Boeing 747 is a large, long-range wide-body airliner designed and manufactured by Boeing Commercial Airplanes in the United States. After introducing the 707 in October 1958, Pan Am wanted a jet 2+1⁄2 times its size, to reduce its seat cost by 30% to democratize air travel. In 1965, Joe Sutter left the development program to design the 747, the first twin aisle airliner. In April 1966, Pan Am ordered 25 Boeing 747-100 aircraft and in late 1966, Pratt & Whitney agreed to develop its 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 first flight took place on February 9, 1969, and the 747 was certified in December of that year. It entered service with Pan Am on January 22, 1970. The 747 was the first airplane dubbed a "Jumbo Jet", the first wide-body airliner.
The Boeing 747, here an Iberia 747-200.
The 747 is a quadjet, initially powered by turbofan engines, then GE 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 Mach 0.85 (490 kn; 900 km/h) , 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to a freighter airplane by installing a front cargo door, as it was initially thought that it would eventually be superseded by supersonic transports.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 -200 in 1971, with more powerful engines for a heavier maximum takeoff weight (MTOW) of 833,000 lb (378 t) from the initial 735,000 lb (333 t), for a longer 6,560 nmi (12,150 km) range up from 4,620 nmi (8,560 km). 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 RB-211 and CF6 versions, along with the PW4000 (the JT9D successor), 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, with new General Electric GEnx engines, and was first delivered in October 2011. The 747 is the basis for several government and military variants, such as the VC-25 (Air Force One), Emergency Airborne Command Post, Shuttle Carrier Aircraft, and some experimental testbeds such as the YAL-1 and SOFIA airborne observatory.
By June 2020, 1,556 aircraft had been built, with fifteen 747-8s remaining on order. In 2022, manufacture of the 747 is scheduled to end after a 54-year production run. Initial competition came from the smaller trijet widebodies: the Lockheed L-1011 (introduced in 1972), McDonnell Douglas DC-10 (1971) and later MD-11 (1990). Airbus competed with later variants with the heaviest versions of the A340 until surpassing the 747 in size with the A380, introduced in 2007; while Airbus announced that it will end A380 production in 2021.
Development
In 1963, the United States Air Force started 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 (CX-HLS) in March 1964 for an aircraft with a load capacity of 180,000 pounds (81.6 t) and a speed of Mach 0.75 (500 mph or 800 km/h), and an unrefueled range of 5,000 nautical miles (9,300 km) with a payload of 115,000 pounds (52.2 t). The payload bay had to be 17 feet (5.18 m) wide by 13.5 feet (4.11 m) high and 100 feet (30 m) 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.
Cargo nose door open with cargo loader
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.
Airliner 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 the early 1960s, even before it lost the CX-HLS contract, Boeing was asked by Juan Trippe, president of Pan Am, one of their most important airline customers, to build a passenger aircraft more than twice the size of the 707. During this time, airport congestion, worsened by increasing numbers of passengers carried on relatively small aircraft, became a problem that Trippe thought could be addressed by a larger new aircraft.
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 design study with Pan Am and other airlines to better understand their requirements. At the time, many thought that the 747 would eventually be superseded by supersonic transport aircraft. Boeing responded by designing the 747 so it could be adapted easily to carry freight and remain in production even if sales of the passenger version declined.
An Iran Air 747-200, showing the early-production 747 cockpit, located on the upper deck.
In April 1966, Pan Am ordered 25 Boeing 747-100 aircraft for US$525 million (equivalent to $3.2 billion in 2019 dollars). 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 effort
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 design 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 this was initially specified as a "lounge" area with no permanent seating. (A different configuration that had been considered to keep the flight deck out of the way for freight loading had the pilots below the passengers, and was dubbed the "anteater".)
The Pratt & Whitney JT9D high-bypass turbofan engine was developed for the 747.
One of the principal technologies that enabled an aircraft as large as the 747 to be drawn up was the high-bypass turbofan engine. This engine technology was thought to be capable of delivering double 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 increase 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. The delivery date left 28 months to design the aircraft, which was 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.
Production plant
Airplane assembly hall, featuring heavy machinery. Large cylindrical airplane sections and wings are readied for mating with other major components. Above are the cranes which ferry heavy and outsize parts of the 747.
As Boeing did not have a plant large enough to assemble the giant airliner, they chose to build a new plant. The company considered locations in about 50 cities, and eventually decided to build the new plant some 30 miles (50 km) north of Seattle on a site adjoining a military base at Paine Field near Everett, Washington. It bought the 780-acre (320 ha) 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 four million cubic yards (three million cubic meters) 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 substantially expanded several times to permit construction of other models of Boeing wide-body commercial jets.
Development and testing
Before the first 747 was fully assembled, testing began on many components and systems. One important test involved the evacuation of 560 volunteers from a cabin mock-up via the aircraft's emergency chutes. The first full-scale evacuation took two and a half minutes instead of the maximum of 90 seconds mandated by the Federal Aviation Administration (FAA), and several volunteers were injured. Subsequent test evacuations achieved the 90-second goal but caused more injuries. Most problematic was evacuation from the aircraft's upper deck; instead of using a conventional slide, volunteer passengers escaped by using a harness attached to a reel. Tests also involved taxiing such a large aircraft. Boeing built an unusual training device known as "Waddell's Wagon" (named for a 747 test pilot, Jack Waddell) that consisted of a mock-up cockpit mounted on the roof of a truck. While the first 747s were still being built, the device allowed pilots to practice taxi maneuvers from a high upper-deck position.
The prototype 747 was first displayed to the public on September 30, 1968.
In 1968, the program cost was US$1 billion (equivalent to $5.7 billion in 2019 dollars). On September 30, 1968, the first 747 was rolled out of the Everett assembly building before the world's press and representatives of the 26 airlines that had ordered the airliner. Over the following months, preparations were made for the first flight, which took place on February 9, 1969, with test pilots Jack Waddell and Brien Wygle at the controls and Jess Wallick at the flight engineer's station. Despite a minor problem with one of the flaps, the flight confirmed that the 747 handled extremely well. The 747 was found to be largely immune to "Dutch roll", a phenomenon that had been a major hazard to the early swept-wing jets.
During later stages of the flight test program, flutter testing showed that the wings suffered oscillation under certain conditions. This difficulty was partly solved by reducing the stiffness of some wing components. However, a particularly severe high-speed flutter problem was solved only by inserting depleted uranium counterweights as ballast in the outboard engine nacelles of the early 747s. This measure caused anxiety when these aircraft crashed, for example El Al Flight 1862 at Amsterdam in 1992 with 622 pounds (282 kg) of uranium in the tailplane (horizontal stabilizer).
The flight test program was hampered by problems with the 747's JT9D engines. Difficulties included engine stalls caused by rapid throttle movements and distortion of the turbine casings after a short period of service. The problems delayed 747 deliveries for several months; up to 20 aircraft at the Everett plant were stranded while awaiting engine installation.The program was further delayed when one of the five test aircraft suffered serious damage during a landing attempt at Renton Municipal Airport, the site of Boeing's Renton factory. The incident happened on December 13, 1969 when a test aircraft was flown to Renton to have test equipment removed and a cabin installed. Pilot Ralph C. Cokely undershot the airport's short runway and the 747's right, outer landing gear was torn off and two engine nacelles were damaged.[60][61] However, these difficulties did not prevent Boeing from taking a test aircraft to the 28th Paris Air Show in mid-1969, where it was displayed to the public for the first time. The 747 received its FAA airworthiness certificate in December 1969, clearing it for introduction into service.
The huge cost of developing the 747 and building the Everett factory meant that Boeing had to borrow heavily from a banking syndicate. During the final months before delivery of the first aircraft, the company had to repeatedly request additional funding to complete the project. Had this been refused, Boeing's survival would have been threatened. The firm's debt exceeded $2 billion, with the $1.2 billion owed to the banks setting a record for all companies. Allen later said, "It was really too large a project for us." Ultimately, the gamble succeeded, and Boeing held a monopoly in very large passenger aircraft production for many years.
Entry into service
On January 15, 1970, First Lady of the United States Pat Nixon christened Pan Am's first 747 at Dulles International Airport (later Washington Dulles International Airport) in the presence of Pan Am chairman Najeeb Halaby. Instead of champagne, red, white, and blue water was sprayed on the aircraft. The 747 entered service on January 22, 1970, on Pan Am's New York–London route; the flight had been planned for the evening of January 21, but engine overheating made the original aircraft unusable. Finding a substitute delayed the flight by more than six hours to the following day when Clipper Victor was used.
First Lady Pat Nixon christened the first commercial 747 on January 15, 1970.
The 747 enjoyed a fairly smooth introduction into service, overcoming concerns that some airports would not be able to accommodate an aircraft that large. Although technical problems occurred, they were relatively minor and quickly solved. After the aircraft's introduction with Pan Am, other airlines that had bought the 747 to stay competitive began to put their own 747s into service. Boeing estimated that half of the early 747 sales were to airlines desiring the aircraft's long range rather than its payload capacity. While the 747 had the lowest potential operating cost per seat, this could only be achieved when the aircraft was fully loaded; costs per seat increased rapidly as occupancy declined. A moderately loaded 747, one with only 70 percent of its seats occupied, used more than 95 percent of the fuel needed by a fully occupied 747. Nonetheless, many flag-carriers purchased the 747 due to its prestige "even if it made no sense economically" to operate. During the 1970s and 1980s, over 30 regularly scheduled 747s could often be seen at John F. Kennedy International Airport.
The recession of 1969-1970, despite having been characterized as relatively mild, greatly affected Boeing. For the year and a half after September 1970, it only sold two 747s in the world, both to Irish flag carrier Aer Lingus. No 747s were sold to any American carrier for almost three years. When economic problems in the US and other countries after the 1973 oil crisis led to reduced passenger traffic, several airlines found they did not have enough passengers to fly the 747 economically, and they replaced them with the smaller and recently introduced McDonnell Douglas DC-10 and Lockheed L-1011 TriStar trijet wide bodies (and later the 767 and A300/A310 twinjets). Having tried replacing coach seats on its 747s with piano bars in an attempt to attract more customers, American Airlines eventually relegated its 747s to cargo service and in 1983 exchanged them with Pan Am for smaller aircraft; Delta Air Lines also removed its 747s from service after several years. Later, Delta acquired 747s again in 2008 as part of its merger with Northwest Airlines, although it retired the Boeing 747-400 fleet in December 2017.
International flights bypassing traditional hub airports and landing at smaller cities became more common throughout the 1980s, thus eroding the 747's original market. Many international carriers continued to use the 747 on Pacific routes. In Japan, 747s on domestic routes were configured to carry nearly the maximum passenger capacity.
Improved 747 versions
After the initial 747-100, Boeing developed the -100B, a higher maximum takeoff weight (MTOW) variant, and the -100SR (Short Range), with higher passenger capacity. Increased maximum takeoff weight allows aircraft to carry more fuel and have longer range. The -200 model followed in 1971, featuring more powerful engines and a higher MTOW. Passenger, freighter and combination passenger-freighter versions of the -200 were produced. The shortened 747SP (special performance) with a longer range was also developed, and entered service in 1976.
Stretched upper deck cabin of later 747s with six-abreast seating
The 747 line was further developed with the launch of the 747-300 on June 11, 1980, followed by interest from Swissair a month later and the go-ahead for the project. The 300 series resulted from Boeing studies to increase the seating capacity of the 747, during which modifications such as fuselage plugs and extending the upper deck over the entire length of the fuselage were rejected. The first 747-300, completed in 1983, included a stretched upper deck, increased cruise speed, and increased seating capacity. The -300 variant was previously designated 747SUD for stretched upper deck, then 747-200 SUD, followed by 747EUD, before the 747-300 designation was used. Passenger, short range and combination freighter-passenger versions of the 300 series were produced.
Launch Customer Northwest Airlines introduced the 747-400 in 1989.
In 1985, development of the longer range 747-400 began. The variant had a new glass cockpit, which allowed for a cockpit crew of two instead of three, new engines, lighter construction materials, and a redesigned interior. Development costs soared, and production delays occurred as new technologies were incorporated at the request of airlines. Insufficient workforce experience and reliance on overtime contributed to early production problems on the 747-400. The -400 entered service in 1989.
In 1991, a record-breaking 1,087 passengers were flown in a 747 during a covert operation to airlift Ethiopian Jews to Israel. Generally, the 747-400 held between 416 and 524 passengers. The 747 remained the heaviest commercial aircraft in regular service until the debut of the Antonov An-124 Ruslan in 1982; variants of the 747-400 surpassed the An-124's weight in 2000. The Antonov An-225 Mriya cargo transport, which debuted in 1988, remains the world's largest aircraft by several measures (including the most accepted measures of maximum takeoff weight and length); one aircraft has been completed and is in service as of 2017. The Scaled Composites Stratolaunch is currently the largest aircraft by wingspan.
Design
The Boeing 747 is a large, wide-body (two-aisle) airliner with four wing-mounted engines. Its wings have a high sweep angle of 37.5° for a fast, efficient cruise speed of Mach 0.84 to 0.88, depending on the variant. The sweep also reduces the wingspan, allowing the 747 to use existing hangars. Its seating capacity is over 366 with a 3–4–3 seat arrangement (a cross section of three seats, an aisle, four seats, another aisle, and three seats) in economy class and a 2–3–2 layout in first class on the main deck. The upper deck has a 3–3 seat arrangement in economy class and a 2–2 layout in first class.
Three-view diagram of the original Boeing 747-100, showing its general configuration maintained in later variants
Raised above the main deck, the cockpit creates a hump. This raised cockpit allows front loading of cargo on freight variants. The upper deck behind the cockpit provides space for a lounge and/or extra seating. The "stretched upper deck" became available as an alternative on the 747-100B variant and later as standard beginning on the 747-300. The upper deck was stretched more on the 747-8. The 747 cockpit roof section also has an escape hatch from which crew can exit during the events of an emergency if they cannot do so through the cabin.
The 747's maximum takeoff weight ranges from 735,000 pounds (333,400 kg) for the -100 to 970,000 lb (439,985 kg) for the -8. Its range has increased from 5,300 nautical miles (6,100 mi, 9,800 km) on the -100 to 8,000 nmi (9,200 mi, 14,815 km) on the -8I.
The 747 has redundant structures along with four redundant hydraulic systems and four main landing gears each with four wheels; these provide a good spread of support on the ground and safety in case of tire blow-outs. The main gear are redundant so that landing can be performed on two opposing landing gears if the others are not functioning properly. The 747 also has split control surfaces and was designed with sophisticated triple-slotted flaps that minimize landing speeds and allow the 747 to use standard-length runways.
For transportation of spare engines, the 747 can accommodate a non-functioning fifth-pod engine under the aircraft's port wing between the inner functioning engine and the fuselage. This fifth engine mount point is also used by Virgin Orbit's LauncherOne program. Virgin Orbit's 747-400, dubbed Cosmic Girl, carries the orbital-class rocket to cruise altitude, where the rocket is deployed and then carries its small satellite payload the rest of the way to orbit.
End of production
On July 27, 2016, in its quarterly report to the Securities and Exchange Commission, Boeing discussed the potential termination of 747 production due to insufficient demand and market for the aircraft. With a firm order backlog of 21 aircraft and a production rate of six per year, program accounting has been reduced to 1,555 aircraft, and the 747 line could be closed in the third quarter of 2019. In October 2016, UPS Airlines ordered 14 -8Fs to add capacity, along with 14 options, which it took in February 2018 to increase the total to 28 -8Fs on order. The backlog then stood at 25 aircraft, though several of these are orders from airlines that no longer intend to take delivery. Deliveries are scheduled through 2022.
On July 2, 2020, it was reported that Boeing planned to end 747 production in 2022 upon delivery of the remaining jets on order to UPS and the Volga-Dnepr Group due to low demand. On July 29, 2020, Boeing confirmed that the final 747 would be delivered in 2022 as a result of "current market dynamics and outlook" stemming from the COVID-19 pandemic, according to CEO David Calhoun. As of January 2021 Boeing is to deliver the last four 747s to Atlas Air in 2022.
