| 词条 | Boeing 757 | ||||||||||||||||||
| 释义 |
The Boeing 757 is a mid-size, narrow-body twin-engine airliner that was designed and built by Boeing Commercial Airplanes. It is the manufacturer's largest single-aisle passenger aircraft and was produced from 1981 to 2004. The twinjet has a two-crew member glass cockpit, turbofan engines of sufficient power to allow takeoffs from relatively short runways and higher altitudes, a conventional tail and, for reduced aerodynamic drag, a supercritical wing design. Intended to replace the smaller three-engine 727 on short and medium routes, the 757 can carry 200 to 295 passengers for a maximum of {{Convert|3150|to|4100|nmi|km|lk=in}}, depending on variant. The 757 was designed concurrently with a wide-body twinjet, the 767, and, owing to shared features, pilots can obtain a common type rating that allows them to operate both aircraft. The 757 was produced in two fuselage lengths. The original {{nowrap|757-200}} entered service in 1983; the {{nowrap|757-200PF}}, a package freighter (PF) variant, and the {{nowrap|757-200M}}, a passenger-freighter combi model, debuted in the late 1980s. The stretched {{nowrap|757-300}}, the longest narrow-body twinjet ever produced,[1] began service in 1999. Passenger {{nowrap|757-200s}} have been modified to special freighter (SF) specification for cargo use, while military derivatives include the C-32 transport, VIP carriers, and other multi-purpose aircraft. Private and government operators have also customized the 757 for research and transport roles. All 757s are powered by Rolls-Royce RB211 or Pratt & Whitney PW2000 series turbofans. Eastern Air Lines and British Airways placed the 757 in commercial service in 1983. The narrow-body twinjet succeeded earlier single-aisle airliners, and became commonly used for short and mid-range domestic routes, shuttle services, and transcontinental U.S. flights. After regulators granted approval for extended flights over water (ETOPS) in 1986, airlines also began using the aircraft for intercontinental routes. Major customers for the 757 included U.S. mainline carriers, European charter airlines, and cargo companies. The airliner has recorded eight hull-loss accidents, including seven fatal crashes, {{as of|2015|09|lc=y}}.[3]Production of the 757 ended in October 2004, after 1,050 had been built for 54 customers. The {{nowrap|757-200}} was by far the most popular model, with 913 built. Diminished sales amid an airline industry trend toward smaller jetliners led Boeing to end production without a direct replacement, in favor of the 737 family. The last 757 was delivered to Shanghai Airlines in November 2005. In July 2017, 666 of the narrow-body twinjets were in airline service; Delta Air Lines was the largest operator with 127 aircraft.[2] DevelopmentBackgroundIn the early 1970s, following the launch of the wide-body 747, Boeing began considering further developments of its narrow-body 727 trijet.[3] Designed for short and medium length routes,[4] the three-engined 727 was the best-selling commercial jetliner of the 1960s and a mainstay of the U.S. domestic airline market.[3][5] Studies focused on improving the 189-seat {{nowrap|727-200}}, the most successful 727 variant.[9] Two approaches were considered: a stretched {{nowrap|727-300}}, and an all-new aircraft code-named 7N7.[6] The former was a cheaper derivative using the 727's existing technology and tail-mounted engine configuration,[6] while the latter was a twin-engine aircraft which made use of new materials and improvements to propulsion technology which had become available in the civil aerospace industry.[12] United Airlines provided input for the proposed 727-300, which Boeing was poised to launch in late 1975,[6] but lost interest after examining development studies for the 7N7.[6] Although the {{nowrap|727-300}} was offered to Braniff International Airways and other carriers, customer interest remained insufficient for further development.[3] Instead, airlines were drawn to the high-bypass-ratio turbofan engines, new flight deck technologies, lower weight, improved aerodynamics, and reduced operating cost promised by the 7N7.[6][12] These features were also included in a parallel development effort for a new mid-size wide-body airliner, code-named 7X7, which became the 767.[7] Work on both proposals accelerated as a result of the airline industry upturn in the late 1970s.[3][8]By 1978, development studies focused on two variants: a {{nowrap|7N7-100}} with seating for 160, and a {{nowrap|7N7-200}} with room for over 180 seats.[9] New features included a redesigned wing, under-wing engines, and lighter materials, while the forward fuselage, cockpit layout, and T-tail configuration were retained from the 727.[10] Boeing planned for the aircraft to offer the lowest fuel burn per passenger-kilometer of any narrow-body airliner.[11] On August 31, 1978, Eastern Air Lines and British Airways became the first carriers to publicly commit to the 7N7 when they announced launch orders totaling 40 aircraft for the {{nowrap|7N7-200}} version.[9][11] These orders were signed in March 1979, when Boeing officially designated the aircraft as the 757.[9] The shorter {{nowrap|757-100}} did not receive any orders and was dropped; 737s later fulfilled its envisioned role.[12] Design effortThe 757 was intended to be more capable and more efficient than the preceding 727.[13] The focus on fuel efficiency reflected airline concerns over operating costs, which had grown amid rising oil prices during the Yom Kippur War of 1973.[9][14] Design targets included a 20 percent reduction in fuel consumption from new engines, plus an additional 10 percent from aerodynamic improvements, versus preceding aircraft.[14] Lighter materials and new wings were also expected to improve efficiency.[9] The maximum take-off weight (MTOW) was set at {{convert|220000|lb|kg|sigfig=3}},[33] which was {{convert|10000|lb|kg|sigfig=3}} more than the 727.[34] The 757's higher thrust-to-weight ratio allowed it to take off from short runways and serve airports in hot and high climates, offering better takeoff performance than that offered by competing aircraft. Competitors needed longer takeoff runs at airports at higher elevations, with higher ambient temperatures and thinner air. Boeing also offered options for higher payload capability.[15][16] The twin-engine configuration was chosen for greater fuel efficiency versus three- and four-engine designs.[17] Launch customers Eastern Air Lines and British Airways selected the {{nowrap|RB211-535C}} turbofan built by Rolls-Royce, which was capable of {{convert|37400|lbf|kN|}} of thrust.[18] This marked the first time that a Boeing airliner was launched with engines produced outside the U.S.[9] Domestic manufacturer Pratt & Whitney subsequently offered the {{convert|38200|lbf|kN|}} thrust PW2037,[18] which Delta Air Lines launched with an order for 60 aircraft in November 1980.[9][19] General Electric also offered its {{nowrap|CF6-32}} engine early in the program, but eventually abandoned its involvement due to insufficient demand.[20] As development progressed, the 757 increasingly departed from its 727 origins and adopted elements from the 767,[9] which was several months ahead in development.[21] To reduce risk and cost, Boeing combined design work on both twinjets,[3][17] resulting in shared features such as interior fittings and handling characteristics.[48] Computer-aided design, first applied on the 767, was used for over one-third of the 757's design drawings.[22] In early 1979, a common two-crew member glass cockpit was adopted for the two aircraft, including shared instrumentation, avionics, and flight management systems.[23] In October 1979 the nose was widened and dropped to reduce aerodynamic noise by six dB, to improve the flight deck view and to give more working area for the crew for greater commonality with the 767, as the T-tail was substituted by a conventional tail earlier in the year.[24] Cathode-ray tube (CRT) color displays replaced conventional electromechanical instruments,[23] with increased automation eliminating the flight engineer position common to three-person cockpits.[23] After completing a short conversion course, pilots rated on the 757 could be qualified to fly the 767 and vice versa, owing to their design similarities.[23] A new aft-loaded shape which produced lift across most of the upper wing surface, instead of a narrow band as in previous airfoil designs, was used for the 757's wings.[9] The more efficient wings had less drag and greater fuel capacity,[9] and were similar in configuration to those on the 767.[22] A wider wingspan than the 727's produced less lift-induced drag, while larger wing roots increased undercarriage storage space and provided room for future stretched versions of the aircraft.[22] One of the last 727 vestiges, the T-tail, was dropped in mid-1979 in favor of a conventional tail.[9] This avoided the risk of an aerodynamic condition known as a deep stall, and allowed for more passengers to be carried in a less tapered rear fuselage.[25] At {{convert|155.3|ft|sigfig=3}} in length,[61] the {{nowrap|757-200}} was {{convert|2.1|ft|sigfig=3}} longer than the {{nowrap|727-200}}, and with a greater proportion of its internal volume devoted to cabin space, seating was available for 239 passengers, or 50 more than its predecessor.[26][63] The fuselage cross-section, whose upper lobe was common to the 707 and 737,[27][28] was the only major structural feature to be retained from the 727.[29] This was mainly to reduce drag,[14] and while a wider fuselage had been considered, Boeing's market research found low cargo capacity needs and reduced passenger preference for wide-body aircraft on short-haul routes.[10][17] Production and testingBoeing built a final assembly line in Washington at its Renton factory,[30] home of 707, 727, and 737 production, to produce the 757.[31] Early in the development program, Boeing, British Airways, and Rolls-Royce unsuccessfully lobbied the British aircraft industry to manufacture 757 wings.[11][32] Ultimately, about half of the aircraft's components, including the wings, nose section, and empennage, were produced in-house at Boeing facilities, and the remainder subcontracted to primarily U.S.-based companies.[33] Fairchild Aircraft made the leading edge slats, Grumman supplied the flaps, and Rockwell International produced the main fuselage.[33] Production ramp-up for the new narrow-body airliner coincided with the winding-down of the 727 program,[33] and final assembly of the first aircraft began in January 1981.[18] The prototype 757 rolled out of the Renton factory on January 13, 1982.[78] The aircraft, equipped with {{nowrap|RB211-535C}} engines,[34] completed its maiden flight one week ahead of schedule on February 19, 1982.[35] The first flight was affected by an engine stall, following indications of low oil pressure.[81] After checking system diagnostics, company test pilot John Armstrong and co-pilot Lew Wallick were able to restart the affected engine, and the flight proceeded normally thereafter.[36] Subsequently, the 757 embarked on a seven-day weekly flight test schedule.[37] By this time, the aircraft had received 136 orders from seven carriers, namely Air Florida, American Airlines, British Airways, Delta Air Lines, Eastern Air Lines, Monarch Airlines, and Transbrasil.[18] The seven-month 757 flight test program used the first five aircraft built.[38] Tasks included flight systems and propulsion tests, hot and cold weather trials, and route-proving flights.[39] Data from the 767 program helped expedite the process.[37] After design issues were identified, the 757's exit doors received dual-spring mechanisms for easier operation, and the fuselage was strengthened for greater bird strike resistance.[88] The production aircraft was {{convert|3600|lb|kg|sigfig=3}} lighter than originally specified, and recorded a three percent better-than-expected rate of fuel burn.[39] This resulted in a range increase of {{convert|200|nmi|km|sigfig=3}}, and prompted Boeing to tout the aircraft's fuel efficiency characteristics.[39] After 1,380 flight test hours,[91] the RB211-powered 757 received U.S. Federal Aviation Administration (FAA) certification on December 21, 1982, followed by UK Civil Aviation Authority (CAA) certification on January 14, 1983.[36][38] The first delivery to launch customer Eastern Air Lines occurred on December 22, 1982, about four months after the first 767 deliveries.[36][95] The first 757 with PW2037 engines rolled out about one year later, and was delivered to Delta Air Lines on November 5, 1984.[36] Service entry and operationsEastern Air Lines operated the first commercial 757 flight on January 1, 1983, on the Atlanta-to-Tampa route.[36] On February 9, 1983, British Airways began using the aircraft for London-to-Belfast shuttle services, where it replaced Hawker Siddeley Trident 3B trijets.[40] Charter carriers Monarch Airlines and Air Europe also began 757 operations later that year.[41] Early operators noted improved reliability and quieter performance compared with previous jetliners.[41] Transition courses eased pilots' introduction to the new CRT-based cockpit, and no major technical issues arose.[41] Eastern Air Lines, the first 727 operator to take delivery of 757s, confirmed that the aircraft had greater payload capability than its predecessor, along with lower operating costs through improved fuel burn and the use of a two-crew member flight deck.[41] Compared with the 707 and 727, the new twinjet consumed 42 and 40 percent less fuel per seat, respectively, on typical medium-haul flights.[10] Despite the successful debut, 757 sales remained stagnant for most of the 1980s, a consequence of declining fuel prices and a shift to smaller aircraft in the post-deregulation U.S. market.[36] Although no direct competitor existed,[17] 150-seat narrow-bodies such as the McDonnell Douglas MD-80 were cheaper to acquire and carried nearly as many passengers as some airlines' 757s.[15][36] A three-year sales drought abated in November 1983 when Northwest Airlines placed orders for 20 aircraft, which averted a costly production rate decrease.[42] In December 1985, a freighter model, the {{nowrap|757-200PF}}, was announced following a launch order for 20 aircraft from UPS Airlines,[36] and in February 1986, a freighter-passenger combi model, the {{nowrap|757-200M}}, was launched with an order for one aircraft from Royal Nepal Airlines.[43] The freighter model included a main deck cargo hold and entered service with UPS in September 1987.[111] The combi model could carry both cargo and passengers on its main deck and entered service with Royal Nepal Airlines in September 1988.[43] In the late 1980s, increasing airline hub congestion and the onset of U.S. airport noise regulations fueled a turnaround in 757 sales.[36] From 1988 to 1989, airlines placed 322 orders, including a combined 160 orders from American Airlines and United Airlines.[36][44] By this time, the 757 had become commonplace on short-haul domestic flights and transcontinental services in the U.S.,[111] and had replaced aging 707s, 727s, Douglas DC-8s, and McDonnell Douglas DC-9s.[45] The {{nowrap|757-200's}} maximum range of {{convert|3900|nmi|km|sigfig=3}},[61] which was over one-and-a-half times the 727's,[26] allowed airlines to use the aircraft on longer nonstop routes.[46] The 757 was also flown out of airports with stringent noise regulations, such as John Wayne Airport in Orange County, California,[47] and airports with aircraft size restrictions, such as Washington National Airport near downtown Washington, D.C.[8] The largest U.S. operators, Delta Air Lines and American Airlines, would ultimately operate fleets of over 100 aircraft each.[111] In Europe, British Airways, Iberia, and Icelandair were the 757's largest mainline customers,[124] while other carriers such as Lufthansa rejected the type as too large for their narrow-body aircraft needs.[88] Many European charter airlines, including Air 2000, Air Holland, and LTU International,[95] also acquired the twinjet for holiday and tour package flights in the late 1980s.[111][45] In Asia, where even larger aircraft were commonly preferred because of greater passenger volumes, the 757 found fewer orders.[48] A 1982 sales demonstration was unable to attract a purchase from potential customer Japan Airlines,[95][49] and the first Asian customer, Singapore Airlines, sold its four 757s in 1989 in favor of standardizing on the 240-seat wide-body Airbus A310, just five years after debuting the type on Indonesian and Malaysian routes.[50] The 757 fared better in China, where following an initial purchase by the CAAC Airlines in 1987,[111] orders grew to 59 aircraft, making it the largest Asian market.[95] Operators such as China Southern, China Southwest, Shanghai Airlines, Xiamen Airlines, and Xinjiang Airlines used the 757 on medium length domestic routes.[51] In 1986, the FAA approved RB211-powered 757s for extended-range twin-engine operational performance standards (ETOPS) operations over the North Atlantic,[11][52] following precedents set by the 767.[53] Under ETOPS regulations, a set of safety standards governing twinjet flights over oceans and other areas without nearby suitable landing sites, airlines began using the aircraft for mid-range intercontinental routes.[11] Although the 757 was not originally intended for transoceanic flights, regulators based their decision on its reliable performance record on extended transcontinental U.S. services.[53][141] ETOPS certification for 757s equipped with PW2000 series engines was granted in 1992.[43] In the early 1990s, the FAA and other U.S. government agencies, including the National Aeronautics and Space Administration (NASA) and the National Transportation Safety Board (NTSB), began studying the 757's wake turbulence characteristics.[54] This followed several incidents, including two fatal crashes, in which small private aircraft experienced loss of control when flying close behind the twinjet.[54] Smaller airliners had also suffered unexpected rolling movements when flying behind 757s.[54] Investigators focused on the aircraft's aft-loaded wing design, which at certain points during takeoff or landing could produce wingtip vortices that were stronger than those emanating from larger 767s and 747s.[55] Other tests were inconclusive, leading to debate among government agencies, and in 1994 and 1996 the FAA updated air traffic control regulations to require greater separation behind the 757 than other large-category jets.[54][56] The 757 became the only sub//#55'>55]-> }}
External links{{Commons and category|Boeing 757|Boeing 757}}
7 : Boeing aircraft|United States airliners 1980–1989|United States cargo aircraft 1980–1989|Twinjets|Boeing 757|Aircraft first flown in 1982|Low-wing aircraft |
||||||||||||||||||
| 随便看 |
|
开放百科全书收录14589846条英语、德语、日语等多语种百科知识，基本涵盖了大多数领域的百科知识，是一部内容自由、开放的电子版国际百科全书。