AllExperts > Encyclopedia 
Search      
Find out about volunteering to AllExperts

Boeing 787: Encyclopedia BETA


Free Encyclopedia
 Index · Browse A-Z  · Questions and Answers ·
|
Encyclopedia

Browse A-Z
ABCDEFGHIJKLMNOPQRSTUVWXYZNum


License
Disclaimer

 
 
 
 
Free Online Courses
12 Weeks to Weight Loss
Take Charge of Stress
Learn How to Bake
Budgeting 101
Deeper Faith
DIY Fashion Makeover

       MORE E-COURSES
 
    |June 2, 2004|

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z  Misc

Boeing 787



Prior to January 28, 2005, the 787 was known as the developmental designator 7E7. On April 26, 2005, one year to the day after the launch of the program, the final look of the external 787 design was frozen. With a less rakish nose and a more conventional tail, the final design has aerodynamics superior to the initial 7E7 concept.

Development

Background

Boeing_sonic.jpg

Artist's concept of the Sonic Cruiser, a proposed replacement for the 767.

When 767 sales began to weaken in the face of competition from the Airbus A330-200 in the late 1990s, Boeing began to consider a replacement. As the Boeing 747-400 was also beginning to lose traction, the company proposed two new aircraft — the Sonic Cruiser and the 747X.The Sonic Cruiser was intended to achieve higher speeds (approximately Mach 0.98) while burning fuel at the same rate as the existing 767 and A330 products. The 747X, intended to compete with the Airbus A380, would stretch the 747-400 and give it a composite supercritical wing to improve efficiency. The limited potential market for superjumbos was an issue, however; the earlier Douglas DC-10 and Lockheed L-1011 widebodies split a similarly limited market and drove both companies out of their strong positions in the commercial aircraft market.

Market interest for the 747X was tepid; the Sonic Cruiser had brighter prospects. Several major airlines, primarily in the United States, voiced their optimism for the concept. By decreasing travel time, they would be able to increase customer satisfaction and aircraft utilization.

In the aftermath of the September 11, 2001 attacks, the global airline market was upended. Airlines were not able to justify large capital expenditures, and due to increased petroleum prices, were more interested in efficiency than speed. The worst-affected airlines were in the United States — those same airlines were considered to be the most likely customer of the Sonic Cruiser. Boeing proceeded to offer airlines the option of using the airframe for either higher speed or increased efficiency. Due to high projected airframe costs, demand continued to evaporate. Eventually, Boeing switched tracks and decided to offer an alternative project, cancelling the 747X once Airbus launched production of the Airbus A380 aircraft.

787

ANA-7E7.jpg

Artist's concept of the 7E7 that shows the nose and tail prior to the final '787' redesign; livery of launch customer All Nippon Airways.

The replacement for the Sonic Cruiser project was dubbed the 7E7 (with a development code name of Y2.) The "E" was said to stand for various things, depending upon the audience. To some, it stood for "efficiency," to others it stood for "environmentally friendly," etc. In the end, Boeing claimed it merely stood for "Eight," after the aircraft was eventually rechristened "787".

The 787 essentially uses the technology proposed for the Sonic Cruiser in a more conventional airframe configuration (see Features). Boeing claims that the 787 will be up to 20% more fuel-efficient than current comparable aircraft. Roughly one-third of this efficiency improvement will come from the engines; another third from aerodynamic improvements and the increased use of lighter weight composite materials; and the other third from advanced systems. The most notable system advancement contributing to efficiency is a "more electric architecture" which replaces bleed air and hydraulic power with electrically powered compressors and pumps. Technology from the Sonic Cruiser and 787 will be used as part of Boeing's project to replace its entire airliner product line, called the Yellowstone Project (of which the 787 is the first stage).

Boeing selected two engine types, the General Electric (GE) GEnx and Rolls-Royce Trent 1000 to power the 787. Significantly, this leaves Pratt & Whitney, which normally has an entrant in this market space, unable to offer one of its own engines to 787 customers. Boeing may have wished to rely on two evolved versions of existing engines rather than the higher-risk option of an all new Pratt & Whitney engine, particularly in light of Pratt & Whitney's recent failures in the Regional Jet market and failed PW6000 engine for the A318. For the first time in commercial aviation, both engine types will have a standard interface with the aircraft, allowing any 787 to be fitted with either a GE or Rolls-Royce engine at any time. Engine interchangeability makes the 787 a far more flexible asset to airlines, allowing them to change from one manufacturer's engine to the other's in light of any future engine developments which conform more closely to their operating profile. The engine market for the 787 is estimated at $40 billion USD over the next 25 years.

The launch of a new airliner can be expected to draw scathing comments from competitors, Boeing's doubt over the A380 and Airbus' mocking of the Sonic Cruiser being recent examples. The 787 is no exception, as Airbus' John Leahy has made attempts at refuting all of Boeing's claims, openly criticizing the large-scale use of composites in the 787's fuselage as being "rushed and ridiculous," ignoring the fact that Boeing built and tested the first composite section while examining the Sonic Cruiser concept nearly five years ago [1] making the 787 a significantly refined product [2]. Airbus recently offered the competing A350 using derivatives of the turbofans developed for the 787, modified to generate bleed air. This new jet will make less widespread use of composites with Airbus preferring aluminium-lithium alloys for the fuselage [3]. As of October 13, 2005 the A350 had 143 commitments from various airline companies, however it was recently announced that the A350 would not be available until 2011, three years after the 787 will be in service. In comparison the 787 already has over 400 firm orders so far.

In order to compete with the larger version of the A350, and especially to compete for the large order from Emirates and an order from British Airways, Boeing has announced it will produce a "787-10," with seating capacity between 290 - 310. [4] This has been reported in numerous articles [5], including on ATW Online's daily news [6]. Production of this new model is projected for 2012. Formal launch may come in late 2006 or 2007."Boeing Considers Second Assembly Line For 787 Dreamliner." Pearson, D. The Wall Street Journal. April 27, 2006.

Sales

On April 26, 2004, the Japanese airline All Nippon Airways (ANA) became the launch customer for the 787, then still-known as the 7E7, announcing a firm order for 50 aircraft to be delivered beginning in 2008. ANA's order was for thirty 787-3, 300 seat, one-class domestic aircraft, and twenty 787-8, long-haul, 230 seat, two-class aircraft for international routes such as Tokyo Narita-Los Angeles. The aircraft will allow new routes to be opened to mid-sized cities not previously served, such as Denver and Montreal. Like launch customers of past aircraft, ANA is rumored to have received a significant discount of around 40-50% off the original price. This may never be easily confirmed, but the practice is very common in the aviation industry.

Customer announced orders and commitments for the 787 reached 237 aircraft during the first year of sales, and exceeded 400 in June of 2006. This makes the 787 the fastest-ever selling airliner upon launch; by comparison, the 747 sold 92 units during its first full year of sales. Boeing expects to have 500 firm orders by entry into service (EIS).

The 787-3 and 787-8 variants will be available first, while the 787-9 will enter service 2010, in spite of earlier suggestions that it would be delayed as orders for the 787-3 and 787-8 sold out early production. As of June 16, 2006, five customers had placed orders for a total of 48 787-9s.

The 787-8 variant was priced at a list price of $US 120 million per aircraft, surprising the industry, which was expecting a much higher price tag. There have been two price increases since launch and a 787-8 currently sells for $US 148-157.5 million. The 787-3 is listed at $US 138-143 million, while the 787-9 is listed at $US 178.5-188 million. [7]

Orders and options

|April 26, 2004|
Date Airline EIS Type Engine
787-3787-8787-9 TBA OptionsRightsGERR
Flag_of_Japan.svg

All Nippon Airways [8]|2008
3020  50   
Flag_of_New_Zealand.svg

Air New Zealand [9]|2008
 2  16   
July 7, 2004|

First Choice Airways[10]|2009
 6  6   

Blue Panorama [11]|2009 4  2   October 21, 2004

Primaris Airlines [12]2008 20  15   |December 22, 2004|

Japan Airlines [13]|20081317  20   |December 29, 2004|
Flag_of_the_United_States.svg

Continental Airlines [14]|2009 10       |December 31, 2004|

Vietnam Airlines [15]|2010 4  11   January 28, 2005|

Air China [16]|2008 15      |

China Eastern [17]|2008 15      |

China Southern [18]|2008 10      |

Hainan Airlines [19]|2008 8      |

Shanghai Airlines [20]|2008 9      |

Xiamen Airlines [21]|2008 3      |February 4, 2005|

Ethiopian Airlines [22]|2008 5    5   |February 25, 2005|
Flag_of_Iceland.svg

Icelandair [23]|2010 2    5   |April 11, 2005|

Korean Air [24]|2010 10  10    |April 25, 2005|
Flag_of_Canada.svg

Air Canada [25]|2010 14  46    |April 26, 2005|

Air India [26]|2008 20  7    |May 5, 2005|
Flag_of_the_United_States.svg

Northwest Airlines [27]|2008 18  50    |May 16, 2005|

LCAL [28]|2009 6       |May 31, 2005|

Ethiopian Airlines [29]|2008 5*    -5   |July 31, 2005|
Flag_of_Morocco.svg

Royal Air Maroc [30] |2008 4  1   |September 7, 2005|
Flag_of_Poland.svg

LOT Polish Airlines [31]|2008 7  25  September 16, 2005

Garuda Indonesia [32]2011 10      |October 13, 2005|

ILFC [33]|2010  20  4    |October 25 2005|
Flag_of_New_Zealand.svg

Air New Zealand [34]|2008 2        |December 13 2005|
Flag_of_Australia.svg

Qantas [35] |2008 15 30   2050  December 19 2005

CR Airways [36]2008   10    |December 30, 2005|
Flag_of_India.svg

Air India [37]|2008 7*   -7    |December 31, 2005|

LCAL [38]|2009   8     |  |March 3, 2006|

Unidentified customer|?  1     |March 6, 2006|

Kenya Airways [39]|2010 6   6   | |April 5, 2006|
Flag_of_Iceland.svg

Icelandair [40]|2012 2*     -2   |April 25, 2006|

Air Pacific [41]|2011  5   3   |May 11, 2006|
Flag_of_New_Zealand.svg

Air New Zealand [42]|2010 -4 4     |June 6, 2006|
Flag_of_the_United_States.svg

Continental Airlines [43]|2009 10       -June 14, 2006

Singapore Airlines [44]2011  20  20   June 16, 2006>

Xiamen Airlines [45] -3**      July 6, 2006>

Primaris Airlines [46] -20**  -15**   July 18, 2006>

Blue Panorama [47]  -4  -2   July 18, 2006>
Flag_of_the_United_States.svg

Pegasus Aviation [48]|2009 6      |july 19, 2006|

ILFC [49]|2012    2*-2    |July 28, 2006|Boeing Business Jet [50]   2    |August 7, 2006|

Flyglobespan [51]|2010     2   
>- bgcolor="#efefef"Sub-totals43 281 70 14 242 81 121 95 - bgcolor="#efefef"Totals408 (368 firm, 40 pending) 323
Entries shaded in pink have been announced, but have not yet signed a firm contract.
* Indicates an exercised option or purchase right
** Indicates a cancellation.
Blue Panorama transferred its order to Pegasus Aviation Leasing Company.

Placement of leased aircraft

Leasing companies ILFC and LCAL have orders for 34 787s as of June 16, 2006. On May 12, 2006, ILFC announced it had placed two 787-8s with Air Seychelles. The aircraft will be delivered in May and September of 2010, on 12 year leases. [52] On May 29, 2006, ILFC reached an agreement with Aeroméxico to place 3 787-8s with that airline. The aircraft will be delivered from the beginning of 2010, for an unspecified lease period. [53] On August 7, Flyglobespan concluded the undefined purchase of 2 Boeing 787-8.

Expected future sales

Emirates Airlines has shown an interest in the 787, and has been courting Boeing and Airbus for some time. Emirates recently has been pushing Boeing to develop a second stretch of the aircraft, the 787-10. A decision is expected to be announced within the next 6 months.

Arkia Israel Airlines is in talks with Boeing to purchase 4 787s for use on services to the USA. [54]

Airlines which have declared an interest in a next-generation aircraft (but not committed to the 787 or A350) include American Airlines, "Good news for Boeing, Airbus" The News Tribune July 23, 2006 British Airways, "BA stays silent on price fixing inquiry" Forbes.com July 18 2006 Etihad UAE Etihad says A380 plane delay won't hurt growth

Production

Fuselage barrel sections from Alenia and Vought will be flown to Everett on modified 747s.

Boeing will manufacture the 787's tail fin at its Frederickson, Washington, plant, ailerons and flaps at Boeing Australia, and fairings at Boeing Canada. For its entire history, Boeing has jealously guarded its techniques for designing and mass producing commercial jetliner wings. Due to economic realities, the wings will be manufactured by Japanese companies in Nagoya, e.g. Mitsubishi Heavy Industries, while the horizontal stabilizers will be manufactured by Alenia Aeronautica in Italy, and the fuselage sections by Vought in South Carolina, Alenia in Italy, Kawasaki Heavy Industries in Japan, and Spirit AeroSystems, in Wichita. "Boeing 787: Parts from around world will be swiftly integrated", The Seattle Times, September 11, 2005.

Japanese industrial participation is very important to the project, with 35% workshare, with many of the subcontractors supported and funded by the Japanese government. On April 26 2006, Japanese manufacturer Toray industries and Boeing announced a production agreement involving $6 billion worth of carbon fiber. The deal is an extension of a contract signed in 2004 between the two companies and eases some concerns that Boeing might have difficulty maintaining its production goals for the 787.

From France, Messier-Dowty will build the landing gear and Thales will supply the integrated standby flight display, electrical power conversion system, and in-flight entertainment.

Honeywell and Rockwell-Collins will provide flight control, guidance and other avionics systems, including standard dual head up guidance systems. Future integration of forward looking infrared is being looked at by Flight Dynamics allowing improved visibility using thermal sensing as part of the HUD system, allowing pilots to "see" through the clouds.

Hamilton Sundstrand will provide power distribution and management systems to the aircraft, including manufacture and production of Generator Control Units (GCUs) as well as integration of power transfer systems that can move power from the Auxiliary Power Unit (APU) and the main engines to the necessary parts and machinery of the aircraft.

Nose section of the 787-8, unveiled at Spirit Wichita for the first time.

The final assembly will consist of attaching fully-completed subassemblies, instead of building the complete aircraft from the ground up. This is a technique which Boeing has previously used on the 737 program, which involves shipping fuselage barrel sections by rail from Spirit's Wichita, Kansas facility to Boeing's narrowbody final assembly plant at Renton, Washington. Airbus has also used this technique in the past, although in its case it is more of a political necessity resulting from partner nations' divided workshare. After stiff competition, Boeing announced on December 16, 2003 that assembly would take place in Everett, Washington, employing 800 to 1,200 people.

The 787 will undergo wind-tunnel testing at Boeing's Transonic Wind Tunnel, QinetiQ's five-meter wind tunnel based in Farnborough, UK, and NASA Ames Research Center's wind tunnel, as well as at the French aerodynamics research agency, ONERA.

The first composite section rolled out in January 2005, and final external design was set in April 2005.On June 30, 2006 Boeing celebrated the start of major assembly of the first 787 at Fuji Heavy Industries' new factory in Handa, Japan, near Nagoya.[55]

Boeing intends to deliver 118 aircraft during the first 18 months of production. Due to customer demand, Boeing is currently considering whether to open a second production line. Some of the difficulty in this case revolves around the production capacity of suppliers. For example, Alenia is said to only be able to produce seven 787 fuselage sections per month. Difficulties in increasing production rates resulted in severe delivery delays in 1999.

Features

Boeing 787-8 3-view diagram.

* 18.5 in (47 cm) seat-bottom width (depending on aisle armrest widths) in 2+4+2 or 3+2+3 arrangements. Seat widths would be appoximately 17.2 in (43.7 cm) for 3+3+3 seating.
* Cabin interior width 50 in (127 cm) from the floor is 18 ft 7 in (566 cm) and was recently increased by 1 inch (2.5cm). The 787's interior cabin width, measured at seated eye level (where width is, according to Boeing studies, actually perceived) is a full 15 in (38 cm) greater than that of the Airbus A330 and A340. Two class configuration of 240 seats in two class domestic with 46 in (116.8 cm) first class pitch and 34 in (59.7 cm) coach class. 296 passengers can be seated in a high density 3+2+3 coach arrangement with 36 in (91.4 cm) Business and 32 in (81.3 cm) Coach pitch. Up to 234 passengers may be seated in a three-class setup that uses 61 in (154.9 cm) pitch in First Class (2+2+2 or 2+1+2), 39 in (99 cm) pitch for Business (2+3+2 or 2+2+2) and 32 in (81.3 cm) for Coach (2+4+2).
* Cruise speed: 0.85 Mach (903 km/h or 561 mph at altitude)
* Range of 8,500 nautical miles (15,700 km), enough to cover the Los Angeles to Hong Kong or New York to Tokyo routes.
* Construction materials (by weight): 50% composite, 20% aluminum, 15% titanium, 10% steel, 5% other. Composite materials are significantly lighter and stronger than traditional aircraft materials, making the 787 a very light aircraft for its capabilities. By volume, the 787 will be 80% composite. This will allow the potential to take off from, and land on, relatively short airstrips as the 767 can, yet still have the capability to fly long-haul distances. [56]
* The 787 production line will be able to finish an aircraft in as little as three days, compared to 11 days for the 737.
* Larger windows than any other civil air transport (27 cm by 47 cm), with a higher eye level, so passengers can see the horizon, with liquid crystal display (LCD)-based "auto-dimming" to reduce cabin glare and maintain transparency. These are to be supplied by PPG[57].
* Light-emitting diode (LED) cabin lighting (three color) will be used instead of fluorescent tubes, allowing the aircraft to be entirely 'bulbless' and have 128 color combinations.
* A version of EthernetAvionics Full-Duplex Switched Ethernet (AFDX) / ARINC 664 -- will be used to transmit data between the flight deck and aircraft systems.
* LCD multi-function displays on the flight deck, all of which will use an industry standard GUI widget toolkit (Cockpit Display System Interfaces to User Systems / ARINC 661) [58]
* Bleedless turbofans, allowing elimination of superheated air conduits normally used for de-icing, aircraft power, and other functions. These systems are to be replaced with an all-electrical system.
* Cabin air provided by electrically driven compressors (no engine bleed air).
* Higher humidity in the passenger cabin because of the use of composites (which do not corrode).
* The internal pressure will be increased, to the equivalent of 6000 feet (1800 m) altitude versus 8000 (2400 m) on conventional aircraft. This will significantly improve passenger comfort.
* Boeing is experimenting with several engine noise reducing technologies for the 787. Among these are a redesigned air inlet containing sound-absorbing materials and redesigned exhaust duct covers whose rim is tipped in a toothed pattern to allow for quieter mixing of exhaust and outside air. Boeing expects these developments to make the 787 significantly quieter both inside and outside the passenger cabin.
* Improved ride quality through Active Gust Alleviation system, similar to that Boeing built for the B-2 bomber.

Early concept images of the 787 included rakish cockpit windows, a dropped nose, and a distinctive "shark-fin" vertical stabilizer. The final styling of the aircraft was more conservative, with the fin less radical than on earlier images, but the nose and cockpit windows were retained. The nose is very similar to that of the Dornier 328Jet.

Variants

Air New Zealand will be the launch customer for the initial stretch version, the 787-9.

The 787 is currently being offered in three variants:
* The 787-3 will be a 296 seat (two class) short-range version targeted at high density flights, with a range of 3,500 nautical miles (6,500 km). EIS is 2010. Boeing is targeting the 787-3 to replace the Airbus A300, Boeing 767-200 and 767-300 used in Japan domestic routes. The 787-3 will have no direct counterpart from Airbus.
* The 787-8 will be the baseline model, with 223 seats in three classes and a range of 8,500 nautical miles (15,700 km). EIS is 2008. Boeing is targeting the 787-8 to replace the 767-300ER. The 787-8 will have no direct counterpart from Airbus.
* The 787-9 will be a stretched variant, seating 259 in three classes. The targeted EIS is set at 2010 [59]. Boeing is targeting the 787-9 to replace the Airbus A330-200 and A340-200, Boeing 767-400ER, McDonnell Douglas DC-10, and Lockheed L-1011. Airbus is offering the A350-800 in competition.

In addition, Boeing is studying the 787-10, a stretched variant seating roughly 300 which is intended to compete with the planned Airbus A350-900. The 787-10 would supersede the 777-200A and 777-200ER in Boeing's current lineup, and could also be targeted to replace the Airbus A330-300 and A340-300, and McDonnell Douglas MD-11. Emirates Airlines and Qantas have shown interest in such variant which would enter service in 2012. This variant has not yet been officially launched by Boeing, but Mike Bair, head of the 787 Program, has already stated that "It's not a matter of if, but when we are going to do it... The 787-10 will be a stretched version of the 787-9 and sacrifice some range to add extra seat and cargo capacity". "Boeing to Build Stretch 787 Jet," The Wall Street Journal, March 27, 2006.However, while Boeing is optimizing the 787-9, many aerodynamic improvement will be found on the 787-10 [If the plane will be released]. If it is a requirement, Boeing will request a more powerful engine with higher thrust ratings.

Specifications

Comparison with other Boeing aircraft

787-3787-8787-9787-10
(estimated)
757-300
(for comparison)
767-300ER
(for comparison)
767-400ER
(for comparison)! 777-200ER
(for comparison)
Length:55.5 m55.5 m63 m68.9 m54.5 m54.9 m61.4 m63.7 m
Height:16.5 m16.5 m16.5 m16.5 m13.6 m15.8 m16.8 m18.5 m
Wingspan:51.6 m58.8 m60.0 m60.0 m38 m47.6 m51.9 m60.9 m
Cross section:5.77 m5.77 m5.77 m5.77 m3.5 m4.70 m4.70 m6.20 m
MTOW:163.5 t216.5 t244.9 t244.9 t123.6 t186.9 t204.1 t297.6 t
Seats:290-330210-250250-290300-350243
two class
218
three class
245
three class
301
three class
Cargo:16 tons16 tons16 tons?10 tons
Engine:GE GEnx or
RR Trent 1000
GE GEnx or
RR Trent 1000
GE GEnx or
RR Trent 1000
GE GEnx or
RR Trent 1X88-77
RR RB211-535
or P&W
2037/40/43
GE CF6-80A2/C2 or
P&W PW4062 or
RR RB211-524
GE CF6-80C2 or
P&W PW4062
P&W 4090 or
RR Trent 895 or
GE GE90-94B
Cruising speed:0.85 Mach0.85 Mach0.85 Mach0.85 Mach0.80 Mach0.80 Mach0.80 Mach0.84 Mach
Range¹:6,498km (3,509nm)15,699km (8,477nm)16,299km (8,801nm)15,699km (8,477nm)6,285km (3,394nm)11,137km (6,014nm)10,452km (5,644nm)14,315km (7,730nm)
Maximum fuel:124,700 L124,700 L138,700 L145,685 L171,160 L
Service ceiling:13,000 m13,000 m13,000 m13,000 m13,000 m13,000 m13,000 m
EIS:2009filler200820104Q2012filler1999198820001997
¹ With full load (passengers and cargo), from [60]

Comparison with Airbus A350 XWB 900

A350 XWB-900
Singapore Airlines orders 20 Airbus A350 XWB-900s and 9 Airbus A380s!787-10
Length:64.0 m68.9 m
Height:17.0 m16.5 m
Wingspan:64.0 m60.0 m
Cross section:5.91 m5.77 m
MTOW:265.0 t244.9 t
Seats:314 (three class)300-350
Cargo:20 tonnes
Engine:RR Trent 1700 (confirmed) or
GE GEnx (proposed)
GE GEnx or RR Trent 1X88-77
Cruising speed:0.85 Mach0.85 Mach
Range:15,700 km (8,500 nm)15,700 km (8,500 nm)
Maximum fuel:145,685 L
EIS:2012}

The Boeing 787-10's specifications are based from[61]

References

External links

* 787 Facts (from BCA)
* Customer list (from BCA)
* Boeing 787 Airport Compatibility brochure (from BCA)
*BCA order sheet for the 787, does not include announced but unsigned contracts.
* 787 videos.
*Boeing 787 Dreamliner Official Homepage (From Boeing)
* Boeing 787 photos (from BCA)
* A detailed analysis of the 787's business affairs (pdf)
* Aircraft-Info.net - Boeing 787
* ANA info page on 787
* 787 and WTO
* Aerospace-Technology
* Video of 787 composite tape laying, The Chicago Tribune.

Related content



Email this page
About Us | Advertise on This Site | User Agreement | Privacy Policy | Kids' Privacy Policy | Help
About and About.com are registered trademarks of About, Inc. The About logo is a trademark of About, Inc. All rights reserved.
This is the "GNU Free Documentation License" reference article from the English Wikipedia. All text is available under the terms of the GNU Free Documentation License. See also our Disclaimer.