Boeing 747
The Boeing 747 is a long-range wide-body airliner designed and manufactured by Boeing Commercial Airplanes in the United States between 1968 and 2023.
After the introduction of the 707 in October 1958, Pan Am wanted a jet times its size, to reduce its seat cost by 30%. In 1965, Joe Sutter left the 737 development program to design the 747. In April 1966, Pan Am ordered 25 Boeing 747-100 aircraft, and in late 1966, Pratt & Whitney agreed to develop the JT9D engine, a high-bypass turbofan. On September 30, 1968, the first 747 was rolled out of the custom-built Everett Plant, the world's largest building by volume. The 747's first flight took place on February 9, 1969, and the 747 was certified in December 1969. It entered service with Pan Am on January 22, 1970. The 747 was the first airplane called a "Jumbo Jet" as the first wide-body airliner.
The 747 is a four-engined jet aircraft, initially powered by Pratt & Whitney JT9D turbofan engines, then General Electric CF6 and Rolls-Royce RB211 engines for the original variants. With a ten-abreast economy seating, it typically accommodates 366 passengers in three travel classes. It has a pronounced 37.5° wing sweep, allowing a cruise speed, and its heavy weight is supported by four main landing gear legs, each with a four-wheel bogie. The partial double-deck aircraft was designed with a raised cockpit so it could be converted to a freighter airplane by installing a front cargo door, as it was initially thought that it would eventually be superseded by supersonic transports.
Boeing introduced the 747-200 in 1971, with uprated engines for a heavier maximum takeoff weight of from the initial, increasing the maximum range from. It was shortened for the longer-range 747SP in 1976, and the 747-300 followed in 1983 with a stretched upper deck for up to 400 seats in three classes. The heavier 747-400 with improved RB211 and CF6 engines or the new PW4000 engine, and a two-crew glass cockpit, was introduced in 1989 and is the most common variant. After several studies, the stretched 747-8 was launched on November 14, 2005, using the General Electric GEnx engine first developed for the 787 Dreamliner, and was first delivered in October 2011. The 747 is the basis for several government and military variants, such as the VC-25, E-4 Emergency Airborne Command Post, Shuttle Carrier Aircraft, and some experimental test aircraft such as the YAL-1 and SOFIA airborne observatory.
Initial competition came from the smaller trijet widebodies: the Lockheed L-1011, McDonnell Douglas DC-10 and later MD-11. Airbus competed with later variants with the heaviest versions of the A340 until surpassing the 747 in size with the A380, delivered between 2007 and 2021. Freighter variants of the 747 remain popular with cargo airlines. The final 747 was delivered to Atlas Air in January 2023 after a 54-year production run, with 1,574 aircraft built.
, 65 Boeing 747s have been lost in accidents and incidents, in which a total of 3,746 people have died.
Development
Background
In 1963, the United States Air Force began a series of study projects on a very large strategic transport aircraft. Although the C-141 Starlifter was being introduced, officials believed that a much larger and more capable aircraft was needed, especially to carry cargo that would not fit in any existing aircraft. These studies led to initial requirements for the CX-Heavy Logistics System in March 1964 for an aircraft with a load capacity of and a speed of Mach 0.75, and an unrefueled range of with a payload of. The payload bay had to be wide by high and long with access through doors at the front and rear.The desire to keep the number of engines to four required new engine designs with greatly increased power and better fuel economy. In May 1964, airframe proposals arrived from Boeing, Douglas, General Dynamics, Lockheed, and Martin Marietta; engine proposals were submitted by General Electric, Curtiss-Wright, and Pratt & Whitney. Boeing, Douglas, and Lockheed were given additional study contracts for the airframe, along with General Electric and Pratt & Whitney for the engines.
The airframe proposals shared several features. As the CX-HLS needed to be able to be loaded from the front, a door had to be included where the cockpit usually was. All of the companies solved this problem by moving the cockpit above the cargo area; Douglas had a small "pod" just forward and above the wing, Lockheed used a long "spine" running the length of the aircraft with the wing spar passing through it, while Boeing blended the two, with a longer pod that ran from just behind the nose to just behind the wing. In 1965, Lockheed's aircraft design and General Electric's engine design were selected for the new C-5 Galaxy transport, which was the largest military aircraft in the world at the time. Boeing carried the nose door and raised cockpit concepts over to the design of the 747.
Proposal
The 747 was conceived while air travel was increasing in the 1960s. The era of commercial jet transportation, led by the enormous popularity of the Boeing 707 and Douglas DC-8, had revolutionized long-distance travel. In this growing jet age, Juan Trippe, president of Pan American Airways, one of Boeing's most important airline customers, asked for a new jet airliner times size of the 707, with a 30% lower cost per unit of passenger-distance and the capability to offer mass air travel on international routes. Trippe also thought that airport congestion could be addressed by a larger aircraft.File:Iran Air Boeing 747-200 cockpit Sharifi.jpg|thumb|An Iran Air 747-200, showing an early-production 747 cockpit with a flight engineer, located on the upper deck |alt= A view of an early-production 747 cockpit
In 1965, Joe Sutter was transferred from Boeing's 737 development team to manage the design studies for the new airliner, already assigned the model number 747. Sutter began a study with Pan Am and other airlines to better understand their requirements. At the time, many thought that long-range subsonic airliners would eventually be superseded by supersonic transport aircraft. Boeing responded by designing the 747 so it could be easily adapted to carry freight and remain in production even if sales of the passenger version declined.
In April 1966, Pan Am ordered 25 Boeing 747-100 aircraft for US$525 million. During the ceremonial 747 contract-signing banquet in Seattle on Boeing's 50th Anniversary, Juan Trippe predicted that the 747 would be "…a great weapon for peace, competing with intercontinental missiles for mankind's destiny". As launch customer, and because of its early involvement before placing a formal order, Pan Am was able to influence the design and development of the 747 to an extent unmatched by a single airline before or since.
Design
Ultimately, the high-winged CX-HLS Boeing design was not used for the 747, although technologies developed for their bid had an influence. The original design included a full-length double-deck fuselage with eight-across seating and two aisles on the lower deck and seven-across seating and two aisles on the upper deck. However, concern over evacuation routes and limited cargo-carrying capability caused this idea to be scrapped in early 1966 in favor of a wider single deck design. The cockpit was therefore placed on a shortened upper deck so that a freight-loading door could be included in the nose cone; this feature produced the 747's distinctive "hump". In early models, what to do with the small space in the pod behind the cockpit was not clear, and it was initially specified as a "lounge" area with no permanent seating.One of the principal technologies that enabled an aircraft as large as the 747 was the high-bypass turbofan engine. This engine technology was thought to be capable of delivering twice the power of the earlier turbojets while consuming one-third less fuel. General Electric had pioneered the concept but was committed to developing the engine for the C-5 Galaxy and did not enter the commercial market until later. Pratt & Whitney was also working on the same principle and, by late 1966, Boeing, Pan Am and Pratt & Whitney agreed to develop a new engine, designated the JT9D to power the 747.
The project was designed with a new methodology called fault tree analysis, which allowed the effects of a failure of a single part to be studied to determine its impact on other systems. To address concerns about safety and flyability, the 747's design included structural redundancy, redundant hydraulic systems, quadruple main landing gear and dual control surfaces. Additionally, some of the most advanced high-lift devices used in the industry were included in the new design, to allow it to operate from existing airports. These included Krueger flaps running almost the entire length of the wing's leading edge, as well as complex three-part slotted flaps along the trailing edge of the wing. The wing's complex three-part flaps increased wing area by 21% and lift by 90% when fully deployed compared to their non-deployed configuration.
Boeing agreed to deliver the first 747 to Pan Am by the end of 1969. That date left 28 months to design the aircraft, just two-thirds of the normal time. The schedule was so fast-paced that the people who worked on it were given the nickname "The Incredibles". Developing the aircraft was such a technical and financial challenge that management was said to have "bet the company" when it started the project. Due to its massive size, Boeing subcontracted the assembly of subcomponents to other manufacturers, notably Northrop and Grumman for fuselage parts and trailing edge flaps respectively, Fairchild for tailplane ailerons, and Ling-Temco-Vought for the empennage.
Assembly plant
Boeing did not have a plant large enough to assemble the giant airliner, so they chose to build a new plant. The company considered locations in about 50 cities, and eventually decided to build the new plant some north of Seattle on a site adjoining a military base at Paine Field near Everett, Washington. It bought the site in June 1966.Developing the 747 had been a major challenge, and building its assembly plant was also a huge undertaking. Boeing president William M. Allen asked Malcolm T. Stamper, then head of the company's turbine division, to oversee construction of the Everett factory and to start production of the 747. To level the site, more than of earth had to be moved. Time was so short that the 747's full-scale mock-up was built before the factory roof above it was finished. The plant is the largest building by volume ever built, and has been expanded several times to permit construction of other models of Boeing wide-body commercial jets.