CANT Z.511

The CANT Z.511 was a four-engine long-range seaplane designed by Filippo Zappata of the "Cantieri Riuniti dell'Adriatico" (CRDA) company. Originally designed for the Central and South Atlantic passenger routes, it was later adapted as a military transport and special raider.

Design and development
The design for the construction of a large four-engine, twin-float seaplane began at the end of September 1937, when the technical department of CRDA accepted the specifications of the LATI (Compagnia Ala Littoria) company, created in 1939, who required a long-range seaplane for carrying mail, cargo and passengers to Latin America.

These plans were cancelled on the outbreak of World War II, but a version of the aircraft was adapted for long-range maritime patrol, armed with 10 single-mount 12.7 mm (.5 in) machine guns in both sides, in two upper turrets, and belly positions. Plans were made to install 20 mm cannons in a front turret or in a glazed nose position, and more machine guns in a tail position.

For bombing, it was adapted to carry up to 4,000 kg (8,800 lb) of bombs in an internal bomb bay and on outer wing positions: up to four launch racks, for 454 mm (17.7 in) air-launched torpedoes for surface attack, or "Maiale" manned torpedoes or midget submarines for special operations.

The original engines were relatively underpowered, so Zappata asked the authorities for permission to acquire 1,193 kW (1,600 hp) Wright Double Cyclones from the United States. Due to the deteriorating international situation, however, he was unable to obtain authorization. The CANT Z.511 civil aircraft could theoretically carry 16 passengers over 5,000 km (3,100 mi). Later, when adapted as a military transport, four 1,119 kW (1,500 hp) Piaggio P.XII RC 35 were used, giving only adequate power to an aircraft weighing up to 34 tonnes (37 tons), giving it a maximum range of 4,500 km (2,800 mi).

Flight tests
The Z.511 had its first test flights at Monfalcone, Venezia Giulia (north-eastern Italy) between October 1940 and March 1942. Between 28 February and 1 March 1942, test pilot Mario Stoppani succeeded in taking off and landing fully loaded in very rough seas, with 1.5 m (5 ft) waves and winds of 55–65 km/h (34-40 mph). The Z.511 prototype was then transported to Grado, Venezia (further away from the insecure Yugoslavian border) for further evaluations; the last test and operational flight occurred on 1 September 1943, the same day that the Italian Armistice was signed.

After the division of the Italian forces, one aircraft was appropriated by the Fascist Aeronautica Nazionale Repubblicana. However, it had been damaged only three weeks before by British fighters, which had strafed it on Lake Trasimeno where it was undergoing final trials. It was transferred to the seaplane base at Vigna di Valle. There it suffered from sabotage by base personnel to prevent it falling into the hands of either the Allies or the Germans. The other aircraft, still under construction at the CRDA factory, was retained by Axis forces and scrapped for the metal, which was sent to Germany.

Planned operations
In early 1942, plans for a number of different long-range special missions were made. The unique and unusual ideas were proposed by the Aviazione Ausiliaria per la Marina (Naval Aviation Service) as well as strategists of the Regia Aeronautica.

Several projects were considered:
 * An operation to liberate 55 captured Italian soldiers and pilots held in Jeddah, Saudi Arabia, by Arab-British forces.


 * An air-raid on the strategic Soviet ports of Batumi and Poti in the Black Sea, or a raid against the port of Baku in the Caspian Sea.


 * An attack on British oil installations at Bahrain on the Persian Gulf; such a plan was indeed carried out by the Royal Italian Air Force.
 * A non-stop Rome-Buenos Aires flight (of 8,000 km/5,000 mi) to evacuate prominent political and military Fascist personalities if needed.


 * A special propaganda mission, taking off from Bordeaux, France, refuelling from German Kriegsmarine "Milch Kuhn" ("milk cow") U-boat supply submarines, to fly over New York City, dropping one ton of propaganda leaflets.
 * A raid against the Port of New York, with two aircraft each carrying four Siluro a Lenta Corsa human torpedoes (nicknamed "Maiale") to attack port facilities and ships. The crews were 16 special naval volunteers, who after completing their mission would be permitted to surrender, since there was no provision for them to return to the seaplanes. By May 1943, Kriegsmarine U-boat support had been obtained, the CANTs had successfully tested launching the Maiale, and volunteers from the Decima Flottiglia MAS had been chosen and trained for the one-way operation. The raid was scheduled for mid-June; however, the aircraft was damaged by British fighters when the CANT's base in Lake Trasimeno was strafed. The arrest of Mussolini in July 1943, and the subsequent signing of the Italian Armistice by Marshal Pietro Badoglio (the new Italian leader), meant that the New York raid, and all other plans, were cancelled.