A wide-body aircraft, also known as a twin-aisle aircraft and in the largest cases as a jumbo jet, is an airliner with a fuselage wide enough to accommodate two passenger aisles with seven or more seats abreast. The typical fuselage diameter is 5 to 6 m (16 to 20 ft). In the typical wide-body economy cabin, passengers are seated seven to ten abreast, allowing a total capacity of 200 to 850 passengers. Seven-abreast aircraft typically seat 160 to 260 passengers, eight-abreast 250 to 380, nine- and ten-abreast 350 to 480. The largest wide-body aircraft are over 6 m (20 ft) wide, and can accommodate up to eleven passengers abreast in high-density configurations. By comparison, a typical narrow-body aircraft has a diameter of 3 to 4 m (10 to 13 ft), with a single aisle, and seats between two and six people abreast. Wide-body aircraft were originally designed for a combination of efficiency and passenger comfort and to increase the amount of cargo space. However, airlines quickly gave in to economic factors, and reduced the extra space to insert more seats and increase revenue and profits. Wide-body aircraft are also used by commercial cargo airlines, along with other specialised uses. By the end of 2018, more than 9,100 wide-body airplanes had been delivered, with production peaking at 412 in 2015.
History
1960s
Following the success of the Boeing 707 and Douglas DC-8 in the late 1950s and early 1960s, airlines began seeking larger aircraft to meet the rising global demand for air travel. Engineers were faced with many challenges as airlines demanded more passenger seats per aircraft, longer ranges and lower operating costs. Early jet aircraft such as the 707 and DC-8 seated passengers along either side of a single aisle, with no more than six seats per row. Larger aircraft would have to be longer, higher (double-deck aircraft), or wider in order to accommodate a greater number of passenger seats. Engineers realised having two decks created difficulties in meeting emergency evacuation regulations with the technology available at that time. During the 1960s, it was also believed that supersonic airliners would succeed larger, slower planes. Thus, it was believed that most subsonic aircraft would become obsolete for passenger travel and would be eventually converted to freighters. As a result, airline manufacturers opted for a wider fuselage rather than a taller one (the 747, and eventually the McDonnell Douglas DC-10 and Lockheed L-1011 TriStar). By adding a second aisle, the wider aircraft could accommodate as many as 10 seats across, but could also be easily converted to a freighter and carry two eight-by-eight freight pallets abreast. The engineers also opted for creating "stretched" versions of the DC-8 (61, 62 and 63 models), as well as longer versions of Boeing's 707 (-320B and 320C models) and 727 (-200 model); and Douglas' DC-9 (-30, -40, and -50 models), all of which were capable of accommodating more seats than their shorter predecessor versions.
1970s The wide-body age of jet travel began in 1970 with the entry into service of the first wide-body airliner, the four-engined, partial double-deck Boeing 747. New trijet wide-body aircraft soon followed, including the McDonnell Douglas DC-10 and the L-1011 TriStar. The first wide-body twinjet, the Airbus A300, entered service in 1974. This period came to be known as the "wide-body wars". L-1011 TriStars were demonstrated in the USSR in 1974, as Lockheed sought to sell the aircraft to Aeroflot. However, in 1976 the Soviet Union launched its own first four-engined wide-body, the Ilyushin Il-86.
After the success of the early wide-body aircraft, several subsequent designs came to market over the next two decades, including the Boeing 767 and 777, the Airbus A330 and Airbus A340, and the McDonnell Douglas MD-11. In the "jumbo" category, the capacity of the Boeing 747 was not surpassed until October 2007, when the Airbus A380 entered commercial service with the nickname "Superjumbo". Both the Boeing 747 and Airbus A380 "jumbo jets" have four engines each (quad-jets), but the upcoming Boeing 777X ("mini jumbo jet") is a twinjet. The production of the large Boeing 747-8 and Airbus A380 four-engine, long-haul jets has come to an end as airlines are now preferring the smaller, more efficient Airbus A350, Boeing 787 and Boeing 777X twin-engine, long-range airliners.
Design
Fuselage
Although wide-body aircraft have larger frontal areas (and thus greater form drag) than narrow-body aircraft of similar capacity, they have several advantages over their narrow-body counterparts, such as:
Larger cabin space for passengers, giving a more open feeling. Lower ratio of surface area to volume, and thus lower drag per passenger or cargo volume. The only exception to this would be with very long narrow-body aircraft, such as the Boeing 757 and Airbus A321. Twin aisles that accelerate loading, unloading, and evacuation compared to a single aisle (wide-body airliners typically have 3.5 to 5 seats abreast per aisle, compared to 5–6 on most narrow-body aircraft). Reduced overall aircraft length for a given capacity, improving ground manoeuvrability and reducing the risk of tail strikes. Greater under-floor freight capacity. Better structural efficiency for larger aircraft than would be possible with a narrow-body design.
British and Russian designers had proposed wide-body aircraft similar in configuration to the Vickers VC10 and Douglas DC-9, but with a wide-body fuselage. The British BAC Three-Eleven project did not proceed due to lack of government backing, while the Russian Ilyushin Il-86 wide-body proposal eventually gave way to a more conventional wing-mounted engine design, most likely due to the inefficiencies of mounting such large engines on the aft fuselage.
Engines
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