SNCASE merged into the larger Sud Aviation conglomerate before the aircraft entered revenue service on April 26, 1959, with Scandinavian Airlines System (SAS); 282 were built until production ended in 1972.
This called for an aircraft capable of carrying 55 to 65 passengers and 1,000 kg (2,200 lb) of cargo on routes up to 2,000 km (1,100 nmi; 1,200 mi) with a cruising speed of about 600 km/h (320 kn; 370 mph).
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.
[2][3] 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.
[2] 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.
On 27 May 1955, the first prototype conducted its maiden flight, powered by a pair of British Rolls-Royce RA-26 Avon Mk.522, capable of providing 4,536 kgf (44,480 N; 10,000 lbf) of unitary thrust.
[3] 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.
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.
[3] 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.
[3] 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.
[5] The more high-profile modifications included a stretch of the fuselage by 33 inches (84 cm); a highly altered wing; an aerodynamic 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 hydraulic system and the use of AC-based generators in place of earlier DC counterparts along with an auxiliary power unit (APU).
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.
[6] The Caravelle was typically powered by a pair of British-built Rolls-Royce Avon turbojet engines, installed in a rear-mounted position close to the tail unit.
[5] On later variants, soundproofing in the form of readily removable mattress-like rolls that fixed in place via existing brackets was added to the design.
[2] From September 1963 onwards, an autolanding capability (via two separate systems, of which one was self-contained while the other was integrated with the airliner's autopilot), was made available for the Caravelle by Sud Aviation.
However, the Australian government blocked the order, saying that any further diversity in full-size airliners used on domestic routes would have an adverse impact on aircraft servicing within Australia.