Editing Boeing 777 (section)

===Airframe and systems===
[[File:A6-ECF B777-300 Emirates front (4134226438).jpg|thumb|An Emirates 777-300ER in 2009, showing the circular fuselage profile, [[Dihedral (aeronautics)|dihedral]] wings, and [[General Electric GE90|GE90]] turbofan engines, the largest jet engine in service until surpassed by the [[General Electric GE9X]].]]
[[File:aa.b777-200er.n788an.mains.arp.jpg|thumb|777-200ER of [[American Airlines]] in 2007 with [[Rolls-Royce Trent 800|Trent 800]] engines, extended slats, flaps, and six-wheel landing gear |alt=Aircraft belly section. Close view of engines, extended landing gear and angled control flaps.]]
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The [[airframe]] incorporates the use of [[composite materials]], accounting for nine percent of the original structural weight, while the third-generation models, the 777-8 and 777-9, feature more composite parts.<ref>{{Harvnb|Norris|Wagner|1996|p=35}}</ref> Composite components include the cabin floor and rudder, with the 777 being the first Boeing airliner to use composite materials for both the horizontal and vertical stabilizers ([[empennage]]).<ref>{{cite conference |url=http://www.iccm-central.org/Proceedings/ICCM16proceedings/contents/pdf/MonA/MoAM1-01sp_roeselerw228184p.pdf |title=COMPOSITE STRUCTURES: THE FIRST 100 YEARS |author=William G. Roeseler |author2=Branko Sarh |author3=Max U. Kismarton |book-title=16TH INTERNATIONAL CONFERENCE ON COMPOSITE MATERIALS |date=July 9, 2007}}</ref> The main fuselage cross-section is fully circular,<ref>{{Harvnb|Birtles|1998|pp=52}}</ref><ref>{{Harvnb|Norris|Wagner|1996|p=92}}</ref> and tapers rearward into a blade-shaped tail cone with a port-facing [[auxiliary power unit]].<ref name=boeingjets>{{Harvnb|Norris|Wagner|1996|p=89}}</ref>

The wings on the 777 feature a [[supercritical airfoil]] design that is swept back at 31.6&nbsp;degrees<!-- (all models outside the 777-8X and 777-9X) --> and optimized for cruising at Mach&nbsp;0.83 (revised after flight tests up to Mach 0.84).<ref>{{Harvnb|Norris|Wagner|1999|p=130}}</ref> The wings are designed with increased thickness and a longer span than previous airliners, resulting in greater payload and range, improved takeoff performance, and a higher [[cruising altitude]].<ref name="Eden 2008, p. 107" /> The wings also serve as fuel storage, with longer-range models able to carry up to {{convert|47890|gal|L}} of fuel.<ref name="Boeing_777_airport_report_gen2" /> This capacity allows the 777-200LR to operate ultra-long-distance, trans-polar routes such as [[Toronto]] to [[Hong Kong]].<ref name="enroute">{{cite journal |last=Morris |first=Doug |title=What determines the kind of aircraft that will be used for a particular route? |journal=EnRoute |date=March 2012 |url=http://www.enroute.aircanada.com/en/articles/what-determines-the-kind-of-aircraft-that-will-be-used-for-a-particular-route-1 |access-date=March 17, 2012 |archive-date=April 4, 2012 |archive-url=https://web.archive.org/web/20120404064458/http://www.enroute.aircanada.com/en/articles/what-determines-the-kind-of-aircraft-that-will-be-used-for-a-particular-route-1 |url-status=dead}}</ref> In 2013, a new wing made of composite materials was introduced for the upgraded 777X, with a wider span and design features based on the 787's wings.<ref name="777xdubai" />

Folding wingtips, {{convert|21|ft|sigfig=3}} long, were offered when the 777 was first launched, to appeal to airlines who might use gates made to accommodate smaller aircraft, but no airline purchased this option.<ref>{{cite web |url=https://www.caa.govt.nz/aircraft/Type_Acceptance_Reps/Boeing_777.pdf |title=Type Acceptance Report – Boeing 777 |work=[[Civil Aviation Authority of New Zealand]] |access-date=December 1, 2008 |archive-url=https://web.archive.org/web/20081219112154/https://www.caa.govt.nz/aircraft/Type_Acceptance_Reps/Boeing_777.pdf |archive-date=December 19, 2008 |url-status=dead}}</ref> Folding wingtips reemerged as a design feature at the announcement of the upgraded 777X in 2013. Smaller folding wingtips of {{convert|11|ft|sigfig=3}} in length will allow 777X models to use the same airport gates and taxiways as earlier 777s.<ref name="777xdubai" /> These smaller folding wingtips are less complex than those proposed for earlier 777s, and internally only affect the wiring needed for wingtip lights.<ref name="777xdubai" />

The aircraft features the largest landing gear and the biggest tires ever used in a commercial jetliner.<ref>{{Harvnb|Eden|2008|p=111}}</ref> The six-wheel [[Bogie#Bogie (aircraft)|bogies]] are designed to spread the load of the aircraft over a wide area without requiring an additional centerline gear. This helps reduce weight and simplifies the aircraft's braking and hydraulic systems. Each tire of a 777-300ER six-wheel main landing gear can carry a load of {{cvt|59490|lb|kg}}, which is heavier than other wide-bodies such as the 747-400.<ref>{{cite web |url=http://www.flightglobal.com/articles/2006/03/28/205694/adp-to-revamp-runway-at-orly.html |archive-url=https://web.archive.org/web/20090414031605/http://www.flightglobal.com/articles/2006/03/28/205694/adp-to-revamp-runway-at-orly.html |archive-date=April 14, 2009 |title=ADP to revamp runway at Orly |last=Turner |first=Aimee |date=March 28, 2006 |work=Flight International |access-date=April 2, 2009}}</ref> The aircraft has triple redundant [[hydraulic]] systems with only one system required for landing.<ref>{{Harvnb|Birtles|1998|p=66}}</ref> A [[ram air turbine]]—a small retractable device which can provide emergency power—is also fitted in the [[wing root]] [[Aircraft fairing|fairing]].<ref>{{Harvnb|Birtles|1998|p=60}}</ref>