外文文献

Aeronautical Technologies for the 21st Century
1. introduction
Throughout the latter half of this century the U. S. aeronautics industry has been one of the undisputed success stories in global competitiveness. From the end of World War II into the last decade, U. S. aircrafts, engines, and parts have been among the leaders of, and in most cases have dominated, both the domestic and the foreign markets for subsonic transports, general aviation, commuter, and military aircraft. The buildup of the global transportation infrastructure (i. e. , airports and air traffic management systems) has also been driven by U. S. technology and products. The aeronautics industry IS the largest positive industrial contributor to the U. S. balance of trade, plays a vital role In maintaining the safety and convenience of air travel throughout the world, and provides important contributions to the defense of U. S. interests. Further, U. S. aircrafts are flown in even the most remote parts of the world, engendering national pride and international prestige. The importance that foreign governments ascribe to developing their domestic aeronautics industries IS evidence of the perceived benefits from a strong aircraft industry. Europe and the Pacific rim countries have spawned numerous government and industry consortia aimed at producing aircraft and components across the entire range of the market. The European consortium, Airbus Industries, has moved into second place in the market for commercial transport aircraft, while the emerging Asian aircraft industries have begun to forge alliances with the two dominant U. S. companies, Boeing and McDonnell Douglas. Foreign interests dominate the commuter aircraft industry and are making roads into the general aviation market. European and Far Eastern nations have begun to apply significant effort toward developing the technological base needed to compete even more effectively over t he next several decades. The inference is obvious-these nations believe it is in their national interest to maintain a healthy, broad-based domestic aircraft industry. In keeping with the charter of the National Aeronautics and Space Administration (NASA) to preserve 'the role of the United States as a leader in aeronautical technology.' NASA's Office of Aeronautics and Space Technology asked the Aeronautics and Space Engineering Board of the National Research Council to assist in assessing the current status of aeronautics in the United States and to help identify the technology advances necessary to meet the challenges of the next several decades. The Neronautics and Space Engineering Board established the Committee on Aeronautical Technologies, which defined an approach to helping NASA determine the appropriate level and focus of its ncar-term technology devlopment efforts to maintain a leadership role in the years 2000-2020. The Committee discussed the transportation infrastructure that would likely exist in 2 020. From this. an estimate was made of the types and capabilities of aircraft required to

compete in the global market in the 2000-2020 time frame. Based on these projections, the Committee identified the high-leverage technologies that offer the most significant advances in aerona u tics to ensure long-term competi t i veness for U. S. ai rcrnf t s. engll1es, and components. and to enhance performance and safety in the total air transportation system.

2. The Technological Challenge
The fact that U. S. market share in aeronautics is eroding is well documented and is discussed in detail. The ultimate cause of eroding market share is that. for a variety of reasons. foreign competitors are able to market products that have lower total ownership costs than U. S. products. This can be achieved. for example. through implementation of new technologies t ha t reduce long-term opera ti ng costs. or through prod uct s t ha t en ter the market with significantly lower purchase price. This presents a challenge to the industry and to the U. S. government. U. S. aircrafts, engines, and parts manufacturers must improve the quality. capability. and timeliness of their products, at reduced cost. to maintain or increase their market share. Without advanced technology. market share will certainly be lost. but advanced technology cannot. by itself. ensure competitive products. Foreign governments have undertaken determined. coordinated efforts to compete 111 all sectors of the market from general aviation through supersonic aircraft, and in most cases they have been successful. In terms of the current impact on the U. S. industry, this attack is most visible in the subsonic transport market that has historically been dominated by Boeing. Lockheed. and McDonnell Douglas. This segment of the market generates the highest revenues for aircrafts, engines, and parts manufacturers. A long and successful history does not imply that there are no significant future gains to be realized. McDonnell Douglas and Boeing project a potential growth of I trillion passcnger-miles each decade to 2 trillion in the year 2000, and 4 trillion by 2020. most of which will be carried on advanced subsonic transport aircraft. Such estimates indicate that technical advances resulting in increased range and safety. and reduced fuel consumption, noise, and emiSSions can have significant effects on the competitive posture of the nation that produces them. Although increased research into advanced subsonic aircraft technologies is needed to bring about a near-term competitive advantage, without continued resources applied to the environmental and economic viability of supersonic aircraft, U. S. participation in that important future market may be forfeited. Similarly, advances in the technology of the global air traffic management (ATM) system can reduce congestion both in the air and on the ground, and make traveling by air safer and easier for everyone.

3. Needs for the Future
The Committee identified seven needs that must be addressed by the U. S. aeronautics community, including. ASA. the Federal Aviation Administration (FAA), aircraft manufacturers, and air carriers. if the United States is to maintain or increase its share of the global aircraft market: lower cost and greater convenience, greater capacity to handle passengers and cargo, reduced environmental impact, greater aircraft and ATM system safety, improved aircraft performance. more efficient technology transfer from I ASA to industry, and reduced product developr.nent times. Neither the Committee's charter nor its makeup allowed detailed consideration of the latter two needs, so these are not discussed in detail. The remaining five are discussed below in terms of the needs of industry and the nation. (l) Lower cost/greater convemence: Generally, people choose air travel over automobile, bus, ship, or rail because their desire for shorter trip times justifies the cost. Also, in many cases, air travel is the only choice, so that if the cost is excessive the potential traveler does not make the trip. To open new markets in developing nations and to expand current markets, the cost of the service must remain low enough to maintain that justification. Furthermore, the level of convenience of the service must not be compromised such that passengers In existing markets are driven to other forms of transportation. In short, advances in the speed, range, or payload of the various classes. of aircraft must not be accompanied by large increases in cost or degradation of service. Thus, greater fuel effi'ciency and reduced operational costs must be vigorously pursued, and increases in airport and ATM system capacity must not come at the expense of convenience. (2) Greater capacity to handle passengers and cargo: A major factor that may Impose a ceiling on the ability of the aviation industry to respond to the growing demand for air travel is airport and ATM system capacity. Where local restrictions allow, it is simplest to build more airports and runways. However, this is not possible in most cases. Rather, to open u;) new markets or to expand existing markets, it is imperative that both the ATM system and the existing airports be capable of dealing with more people and packages flying on more and different kinds of aircraft. Safe reductions in aircraft separation, better real-time weather reporting, and facilities for a wide variety of long-and short-range aircraft all contribute to the ability to move more people and cargo through the system, and thus to the growth of both the industry and the economy. (3) Reduced environmental impact: The impact of aircraft on the environment IS a limiting factor on the growth of the industry. Aircraft nOise restrictions limit the proximity of airports to major population centers, the utility of rotorcraft within cities, and the potential for supersonic flight over land. In addition, a change in the ozone level that

results from the emission of nitrogen oxide and hydrocarbons by aircraft is an area of growing cmcern that may, in the near future, limit the number and types of aircraft that fly over the United States and other environmentally conscious countries. (4) Greater aircraft/ATM system safety: As more planes takeoff and land each year, it is vital that the rate of accidents continues to decrease to avoid the perception that air travel is unsafe. (5) Improved aircraft performance: Advances in performance of conventional subsonic aircraft. rotorcraft, short takeoff and landing aircraft, and supersonic aircraft will enable more viable expansion into new markets and expansion of existing routes. (6) The Committee grouped advanced aircraft into three classes, within which recommendations were prepared that cut across specific technologies: advanced subsonic transport aircraft; high-speed civil transports (HSCTs), the next generation of supersonic transports; short-haul aircraft (commuters, rotorcraf t, and general aviation aircraft). Similarly, the Committee identified five generic disciplines that encompass the technologies that will provide the greatest overall benefi t toward meeting future needs: ① aerodynamics, ② propulsion, ③ materials and structures, ④ avionics and controls, and ⑤cognitive engineering. On October 29th, 2002, Forum on Aeronautical Engineering Science and Technology sponsored by Division of Mechanical and Vehicle Engineering of CAE was convened in Beijing Science &. Technology Hall. The theme is 'Achievement and Prospectus of China's Aeronautical Engineering. ' The forum was presided by Academician Gu Songfen and Liu Daxiang of CAE in turn. Academician Gu Songfen briefed the history of aeronautical engineering in nearly 100 years, praised the achievement of China's aeronautical engineering in recent years, and expounded the significance of this forum. Then, Researcher Ni Xianping and Yin Zeyong, Professor Fan Wei, Researcher Li Likun, Academician Zhang Yanzhong, Associate Professor Chen Yong, Senior Engineer Su Muhuai, Professor Li Yinghong delivered speeches on 'Development and Contemplation of Helicopter Technology', 'Vigorously Strengthen the Development of Medium &. Small Aero Engine Technology in China', ' Latest Development of Research of New Concept Pulse Knocking Engine', 'Status, Orientation and Strategy of Air-to-Air Missile', 'Status of Research of Intelligent Structural System of Aircraft', 'Research and Application of Hum.an Factor of Civil Aviation', 'Development of Tableland Aeronautical Engineering', etc.