Editing Boeing 707 (section)

==Development==

===Model 367-80 origins===
{{main|Boeing 367-80}}
[[File:Boeing 367-80 in flight.jpg|thumb|The 707 was based on the [[Boeing 367-80|367-80]] "Dash&nbsp;80"]]
[[File:Washington National Airport Sept 1961 f.jpg|thumb|N708PA, the first Boeing 707 built (1957). This airplane would later crash as [[Pan Am Flight 292]].]]

During and after World War II, Boeing was known for its military aircraft. The company had produced innovative and important bombers, from the [[Boeing B-17 Flying Fortress|B-17 Flying Fortress]] and [[B-29 Superfortress]] to the jet-powered [[B-47 Stratojet]] and [[B-52 Stratofortress]], but its commercial aircraft were not as successful as those from [[Douglas Aircraft]] and other competitors. As Douglas and [[Lockheed Corporation|Lockheed]] dominated the postwar air transport boom, the demand for Boeing's offering, the [[Boeing 377 Stratocruiser|377 Stratocruiser]], quickly faded with only 56 examples sold and no new orders as the 1940s drew to a close. That venture had netted the company a $15 million loss.<ref>[https://web.archive.org/web/20061222070652/http://www.time.com/time/magazine/article/0,9171,857520,00.html "Gamble in the Sky."] ''[[Time (magazine)|Time]]'', July 19, 1954. Retrieved December 27, 2009.</ref> During 1949 and 1950, Boeing embarked on studies for a new jet transport and saw advantages with a design aimed at both military and civilian markets. [[Aerial refueling]] was becoming a standard technique for military aircraft, with over 800 [[KC-97 Stratofreighter]]s on order. The KC-97 was not ideally suited for operations with the USAF's new fleets of jet-powered fighters and bombers; this was where Boeing's new design would win military orders.<ref>{{Cite book |last=Wilson |first=Stewart |title=Boeing 707, Douglas DC-8, and Vickers VC-10 |location=Fyshwick, Australia |publisher=Aerospace Publications|isbn=978-1-875671-36-6 |year=1998|page=18}}</ref>

As the first of a new generation of American passenger jets, Boeing wanted the aircraft's model number to emphasize the difference from its previous propeller-driven aircraft, which bore 300-series numbers. The 400-, 500- and 600-series were already used by their missiles and other products, so Boeing decided that the jets would bear 700-series numbers, and the first would be the 707.<ref name="irving171">Irving 1994, p. 171.</ref>  The marketing personnel at Boeing chose 707 because they thought it was more appealing than 700.<ref name="why7">{{cite web|url=https://www.boeing.com/news/frontiers/archive/2004/february/i_history.html|archive-url=https://web.archive.org/web/20210416224312/https://www.boeing.com/news/frontiers/archive/2004/february/i_history.html|archive-date=April 16, 2021|title=Boeing Frontiers Online: Why 7's been a lucky number|first=Mike|last=Lombardi|website=www.boeing.com|url-status=live|access-date=June 13, 2021|date=March 2004}}</ref>

The project was enabled by the [[Pratt & Whitney JT3C]] [[turbojet]] engine, the civilian version of the [[Pratt & Whitney J57|J57]] that yielded much more power than the previous generation of jet engines and was proving itself with the B-52.  Freed from the design constraints imposed by limitations of late-1940s jet engines, developing a robust, safe, and high-capacity jet aircraft was within reach for Boeing.  Boeing studied numerous wing and engine layouts for its new transport/tanker, some of which were based on the B-47 and C-97, before settling on the [[Boeing 367-80|367-80]] "Dash 80" [[quadjet]] [[prototype]] aircraft. Less than two years elapsed from project launch in 1952 to rollout on May 14, 1954, with the first Dash 80 flying on July 15, 1954.<ref name="ar 2022-01-08">{{cite web |last1=Thomas |first1=Geoffrey |title=The birth of the Boeing 707 was no secret - everyone knew! |url=https://www.airlineratings.com/news/birth-boeing-707-no-secret-everyone-knew/ |website=Airline Ratings |access-date=June 3, 2023 |language=en-AU |date=January 8, 2022}}</ref> The prototype was a proof-of-concept aircraft for both military and civilian use.<ref name="ar 2022-01-08"/> The [[United States Air Force]] was the first customer, using it as the basis for the [[KC-135 Stratotanker]] aerial refueling and cargo aircraft.

Whether the passenger 707 would be profitable was far from certain. At the time, nearly all of Boeing's revenue came from military contracts.  In a demonstration flight over [[Lake Washington]] outside [[Seattle]], on August 7, 1955, test pilot [[Tex Johnston]] performed a [[barrel roll]] in the 367-80 prototype.<ref name="Ruffin">{{cite book|last=Ruffin|first=Steven A|title=Aviation's Most Wanted: The Top 10 book of Winged Wonders, Lucky Landings and Other Aerial Oddities|year=2005|publisher=Potomac Books|location=Washington D.C.|isbn=978-1574886740|page=320}}</ref> Although he justified his unauthorized action to [[William McPherson Allen|Bill Allen]], then president of Boeing, as selling the airplane with a 1 'g' maneuver he was told not to do it again.<ref>{{cite book |last=Johnston |first=A. M. |author-link=Alvin M. Johnston |title=Tex Johnston: Jet-Age Test Pilot |publisher=[[Smithsonian Books]] |date=December 2000 |page=[https://archive.org/details/texjohnstonjetag00john/page/204 204] |isbn=978-1-56098-931-8 |url=https://archive.org/details/texjohnstonjetag00john|url-access=registration}}</ref>

The {{cvt|132|in|mm}} wide fuselage of the Dash 80 was large enough for four-abreast (two-plus-two) seating like the Stratocruiser. Answering customers' demands and under Douglas competition, Boeing soon realized this would not provide a viable payload, so it widened the fuselage to {{cvt|144|in|sigfig=3}} to allow five-abreast seating and use of the KC-135's tooling.<ref>Francillon, René. ''Boeing 707: Pioneer Jetliner''. Shrewsbury, Shropshire, UK: Motor Books International, 1999. {{ISBN|978-0-7603-0675-8}}. p. 34</ref> Douglas Aircraft had launched its [[Douglas DC-8|DC-8]] with a fuselage width of {{cvt|147|in|sigfig=3}}. The airlines liked the extra space and six-abreast seating, so Boeing increased the 707's width again to compete, this time to {{cvt|148|in|sigfig=3}}.<ref name="irving194">{{harvnb|Irving|1994|pp=194–197}}</ref>

===Production and testing===
[[File:Boeing 707-123B, American Airlines JP6986482.jpg|thumb|Boeing 707 six-abreast cabin]]

The first flight of the first-production 707-120 took place on December 20, 1957, and FAA certification followed on September 18, 1958.<ref name="Pither21">{{harvnb|Pither|1998|p=21}}</ref> Both test pilots [[Joseph John "Tym" Tymczyszyn]] and James R. Gannett were awarded the first [[Iven C. Kincheloe Award]] for the test flights that led to certification.<ref>[http://www.setp.org/about-setp/history.html "Society of Experimental Test Pilots, History."] ''setp.org''. Retrieved January 11, 2014.</ref> A number of changes were incorporated into the production models from the prototype. A [[Krueger flaps|Krueger flap]] was installed along the leading edge between the inner and outer engines on early 707-120 and -320 models.<ref name="Bowers434">{{harvnb|Bowers|1989|p=434}}</ref><ref name="airlinercafe.com">[http://www.airlinercafe.com/page.php?id=72 "Boeing 707."] {{Webarchive|url=https://web.archive.org/web/20210317031322/https://www.airlinercafe.com/page.php?id=72 |date=March 17, 2021}} ''airlinercafe.com''. Retrieved December 27, 2009.</ref> This was in response to [[de Havilland Comet]] overrun accidents which occurred after over-rotating on take-off. Wing stall would also occur on the 707 with over-rotation so the leading-edge flaps were added to prevent stalling even with the tail dragging on the runway.<ref>Cook, William H. ''Road to the 707: The Inside Story of Designing the 707''. Bellevue, WA: TYC Publishing Company, 1991. {{ISBN|978-0-9629605-0-5}}, p.249</ref>

===Further developments===
[[File:Western 707.jpg|thumb|The -320 and -420 are 8 ft (2.4 m) longer than the initial -120; later 707s were powered by [[JT3D]] turbofans.]]
{{more citations needed section|date=December 2016}}

The initial standard model was the 707-120 with JT3C turbojet engines. [[Qantas]] ordered a shorter-bodied version called the 707-138, which was a -120 with six fuselage frames removed, three in front of the wings, and three aft. The frames in the 707 were set {{cvt|20|in}} apart, so this resulted in a shortening of {{cvt|10|ft}} to a length of {{cvt|134|ft|6|in|sigfig=3}}. With the maximum takeoff weight the same as that of the -120 ({{cvt|247,000|lb|t}}), the -138 was able to fly the longer routes that Qantas needed.<ref name="airlinercafe.com"/> [[Braniff International Airways]] ordered the higher-thrust version with [[Pratt & Whitney JT4]]A engines, the 707-220. The final major derivative was the 707-320, which featured an extended-span wing and JT4A engines, while the 707-420 was the same as the -320, but with [[Rolls-Royce Conway|Conway]] turbofan engines.

Though initially fitted with turbojet engines, the dominant engine for the Boeing 707 family was the [[Pratt & Whitney JT3D]], a [[turbofan]] variant of the JT3C with lower fuel consumption and higher thrust. JT3D-engined 707s and 720s were denoted with a "B" suffix. While many 707-120Bs and -720Bs were conversions of existing JT3C-powered machines, 707-320Bs were available only as newly built aircraft, as they had a stronger structure to support a maximum takeoff weight increased by {{cvt|19000|lb}}, along with modifications to the wing. The 707-320B series enabled nonstop westbound flights from Europe to the West Coast of the United States and from the US to Japan.

The final 707 variant was the 707-320C, (C for "Convertible"), which had a large fuselage door for cargo. It had a revised wing with three-sectioned leading-edge flaps, improving takeoff and landing performance and allowing the ventral fin to be removed (although the taller fin was retained). The 707-320Bs built after 1963 used the same wing as the -320C and were known as 707-320B Advanced aircraft.

In total, 1,010 707s were built for civilian use between 1958 and 1978, though many of these found their way to military service. The 707 production line remained open for purpose-built military variants until 1991,<ref>{{citation |url=https://www.bbc.com/culture/article/20141020-the-plane-that-changed-air-travel |title=Boeing 707: The aircraft that changed the way we fly |last=Glancey |work=[[BBC News]] |first=Jonathan |quote=Boeing built 1,010 707s for commercial airlines between 1958 and 1978, and a further 800 for the military up until 1991 |archive-url=https://web.archive.org/web/20211125215551/https://www.bbc.com/culture/article/20141020-the-plane-that-changed-air-travel |date=October 19, 2014 |archive-date=November 25, 2021 |access-date=November 30, 2021 |url-status=live}}</ref> with the last new-build 707 airframes built as [[Boeing E-3 Sentry|E-3]] and [[Boeing E-6 Mercury|E-6]] aircraft.{{citation needed|date=December 2021}}

Traces of the 707 are still found in the [[Boeing 737|737]], which uses a modified version of the 707's fuselage, as well as the same external nose and cockpit configurations as those of the 707. These were also used on the previous [[Boeing 727|727]], while the [[Boeing 757|757]] also used the 707 fuselage cross-section.