Sud Aviation Caravelle

The Sud Aviation SE 210 Caravelle is a French short/medium-range jet airliner. It holds the distinction of being the world's first jet-powered airliner to be developed for the short/medium-range market.

Development of the Caravelle by the French aircraft manufacturer SNCASE, a company that was keen to produce a passenger aircraft that utilised newly developed jet propulsion technology, began in the early 1950s. In order to achieve this, SNCASE formed partnerships with British companies such as de Havilland (which provided designs and components that it had developed for its own jet-powered airliner, the de Havilland Comet) and Rolls-Royce Limited (the supplier of the Caravelle's Rolls-Royce Avon turbojet engines). While much of the airliner's development, including its maiden flight on 27 May 1955, was conducted by SNCASE. By the time that the Caravelle entered revenue service on 26 April 1959, the firm had been merged into the larger Sud Aviation conglomerate.

Within a few years of commencing passenger services, the Caravelle became one of the most successful European first-generation jetliners. The airliner achieved substantial sales to operators throughout Europe and even managed to penetrate the U.S. market with United Airlines placing an order for 20 Caravelles.[3] The Caravelle established the aft-mounted engine, clean-wing design configuration that is still used widely by smaller jetliners.[3]

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 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). 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.[3][4]

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 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 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 Marborés as auxiliaries. SNCASE had also returned a number of designs from the X-200 to X-210, all of these being purely jet-powered.[3]

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 had already begun to offer a new version of the Avon that was to be capable of developing 9,000 lbf (40 kN) of thrust, which would render the auxiliary engines of the S.O.60 and the third engine featured on the X-210 unnecessary.[3] The Committee issued a request for SNCASE to re-submit its X-210 proposal as a twin-Avon design.[4] In doing so, SNCASE decided not to bother moving 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 SGACC.[clarification needed][3]

The unusual cockpit window arrangement of the Caravelle. The entire cockpit design was licensed directly from the de Havilland Comet.

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 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.[3] A distinctive design feature was the cabin windows in the shape of a 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), christened by 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 RA-26 Avon Mk.522, capable of providing 4,536 kgf (44,480 N; 10,000 lbf) of unitary thrust. For the maiden flight, which had a total duration of 41 minutes, the crew consisted of Pierre Nadot (first officer), André Moynot (second officer), Jean Avril (mechanic), André Préneron (radio operator) and Roger Beteille.[3]

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.[3] By October 1956, both prototypes had accumulated in excess of 1,000 flight hours.[4] 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.[4]

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.[4] 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.[4] 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;[clarification needed] shortly thereafter, the type commenced operations with Air France as well.[3]

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.[4] 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.[4] 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.[3]

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.[5] 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 wing spoilers.[5]

The Caravelle 10A and 10B, which differed only in the engines used and were commonly referred to as the Super Caravelle, featured the improvements of the VI-R in addition to a high degree of further design changes.[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 redesigned wing was equipped with double-slotted Fowler flaps, additional and repositioned stall vanes,[clarification needed] 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.[5]

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 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.[3]

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.[3]

Rear fuselage of a Caravelle, showing its Rolls-Royce Avon turbojet engine

The Caravelle belongs to the first generation of passenger aircraft to use newly developed jet propulsion technology, and it was the first jet airliner developed specifically for the short/medium-range sector of the market. Early in the Caravelle's career, its chief competitors were propeller-driven aircraft, such as the British-built Vickers Viscount and the U.S.-built Convair CV-440.[4] Reportedly, the Caravelle proved to be a highly reliable airliner during its early years of service. The low accident rate for the type led to lower than average insurance premiums for Caravelle operators.[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.[4] Various models of the Avon engine were adopted for different versions of the airliner, often with increased thrust and additional features such as thrust reversers. Alternative powerplants were adopted or proposed for some Caravelle models, such as the U.S.-built Pratt & Whitney JT8D-1 and General Electric CJ-805-23C engines.[7]

The Caravelle was designed to maximise passenger comfort and operator convenience. The rear entry door had built-in stairs that, while adding structural complexity, meant that mobile airport stairs were unnecessary.[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.[5] In some configurations, the Caravelle's cabin was furnished with a number of rearward-facing passenger seats, which was an uncommon arrangement amongst civil aircraft.[3] 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.[6]

The final assembly line for the Caravelle was at Sud Aviation's factory at Blagnac Airport near Toulouse. Much of the aircraft was manufactured at other sites across France and in other countries, however.[7] The production of large portions of the Caravelle had been subcontracted to other manufacturers; these included the Italian aircraft manufacturer Fiat Aviazione, which produced the aircraft's tailplane, fin, ailerons, and engine nacelles; and French aviation firm Breguet Aviation, which performed the outfitting of the rear fuselage; while much of the ancillary equipment of the Caravelle originated from either British or U.S. manufacturers. Sud Aviation constructed and outfitted the nose section, along with manufacturing the tailcone, rudder, Fowler flaps, both the leading edges and trailing edges of the wing, and the majority of the fuselage.[4]

The triangular windows of the Caravelle remained unaltered throughout its development.
This variant had the same external configuration as variant I but with more powerful engines, the Rolls-Royce Avon RA-29/1 Mk.526 giving improved capabilities. The first flight took place on 11 February 1960. Caravelle I and IA aircraft were later converted to the III variant.
Sales: 12 built. Deliveries were to Air France, SAS, Air Algérie, Finnair, and Royal Air Maroc.
A combination of the 10B's engines on the Series VI-R fuselage, creating a smaller but higher powered aircraft. Maximum weight at take-off was increased to 52,000 kg (115,000 lb) (6,000 kg or 13,000 lb more than the Series I and 2,000 kg or 4,400 lb more than the Series VI-R). It first flew on 8 January 1965 and received U.S. certification on 23 May of that same year.
The 11R had a fuselage length of 31.72 m (104 ft 1 in) (70 cm or 28 in more than other variants) and incorporated a 3.32 m × 1.84 m (10.9 ft × 6.0 ft) cargo door in the port side. This enabled it to carry a mixed load of passengers and cargo. First flight of the series 11R was on 21 April 1967.
A JAT Sud Aviation SE-210 Caravelle VI-N at Düsseldorf Airport, June 1973

For 45 years of commercial exploitation, 67 Caravelles have been withdrawn from service as a result of destruction or for irreparable damage. None of these accidents and incidents are attributed to a design defect, only a few technical failures, human errors, or sabotage. The total loss of life in accidents in Caravelle is more than 1,300. The accident rate per million flights is estimated at more than 5.5, compared with less than 1 for the most recent airliners .

Cockpit of Sud Caravelle airliner formerly PH-TRO of Transavia, on display at Aviodrome Lelystad in 2009