In 1931 the Cantiere Navale Triestino company acquired the services of Filippo Zappata, and also changed its name to Cantieri Riuniti dell’Adriatico, under which a number of civil and military seaplanes and land based aircraft were subsequently produced. The first Zappata designed prototype aircraft from the CRDA was a single engined flying boat, designed as a maritime reconnaissance bomber. Designated Z.501 and named Gabbiano (seagull), it flew for the first time at Monfalcone, Trieste, in 1934. With the civil registration I-AGIL, it set up an international distance record for seaplanes in October 1934, flying non stop for 4120 km (2560 miles) from Monfalcone to Massawa in Eritrea. A short time later a French aircraft took the record, but the Gabbiano reclaimed it in July 1935 with a 4957 km (3080 mile) flight from Monfalcone to Berbera in Somaliland.
It was in its designed role that the Z.501 entered service with the Squadriglie da Ricognizione Marittima (marine reconnaissance squadron) of the Regia Aeronautica (Italian air force) in 1936, after an order for production aircraft had been placed; an eventual total of 445 were built. In full military condition, the Gabbiano’s maximum range was 2400 km (1490 miles). The flying boat was of wooden construction, with fabric covered wings and tail, and was powered by a 900 hp Isotta Fraschini Asso XI R2 C15 12 cylinder V type engine mounted above the centre section of the parasol wing mounted on struts up high and away from the fuselage. It carried a normal crew complement of four or five men. Initial armament was three 7.7 mm (0.303 in) Breda SAFAT machine guns, one in an open position above the nose and the other two in semi enclosed positions in the middle of the fuselage and in the rear of the over wing engine nacelle. Racks attached to the inner¬ wing bracing struts could carry a variety of small bombs up to a maximum load of 640 kg (1410 lb), typical combinations including two 250 kg (551 1b), four 160 kg (353 1b) or four 100 kg (220 1b) bombs. Romania purchased a few Z.501s in 1937 38, and some saw service on the rebel Nationalist side in the Spanish civil war of 1936 39.

When Italy entered the Second World War in June 1940, the Regia Aeronautica had 202 Z.501s in front line service with maritime reconnaissance squadrons, air/sea rescue and other units. During the following year the nose gun was removed, to allow for an enclosed observer’s cockpit in that position. At the Italian armistice in September 1943 the Gabbiano was still in use; about 20 continued serving with the co belligerent Italian forces and others with the pro German Aviazione della RSI (the airforce of Mussolini’s short¬lived Italian Social Republic set up after the armistice), until the end of the war, and a few survived with the Italians until 1950. The Z.501 finished the war without a single air-to-air kill.

CANT Z.501 Gabbiano (Gull)
Engine: 1 x Isotta Fraschini Asso XI R2C.15 12-cylinder, 900hp.
Length: 46.92ft (14.3m)
Wing span: 73.82ft (22.50m)
Wing area: 667.368 sq.ft / 62.0 sq.m
Cruising speed: 130 kts / 240 km/h
Cruising altitude: 6562 ft / 2000 m
Wing load: 23.17 lb/sq.ft / 113.0 kg/sq.m
Height: 14.44 ft (4.40m)
Maximum Speed: 171mph (275kmh; 148kts)
Maximum Range: 1,491miles (2,400km)
Range (max. weight): 540 nm / 1000 km
Rate-of-Climb: 820ft/min (250m/min)
Service Ceiling: 22,966ft (7,000m; 4.3miles)
Armament: 3 x 7.7mm machine gun
Up to 1,411lbs (640 kg) of bombs.
Structure:
Accommodation: 4 to 5
Hardpoints: 2
Empty Weight: 8,488lbs (3,850kg)
Maximum Take-Off Weight: 15,543lbs (7,050kg)