Editing Airbus A340 (section)

==Design==
[[File:A340-600 clean-wing bottom plan-view.jpg|thumb|The 9.2 [[wing aspect ratio|aspect ratio]] and 31° [[wing sweep|sweep]] of the A340-600 wing]]

The Airbus A340 is a [[twin-aisle]] passenger airliner that was the first long-range Airbus,{{sfn|Obert|2009|p=261}} powered by four [[turbofan]] jet engines.<ref name="Montalk">{{cite web |last=de Montalk |first=J.P. Potocki |title= New Avionics Systems — Airbus A330/A340 |url= http://www.davi.ws/avionics/TheAvionicsHandbook_Cap_30.pdf |archive-url= https://web.archive.org/web/20160331163457/http://www.davi.ws/avionics/TheAvionicsHandbook_Cap_30.pdf |url-status= dead |archive-date= 31 March 2016 |date= 2001 |publisher= CRC Press LLC}}</ref> It was developed with technology from earlier Airbus aircraft and their features, like the A320 [[glass cockpit]]; it shares many components with the A330, notably identical [[fly-by-wire]] control systems and similar wings.{{sfn|Lawrence|Thornton|2005|p=73}}{{sfn|Obert|2009|pp=261, 448}} Its features and improvements were usually shared with the A330.{{sfn|Gunston|2009|p=188}} The four engines configuration avoided the [[ETOPS]] constraints such as more frequent inspections.

The A340 has a low [[cantilever wing]]; the A340-200/300 wing is virtually identical to that of the A330, with both engine pylons used while only the inboard one is used on the A330. The two engines for each wing provide a more distributed weight and a more outboard engine weight for a lower wing root bending moment at equal {{abbr|TOW|take off weight}}, allowing a higher wing limited [[MTOW]] for more range. However, the four engines of the A340-200/300 burn more fuel than the A330-200/300. The wings were designed and manufactured by BAe, which developed a long, slender wing with a high [[wing aspect ratio|aspect ratio]] for a higher aerodynamic efficiency.{{sfn|Norris|Wagner|2001|pages=50–51}}{{efn|The higher the aspect ratio, the greater the aerodynamic efficiency: ''A higher aspect ratio wing has a lower drag and a slightly higher lift than a lower aspect ratio wing''.<ref>{{cite web|url=http://www.grc.nasa.gov/WWW/K-12/airplane/geom.html|publisher=NASA|access-date=17 March 2011|title=Wing Geometry Definitions|archive-date=7 March 2011|archive-url=https://web.archive.org/web/20110307125108/http://www.grc.nasa.gov/WWW/K-12/airplane/geom.html|url-status=dead}}</ref>}}

The wing is swept back at 30 degrees, allowing a maximum operating [[Mach number]] of 0.86.{{sfn|Norris|Wagner |2001|p=50}}<ref name=Airbus_A330-300_specs/> To reach a long span and high [[Aspect ratio (wing)|aspect ratio]] without a significant weight penalty, the wing has a relatively high [[thickness-to-chord ratio]] of 11.8%<ref name=Ciornei2005>{{cite web |url= https://www.fzt.haw-hamburg.de/pers/Scholz/arbeiten/TextCiornei.pdf |title= Mach number, relative thickness, sweep and lift coefficient of the wing – An empirical investigation of parameters and equations |author= Simona Ciornei |date= 31 May 2005 |publisher= Hamburg University of Applied Sciences}}</ref> or 12.8%.{{sfn|Gunston|2009|p=195}}{{efn|This is the thickness to chord ratio of the early Airbus A340 variants, which share the same wing with the A330}} Jet airliners have thickness-to-chord ratios ranging from 9.4% ([[MD-11]] or [[Boeing 747]]) to 13% ([[Avro RJ]] or [[737 Classic]]).<ref>{{cite web |url= https://booksite.elsevier.com/9780340741528/appendices/data-a/default.htm |title=Aircraft Data File |publisher= Elsevier |work= Civil Jet Aircraft Design |date= July 1999}}</ref> Each wing also has a {{cvt|2.74|m|ft|adj=on}} tall [[Wingtip device|winglet]] instead of the wingtip fences found on earlier Airbus aircraft. The failure of the ultra-high-bypass [[IAE SuperFan]], promising around 15% better [[Fuel economy in aircraft|fuel burn]], led to wing upgrades to compensate.{{sfn|Norris|Wagner |2001|p=31}}{{sfn|Gunston|2009|p=197}} Originally designed with a {{cvt|56|m|ft}} [[Wingspan|span]], the wing was later extended to {{cvt|58.6|m|ft}} and finally to {{cvt|60.3|m|ft}}.{{sfn|Norris|Wagner |2001|p=31}} This wingspan is similar to that of the larger [[Boeing 747]]-200, but with 35% less wing area.{{sfn|Norris|Wagner |2001|p=50}}<ref name=Airbus_A330-300_specs>{{cite web |url=http://www.airbus.com/aircraftfamilies/passengeraircraft/a330family/a330-300/specifications/ |title= A330-300 Dimensions & key data |publisher=Airbus S.A.S |access-date=20 November 2012}}</ref>

The A340 uses a modified A320 [[glass cockpit]], with [[side-stick]] controls instead of a conventional [[Yoke (aircraft)|yoke]]. The main instrument panel is dominated by six [[Electronic visual display|display]]s, [[cathode-ray tube]] monitors initially then [[liquid crystal display]]s.<ref name="Montalk"/> Flight information is directed via the [[Electronic Flight Instrument System]] (EFIS) and systems information through the [[Electronic Centralised Aircraft Monitor]] (ECAM).<ref name=A330_aero-tech.com>{{cite web |url=http://www.aerospace-technology.com/projects/a330/ |title=Airbus A330 Wide-Bodied Medium/Long-Range Twin-Engine Airliner, Europe |publisher=Aerospace-technology.com |access-date=31 January 2011}}</ref>{{Unreliable source?|reason=domain on WP:BLACKLIST|date=June 2016}}<ref>{{cite web|url=http://www.smartcockpit.com/data/pdfs/plane/airbus/A330/misc/A330_Flight_Deck_and_Systems_Briefing_For_Pilots.pdf |archive-url=https://web.archive.org/web/20091228233548/http://www.smartcockpit.com/data/pdfs/plane/airbus/A330/misc/A330_Flight_Deck_and_Systems_Briefing_For_Pilots.pdf |url-status=dead |archive-date=28 December 2009 |access-date=31 January 2011 |title=A330 Flight deck and systems briefing for pilots |publisher=Airbus S.A.S |page=173 |date=March 1999 }}</ref>

The aircraft monitors various sensors and automatically alerts the crew to any parameters outside their normal range. Pilots can also inspect individual systems. Electronic manuals are used instead of paper ones, and web-based updates are optional.<!--ref name="smart"/--> Maintenance difficulty and cost were reduced to half of that of the earlier and smaller [[Airbus A310]].<ref name="smart">Dubois, Thierry. [http://www.aviationtoday.com/regions/usa/Airbus-A340-Smart-Design_286.html#.U2kn201OWmQ "Airbus A340: Smart Design."] {{webarchive |url=https://web.archive.org/web/20160813084012/http://www.aviationtoday.com/regions/usa/Airbus-A340-Smart-Design_286.html#.U2kn201OWmQ |date=13 August 2016 }} ''Aviation Today'', 1 June 2003.</ref> Improved engine control and monitoring improved time on the wing. The centralised maintenance computer can transmit real-time information to ground facilities via the onboard satellite-based [[ACARS]] datalink.<ref name="Montalk"/><ref name="smart"/> Heavy maintenance, like structural changes, remained unchanged, while cabin enhancements, like the [[in-flight entertainment]], were increased over preceding airliners.<ref name="smart"/>

<gallery mode="packed" heights="160px">
File:Airbus A340-313E, Finnair JP7679383.jpg|The A340-200/300 is powered by four [[CFM56]]-5Cs with [[exhaust mixer]]s.
File:STC 0024 (4280288402).jpg|The A340-500/600 is powered by four larger [[Rolls-Royce Trent 500]]s with separate flows.
</gallery>