主题：【原创】航空史上十大名机 -- 晨枫

直到前两天的空中客车A380问世，这一纪录才被打破。

记得这个经典镜头吗？波音747身上背一个航天飞机，当时我看到这则新闻的时候，觉得真是酷毙了,牛！

[SIZE=3]Historical background[/SIZE]

The 747 was born out of the explosion of air travel in the 1960s. The era of commercial jet transportation led by the enormous popularity of the Boeing 707 had revolutionised long distance travel and made possible the concept of the "global village." Boeing had already developed a study for a very large airplane while bidding on a US military contract for a huge airlifter. Boeing lost the contract to Lockheeds C-5A Galaxy but came under pressure from its most loyal airline customer Pan Am to develop a giant passenger plane which would be over twice the size of the 707. In 1966 Boeing proposed a preliminary configuration for the airliner, which was to be called the 747, and Pan Am ordered 25 of the initial -100 series. The design was a full length double decker, but due to issues with evacuation routes this idea was scrapped in favor of a wide-body design.

At the time, it was widely thought that the 747 would be replaced in the future with an SST (SuperSonic Transport) design. Boeing took the shrewd move and designed the 747 so that it could easily be adapted to carry freight, knowing that when sales of the passenger version dried up, it could remain in production as a cargo aircraft. The cockpit was moved to a shortened upper deck so that a nose cone loading door could be included, creating the 747's distinctive "bulge." However, the supersonic transports such as Boeing's still-born SST and the Concorde never lived up to their promise, being too expensive to operate profitably at a time when fuel prices were soaring. The upper deck was initially used as a luxurious first-class lounge/bar area, but is now most often used for extra seating capacity. After being expected to wither on the vine with only 400 sales, the 747 outlived many of its critics and production passed the 1,000 mark in 1993. The expected slow-down in sales of the passenger version in favor of the cargo derivative has only happened in the early 2000s.

The development of the 747 was a huge undertaking. Boeing did not have a factory big enough to assemble the giant aircraft, so the company had to build an all-new assembly building near Everett, Washington. This factory is the largest building ever built. Pratt and Whitney developed a massive high-bypass turbofan engine, the JT9D, that was, in the beginning, exclusively for the 747. To appease concerns about the safety and flyability of such a massive aircraft, the 747 was designed with four backup hydraulic systems, split control surfaces, multiple structural redundancy, and sophisticated flaps which allow it to use standard-length runways.

Initially, Boeing found that the 747 was being treated with skepticism by many airlines. At the time, Boeing's rivals, McDonnell Douglas and Lockheed, were working on wide-body three-engine "tri-jets", which were significantly smaller than the proposed 747. Many airlines wondered if the 747 would prove too large for an average long distance flight and instead invested in tri-jets. Furthermore, there was worry about whether the 747 would be compatible with existing airport infrastructure.

Another issue raised by the airlines was fuel efficiency. A three-engine airliner burns significantly less fuel per flight than a four-engine, and with airlines trying to lower costs, fuel efficiency was a large issue (this issue would return to haunt Boeing during the 1970s).

Boeing had promised the 747 to Pan Am by 1970, so it had less than four years to develop, build and test the 747. Work progressed at such a breakneck pace that all those who worked on the development of the 747 were given the nickname "The Incredibles". The massive cost of developing the 747 and building the Everett factory meant that Boeing had gambled its very existence on the 747's success, and the company was nearly bankrupted in the early 1970s. The gamble paid off however, and Boeing enjoyed a monopoly on very large passenger transports that has only been broken 35 years later with the advent of the Airbus A380.