Editing Boeing 747 (section)

== Design ==
[[File:Boeing 747-100 3-view.png|thumb|upright|Three-view diagram of the original Boeing 747-100, showing its general configuration maintained in later variants]]
{{for|design details of a particular generation|Boeing 747-400#Design{{!}}Boeing 747-400|Boeing 747-8#Design{{!}}747-8|Boeing 747SP#Design{{!}}747SP}}

The Boeing 747 is a large, wide-body (two-aisle) airliner with four wing-mounted engines. Its wings have a high [[swept wing|sweep]] angle of 37.5° for a fast, efficient cruise speed<ref name="Sutter_p93">Sutter 2006, p. 93.</ref> of Mach&nbsp;0.84 to 0.88, depending on the variant. The sweep also reduces the wingspan, allowing the 747 to use existing [[hangar]]s.<ref name=ucfc747 /><ref>Bowers 1989, p. 508.</ref> Its seating capacity is over 366 with a 3–4–3 seat arrangement (a cross section of three seats, an aisle, four seats, another aisle, and three seats) in economy class and a 2–3–2 layout in first class on the main deck. The upper deck has a 3–3 seat arrangement in economy class and a 2–2 layout in first class.<ref>{{Cite web |date=May 1984 |title=Airplane description |url=http://www.boeing.com/commercial/airports/acaps/7471sec2.pdf |url-status=dead |archive-url=https://web.archive.org/web/20060619025715/http://www.boeing.com/commercial/airports/acaps/7471sec2.pdf |archive-date=June 19, 2006 |access-date=June 19, 2006}} ''The Boeing Company''. Retrieved: December 13, 2007.</ref>

Raised above the main deck, the cockpit creates a hump. This raised cockpit allows front loading of cargo on freight variants.<ref name=Sutter_p93 /> The upper deck behind the cockpit provides space for a lounge and/or extra seating. The "stretched upper deck" became available as an alternative on the {{not a typo|747-100B}} variant and later as standard beginning on the 747-300. The upper deck was stretched more on the 747-8. The 747 cockpit roof section also has an escape hatch from which crew can exit during the events of an emergency if they cannot do so through the cabin.

The 747's maximum takeoff weight ranges from {{Convert|735000|lb|t|abbr=out}} for the -100 to {{Convert|970000|lb|t|abbr=out}} for the -8. Its range has increased from {{Convert|5300|nmi|abbr=out}} on the -100 to {{Convert|8000|nmi|abbr=out}} on the -8I.<ref>[https://web.archive.org/web/20071210173616/http://www.boeing.com/commercial/747family/pf/pf_classics.html "Boeing 747-100/200/300 Technical Specifications"]. ''The Boeing Company''. Retrieved: December 13, 2007.</ref><ref>[http://www.boeing.com/commercial/747family/747-8_fact_sheet.html "Boeing 747-8 Technical Specifications"]. ''The Boeing Company''. Retrieved: December 13, 2007.</ref>

[[File:Air New Zealand Boeing 747-400 (ZK-SUH) arrives London Heathrow 17Oct2010 arp.jpg|thumb|Front view showing the triple-slotted trailing edge [[flap (aeronautics)|flaps]]]]
The 747 has redundant structures along with four redundant hydraulic systems and four main landing gears each with four wheels; these provide a good spread of support on the ground and safety in case of tire blow-outs. The main gear are redundant so that landing can be performed on two opposing landing gears if the others are not functioning properly.<ref name="Sutter_p128-31">Sutter 2006, pp.&nbsp;128–131.</ref> The 747 also has split control surfaces and was designed with sophisticated triple-slotted flaps that minimize landing speeds and allow the 747 to use standard-length runways.<ref name="Sutter_p121-2">Sutter 2006, pp. 121–122.</ref>

For transportation of spare engines, the 747 can accommodate a non-functioning fifth-pod engine under the aircraft's port wing between the inner functioning engine and the fuselage.<ref>{{Cite web |year=2008 |title=Special Report: Air India Flight 182 |url=http://www.airdisaster.com/special/special-ai182.shtml |url-status=usurped |archive-url=https://web.archive.org/web/20091007035356/http://www.airdisaster.com/special/special-ai182.shtml |archive-date=October 7, 2009 |access-date=December 13, 2007 |website=airdisaster.com}}</ref><ref>[http://www.courts.gov.bc.ca/Jdb-txt/SC/05/03/2005BCSC0350.htm "Her Majesty the Queen Against Ripudaman Singh Malik and Ajaib Singh Bagri"]. ''Supreme Court of British Columbia''. Retrieved: December 13, 2007.</ref> The fifth engine mount point was also used by [[Virgin Orbit]]'s [[LauncherOne]] program to carry an orbital-class rocket to cruise altitude where it was deployed.<ref>{{Cite news |date=August 28, 2018 |title=Virgin Orbit performs LauncherOne aircraft flight tests |work=SpaceNews.com |url=https://spacenews.com/virgin-orbit-performs-launcherone-aircraft-flight-tests/ |access-date=November 22, 2018}}</ref><ref>{{Cite news |last=Bergin |first=Chris |title=Cosmic Girl takes LauncherOne on its first captive carry flight test – NASASpaceFlight.com |work=NASASpaceflight.com |url=https://www.nasaspaceflight.com/2018/11/cosmic-girl-launcherone-first-captive-carry-test/ |access-date=November 22, 2018}}</ref>