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Wide-body aircraft

By Wikipedia,
the free encyclopedia,

http://en.wikipedia.org/wiki/Wide-body_aircraft


The Airbus A380 is the world's largest and widest passenger aircraft
The Airbus A380 is the world's largest and widest passenger aircraft

A wide-body aircraft is a large airliner with two passenger aisles, also known as a twin-aisle aircraft. The typical fuselage diameter is 5 to 6 m (16 to 20 ft). In the typical widebody economy cabin, passengers are seated seven to ten abreast, allowing a total capacity of 200 to 600 passengers. The largest widebody aircraft are over 6 m (20 ft) wide, and can accommodate up to eleven passengers abreast in high-density configurations. As well, wide-body aircraft are used for the transport of commercial freight and cargo and other special uses, described further below.

For comparison, a traditional narrow-body airliner has a diameter of 3 to 4 m (10 to 13 ft), with a single aisle, and seats between two and six people abreast.

Widebody aircraft were originally designed for a combination of efficiency and passenger comfort. However, airlines quickly gave in to economic factors, and reduced the extra passenger space in order to maximize revenue and profits. Depending on how the airline configures the aircraft, the size and seat pitch of the airline seats will vary significantly. For example, aircraft scheduled for shorter flights are often configured at a higher seating density than long-haul aircraft.

Due to current economic pressures on the airline industry, high seating densities in the economy cabin are likely to continue.

History


Boeing 747, the first wide-body passenger aircraft, operated by Pan American World Airways
Boeing 747, the first wide-body passenger aircraft, operated by Pan American World Airways

Following the success of the narrow-body Boeing 707 and Douglas DC-8 in the late 1950s, 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 fuel 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 (such as a double deck), or wider in order to accommodate the greater number of passenger seats. Engineers also realized that lengthening the fuselage would have resulted in aircraft that would be too long to be handled by airports, while having two decks created difficulties in meeting emergency evacuation regulations, which were extremely challenging provided the technology available at the time. These parameters left a wider fuselage as the best option: by adding a second aisle, the wider aircraft could accommodate as many as 10 seats across.

The widebody age began in 1970 with the entry into service of the first wide-body airliner, the four-engined Boeing 747. The main deck of the 747 features twin aisles and seats ten people abreast, while the upper-deck "hump" of the aircraft seats six abreast along a single aisle. New trijet wide-body aircraft soon followed, including the McDonnell Douglas DC-10 and the Lockheed L-1011 Tristar. In 1974, Airbus introduced the Airbus A300, the first wide-body twinjet.

After the success of the early widebody aircraft, several successors came to market over the next two decades, including the Airbus A330-A340 Series and the Boeing 767-777. 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.

Design considerations


Cross-section comparison of Airbus A380 versus Boeing 747-400
Cross-section comparison of Airbus A380 versus Boeing 747-400

Although wide-body aircraft have a larger frontal area (and thus greater form drag) than a narrow-body aircraft of similar capacity, they have several advantages over their narrow-body counterparts:


Airbus A300 cross-section, showing cargo, passenger, and overhead areas
Airbus A300 cross-section, showing cargo, passenger, and overhead areas
  • Larger volume of space for passengers, giving a more open feeling to the space
  • Lower ratio of surface area to volume, and thus lower drag on a per-passenger basis
  • Twin aisles that accelerate loading, unloading, and evacuation compared to a single aisle
  • Wider fuselage that reduces the overall aircraft length, 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 widebody aircraft similar in configuration to the Vickers VC-10 and Douglas DC-9, but with a wide-body fuselage. The British Three-Eleven project never left the drawing board, while the Russian 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 a large engine on the aft fuselage.

Engines


Mechanic working on a Rolls Royce Trent 900 engine during testing. The Trent is a typical type of high bypass turbofan used in wide-body airliners.
Mechanic working on a Rolls Royce Trent 900 engine during testing. The Trent is a typical type of high bypass turbofan used in wide-body airliners.

As jet engine power and reliability have increased over the last decades, most of the widebody aircraft built today have only two engines. A twinjet design is more fuel-efficient than a comparable trijet or four-engined aircraft. The increased reliability of modern jet engines also allows aircraft to meet the ETOPS certification standard, which calculates reasonable safety margins for flights across oceans. The trijet design has been eliminated due to higher maintenance and fuel costs, and only the heaviest widebody aircraft today are built with four engines (the Airbus A340-600, Airbus A380 and Boeing 747-8).

The Boeing 777 twinjet features the largest and most powerful jet engine in the world, the General Electric GE90, which is 128 inches (3.25 m) in diameter. This is almost as wide as the entire fuselage of a Boeing 737 at 148 inches (3.76 m).

The massive maximum takeoff weight of the Airbus A380 (560,000 kilograms (1,234,588.67 lb)) would not have been possible without the engine technology developed for the Boeing 777. The Trent 900 engine pictured, used on the Airbus A380 has a fan blade diameter of 116 inches (2.95 m), only slightly smaller than the GE90 engines on the Boeing 777.

Interiors

The interiors of aircraft, known as the aircraft cabin, have been under constant evolution since the first passenger aircraft. Bar and lounge areas which were once installed on the Boeing 747 have mostly disappeared, but a few have returned in first or business class on the Airbus A340-600 and on the Airbus A380.

Emirates has installed showers for First Class passengers on the A380; twenty-five minutes are allotted for use of the room, and the shower operates for a maximum of five minutes.

A comparison of interior cabin widths and economy class seating layout is further below in this article under widebody specifications, and further information can be found under external links.


Wake turbulence and separation


This picture from a NASA study on wingtip vortices qualitatively illustrates the wake turbulence.
This picture from a NASA study on wingtip vortices qualitatively illustrates the wake turbulence.

Aircraft are categorized by ICAO according to the wake turbulence they produce. Because wake turbulence is generally related to the weight of an aircraft, these categories are based on one of four weight categories: light, medium, heavy, and super.

Due to their weight, all current widebody aircraft are categorized as heavy, or in the case of the A380, super.

The wake-turbulence category also is used to guide the separation of aircraft. Super and heavy-category aircraft require greater separation behind them than those in other categories. In some countries, such as the United States, it is a requirement to suffix a heavy (or super) aircraft's call sign with the word "heavy" (or super) when communicating with air traffic control in certain areas.

All wide-body airlines

Very few passenger airlines have been economically successful operating a fleet consisting solely of widebody aircraft. The following companies operate an all-widebody fleet:


Airbus A340 from Air Tahiti Nui at the 2005 Paris Air Show
Airbus A340 from Air Tahiti Nui at the 2005 Paris Air Show

Special uses


A U.S. Space Shuttle mounted on a specially modified Boeing 747
A U.S. Space Shuttle mounted on a specially modified Boeing 747

Widebody aircraft are used in science, research, and the military. Two specially modified Boeing 747 aircraft, the Shuttle Carrier Aircraft, are used to transport the U.S. Space Shuttle. Some widebody aircraft are used as flying command posts by the military, such as the Boeing E-4, while the Boeing E-767 is used for Airborne Early Warning and Control. New military weapons are tested aboard widebodies, as in the laser weapons testing on the Boeing YAL-1. Other widebody aircraft are used as flying research stations, such as the joint German-U.S. Stratospheric Observatory for Infrared Astronomy. Both Airbus and Boeing four-engine widebody aircraft are used to test new generations of aircraft engines in-flight. A few aircraft have also been converted for aerial firefighting, such as the DC-10-based Tanker 910 and the 747-based Evergreen Supertanker.

Some widebody aircraft are used as VIP transport. Germany uses the Airbus A310, while Russia uses the Ilyushin Il-96 to transport their highest leaders. The specially modified Boeing 747-200 used by the President of the United States is known as Air Force One, or the Boeing VC-25. More information can be found under: Air transports of heads of state and government.

Future development


The Boeing 787, the first large composite aircraft, expected in service in 2010
The Boeing 787, the first large composite aircraft, expected in service in 2010

Airbus and Boeing are racing to market with two new wide-body designs, currently in development. Both manufacturers have been under significant pressure to see who can get the most orders.

Currently, the Boeing 787 has received more orders than Airbus, and will be first to enter into service with the airlines. The 787 is also the first large commercial aircraft to utilize a monolithic composite fuselage.

The initial Airbus A350 design was only a minor upgrade to that of the A330/A340 series, but Airbus was forced to make significant design changes in response to feedback from the airlines. In addition to being a few inches wider than the Boeing, Airbus claims that the A350 final specifications will be better than that of the 787.

The article on competition between Airbus and Boeing further discusses the rivalry, while order counts between the two aircraft can be compared under Airbus A350 orders versus Boeing 787 orders.

Widebody specifications


Gallery

Trivia

  • The lightest widebody aircraft ever built was the Airbus A300B1 with a maximum take-off weight of 291,000 lb (132,000 kg).
  • The Trent 900 engines used on the Airbus A380 are designed to fit into a Boeing 747-400F freighter for transport.

See also

External links

Wikipedia links




Text from Wikipedia is available under the Creative Commons Attribution/Share-Alike License; additional terms may apply.


Published - July 2009














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