Simanaitis Says

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A WINGED armada of 24 Savoia-Marchetti SM.55X flying boats transported Italo Balbo and his 96 colleagues in their mass flight from Orbetello, Italy, to the 1933 Chicago World’s Fair ( One of the more successful designs of Ing. Alessandro Marchetti, the twin-hulled SM.55 made aviation history from its 1924 debut well into the 1940s.

Savoia-Marchetti SM.55X.

Savoia-Marchetti SM.55X.

The SM.55 was originally planned as a torpedo bomber/mine layer. Cargo, fuel and any passengers were accommodated in its twin hulls. The pilot, copilot and crew resided in its thick wing section between the hulls. Originally open-cockpit, the SM. acquired wider, deeper hulls and an enclosed flight deck by 1930.

SM.55X buzzes Chicago landmark in Microsoft Computer Flight Simulator. Model by Massimo Taccoli.

SM.55X buzzes Chicago’s Adler Planetarium in Microsoft Computer Flight Simulator. Model by Massimo Taccoli.

The SM.55X was a variant powered by twin counter-rotating Isotta-Fraschini Asso 750 engines, one operated tractor fashion, the other pusher, both angled on struts above the center wing panel. (This mounting permitted in-flight maintenance by an intrepid mechanic.)

Isotta-Fraschini Asso 750 broad-angle V-18

Isotta-Fraschini Asso 750 broad-arrow 18-cylinder.

The Asso (Ace) 750 was a liquid-cooled 18-cylinder of broad-arrow layout (see for another such design). The Asso featured double overhead camshafts for each of its three banks, four valves per cylinder and produced 830 hp.

flight deck

A view from the SM.55X flight deck of the George Washington Bridge and New York City skyline.

The flight deck was not particularly spacious, but fully equipped with instrumentation of the era. Italo Balbo commanded the mass flights from the lead Squadriglie Nere (Black Squadron) aircraft. Crews of each SM.55X consisted of four, two officers at the controls and two enlisted men serving as mechanics.

The black trim identifies this as Nere

The black and other trim identify this as Italo Balbo’s command SM.55X.

There were crew accommodations within the hulls as well. In fact, civilian versions of the SM.55 carried as many as 11 passengers there given somewhat larger viewports.

In 1926, the SM.55 set 14 records for speed, altitude and distance. A Brazilian crew flew the Atlantic in 1927. A year later, Italo Balbo undertook a Western Mediterranean Cruise with 61 seaplanes, nine of which were SM.55s. This was followed in 1929 by an Eastern Mediterranean Cruise, almost a sales trip, that visited Greece, Turkey, Bulgaria, Romania and the Soviet Union. SM.55s were the predominant aircraft.

The first chevron of

The first chevron of Squadriglie Nere, led by Italo Balbo’s SM.55X.

In 1930, Balbo led a South American Cruise with yet another enhancement of the SM.55. One design change was sealing off the flight deck from the fuel tanks—so that the crew could safely smoke. There’s a jaunty Italian video of this flight at

Last, in 1933 came the SM.55Xs’ Crociera Aerea Del Decennale, the Decennial Aerial Cruise celebrating the 10th anniversary of the Italian Air Force. This visit to the Chicago World’s Fair was the longest and most difficult of Balbo’s mass flights.

Its highlights are given, albeit in Italian with more than a few Fascist overtones, on a video at The straight-arm salutes and 14 minutes are more than balanced, though, by scenes of Balbo wearing his Sioux headdress. ds

© Dennis Simanaitis,, 2013

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This entry was posted on August 18, 2013 by in Vintage Aero and tagged , , .
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