Savoia-Marchetti S.55
The Savoia-Marchetti S.55 was an Italian twin-hull flying boat designed by Alessandro Marchetti and first flown in 1924. Its two hulls carried the passengers and cargo, its crew sat in the thick centre wing, and two engines in tandem above the wing drove tractor and pusher propellers. Built in civil and military versions, it set world records, served the Regia Aeronautica as a maritime bomber and patrol aircraft, and won fame through the mass formation Atlantic crossings of 1930 and 1933 led by Italo Balbo. Only one original survives, in Brazil, joined in 2023 by a full-size replica in Italy.
Why It Mattered
The S.55 put its crew inside the wing and its passengers inside two separate hulls, a layout no other production flying boat adopted. Within two years of first flying it was setting world records, and within a decade it had carried the first mass formation crossings of the Atlantic. Those crossings were feats of organisation, and also showcases: Vintage Aviation News notes that one key drive behind them was promotion of the Italian state of the day. The formations were famous enough that their leader's name, Balbo, entered English as a word for a large formation of aircraft.
Design Notes
Alessandro Marchetti designed the S.55 at SIAI in response to a 1923 Regia Aeronautica competition for a long-range, over-water torpedo bomber. Cargo and passengers rode in the twin hulls, which could be arranged in cabins for as many as twelve people, while the pilots sat in a cockpit in the leading edge of the thick centre wing. A torpedo could be slung between the hulls, where it sat on the centre of gravity and could be loaded from a boat positioned alongside. Two engines sat in tandem in a nacelle above the wing, driving tractor and pusher propellers, a position that kept them clear of the water on take-off and landing. The structure was primarily wood, and the airframe broke down into major sections to make transport and maintenance easier.
Operational History
The prototype flew in August 1924, and by 1926 the S.55 had set 14 world records for speed, altitude and distance with a payload. In February 1927 Francesco de Pinedo's Santa Maria completed the type's first Atlantic crossing, reaching Brazil on 23 February. On 24 April 1927 João Ribeiro de Barros and a crew of three flew the S.55 Jahú non-stop from Santiago Island to Fernando de Noronha; the Smithsonian notes that nobody from the Western Hemisphere had crossed the South Atlantic by air before. In June 1928 an S.55 piloted by Umberto Maddalena located the survivors of Umberto Nobile's crashed airship Italia on an ice floe in the Arctic. Civil operators came first, but with more powerful engines the Regia Aeronautica adopted the type, and from 1929 it was the standard equipment of Italy's maritime bombing units, remaining in service to 1937. Balbo took formation cruises across the Mediterranean in 1928–29 and across the Atlantic to the Americas in 1930, then in July 1933 led 24 S.55Xs in formation from Orbetello to Chicago's Century of Progress exposition. Airlines flew the S.55 as well, Aeroflot among them, and the type won export orders in Brazil, Romania, the United States and the Soviet Union. By the Second World War the type was obsolete, with only a few kept in reserve; the last examples were struck off charge in Italy and Romania by 1943.
Afterlife
Vintage Aviation News puts production at more than 250 aircraft, yet just one complete original survives, the Jahú in Brazil. The Jahú is the aircraft de Barros flew across the South Atlantic in 1927, and it was preserved at the TAM museum in São Carlos, which has since closed. Italy itself had no original example, so the Savoia Marchetti Historical Group, a team built around former SIAI-Marchetti workers, constructed a full-size replica of Balbo's S.55X from Marchetti's original drawings. Seven years and roughly eight thousand person-hours later, the replica was unveiled at the Volandia museum in September 2023, and it remains on display there.