Editing Sud Aviation Caravelle (section)

==Development==
===Origins===
On 12 October 1951, the ''Comité du matériel civil'' (civil aircraft committee) published a specification for a medium-range aircraft, which was later sent to the aviation industry by the ''Direction technique et industrielle''. This called for an aircraft capable of carrying 55 to 65 passengers and {{convert|1000|kg|abbr=on}} of cargo on routes up to {{convert|2000|km|nmi mi|abbr=on|lk=out}} with a cruising speed of about {{convert|600|km/h|kn mph|abbr=on|lk=out}}. The type and number of engines were not specified. Since 1946, various design studies for aircraft in this category had already been underway at several of the leading French aircraft manufacturing organisations, and had resulted in some ambitious concepts being mooted. None of these firms possessed the financial power to independently embark on the substantial development work involved, let alone to establish a manufacturing line for the construction of such aircraft.<ref name="López1"/><ref name = "doug 456"/>

The response to the specification from the French industry was strong, it has been claimed that every major manufacturer submitted at least one proposal; a total of 20 different designs were ultimately received. The majority of these proposals were powered by all-[[turbojet]] engine arrangements, although [[Breguet Aviation|Breguet]] had entered a number of designs that were powered by both turbojet and [[turboprop]] engines; among these was one for a [[Snecma Atar]]-powered tri-jet to be developed in association with the [[Nord Aviation|SNCA du Nord]] and a turboprop type; all of the different designs were designated as ''Br. 978''. [[Hurel-Dubois]] had entered several turboprop designs based on a narrow fuselage and shoulder-mounted wing, similar to many regional propliners. Proposals from [[SNCASO]] included the S.O.60 with two Rolls-Royce Avon RA.7 engines, outfitted with two smaller [[Turbomeca Marboré]]s as auxiliaries. SNCASE had also returned a number of designs from the X-200 to X-210, all of these being purely jet-powered.<ref name="López1"/>

On 28 March 1952, after studying the various entries, the ''Comité du Matériel Civil'' announced that it had produced a short list of three entrants: the four-engined Avon/Marbore SNCASO S.0.60, the twin-Avon Hurel-Dubois project, and the three-engined Avon SNCASE X-210. At this point, British engine manufacturer [[Rolls-Royce Limited|Rolls-Royce]] had already begun to offer a new version of the Avon that was to be capable of developing 9,000&nbsp;lbf (40&nbsp;kN) of thrust, which would render the auxiliary engines of the S.O.60 and the third engine featured on the X-210 unnecessary.<ref name="López1"/> The Committee issued a request for SNCASE to re-submit its X-210 proposal as a twin-Avon design.<ref name = "doug 456"/> In doing so, SNCASE decided to not remove the remaining engines from their rear-mounted position; most designs had placed the engines underneath the wing, where they could be mounted on the spar for lower overall weight, but it was felt that these weight savings were not worth the effort. This turned out to be a benefit to the design, as the cabin noise was greatly reduced as a result. In July 1952, the revised X-210 design with twin Avons was re-submitted to the [[Secretariat General for Civil and Commercial Aviation]] (SGACC).<ref name="López1"/>

===Selection===
[[File:Air Toulouse (F-BMKS), Dublin, February 1993 (02).jpg|thumb|upright|The unusual cockpit window arrangement of the Caravelle, licensed from the [[de Havilland Comet]]]]
[[File:Caravelle cockpit.JPG|thumb|Cockpit]]

Two months later, SNCASE received official notification that its design had been accepted. On 6 July 1953, the SGACC placed a formal order for the construction of a pair of prototypes along with a pair of static airframes for [[Fatigue limit|fatigue testing]]. SNCASE's design licensed several fuselage features from British aircraft company [[de Havilland]], the two companies already having had dealings in respect to several earlier designs. The nose area and cockpit layout were taken directly from the [[de Havilland Comet]] jet airliner, while the rest of the airliner was locally designed.<ref name="López1"/> A distinctive design feature was the cabin windows in the shape of a [[Reuleaux triangle|curved triangle]], which were smaller than conventional windows but gave the same field of view downwards.

On 21 April 1955, the first prototype of the Caravelle (F-WHHH), launched by [[Yvonne de Gaulle|Madame de Gaulle]], was rolled out. On 27 May 1955, the first prototype conducted its [[maiden flight]], powered by a pair of British [[Rolls-Royce Avon|Rolls-Royce RA-26 Avon Mk.522]], capable of providing {{convert|4536|kgf|lk=on|abbr=on}} of unitary thrust. For the maiden flight, which had a total duration of 41 minutes, the crew consisted of Pierre Nadot (Captain), André Moynot (First Officer), Jean Avril (mechanic), André Préneron (radio operator) and [[Roger Beteille]].<ref name="López1"/>

Almost one year later, on 6 May 1956, the second prototype made its first flight. The first prototype had been fitted with a cargo door located on the lower left side of the fuselage, but this door was removed in the second prototype in favour of an all-seating arrangement.<ref name="López1"/> By October 1956, both prototypes had accumulated in excess of 1,000 flight hours.<ref name = "doug 456"/> By the end of 1956, the two aircraft had visited various locations across [[Europe]] and [[North Africa]]; and trials were already underway for French carrier [[Air France]]. During 1957, the second prototype accumulated roughly 2,500 flight hours across various flights conducted throughout North America and [[South America]].<ref name = "doug 456"/>

In 1956, the type received its first order from Air France; it was followed by [[Scandinavian Airlines System]] (SAS) in 1957. More orders followed, which had been partially driven by a campaign of direct presentations held at airshows and dedicated flight demonstrations using the two prototypes to potential customers.<ref name = "doug 456"/> Also during 1956, SNCASE (Sud-Est – Southeast) had merged with SNCASO (Sud-Ouest – Southwest) and several other French aircraft manufacturers to become Sud Aviation; however, the original SE designation assigned to the airliner was retained.<ref name = "doug 456"/> In May 1959, the Caravelle received its airworthiness certification, enabling the type to enter passenger service. On 26 April 1959, the Caravelle performed its first flight with paying passengers on board for Scandinavian operator SAS;<ref>{{Cite web |last=www.posterteam.com |title=SAS Sud Aviation Caravelle |url=https://www.posterteam.com/content/2812/SAS-Sud-Aviation-Caravelle |access-date=2023-01-27 |website=posterteam.com |language=no}}</ref> shortly thereafter, the type commenced operations with Air France as well.<ref name="López1"/>

===Further development===
[[File:2 et 3.02.1962. Michel Debré à Toulouse. L. Bazerque. Préfet Morin. (1962) - 53Fi3390 (cropped).jpg|thumb|Assembly hall in 1962, during a visit of French prime minister [[Michel Debré]]]]
Within four years of entering airliner service, a total of 172 Caravelles had been sold to a range of operators.<ref name = "doug 456">Dougal 1963, p. 456.</ref> Aviation writer M.G. Douglas attributed the type's favourable early sales record to the effective marketing campaign of performing demonstrations to prospective customers using the two prototypes, as well to the Caravelle having effectively no jet-powered rivals, being the only short-haul jetliner for several years following its introduction.<ref name = "doug 456"/> Several models of the Caravelle were developed and produced over the lifetime of the production run, often in response to the increasing power of the available engines, which allowed higher takeoff weights to be adopted.<ref name="López1"/>

By 1963, there were a total of six different versions of the Caravelle in production, designated ''III'', ''VI-N'', ''VI-R'', ''10A'', ''10B'', and ''X-BIR''.<ref name = "doug 457"/> Of these, the Caravelle III was considered to be the basic version of the airliner, while the other variants featured an increasing number of improvements. The Caravelle VI-N was equipped with more powerful Avon 531 engines and an additional [[heat exchanger]] for the [[air conditioning]], while the Caravelle VI-R, which had come about as a result of demands by U.S. carrier [[United Airlines]], was furnished with [[thrust reverser]]-equipped Avon 352s, a revised windscreen design, [[soundproofing]], a new luggage compartment door, and [[Spoiler (aeronautics)|wing spoiler]]s.<ref name = "doug 457"/>

The Caravelle 10A and 10B, which differed only in the engines used and were commonly referred to as the ''Super Caravelle'' (not to be confused with [[Sud Aviation Super-Caravelle|the later supersonic transport design]]), featured the improvements of the VI-R in addition to a high degree of further design changes.<ref name = "doug 457"/> The more high-profile modifications included a stretch of the fuselage by {{convert|33|inch|cm}}; a highly altered wing; an aerodynamic [[Aircraft fairing|fairing]] behind the fin of the tailplane; expanded cargo capacity via raised floor support struts; and higher cabin windows. Other changes included the adoption of variable-displacement pumps for the [[hydraulics|hydraulic]] system and the use of [[Alternating current|AC-based]] [[Electric generator|generator]]s in place of earlier [[Direct current|DC]] counterparts along with an [[auxiliary power unit]] (APU). The redesigned wing was equipped with double-slotted [[Flap (aeronautics)|Fowler flap]]s, additional and repositioned [[Stall strips|stall vanes]],{{clarify|reason=The wikilink is to the article about stall strips, however a stall vane and stall strip are not the same thing|date=November 2018}} aerodynamic improvements to the [[wing root]] and adjustments to the [[leading edge]] that improved the performance of the wing during the crucial takeoff and landing phases of flight.<ref name = "doug 457"/>
 
Despite its commercial success, however, the Caravelle was soon displaced from being the focus of Sud Aviation's development efforts as the majority of the company's design engineers were progressively reallocated onto an entirely new project that was intended to produce a successor to the Caravelle. The project was relatively ambitious, having the aim of producing a viable [[supersonic transport]] that possessed the same general size and range as the Caravelle. It was decided that the envisioned supersonic airliner should be naturally named after the firm's recent success, thus the [[Sud Aviation Super-Caravelle|Super-Caravelle]] name was applied to the design. Ultimately, the work on the Super-Caravelle would be merged with similar work that had been undertaken by Britain's [[Bristol Aeroplane Company]], and would result in the development of [[Concorde]].<ref name="López1"/>

In total, 282 Caravelles of all types were manufactured (2 prototypes or pre-production aircraft and 280 production aircraft); reportedly, Sud Aviation's projected break-even point for the type had been forecast to be around the 200-unit mark.<ref name="López1"/>