The Cantz 511 Long Range Cargo Hydroplane was first designed by Fillipo Zappata. The first flight took place in Monfalcone (Trieste, north-eastern Italy) in October 1940. It's first operational start took place in February 1942 (Italian territory).

The phase of study for the construction of this huge four-engined, double-floated hydroplane (the largest of its category in the world) started at the end of September 1937, when the technical department of CRDA accepted the order of Compagnia Ala Littoria, who requested a long range hydroplane for mail, cargo and passengers link with Latin America. After two years of hard work, the project manager Filippo Zappata and his team were ready with the first prototype. This aircraft - strong and beautiful, able to carry (in theory) 16 passengers to a destination of more than 5.000 km away, flew in October 1940 giving good impressions in spite of its dimensions and its imperfect engines' setting up (after he had tested some national engines, Zappata asked the High Command the permission to purchase six U.S. Wright Cyclone R-2600A propellers: due to the worsening of the diplomatic relationship between Rome and Washington, his request was not accepted).

The CANTZ511 was then provided with four Piaggio P.XII RC.35 1500 hp engines, the only ones to guarantee acceptable performances on an aircraft weighing 34 tons. In April 1941, the prototype flew from Monfalcone to Grado (far from the unsafe Yugoslavian border) for other trials. On January 1942, the hydroplane had to be employed on different long range routes, as the war against the United States prevented the civil use of CANTZ511 in the Atlantic area. The ideas were actually original and unusual. Among the projects taken into consideration, were plans to free fifty Italian soldiers and pilots imprisoned in Jeddah by Arab-English forces; to bomb some Russian ports on the Black Sea (Bathumi and Poti), on the Caspian Sea (Baku), or British bases on the Persian Gulf (Oil ports in Bahrein). Some had the odd idea of a spectacular mission (taking off from Bordeaux and twice supplying from German supply-submarines) in the skies of New York, launching one ton of tri-coloured leaflets.

Some others thought about a non-stop Rome-Buenos Aires raid (8000 km!). None of these projects was carried out. And it was a real pity, as the test pilot Mario Stoppani - between the end of February and the beginning of March 1942, during the last trials - succeeded in taking off and landing (full loaded) with very rough sea, with 1.5 metres high waves and winds blowing at 55-65 kmh.

Article by Alberto Rosselli.