved payload effectiveness, robust techniques for the deployment of submunitions at supersonic speeds, and high-temperature RAM.
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Countermeasures Countermeasures may be active, passive, or self-defensive in nature. Active countermeasures include missiles that home in on enemy radars and the electronic jamming of enemy integrated air defense systems (IADSs)
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There is more than one reason why IR sensors might be used in the ground elements of an IADS. The Air Force should continue to be concerned about the improvement of aircraft-based sensors that have been employed by the United States and by foreign airborne interceptors for decades.
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If these threats begin to emerge, the Air Force should design and demonstrate countermeasures well ahead of their needs in the force. Situation Awareness A maxim of aerial warfare is that the side with the best situation awareness (SA)
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8 FUtURE AiR FoRCE nEEdS FoR SURViVABilitY Some of the requirements associated with improving SA to meet the needs of the next-generation strike aircraft are the following: · Multisensor data and information fusion; · Expanded databases on all IADS elements; · Cross-sensor cueing; · Mobile networks that are trusted and/or secure, wideband, and self-forming; · Apertures and processors compatible with the stealth and speed design; and · Improved sensor aperture integration with advanced sensing modalities. near-term technology needs Commercial off-the-shelf technologies and government off-the-shelf technologies can provide some of the near-term technologies needed for the next-generation survivable aircraft.
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The committee believes that future air vehicles, when coupled with excellent SA, will continue to be survivable and effective against evolving threats. Systems Engineering Approach Required for Program Success The success that the United States has enjoyed in fielding low-signature vehicles depended on the systems engineering approach developed and executed by U.S.
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As discussed in the next chapter, higher speed allows a design with less stringent signature requirements for equivalent susceptibility. This is clear from first-order analyses; however, higher-speed designs require more detailed and careful trade-off studies considering all frequencies projected for future IADSs as well as the influence of air vehicle configuration changes on the angular dependence of the signature.
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Some of those aircraft have been fitted with infrared surveillance and tracking sets to aid in the acquisition, identification, and tracking of opposing aircraft. The roles, capabilities, and limitations of IR sensors in ground-based air defense systems are not so well characterized or understood.
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The committee believes that the Air Force should hedge against the possibility that future asymmetric threat responses will involve exploitation of visual signatures, by thorough assessment of the potential utility and development of CCM technology and concepts. Visual signature control continues to be an area that should be considered for future development.
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Further assessment of this potential threat is merited at all flight speeds. TECHNOLOGY FEASIBILITY ANALYSIS Signature Technology Matrix Readiness Versus Speed The committee assessed the readiness and potential of the technologies that impact signature across a speed regime from subsonic to speeds approaching hypersonic.
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SUMMARY OF SIGNATURE TECHNOLOGY READINESS From a high-level perspective, several general conclusions can be drawn from the assessment, as follows: · As vehicle Mach number approaches the hypersonic region and temperatures rise, fewer signature control technologies are suffi ciently mature to support an air vehicle development program that would meet a 2018 IOC. In the lower supersonic region, there are no major outstanding airframe issues associated with achieving the RCS signature levels required, and the airframe technology is mature enough for a 2018 IOC.
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With increasing speed, this expected signature growth is attributed to higher material temperatures coupled with the need for configuration changes, including those of inlets and nozzles. ONGOING RESEARCH AND DEVELOPMENT PROGRAMS Current R&D programs associated with high-speed vehicle development, initiated under the National Aerospace Initiative of the Director, Defense Research and Engineering, were reviewed.
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For sustained flight at supersonic speeds, temperature limits for signature control technologies should be extended. Additional research is needed on RF signature control technologies capable of sustained operation at elevated temperatures for high-temperature leading-edge materials, exhaust coatings, and engine seals.
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If future aircraft systems carry advanced directed-energy systems, lightweight power-generation systems and advanced thermal balance techniques beyond the present state of the art will be required. For weapons, needed areas of investigation include propulsion and airframe miniaturization technologies, novel seekers for enhanced target recognition, and advanced fuels, as well as issues arising from the specific type of warhead carried.
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