details on its anticipated demands for a heavy helicopter; however, these requirements were revised upwards by the customer, leading to the redesign and emergence of the Super Frelon. Changes included the adoption of much more powerful engines, using three Turbomeca Turmo IIIC turboshaft engines, each capable of generating on the prototypes (later uprated to on production models) in place of the Frelon's Turbomeca Turmo IIIB engines; these drove a six-bladed main rotor, instead of the Frelon's four-bladed one, and a five-bladed (instead of four-bladed) tail rotor. Overall, the modified design provided for a greatly increased gross weight, from , whilst improving the rotorcraft's aerodynamic efficiency and handling qualities. Additional external changes between the Frelon and Super Frelon had been made, such as the original stubby tail boom having been replaced by a more conventional one, albeit with a crank in it to raise the tail rotor clear of vehicles approaching the rear loading ramp. Taking note of American experiments with amphibious helicopters, the Super Frelon's fuselage was redesigned into a hull, featuring a bow, planing bottom and watertight bilge compartments. Various foreign manufacturers participated in the development and manufacturing of the type; American helicopter company Sikorsky was contracted to supply the design of a new six-bladed main rotor and five-bladed tail rotor, while Italian manufacturer Fiat supplied the design for a new main transmission. Into flight On 7 December 1962, the first prototype Super Frelon conducted the type's maiden flight. On 28 May 1963, it was followed by the second prototype. The first prototype was tailored towards meeting the needs of the French Air Force, while the second was fully navalised, including lateral stabilising floats fixed to the undercarriage. On 23 July 1963, a modified prototype Super Frelon helicopter was used to break the FAI absolute helicopter world speed record, having attained a maximum speed of during the flight. Flown by Jean Boulet and Roland Coffignot, a total of three international records were broken, these being: speed over 3 km at low altitude, ; speed at any altitude over 15 and 25 km, ; and 100km closed circuit . By April 1964, the two prototypes had accumulated 388 flying hours, which included 30 hours of seaworthiness trials performed with the second prototype. In January 1964, the third Super Frelon prototype made its first flight, the fourth first flew during May 1964, and a pair of pre-production models were completed during