CANT Z.506 Airone (1937)

Standard Observation Seaplane - 356 built 1934-43

The CANT Z.506 Airone ("Heron") was a trimotor floatplane designed and manufactured by CANT from 1935. It emerged as a transport and postal aircraft with "Ala Littoria" and established 10 world records in 1936, 10 in 1937, becoming an asset for Mussolini's propaganda. In WW2 it was used as a reconnaissance aircraft as well as torpedo bomber and air-sea rescue plane or ambulance. It saw action in Spain with volunteers, was tested by Poland, and served for the Italian Regia Aeronautica as well as the Regia Marina and after the Italian surrender in September 1943, with the Aeronautica Cobelligerante del Sud.

Many were also used by the Aeronautica Nazionale Repubblicana and the Luftwaffe. The Z506 is probably one of the very best floatplanes ever built by Italy and often compared to the equally good and-based SM79 Sparviero. It had an old-school wooden structure, yet very sturdy for handling rough seas, was fast, had a good range was was overall reliable. The SAR used the Z506B until 1959. #ww2 #navalaviation #italiannavy #regiamarina #aviazioneausilariaperlaregiamarina #z506airone #floatplane #trimotor

Development History

Ancestor: The Z505 (1935)

The CANT Z.506 was first envisioned in 1934 as a 12-14-seat transport twin-float floatplane for the Ala Littoria. It was to be powered by three 455 kW (610 hp) Piaggio Stella P.IX radial engines and derived from the larger and heavier Z.505 seaplane. In 1934 Ala Littoria indeed issued a specification for a new modern, fast seaplane for its commercial routes by sea. CRDA took part in the competition with Filippo Zappata's design, low-wing with three-engine and having two floats under the nacelles and moved outwards, for better stability at sea. It was a redical departure from the typical configuration used until then.

The first flight of "MM.268" took place on 10 July 1935. Tests revealed the model was underpowered, and failed to meet specs. Ala Littoria then decided to test Z.505 with a con,ventional undercarriage, hoping eliminating the drag would improved specs. chassis. It was tested alongside the CANT Z.1011. Not adopted for passengers, the Z.505 was purchased as a mail-plane from 1936, the first only entering service as "I-ZAPP" the "I" standing for Zapatta. In 1938 the Comando Aeronautica dell Egeo requisitioned it as personal aircraft of governor Cesare Maria de Vecchi (registred I-VACI) and it operated until the summer of 1941 in the Aegean Islands.

The Z506A (1935)

Z506A, transport variant

Same taking off

Meanwhile work done by Zapatta on the Z506, a remotorized variant, led to the development of the 1936 Z.506A, powered by more powerful 560 kW (750 hp) Alfa Romeo 126 RC.34 nine cylinder radial engines. Each gave 780 CV on takeoff and achieved specs, being adopted by Ala Litorria. They had a wooden structure, covered tulipier wooden lamellas. Wings were composed of three box-type spars, linked by wooden wing-ribs, themselves covered by plywood. Only the floats, 12.50 metres (41 ft) long, were made of duraluminium as they were in contact with water. They were covered in 'Chitonal', a new type of plastic like coating for perfect waterproofing.

I-ALAL, first Z506A model of Ala Littoria

I-POLA, 612ª SAR/transport stormo in Stagnoni

I-VACI, personal transport of governor Cesare Maria de Vecchi

Z506 taking off

As Ala Littoria was impressed, order was made of a serie. The Z.506A, flown mostly by Mario Stoppani, set about twenty altitude, speed and distance records for its class between 1936 and 1938. It held a world record for 308.25 km/h (191.54 mph) speed achieved over 5,000 km (3,100 mi), 319.78 km/h (198.70 mph) over 2,000 km (1,200 mi), 322.06 km/h (200.12 mph) over 1,000 km (620 mi) notably. This boosted Italy's records, a tool widely used by Mussolini to boast Italian's technology superiority, and the Z506A doubled down by a 5,383.6 km (3,345.2 mi) closed circuit at cruise speed. It also held record for the heaviest load of 2,000 kg (4,400 lb) at 7,810 m (25,620 ft) in ceiling and 5,000 kg (11,000 lb) at 6,917 m (22,694 ft). CANT delivered 15 civilian Z506A for Ala Littoria, which boasted on its own brochure such records to attract new international passengers.

The Z506B (1936)

Preserie models

Although the Miliyary at the time already had the Z506 Gabbiano based on its own specs, the Navy in particular started to be interested by the Z506 as well as the Regia Aeronautica. Both wanted a military version and Zapatta thus created the Z.506B. This version was to be armed with bombs, torpedoes, and machine guns posts and thus, needed to be more powerful, so it was procured threee 560 kW (750 hp) Alfa Romeo 127 RC 55 engines. The Z506B first flew on August 19, 1935, two prototypes were made, and they also became record breakers. In early 1936 tyhe model was accepted for production, which started in 1936, ramping up in 1937-1939.

CANT Z509

Meanwhile a larger transport version of the Z.506A was built in 1937, the Z.509. It was Designed as larger and heavier, based on an improved, roomier Z506A fuselage and powered by three Fiat A.80 R.C.41 18-cyl. air-cooled radial piston engines. This enabled it to reach 425 km/h (264 mph, 229 kn) at 4,500 m (14,760 ft) for a cruise speed of 349 km/h (217 mph, 189 kn) and range of 3,748 km (2,329 mi, 2,024 nmi) and up to 3,988 km (2,478 mi; 2,153 nmi), 8,000 m (26,240 ft) altitude. Ala Littoria rerceived three in 1937 as Mail Plane, transatlantic postal service to South America. Further development was abandoned in 1940.

Design of the Z506B

Dashboard

CANT Z.506B production by CANT ("Cantieri Riuniti dell 'Adriatico") in Monfalcone was also passed on to "Cantiere Navale Triestino" (CRDA CANT) in Finale Ligure and reached 314 floatplanes, until production was passed on to Piaggio under licence in January 1943 and reached 320+ aircraft total such was the demand. The model was mostly a roomier, more powerful variant of the Z506A. The final version had a crew of five: Pilot and co-pilot, a navigator/bombardier, and 2-3 gunners (see armament).

Fuselage

The Z506 was a large plane, measuring 19.24 m (63 ft 1 in) overall with a Wingspan of 26.5 m (86 ft 11 in) and height: 7.45 m (24 ft 5 in) from the floats to the tip of tail. In total, Wing area was 86.26 m2 (928.5 sq ft). Empty weight was 8,750 kg (19,290 lb) and up to 12,705 kg (28,010 lb) when fully loaded.

The fuselage had a wooden structure covered in tulipier wooden lamellas with wings structured with three box-type spars and wooden wing-ribs, all covered by plywood. Like the Z506A, duraluminium floats were covered in artificial Chitin ('Chitonal') a composite coating using a long-chain polymer of N-acetylglucosamine, amide derivative of glucose. Present in nature it was atificially recreated as a perfect waterpoofing solution above duralumin, which did not tolerated traditional waterproofing methods. The fact of using wood was quite an advantage at the time, freeing a strategic material for other industries.

Engines

The CANT Z.506 was designed ar first as a 12-14 seat transport twin-float floatplane and initially had three 455 kW (610 hp) Piaggio Stella P.IX radial engines. They were replaced by the more powerful 560 kW (750 hp) Alfa Romeo 126 RC.34 nine cylinder radial engines rated for 780 CV on takeoff, 750 CV at 3,400 meters. These air-cooled radial piston engines were mated to 3-bladed variable-pitch propellers.

Performances were very good in that category at least in 1937, with a top speed of 350 km/h (220 mph, 190 knots), a Cruise speed of 299 km/h (186 mph, 161 knots). Range was 1,998 km (1,241 mi, 1,079 nmi) with a 950 kg (2,095 lb) bomb load, more without, for a total Endurance time of 6 hours 26 minutes. It could reach a service ceiling of 7,000 m (23,000 ft) and could reach 3,999 m (13,120 ft) in 20 minutes. No better engines were provided as production went on until late 1943.

Armament

The armament consisted of a single 12.7 mm (0.50 in) Breda-SAFAT machine gun in dorsal position under a dome glasshouse, collapsible Caproni-Lanciani Delta E dorsal turret to reduce drag when not in use. It was completed by three 7.7 mm (0.30 in) machine guns, one in the ventral position, two on the sides, and one optional in the bombardier's glasshouse forward under the nose. Normal crew was thus composed of two gunners, the pilot and co-pilot, plus a navigator/radio operator. The SAR and transport variants got rid of the side MG posts, with a simple porthole instead.

The Airone could carry 1,200 kg (2,645 lb) of general ordnance into its belly bomb bay or a single 816 kg (1,800 lb) torpedo. The latter was likely the F200/450 x 5.46 model, weighting 1,995 lbs. (905 kg) for 17 ft. 11 in. (5.460 m) in lenght and carrying a 441 lbs. (200 kg) warhead at 3,300 yards (3,000 m) at 40 knots, Powered by Wet-heater. This Fiume (Whitehead) model had earlier a 375 lbs. (175 kg) warhead. In German use it was called the "F5W" type.

Early Service

Ceremony for the initial Z506B records

Stellar performances meant, even without precise specs, the Airone was soon in high demand and production was ramped up, at some point before the Italian capitulation in two CANT and CNT manufacturing plant plus Piaggio. Production stopped afterwards.

Variants

Z506 prototype model

Z.506: Prototype, single built.
Z.506A: Civilian version, 15 made
Z.506B: Military version 314 built by CANT and Piaggio.
Z.506C: Civilian version, 38 built (40 with prototypes).
Z.506S: Air-sea rescue version, conversions only
Z.506 Landplane, single converted for Mario Stoppani endurance record, cancelled.
Z.509: Larger and heavier Z.506B used as Mail Plane (3 built).

Blueprint - 4 views

⚙ CANT Z506 specifications
Gross Weight	8,750 kg (19,290 lb)
Max Takeoff weight	12,705 kg (28,010 lb)
Lenght	19.24 m (63 ft 1 in)
Wingspan	26.5 m (86 ft 11 in)
Height	7.45 m (24 ft 5 in)
Wing Area	86.26 m2 (928.5 sq ft)
Engines	3× Alfa Romeo 126 R.C.34 9-cyl. air-cooled radial piston engines 560 kW (750 hp)
Popellers	3-bladed variable-pitch propellers
Top Speed, sea level	350 km/h (220 mph, 190 kn)
Cruise Speed	299 km/h (186 mph, 161 kn)
Range	1,998 km (1,241 mi, 1,079 nmi)loaded, 6 hours 26 minutes
Climb Rate	3,999 m (13,120 ft) in 20 minutes
Ceiling	7,000 m (23,000 ft)
Armament	12.7 mm (0.5 in) Isotta HMG, 3 × 7.7 mm LMG, 1,200 kg (2,645 lb) bombs/torpedoes
Crew	5

Operational Service

The Airone had 20 years of service under its belt, and it was first used for reconnaissance, and soon was used also as torpedo bomber when the first were dispatched to the aid of Franco in the Spanish Civil War. They remained all that time in Italian hands, with volunteers crew and sporting the spanish nationalisy black cross on a white tail. In June 1940, only 97 Airone were operational, filling two Stormi da Bombardamento Marittimo (sea bombing units) and the 31°Stormo B.M. "autonomo", Squadriglia da Ricognizione Marittima (recce squadron) with 22 planes.

The latter was based at Cagliari-Elmas airport in Sardinia. There was akso the 35° Stormo B.M. (25 Z.506) located in Brindisi, Puglia, used extensively over the Thyrrenian sea, Fench Riveria and Greece.

There were soon four Squadriglie for air-sea rescue missions formed in Orbetello: The 612ª in Stagnoni (immatriculated DAMB, GORO, BUIE, CANT, POLA) and the 614ª in Benghazi (DUCO, ALA, DODO and DAIM). The two other sections were in Torre del Lago and Leros island in the Aegean Sea, later transferred to Rhodes.

The Z.506 saw action on 17 June 1940 after French bombers attacked Elmas base, leaving 21 airmen dead, destroying several CANT Z.501 Gabbiano. A retaliation was organized in the evening of 17 June, with four Z.506Bs from 31° Stormo raiding a French objective in North Africa with two 250 kg, three 100 kg bombs each on their bomb bay. Later the Airone took part in the Battle of Calabria. During the Greek campaign, Airones were used to strike coastal targets and the Corinth canal. They were extensively used to patrol and carry troops assaultinf many Greek islands, notably Corfu, Cephalonia and Zante.

However the RAF soon started to take its toll. Thus by 1942, the model was restricted to reconnaissance and in 1943, they were used for maritime patrol and air-sea rescue, having a specialized variant made, the Z506S. The "S" stand for "Soccorso". Some were captured after September 1943 and Cassibile armistice, by the Luftwaffe in reconnaissance, transport, SAR and ambulance roles, especially in the Aegean islands. Many also landed in Spain after engine failures or other reasons and were integrated in Franco's naval air wing.

Z.506s were still targeted by Allied pilots despite the red crosses. Such instance occured on 12 June 1942, off Malta when a Hawker Hurricane from 46 Squadron shot down one Z.506, and another sent to rescue the first. It seems these "kills" did not made unanimity. One pilot at Sqn. 249 in Malta recalled Sqn Ldr Barton disapproved his conduct, but the AOC approved. One Z506 was uniquely hijacked by prisoners of war and then used by the RAF from Malta, with British markings.

CANT Z.506s were not harmless however, and they sometimes managed to shoot down the Allied aircraft attacking them, like on 7 January 1943, when one Z506B from 188ª Squadriglia inbound to Sardinia repelled two Bristol Blenheim (pilot Maresciallo Ambrogio Serri). Dorsal MG-gunner Armiere Pietro Bonannini fatally hit a first Blenheim, ditching in the sea. The second Blenheim strafed and hit Bonannini but he manage to scores hits and declared another kill. He was later awarded three Medaglie d'Argento al Valore Militare and Medaglia di bronzo al Valor Militare.

With the surrender of 8 September 1943, 70 CANT Z.506s were still operational, 30 Z.506S were integrated into the col-belligrence force, working with the Allies but Germans captured many ohers, used them between Italy, Germany, France, Yugoslavia and especially the Greek islands, even Poland. The 171ª Squadriglia operating now from Toulon was composed of mixed Italian/German crews. Others, luftwaffe officially, were flown by Italian volunteer crews in 1944 and they operated briefly from the Baltic sea, patrolling around Peenemünde. After 1945, the career of the Airone went on as long as there were parts to maintain these. They stayed operational with the new Aviazione Italiana until 1959.