Boeing 747

The Jumbo Jet! 

Not many aircraft can claim to launch a new age in aviation, but that tag can be applied to the Boeing 747 which first flew in 1969. The new airliner spawned the dawn of mass long-distance air travel. Nicknamed the Jumbo Jet, the airliner has been developed into numerous variants and is viewed with such affection that the title ‘Queen of the Skies’ has also been bestowed upon it.

The Jumbo held the record for the world's largest aircraft and greatest passenger capacity for 37 years and with continual development, spawned many variants. The latest of these, the 747-8 Intercontinental, entered service in 2012.

When Boeing’s Model 747 first flew in 1969, it signalled the start of a new era of mass market, long-distance air travel. Aptly nicknamed the ‘Jumbo Jet’, it held the record for the greatest passenger capacity for 37 years and with continual development, spawned many variants. The latest of these, the 747-8 Intercontinental, entered service in 2012.

Origins

In 1964, Boeing, Douglas and Lockheed were competing for a contract to supply a large aircraft for military transport that would be capable of carrying 750 troops over a long distance and using four engines. Boeing spent much time and money designing the aircraft but, in the event, Lockheed received the contract and produced the C-5A Galaxy. Loath to waste the effort it had expended on the project, Boeing decided to pursue a commercial outlet, using the expertise developed for the military aircraft. In the meantime, its marketing people had concluded that, by the 1970s, with the expected yearly increase in airline passenger traffic, there would be scope for a super jet airliner, capable of carrying many more passengers and much more freight than current aircraft over longer distances – thus saving on cost per passenger mile.

Design of Boeing 747 

With this information to hand, Boeing’s Chief of Technology, Joe Sutter, was tasked with designing a new aircraft that would meet these future needs. He soon saw that by using the high-bypass turbofan proposed by General Electric (GE) for the C-5A, there could be a saving of 25% on fuel consumption compared to existing engines. Four of these at 40,000lb (177.60kN) thrust would be more than ample to power a large airliner. In addition increased fuel capacity, Boeing could utilise the specially developed high-lift devices on the wings of the military design, to provide take-off and landing within the confines of standard runways around the world. Further discussions with Boeing’s largest customer, Pan American, concluded that a passenger load of up to 400 was optimal and that the airliner should have a high transonic speed, in the region of 600mph (967km/h), thus necessitating a high sweep back of the wings.

On consideration of the fuselage design, Sutter’s first idea of having two passenger decks was rejected by airline representatives as being unsafe in the case of an accident, because rapid evacuation might be hindered. The final configuration, which was generally agreed, was a single deck, running the full length of the aircraft, right up to the nose, with a dome-shaped flight deck above it – giving the 747 its now familiar shape. The area behind the flight deck was proposed as a small lounge but was eventually increased in size. The huge space below the passenger deck would be used to hold up to 26 containers of luggage and freight. In freighter form, the nose section could be hinged upwards, for front loading of cargo, and the fuselage could accommodate a large cargo door. The widebody interior was originally designed to enable 8ft (2.43m) square pallets to be loaded side by side.

At this stage therefore, a preliminary specification for the Model 747 described a four-engined airliner with a length of 231ft (70.40m), a wing span of 195ft (59.50m), a maximum take-off weight (MTOW) of 713,000lb (323,356kg) and a range of 5,300 miles (8,550km). It was envisaged to carry 305 passengers in economy class and 53 in first class. The flight crew consisted of the captain, co-pilot and flight engineer, two stewards and ten hostesses.

Boeing had had a long and successful association with Pratt & Whitney (P&W) and with the advent of its new 46,500lb (206kN) JT9B high-bypass turbofan, the company opted for this rather than GE’s engine.

Development and construction

It was now up to Boeing’s executive board to give the go-ahead for prototype development. William Allen, the Chief Executive, knew that he had to commit at least $500,000 to development and hesitated to do so. However, in 1966, Pan Am, which was as much involved in the project as Boeing, agreed to sign a contract for 25 passenger aircraft and two freighters, at a cost of $525,000. Even with this incentive, however, Allen knew that in order to give a total commitment, further orders would have to be forthcoming. Nevertheless, he agreed to release the finance to build a completely new factory, next to Paine Field, Everett, Washington State. His confidence in the concept was rewarded when within a year, 20 major airlines had signed up for 100 aircraft. Initial production started in September 1967, but before the first piece of metal had been cut, 14,000 hours of wind tunnel testing was carried out on various models to determine the exact wing and fuselage design.

The high-lift system for the wings consisted of leading edge Krüger flaps inboard of the engines and five sections of variable-camber flaps between them. Five more sections were on the outer leading edge. On the trailing edges were enormous, triple-slotted flaps. When deployed, this system increased the wing area by 25% for take-off or landing. Spoilers on the upper wing were used for roll augmentation and to aid braking. The main landing gear comprised four, four-wheel bogies.

With a 20ft (6.10m) wide passenger cabin, ten abreast seating was possible in a 3-4-3 arrangement, with two aisles. In high-density mode, the cabin could take 500 passengers, but 350 was more typical. The upper lounge behind the flight deck dome could take 32 first-class seats. Boeing signed contracts with several outside suppliers. Its own Wichita plant would supply the nose section, while Northrop would make the wings and main fuselage sections. Fairchild built the flaps and aileron system. A full-sized mock-up was built, minus one wing, engines and seats, in order to check engineering drawings. If everything looked right, non-structural items, such as wiring looms and pipework, could be prepared in advance of the main construction. The first wing assembly was completed in March 1968 and by September the first 747-100 was rolled out. By this time the order book stood at 158.

Boeing 747’s First flight

The 747-100’s maiden flight test programme took place on February 9, 1969, with Jack Waddell as pilot and Brian Wygle as his co-pilot. Jess Wallick was flight engineer. The machine took off in just 4,300ft (1,311m) – less than half the runway – at 164mph (264km/h) and commentators were astonished at how quiet the engines were. After a 90-minute flight, Waddell brought the aircraft back for a perfect landing at 150mph (242km/h), without the use of flaps, and reported only minor problems. He described the 747 as a “one-finger aeroplane” – meaning it was extremely easy to fly.

The aircraft then went to Boeing’s Seattle facility to begin flight testing, gradually accompanied by the next five airframes off the production line. Minor oscillation of the wings was eliminated by reducing the stiffness of some components, but a rather more serious problem was noted with the engines, due to distortion of the turbine casing. This delayed deliveries for several months while redesign was carried out by P&W and left 20 airframes on the production line awaiting engines. However, this did not deter Boeing from sending one of the test aircraft to the Paris Air Show in June 1969, for its first public appearance.

With the engine problem cleared, the FAA gave the 747 its Certificate of Air Worthiness in December. In the meantime, the huge cost of development and testing had meant that Boeing had to continually go to a banking syndicate to obtain loans. Had this finance been refused it would have meant the end of the company, for its resources were tightly stretched. Fortunately, the gamble paid off.

Into service

Pan Am received its first two 747-100s in December, for pilot training. The company’s President, Najeeb Halaby, took one of them aloft himself. In January 1970, the operator inaugurated its first Boeing 747 transatlantic service from New York to London. To the embarrassment of everyone, the first flight was delayed due to an engine overheating problem, but undeterred, the company used a replacement and the age of the ‘Jumbo Jet’ had begun.

Pan Am brought all of its first 25 747s into service during 1970, with schedules from Los Angeles and San Francisco to Honolulu, Hong Kong and Tokyo. In March of that year, American Airlines also introduced the type, followed by Lufthansa in April. By year’s end, 747s were flying with Air France, Alitalia, Continental, Japan Air Lines, National, Northeast and United Airlines – demonstrating the speed with which production had ramped up.

Due to the oil crisis in 1973, air traffic did not increase as fast as predicted and some operators flying with low load factors had to put their 747s into storage and switch to smaller aircraft. However, hoping that this was just a temporary situation, Boeing pressed on with full production of seven per month. In all, 167 747-100 airliners were built – no dedicated freighters were manufactured, but several -100s were converted as freighters later in their careers.

747 variants

In 1971, Boeing introduced the 747-200B to replace the original 100 series. Initially powered by more powerful P&W JT9D-7R4 turbofans providing 54,750lb st (243kN), it was later offered with a choice of Rolls-Royce (RR) or GE engines. With greater range and higher available gross weight, the type was available as a freighter (-200F); convertible (-200C); or Combi, allowing mixed passenger and freight loads (-200M). A total of 393 had been delivered when production ended in 1991.

In 1972, Japan Air Lines and, later, All Nippon Airways, requested a short-range version for high-density domestic routes. Designated 747-100SR (or simply 747SR), it had a maximum take-off weight of 520,000lb (235,830kg) and was able to seat 498 passengers. Powered by 43,000lb st (191kN) P&W JT9D-7As, the airframe was strengthened to cope with more frequent flight cycles. An even higher MTOW addition, the -100BSR, was produced in 1979 for the same operators. Seven of the former and 20 of the latter variants were built. In 1979, for Iran Air and subsequently, for Saudi Airlines, Boeing produced the 747- 100B with a stronger airframe and the same powerplant as the -100SR, it had higher fuel capacity and thus, a longer, 6,080 mile (9,313km) range. Only nine were built.

747SP and -300

Pam Am and Iran Air both requested a longer range, but reduced capacity version of the 747-100 to fly direct from New York to the Middle East. Designated 747SP the type had a fuselage length 48ft (14.63m) shorter than the 100 series, but with the same fuel capacity and powerplant, its range was typically 7,658 miles (12,324km). It entered service with Pan Am in early 1976 and 45 were built.

Introduced in 1980, the 747-300 was basically a Series 200 with the upper deck area behind the flight deck stretched by 23ft (7m) to provide seating for 69 passengers. Minor aerodynamic changes also increased the type’s speed by about 15mph (24km/h). It was also available in Combi (-300M) or short-range (-300SR) forms. Eighty-one were delivered, mostly in standard passenger form.

747-400

The 747-400, launched in 1989 with Northwest Airlines, was the last major revamp of the ‘Classic’ 747 before the introduction of the latest 747-8. The type retained the -300’s stretched upper deck but had a 6ft (1.83m) long wing extension with winglets. This improved fuel efficiency by 4% and increased range to 8,300 miles (13,387km); or up to 8,800 miles (14,195km) in the extended range (-400ER) version with extra fuel tanks. The new flight deck was designed for a crew of just two, by the use of advanced electronics, and behind this was the stretched upper deck.

A choice of three powerplants was given – the P&W PW4062, GE’s CF6-80C2, or RR’s RB211-524. The model was available in freighter (-400F); Combi (-400M); Extended Range (-400ER); Extended Range Freighter (-400ERF) and Domestic (-400D) models – this latter designed for short-haul flights in Japan and minus winglets. There were 694 747-400s delivered – the last in December 2009. Major users are Singapore Airlines, Japan Airlines and British Airways. Several specialised 747 variants for government and military purposes have also been produced, either from new or by conversion. By November 2011, 1,424 747s of all types had been built for more than 100 operators.

747-8

During the last two decades, Boeing mooted the concept of even larger capacity designs of the 747 – the -500X and -600X in 1996, which fed into the -400ER/ERF, and the 747X in 2000 – with stretched fuselage and/or increased wing span; all carrying in excess of 400 passengers up to 9,000 miles (14,520km). These ideas were further developed and in 2004 a 747 Advanced was announced. By late 2005 this had become the 747-8. Two versions, in passenger or cargo configuration, have been designed, with a fuselage stretch of 18ft 3½in (5.58m) over the 747-400 – which brings the total length to 250ft 2in (76.25m).

Wing span is increased by 13ft (3.96m) to 224ft 7in (68.50m); additionally, the wings are thicker and deeper, hold more fuel and have a modified high-lift flap system. The wingtips are raked – similar to those of some Boeing 777 variants and the 787 – and without winglets. This reduces wingtip vortices and decreases drag. The lateral flight controls use fly-by-wire technology as a weight-saving measure, while the use of many carbon fibre components also reduces weight. Power is provided by four 66,500lb st (296kN) GEnx-2B67 turbofans. With an MTOW for both versions of 975,000lb (442,263kg), the 747-8 is the heaviest and largest passenger aircraft ever built in the USA.

The 747-8 Freighter (F) first flew in February 2010, with the first orders having come from Cargolux (ten, with three more added in 2007) and Nippon Cargo Airlines (eight, plus six more in 2007) in 2005. The -8F proved its load-carrying capability in August 2010 during flight testing by taking off at just over 1,000,000lb (453,592kg) gross weight. The freighter’s range is calculated on its maximum cargo load of 295,000lb (134,240kg), rather than on full fuel tanks. Thus, its range is normally quoted as much less than that of the passenger version. With joint FAA and EASA approval given in August 2011, launch customer Cargolux received the first delivery on October 12, 2011. The aircraft immediately entered service by flying to Seattle to pick up freight; then on to its base in Luxembourg. Cathay took the first of its 747-8Fs on October 31, 2011, and on November 2, Atlas Air Worldwide took its initial aircraft. By November 2011, orders for the 747-8F stood at 70, from eight customers: Atlas Air (nine), Cargolux (13), Cathay Pacific (ten), Dubai Aerospace Enterprise (ten), GECAS (two), Korean Air (seven), Nippon Cargo (14) and Volga-Dnepr (five).

747-8 Intercontinental

The 747-8 Intercontinental (I) did not fly until March 20, 2011. With full fuel tanks, it carries 467 passengers in a three-class format, 9,206 miles (14,815km), at a cruising speed of 570mph (917km/h). In the all-economy configuration, the maximum passenger capacity 581. Boeing states that compared with the Series 400, the 747-8I is 30% quieter, 16% more fuel efficient and has a 13% lower seat/mile cost.

In October 2011 the 747-8I visited Barbados for tropical trials. FAA approval was announced on December 14 and to date, there are 48 confirmed orders, 19 of which are for Lufthansa – the first to place an order in 2009. The first airline delivery – to Lufthansa – occurred in 2012.

The balance of 747-8I orders comes from Korean Air (ten), Air China (seven), VIP operators (eight) and two unidentified customers.

To date, all 747-8I examples have been delivered; just one -8F now remains on Boeing’s order book. The last of these is due for delivery in the first quarter of this year.

Production of the largest passenger airliner has since been ceased since January 31, 2023.

By Gerry Sweet