Savoia-Marchetti S.55

The Savoia-Marchetti S.55 is a double-hulled monoplane flying boat designed and produced by the Italian aircraft manufacturer Savoia-Marchetti. It was designed to perform both commercial and military applications.

The S.55 had several innovative design features. While the passengers and cargo were housed in the twin hulls, the flight crew occupied a cockpit located in the thicker section of the wing between the two hulls. The S.55 had two inline contra-rotating propellers, mounted in tandem. The engines are canted sharply at an upward angle. Two wire-braced booms connected the triple-finned tail structure to the twin hulls and wing.

The S.55 made its maiden flight during August 1924. Shortly after its introduction, the S.55 set records for speed, payload, altitude and range. Many saw service with the Regia Aeronautica and foreign operators including the Spanish Air Force and Royal Romanian Naval Aviation as bombers and maritime patrol aircraft. While some examples were active by the outbreak of the Second World War, the type only played a marginal role in the conflict due to their age.