Boeing 747

Boeing 747

Virgin Atlantic Airways Boeing 747-400
Role	Wide-body jet airliner
National origin	United States
Manufacturer	Boeing Commercial Airplanes
First flight	February 9, 1969^[1]
Introduction	1970 with Pan Am^[1]
Status	Active
Primary users	British Airways Japan Airlines Cathay Pacific Korean Air
Produced	1969–present
Number built	1,416 as of May 2009.^[2]
Unit cost	747-100: US$24 million (1967) 747-200: US$39 million (1976) 747-300: US$83 million (1982) 747-400: US$228-260 million (2007)^[3] 747-8: US$285.5-300 million (2007)^[3]^[4]
Variants	Boeing 747SP Boeing VC-25 Boeing 747-400 Boeing 747-8 Boeing 747 LCF

The Boeing 747 is a widebody commercial airliner, often referred to by the nickname "Jumbo Jet". It is among the world's most recognizable aircraft, and was the first widebody ever produced. Manufactured by Boeing's Commercial Airplane unit in the US, the original version of the 747 was two and a half times the size of the Boeing 707, one of the common large commercial aircraft of the 1960s. First flown commercially in 1970, the 747 held the passenger capacity record for 37 years.

The four-engine 747 uses a double deck configuration for part of its length. It is available in passenger, freighter and other versions. Boeing designed the 747's hump-like upper deck to serve as a first class lounge or (as is the general rule today) extra seating, and to allow the aircraft to be easily converted to a cargo carrier by removing seats and installing a front cargo door. Boeing did so because the company expected supersonic airliners, whose development was announced in the early 1960s, to render the 747 and other subsonic airliners obsolete, but that the demand for subsonic cargo aircraft would be robust into the future. The 747 in particular was expected to become obsolete after 400 were sold but it exceeded its critics' expectations with production passing the 1,000 mark in 1993. As of May 2009, 1,416 aircraft have been built, with 107 more in various configurations remaining on order.

The 747-400, the latest version in service, is among the fastest airliners in service with a high-subsonic cruise speed of Mach 0.85 (567 mph or 913 km/h). It has an intercontinental range of 7,260 nautical miles (8,350 mi or 13,450 km). The 747-400 passenger version can accommodate 416 passengers in a typical three-class layout or 524 passengers in a typical two-class layout. The next version of the aircraft, the 747-8, is in production and scheduled to enter service in 2010. The 747 is to be replaced by the Boeing Y3 (part of the Boeing Yellowstone Project) in the future.

Development

Background

In 1963, the US Air Force started a series of study projects on a very large "strategic" transport aircraft. Although the C-141 Starlifter was in the process of being introduced, they felt that a much larger and more capable aircraft was needed, especially the capability to carry "outsized" 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 (81,600 kg) and a speed of Mach 0.75 (500 mph/805 km/h), and an unrefueled range of 5,000 nautical miles (9,260 km) with a payload of 115,000 pounds (52,200 kg). The payload bay had to be 17 feet (5.18 m) wide by 13.5 feet (4.11 m) high and 100 feet (30.5 m) long with access through doors at the front and rear.

Featuring only four engines, the design also required new engine designs with greatly increased power and better fuel economy. On 18 May 1964, airframe proposals arrived from Boeing, Douglas, General Dynamics, Lockheed and Martin Marietta; while engine proposals were submitted by General Electric, Curtiss-Wright, and Pratt & Whitney. After a downselect, Boeing, Douglas and Lockheed were given additional study contracts for the airframe, along with General Electric and Pratt & Whitney for the engines.

All three of the airframe proposals shared a number of features, but one in particular would become iconic on the 747. 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 to 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 transport, the C-5 Galaxy.

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. Even before it lost the CX-HLS contract, Boeing was pressed by Juan Trippe, president of Pan American World Airways (Pan Am), one of its 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 planes, became a problem that Trippe thought could be addressed by a large new aircraft.

In 1965, Joe Sutter was transferred from Boeing's 737 development team to manage the studies for a new airliner, already assigned the model number 747. Sutter initiated a design study with Pan Am and other airlines, in order to better understand their requirements. At the time, it was widely thought that the 747 would eventually be superseded by supersonic transport aircraft. Boeing responded by designing the 747 so that it could be adapted easily to carry freight and remain in production even if sales of the passenger version declined. In the freighter role, the clear need was to support the containerized shipping methodologies that were being widely introduced at about the same time. Standard containers are 8 ft (2.4 m) square at the front (slightly higher due to attachment points) and available in 20 and 40 ft (6.1 and 12 m) lengths. This meant that it would be possible to support a 2-wide 2-high stack of containers two or three ranks deep with a fuselage size similar to the earlier CX-HLS project.

In April 1966, Pan Am ordered twenty-five 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", according to Malcolm T. Stamper, one of the senior management for the 747 program at the time. 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 rows of 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 "bulge". In early models it was not clear what to do with the small space in the pod behind the cockpit, and this 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 to be conceived was the high-bypass turbofan engine. The engine technology was thought to be capable of delivering double the power of the earlier turbojets while consuming a 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 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, in order to allow it to operate from existing airports. These included leading edge slats running almost the entire length of the wing, as well as complex three-part slotted flaps along the rear. The wing's low mounting allows the flaps to capture airflow under them, increasing ground effects.

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 the normal time. The schedule was so fast 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

Because 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 (48 km) north of Seattle on a site adjoining a military base at Paine Field near Everett, Washington. It bought the 780 acre (316 hectare) 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 4 million cubic yards (3.1 million m³) 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 widebody commercial jets.

Development and testing

Before the first 747 was fully assembled, testing began on many components and systems. One important test involved evacuation of 560 volunteers from a cabin mock-up via the plane'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, 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; volunteer passengers, instead of using a conventional slide, escaped by using a harness attached to a reel.

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.

On 30 September 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 plane.

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 plane 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, as did China Airlines Flight 358 at Wanli in 1991 and El Al Flight 1862 at Amsterdam in 1992.

The flight test program was hampered by problems with the plane's JT9D engines. Difficulties included engine stalls caused by rapid movements of the throttles and distortion of the turbine casings after a short period of service. The problems delayed 747 deliveries for several months and stranded up to 20 planes at the Everett plant while they awaited 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, site of Boeing's Renton plant. The test aircraft was being taken to have its test equipment removed and a cabin installed when pilot Ralph C. Cokely undershot the short runway and sheared off the 747's landing gear. However, these difficulties did not prevent Boeing from taking one of the test aircraft to the 28th Paris Air Show in mid-1969, where it was displayed to the general public for the first time. The 747 achieved its FAA airworthiness certificate in December 1969, making it ready 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. 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, Clipper Victor, at Dulles International Airport (later renamed 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 plane. 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.

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 in order to stay competitive began to put their own planes into service. Boeing estimated that half of the early 747 sales were to airlines requiring the aircraft's long range rather than its payload capacity. But though 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.

When economic problems in the United States 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 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.

International flights that bypassed traditional hub airports and landed at smaller cities became more common throughout the 1980s, and this eroded the 747's original market. However, many international carriers continued to use the 747 on Pacific routes. In Japan, 747s on domestic routes are configured to carry close to the maximum passenger capacity.

Improved 747 versions

After the initial 747-100 model, Boeing developed the higher Maximum Takeoff Weight -100B variant and higher passenger capacity -100SR (Short Range) variant. Increased maximum takeoff weight (MTOW) can allow an aircraft to carry more fuel and have longer range. The -200 model followed, entering service in 1971. It featured more powerful engines and higher takeoff weight. Passenger, freighter and combination passenger-freighter versions were produced. The shortened 747SP (special performance) with a longer range was also developed in the mid-1970s.

The 747 line was further developed with the launching of the 747-300 in 1980. The -300 resulted from Boeing studies to increase the seating capacity of the 747. Solutions such as fuselage plugs and extending the upper deck over the entire length of the fuselage were rejected. The early designation of the -300 was 747SUD for "stretched upper deck" then 747-200 SUD, followed by 747EUD, before the 747-300 designation was used. The 300 model was first produced in 1983. It included a stretched upper deck (SUD), increased cruise speed and increased seating capacity. Passenger, short range and combination freighter-passenger versions were produced.

In 1985, development of the longer range 747-400 was begun. The new variant had a new glass cockpit, which allowed for a cockpit crew of two instead of three. Development cost 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.

A size comparison of four large aircraft: the Spruce Goose (gold), the Antonov An-225 (green), an Airbus A380 (pink), and a 747-8 (blue).

In 1991, a record-breaking 1,087 passengers were airlifted aboard a 747 to Israel as part of Operation Solomon. The 747 was the heaviest airliner in regular service until the use of the Antonov An-124 Ruslan in 1982. The 747-400ER model regained that distinction in 2000. The Antonov An-225 cargo transport remains the world's largest aircraft by several measures (including the most accepted measures of maximum gross takeoff weight and length). The Hughes H-4 Hercules is the largest aircraft by wingspan, but it only flew once. Only two An-225 aircraft have been produced, and only one is still flying as of 2007.

Some 747 aircraft have been converted for special uses. A 747-100 owned by General Electric is used as a testbed for their engines such as General Electric GEnx. A firefighting version has been built by Evergreen International.

Future developments

Since the arrival of the 747-400, several stretching schemes for the 747 have been proposed. Boeing announced the larger 747-500X and -600X designs in 1996. The new variants would have cost more than $5 billion to develop, and interest was not sufficient to launch the program. Boeing offered the more modest 747X and 747X stretch derivatives in 2000 as alternatives to the Airbus A3XX. However, the 747X family was unable to attract enough interest to enter production. Boeing switched from the 747X studies to pursue the Sonic Cruiser in 2001 and, after the Sonic Cruiser program was put on hold, the 787. Some of the ideas developed for the 747X were used on the 747-400ER.

After several variants were proposed but later abandoned, some industry observers became skeptical of new aircraft proposals from Boeing. However, in early 2004, Boeing announced tentative plans for the 747 Advanced that were eventually adopted. Similar in nature to the 747-X, the stretched 747 Advanced used technology from the 787 to modernize the design and its systems. The 747 remained the largest passenger airliner in service until the Airbus A380 began airline service in 2007.

On 14 November 2005, Boeing announced it was launching the 747 Advanced as the Boeing 747-8. The last 747-400s were completed in 2009. By 2009, most orders for the 747-8 were for the freighter version, with Lufthansa the sole customer to order the 747-8 Intercontinental. As of February 2009, Boeing was reassessing the 747-8 project. Eventually, the 747 may be replaced in Boeing's lineup by a new design dubbed "Y3".

Design

The Boeing 747 is a large, wide-body (two-aisle) airliner with four wing-mounted engines. The wings have a high sweep angle of 37.5 degrees for a fast, efficient cruise of Mach 0.84 to 0.88, depending on the variant. The sweep also allows the 747 to use existing hangars. Seating capacity is more than 366 with a 3-4-3 seat arrangement (a cross section of 3 seats, an aisle, 4 seats, another aisle, and 3 seats) in economy class and a 2-3-2 arrangement in first class on the main deck. The upper deck has a 3-3 seat arrangement in economy class and a 2-2 arrangement in first class.

Raised above the main deck, the cockpit creates a hump. The raised cockpit is to allow front loading of cargo on freight variants. The upper deck behind the cockpit provides space for a lounge or extra seating. The "stretched upper deck" became available as an option on the 747-100B variant and later as standard on the 747-300.

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 multiple structural redundancy including four redundant hydraulic systems and four main landing gears with 16 wheels, which provide a good spread of support on the ground and safety in case of tire blow-outs. The redundant main gear allows for landing on two opposing landing gears if the others do not function properly. In addition, the 747 has split control surfaces and sophisticated triple-slotted flaps that minimize landing speeds and allow the plane to use standard-length runways. For transportation of spare engines, early 747s could accommodate a non-functioning fifth-pod engine under the port wing of the aircraft between the nearest functioning engine and the fuselage.

Variants

The 747-100 was the original variant launched in 1966. The 747-200 soon followed, with an order in 1968. The 747-300 was launched in 1980 and was followed in 1985 by the 747-400. Lastly, the 747-8 was announced in 2005. Several versions of each variant have been produced. Many of the early variants were in production simultaneously.

747-100

The first 747-100s were built with six upper-deck windows (three per side) to accommodate upstairs lounge areas. Later, as airlines began to use the upper-deck for premium passenger seating instead of lounge space, Boeing offered a 10-window upper deck as an option. Some -100s were retrofitted with the new configuration.

No freighter version of this model was developed by Boeing. However, 747-100s have been converted to freighters. A total of 167 747-100s were built.

A 747-100B version, which has a stronger airframe and undercarriage design as well as an increased maximum takeoff weight (MTOW) of 750,000 lb (340,000 kg) was offered. The 747-100B was delivered only to Iran Air and Saudia (now Saudi Arabian Airlines). Optional engine models were offered by Rolls-Royce (RB211) and GE (CF6), but only Saudia ordered the Rolls-Royce option. A total of nine 747-100Bs were built.

747-100SR

Responding to requests from Japanese airlines, Boeing developed the 747-100SR as a "short range" variant of the 747-100. The SR has a lower fuel capacity but can carry more passengers, up to 498 in early versions and more than 550 in later models, because of increased economy class seating. The 747SR has a modified body structure to accommodate the added stress accumulated from a greater number of takeoffs and landings. The -100SR entered service with Japan Airlines (then Japan Air Lines) on October 7, 1973. Specifically, the SR has extra structural support at the wings, fuselage, and the landing gear along with a 20% reduction in fuel capacity. Later, short range versions of the -100B and the -300 were also developed. The SRs are used primarily on domestic flights in Japan.

Two 747-100SRs were delivered to Japan Airlines with a stretched upper deck to accommodate more passengers. This modification is known as the "SUD" (stretched upper deck). A total of 29 747-100SRs were built.

All Nippon Airways (ANA) operated 747-100SRs on domestic Japanese routes with 455 or 456 seats but retired the last aircraft on 10 March 2006. JAL operated the 747-100B/SR/SUD variant with 563 seats on domestic routes, and retired these planes in the third quarter of 2006.

747SP

The idea for The 747SP came from a joint request between Pan American World Airways and Iran Air who were looking for a high capacity airliner with enough range to cover Pan Am's New York-Middle Eastern routes and Iran Air's planned Tehran-New York route. The Tehran-New York route when launched was the longest non-stop commercial flight in the world. The 747SP is 48 feet 4 inches (14.7 m) shorter than the 747-100. Except for the planned 747-8, the SP is the only 747 with a fuselage of modified length. Fuselage sections were eliminated fore and aft of the wing, and the center section of the fuselage was redesigned. Single-slotted flaps replaced the complex triple-slotted Fowler flaps of the 100 series. The under-wing "canoes", which housed the flap mechanisms on full-size 747s, were eliminated entirely on the SP. The 747SP, compared to earlier variants, had a tapering of the aft upper fuselage into the empennage, a double-hinged rudder, and longer vertical and horizontal stabilizers.

The 747SP was granted a supplemental certificate on 4 February 1976 and entered service with Pan Am, the launch customer and Iran Air, that same year. The aircraft was chosen by airlines wishing to serve major airports with short runways.

A total of 45 747SPs were built. The 44th 747SP was delivered on August 30, 1982. Boeing re-opened the 747SP production line to build one last 747SP five years later in 1987 for an order by the United Arab Emirates government. As of July 2008, 10 Boeing 747SP aircraft were in airline service with Iran Air (3), Iraqi Airways (2), Syrian Arab Airlines (2), Saudi Arabian Airlines (1), and Transatlantic International Airlines (1). NASA's Dryden Flight Research Center has one modified for the SOFIA experiment.

747-200

The 747-200 has more powerful engines, higher takeoff weights (MTOW) and range than the -100. A few early -200s retained the three-window configuration of the -100 on the upper deck, but most were built with a 10-window configuration on each side.

Several versions in addition to the -200 were produced. The 747-200B is an improved version of the 747-200, with increased fuel capacity and more powerful engines; it first entered service in February 1971. The -200B aircraft has a full load range of about 6,857 nmi (12,700 km). The 747-200F is the freighter version of the -200 model. It could be fitted with or without a side cargo door. It has a capacity of 105 tons (95.3 tonnes) and an MTOW of up to 833,000 lb (378,000 kg). It entered first service in 1972 with Lufthansa. The 747-200C Convertible is a version that can be converted between a passenger and a freighter or used in mixed configurations. The seats are removable, and the model has a nose cargo door. The -200C could be fitted with an optional side cargo door on the main deck.

The 747-200M is a combination version that has a side cargo door on the main deck and can carry freight in the rear section of the main deck. A removable partition on the main deck separates the cargo area at the rear from the passengers at the front. This model can carry up to 238 passengers in a 3-class configuration if cargo is carried on the main deck. The model is also known as the 747-200 Combi. As on the -100, a stretched upper deck (SUD) modification was later offered. A total of 10 converted 747-200s were operated by KLM. Union des Transports Aériens (UTA) also had two of these aircraft converted.

A total of 393 of the 747-200 versions had been built when production ended in 1991. Of these, 225 were 747-200s, 73 were 747-200F, 13 were 747-200C, 78 were 747-200M, and 4 were military. Many 747-200s are still in operation, although most large carriers have retired them from their fleets and sold them to smaller operators. Large carriers have sped up fleet retirement following the September 11th attacks and the subsequent drop in demand for air travel, scrapping some or turning others into freighters.

747-300

The most visible difference between the -300 and previous models was a stretched upper deck with two new emergency exit doors and an optional flight-crew rest area immediately aft of the flight deck as standard. (The stretched upper deck had previously been offered as a retrofit and first appeared on two Japanese 747-100 SR models.) Compared to the -200, the upper deck is 23 feet 4 inches (7.11 m) longer than the -200. A new straight stairway to the upper deck instead of a spiral staircase is another difference between the -300 and earlier variants. The staircase creates room below and above for more seats. With minor aerodynamic changes, Boeing increased the cruise speed of the -300 to Mach 0.85 from Mach 0.84 on the -100/-200. The -300 features the same takeoff weight. Two of the three engine choices from the -200 were unchanged in the -300, but the General Electric CF6-80C2B1 was offered instead of the CF6-50E2 offered on the -200.

The 747-300 name, which was proposed for a variant that was never launched, was revived for this new version, which was introduced in 1980. Swissair ordered the first 747-300 on 11 June 1980. The 747-300 first flew on 5 October 1982. Swissair was the first customer to accept delivery on March 23, 1983.

In addition to the passenger version, other versions were available. The 747-300M has cargo capacity in the rear portion of the main deck similar to the -200M, but with the stretched upper deck it can carry more passengers. The 747-300SR is a short range version to meet the need for a high-capacity domestic model. Japan Airlines operated such aircraft with more than 600 seats on the Okinawa–Tokyo route and elsewhere. Boeing never launched a newly built freighter version of the 747-300, but it modified used passenger -300 models into freighters starting in 2000.

A total of 81 aircraft were delivered, 56 for passenger use, 21 -300M and 4 -300SR versions. The 747-300 was soon superseded by the launch of the more advanced 747-400 in 1985, just two years after the -300 entered service. The last 747-300 was delivered in September 1990 to Sabena.

Today, many -300 aircraft are still active, despite a significant loss of interest in the series among large carriers who replaced the 747-300 with the 747-400. Air France, Air India and Qantas were some of the last major carriers to operate the 747-300. On 29 December 2008, Qantas flew its last scheduled 747-300 service, operating from Melbourne to Los Angeles via Auckland. On 20 January 2009, Qantas' last 747-300 was flown to the United States for storage. Carriers still using the -300 include Aerosur, Japan Airlines, Pakistan International Airlines and Saudi Arabian Airlines. Although none were constructed as dedicated freighters, a few -300s have been converted to cargo operations.

747-400

British Airways operates the largest fleet of 747s in the world. The addition of winglets is a noticeable difference between most -400s and earlier variants.

The 747-400 is an improved model with increased range. It has wing-tip extensions of 6 ft (1.8 m), winglets of 6 ft (1.8 m), which improve the 747-400's fuel efficiency by 4% compared to previous 747 versions. It has a new glass cockpit designed for a flight crew of two instead of three. The use of electronics reduced the number of dials, gauges and knobs from 971 to 365. It has tail fuel tanks, revised engines and a new interior. The longer range was used by some airlines to bypass traditional fuel stops, such as Anchorage. The -400 was offered in passenger (400), freighter (400F), combi (400C), domestic (400D), extended range passenger (400ER) and extended range freighter (400ERF) versions. The freighter version does not have an extended upper deck. The 747-400D was built for short range operations and does not include winglets, but these can be retrofitted.

The passenger version first entered service in February 1989 with Northwest Airlines on the Minneapolis to Phoenix route. The combi version entered service in September 1989 with KLM. The freighter version entered service in November 1993 with Cargolux. The 747-400ERF entered service in October 2002 and the 747-400ER entered service the following month with Qantas, the only airline ever to order the passenger version. Some of the last built Boeing 747-400s were delivered with Dreamliner livery along with the modern interior from the Boeing 777.

In January 2004 Boeing and Cathay Pacific launched the Boeing 747-400 Special Freighter program, later referred to as the Boeing Converted Freighter (BCF). The first 747-400BCF was redelivered in December 2005.

The last passenger version of the 747-400 was delivered in April 2005. Boeing announced in March 2007 that it had no plans to produce further passenger versions of the -400. However, orders for 36 -400F and -400ERF freighters were already in place at the time of the announcement. As of May 2009, 692 of the 747-400 series aircraft had been delivered with two -400s (-400ERFs) to be delivered.

747 LCF Dreamlifter

The 747-400 Dreamlifter (originally called the 747 Large Cargo Freighter or LCF) is a Boeing-designed modification of existing 747-400s to a larger configuration to ferry Boeing 787 sub-assemblies to the Boeing plant in Everett, Washington, for final assembly. Evergreen Aviation Technologies Corporation is completing modifications of 747-400s into Dreamlifters in Taiwan. The aircraft flew for the first time on September 9, 2006. The Dreamlifter's only intended purpose is to transport sub-assemblies for the Boeing 787. The aircraft is certified to carry only essential crew and not passengers. Three aircraft have been built, and one on order.

747-8

Boeing announced a new 747 variant, the 747-8 (referred to as the 747 Advanced prior to launch) on 14 November 2005, which will use the same engine and cockpit technology as the 787, hence the use of the "8". Plans call for the new design to be quieter, more economical and more environmentally friendly. The 747-8 is stretched to add more payload capacity. This involves lengthening from 232 to 251 feet (70.8 to 76.4 m), surpassing the Airbus A340-600 to become the world's longest airliner.

The passenger version, dubbed 747-8 Intercontinental or 747-8I, will be able to carry up to 467 passengers in a 3-class configuration and fly more than 8,000 nmi (15,000 km) at Mach 0.855. As a derivative of the already common 747-400, the 747-8 has the economic benefit of similar training and interchangeable parts. The 747-8I is scheduled to enter service in 2010.

Also offered is the 747-8 Freighter or 747-8F, which derives from the 747-400ERF. The 747-8F can accommodate 154 tons (140 tonnes) of cargo. To aid loading and unloading, it features an overhead nose-door. It has 16 percent more payload capacity than the 747-400F and can hold seven additional standard air cargo containers. The 747-8F is scheduled to enter service in 2009.

Several units are under construction at Boeing's Everett facility. The 747-8 has received a total of 105 orders with 78 for the -8F and 27 for the -8I as of May 2009.

Government, military and other variants

20-1101 Japanese Air Force One, one of the two customized Boeing 747-400s that have been part of the Japan Air Self-Defense Force since 1993

Undeveloped variants

Boeing has studied a number of 747 variants that have not gone beyond the concept stage.

747-300 trijet

During the 1970s, Boeing studied the development of a shorter body, three-engined 747 to compete with the smaller L-1011 TriStar and DC-10, which had lower trip costs than the 747SP. The 747-300 trijet would have had more payload, range and passenger capacity. The center engine would have been fitted in the tail with an S-duct intake similar to the L-1011's. However, engineering studies showed that a time-consuming and costly redesign of the 747 wing would be necessary.

747-500X, -600X and -700X

Boeing announced the 747-500X and -600X at the 1996 Farnborough Airshow. The proposed models would have combined the 747's fuselage with a new 251 ft (77 m) span wing derived from the 777. Other changes included adding more powerful engines and increasing the number of tires from two to four on the nose landing gear and from 16 to 20 on the main landing gear.

The 747-500X concept featured an 18 ft (5.5 m) stretch to 250 ft (76.2 m) long, and the aircraft was to carry 462 passengers over a range up to 8,700 nautical miles (10,000 mi, 16,100 km), with a gross weight of over 1.0 Mlb (450 Mg). The 747-600X concept featured a greater stretch to 279 ft (85 m) with seating for 548 passengers, a range of up to 7,700 nmi (8,900 mi, 14,300 km), and a gross weight of 1.2 Mlb (540 Mg). A third study concept, the 747-700X, would have combined the wing of the 747-600X with a widened fuselage, allowing it to carry 650 passengers over the same range as a 747-400. The cost of the changes from previous 747 models, in particular the new wing for the 747-500X and -600X, was estimated to be more than $5 billion. Boeing was not able to attract enough interest to launch the aircraft.

747X and 747X Stretch

As Airbus progressed with its A3XX study, Boeing in 2000 offered the market a 747 derivative as an alternative. This was a more modest proposal than the previous -500X and -600X that would retain the 747's overall wing design and add a segment at the root, increasing the span to 229 ft (69.8 m). Power would have been supplied by either the Engine Alliance GP7172 or the Rolls-Royce Trent 600, which were also proposed for the 767-400ERX. A new flight deck based on the 777's would be used. The 747X aircraft was to carry 430 passengers over ranges of up to 8,700 nmi (10,000 mi, 16,100 km). The 747X Stretch would be extended to 263 ft (80.2 m) long, allowing it to carry 500 passengers over ranges of up to 7,800 nmi (9,000 mi, 14,500 km). Both would feature an interior based on the 777's signature architecture. Freighter versions of the 747X and 747X Stretch were also studied.

Like its predecessor, the 747X family was unable to garner enough interest to justify production, and it was shelved along with the 767-400ERX in March 2001, when Boeing announced the Sonic Cruiser concept. Though the 747X design was less costly than the 747-500X and -600X, it was criticized for not offering a sufficient advance from the existing 747-400. The 747X did not make it beyond the drawing board, but the 747-400X being developed concurrently moved into production to become the 747-400ER.

747-400XQLR

After the end of the 747X program, Boeing continued to study improvements that could be made to the 747. The 747-400XQLR (Quiet Long Range) was meant to have an increased range of 7,980 nmi (9,200 mi, 14,800 km), with improvements to improve efficiency and reduce noise. Improvements studied included raked wingtips similar to those used on the 767-400ER and a sawtooth engine nacelle for noise reduction. Although the 747-400XQLR did not move to production, many of its features were used for the 747 Advanced, which has now been launched as the 747-8.

Accidents and incidents

As of October 2008, the 747 has been involved in 122 incidents, including 48 hull-loss accidents, resulting in 2,850 fatalities. The 747 has been in 35 hijackings which caused 882 fatalities.

Few crashes have been attributed to design flaws of the 747. The Tenerife disaster resulted from pilot error, air traffic control (ATC) error and communications failure, while the Japan Airlines Flight 123 and China Airlines Flight 611 crashes stemmed from improper aircraft repair. United Airlines Flight 811, which suffered an explosive decompression mid-flight on 24 February 1989, led the National Transportation Safety Board (NTSB) to issue a recommendation that 747-200 cargo doors similar to those on the Flight 811 aircraft be modified. Korean Air Lines Flight 007 was shot down by the Soviets in 1983 after it had strayed into Soviet territory, causing U.S. President Ronald Reagan to authorize the then strictly military Global Positioning System (GPS) for civilian use. TWA Flight 800, a 747-100 that exploded in midair on July 17, 1996, led the Federal Aviation Administration to propose a rule requiring installation of an inerting system in the center fuel tank of most large aircraft that was adopted in July 2008, after years of research into solutions. It is expected that the new safety system will cost $100,000 to $450,000 per aircraft and weigh approximately 200 pounds (91 kg).

Aircraft on display

As increasing numbers of "classic" 747-100 and 747-200 series aircraft have been retired, some have found their way into museums or other uses. The City of Everett, the first 747 and prototype is at the Museum of Flight, Seattle, Washington, USA where it is sometimes leased to Boeing for test purposes.

Upon its retirement from service, the first 747 flown commercially was dis-assembled and shipped to Mokpo, South Korea where it was re-assembled and converted into a restaurant. It was originally flown commercially by Pan Am. While it was the first 747 flown commercially, it was actually the second to be built. As of April 2009, the 747 restaurant is closed and abandoned.

Specifications

The 747 parasitic drag, C_DP, is 0.022, and the wing area is 5,500 square feet (511 m), so that f equals about 121 sq ft or 11.2 m². The parasitic drag is given by ½ f ρ_air v² in which f is the product of drag coefficient C_Dp and the wing area.