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. 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. The Committee issued a request for SNCASE to re-submit its X-210 proposal as a twin-Avon design. 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). Selection 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. 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), launched by Madame de Gaulle, was rolled out. On 27 May 1955, the first prototype conducted its maiden