Maintaining U.S. Leadership in Aeronautics Breakthrough Technologies to Meet Future Air and Space Transportation Needs and Goals (1998) / Chapter Skim
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3 Air Vehicle Technology
3 Air Vehicle Technology
Pages 33-52
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From page 33... ...
However, it will be difficult to meet the aggressive NASA goals (in terms of both vehicle attributes and timing) for air transportation cost, efficiency, and environmental compatibility with traditional transport aircraft configurations because they are already highly optimized in design.
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From page 34... ...
Advanced configurations could have a major impact on reducing the cost of air travel and improving the aviation system throughput and could enable the development of a high-speed civil transport aircraft that would reduce travel time to the Far East and Europe. embedded sensors and controls-intelligent gas turbine engines that can control aeroacoustic, aerodynamic, aerothermodynamic, and aeromechanical instabilities, and aircraft with embedded active control systems for controlling {gads, reducing drag, and monitoring health.
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From page 35... ...
Advanced Air Vehicle Configurations This first technology area involves exploring new vehicle design concepts that are based on the overarching necessity for the total integration of component technologies in the development of air vehicles. In addition to benefits, most new technologies create penalties, such as increases in weight or cost or decreases in reliability.
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From page 36... ...
Although both of these concepts look promising, the adoption of either one as a commercial transport aircraft is unlikely until their viability can be proven under actual flight conditions. Existing air transportation system rules would also have to be modified to accommodate the operating procedures these new configurations would require.
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From page 37... ...
Source: The Boeing Company Drag Reduction Technologies Meeting the goal of establishing supersonic air travel at current subsonic travel prices will require improvements in aerodynamic performance through the reduction of drag. Some concepts, such as the generation of a weak plasma flow field to weaken shock strength and ~aminar flow control, have been shown to have some benefit, but they have not been adopted for use on commercial aircraft because of uncertainties about their costs versus their potential benefits.
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From page 38... ...
23 20% higher 4 x 63,600 3 x 61,900 27% lower Thrust/VVeight ratio 0.262 0.226 Thrust specific fuel 0.466 0.466 consumption a Fair comparisons between the BWB and existing commercial transport aircraft are theoretical because no 800 passenger airliners are currently operating. Aeroclynamic/Propu/sive integration One way to explain the potential benefits of airframe/propuIsion integration is to consider the phenomena of flight using the surrounding air as the frame of reference rather than the air vehicle.
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From page 39... ...
In general, acivancecl configurations represent high-risk technologies with potentially high payoffs. Embedded Sensors anc' Controls Embedding sensors and actuators in the subcomponents of air vehicles, such as the airframe structure and the gas turbine engine, will allow many physical properties to be monitored and controlled in a manner that would improve performance and reliability and should advance NASA's air transportation goals.
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From page 40... ...
The worcis "c~osecl-~oop feedback" imply a range of possibilities, inclucling concepts such as designing engine operation to maximize life, monitoring engine conditions to enable retirement for cause, and actively controlling aerodynamic and aeromechanica~ instabilities, such as surge, rotating stall, flutter, main combustor instability, and instabilities associated with after-burner systems. In addition, intelligent gas turbine engines have the potential to reduce noise, either through active noise control or through the direct management of noise sources, perhaps by tailoring rotor wakes.
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From page 41... ...
The development of embedded sensors and controls in air vehicles and components could further a number of NASA's air transportation goals. Better health monitoring, more efficient servicing, and improved performance cou~cl leacl to reduced operating costs and increased safety.
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From page 42... ...
The structural weight fraction of transport aircraft airframes has remained fairly constant over the past 30 years, not because of a lack of progress in structural technology, but because other aircraft components have also benefited from advanced technologies and have maintained their weight fraction values. Engineered materials may offer solutions for continued advancements in airframe structures Engineered materials are specially designed combinations of materials, either in solution (alloys)
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From page 43... ...
High-temperature materials for supersonic engines and airframes could also contribute to meeting NASA's goal of reduced travel time. Advanced Propuision and Power The development of advanced power and propulsion systems will have an impact on achieving NASA's air transportation goals for emissions, noise, safety, air travel cost,
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From page 44... ...
The TWA Flight 800 tragedy has raised concerns about the flammability limits of conventional hydrocarbon fuels, such as Jet A To address these safety concerns, advanced formulations of existing aviation fuel types specifically tailored to achieve appropriate flammability limits should be explored.
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From page 45... ...
However, at high altitude, the power density differences are greatly diminished because fuel cells can retain their power generating capacity at altitude. Furthermore, the chemical power conversion efficiency of fuel cells is about twice as high as the thermodynamic power conversion efficiency of standard propulsion systems.
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From page 46... ...
Production quantities in aviation typically limit what can be achieved through economies of scale, but as automated manufacturing equipment becomes less specialized and more versatile, it is possible to foresee breakthroughs that allow small production runs to benefit fully from automation, without exacting the enormous cost of specialized automation equipment. Lower aircraft purchase costs resulting from low-cost manufacturing should contribute to NASA's goal of reducing the cost of air travel.
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From page 47... ...
NASA can support the integration of manufacturing into the whole air vehicle production and development process by investigating automated fabrication processes, such as manufacturing by light and high-ve~ocity machining, that could directly link design databases to finished assemblies. Automated Manufacturing Processes Labor and associated overhead are the two largest elements in the cost of airframes which in turn is a major factor in the costs of aircraft and air travel.
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From page 48... ...
The benefits for large titanium parts include substantial reductions in material cost, machining cost, first-article time, and cycle time. Parts made with other advanced metallic materials, if developed, could also be produced using this fabrication process, which could reduce material costs and machining costs.
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From page 49... ...
Lower aircraft purchase costs resulting from low-cost manufacturing are necessary for the achievement of NASA's goals of reducing the cost of air travel and reinvigorating the general aviation industry. Lean manufacturing, and automated manufacturing through techniques such as automated and high-ve~ocity machining of parts, sheet metal assembly, and manufacturing by fight, should be investigated.
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From page 50... ...
improving Mocle/s for Propu/sion System Design The design-to-deve~opment process for a jet engine is not only expensive, but also time consuming. It typically takes up to a year longer than the design-to-cleve~opment cycle for an entire commercial transport aircraft.
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From page 51... ...
Finding. To reduce the costs and shorten the development cycle for future air vehicles with performance characteristics that meet NASA's air transportation-relatecl goals, substantial improvements will have to be made in computer-based design, modeling, and simulation.
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From page 52... ...
1997. Potential Breakthrough Technologies, Propulsion Research at the Gas Turbine Laboratory, MIT.
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