Italian medium bomber
The CANT Z.1007 "Alcione" ("Kingfisher") was a three-engined medium bomber designed and produced by the Italian aircraft manufacturer CANT. It was regarded by some as "the best Italian bomber of World War II", although its wooden structure was easily damaged by the climate, as experienced in North Africa and in Russia.
Designed by Filippo Zappata, who also designed the CANT Z.506 Airone, the Z.1007 featured a wooden structure and had "excellent flying characteristics and good stability". The prototype performed its maiden flight during March 1937, and the type entered service with the "Regia Aeronautica" in the following year. The initial production mode, which was powered by Isotta-Fraschini Asso XI.RC inline engines, was not fully satisfactory, and thus was largely confined to use as a trainer while design work continued. An improved model, the "Z.1007bis", was developed to resolve the problems with the original aircraft; it was powered by Piaggio P.XI RC.40 radial engines and featured numerous other design refinements.
Production of the type was relatively slow, even following Italy's entry into the Second World War on 10 June 1940. In October of that year, the combat debut of Z.1007 took place during the Italian invasion of Greece. It was subsequently used for both reconnaissance and bombing missions across multiple theatres of the conflict, including the Mediterranean, North Africa and the Eastern Front, amongst others. It was operated in quantity by the Italian Co-Belligerent Air Force, "Aeronautica Nazionale Repubblicana"; limited numbers were also flown by the Royal Air Force and "Luftwaffe" during the conflict. Due to its vulnerability to damage and fire, the Z.1007 was largely flown at night during the latter portion of its service life.
Design and development.
Background.
During 1935, Filippo Zappata, the chief designer of the "Cantieri Aeronautici e Navali Triestini" (CANT), designed two medium bombers, the twin-engined CANT Z.1011 and the three-engined CANT Z.1007. Both aircraft were to be powered by 619 kW (830 hp) Isotta-Fraschini Asso XI.RC inline engines and were of wooden construction. The Z.1007 was preferred by both Zappata and the Italian Aviation Ministry, which led to an order for 18 aircraft being placed on 9 January 1936. A further order for 16 more aircraft followed on 23 February 1937.
The Z.1007 was developed from the CANT Z.506 Airone seaplane, an aircraft that had established numerous world records in the late 1930s. Unlike the Z.506, it was a land-based version and incorporated many improvements, especially on the powerplant. The first prototype flew in March 1937; during flight testing, it proved to be superior to the Z.1011, being praised for its handling and manoeuvrability alike. However, its performance was lower than predicted; in response, Zappata undertook a major redesign of the Z.1007 while production of the initial version was limited to the existing orders placed before the prototype flew.
The Z.1007 was a mid-winged monoplane with a retractable tailwheel undercarriage. It was typically operated by a crew of five, consisting of two pilots, a flight engineer, a radio operator and a bombardier/navigator. The Z.1007 was fitted with a defensive armament of a 12.7 mm (.5 in) Breda-SAFAT machine gun in an open dorsal position and a 7.7 mm machine gun in a ventral tunnel. In terms of offensive armament, it could carry up to 800 kg (1,760 lb) of bombs. After much experimentation with the prototype, the production aircraft were furnished with annular radiators so their profile was similar to radial engines that would be fitted to the improved later versions. Delivery of production Asso powered Z.1007s started in February 1939, with production ending in October of that year.
Z.1007bis.
Zappata had, meanwhile, continued the development of a considerably changed version, the "Z.1007bis", to resolve the problems with the original aircraft. While the new version was of similar layout, it was a new design. Three Piaggio P.XI RC.40 radial engines (a derivative of the French Gnome-Rhône 14K) of 736 kW (986 hp) takeoff power replaced the less powerful and unreliable liquid cooled engines of the original version. The "bis" was longer with wings of greater span and area, while the aircraft was considerably heavier, weighing 580 kg (1,280 lb) more unladen, with a maximum takeoff weight 888 kg (1,960 lb) greater. It carried heavier offensive and defensive armament.
During July 1939, the prototype "bis" made its first flight; flight testing proved to be successful. The Z.1007bis was promptly ordered into large scale production, permitting deliveries of pre-production aircraft to commence later that same year.
Configuration and problems.
The Z.1007 had a standard monoplane configuration, with a mid-set wing, single tail, retractable undercarriage and a crew of five or six. It had a wooden structure and a clean shape that was much more aerodynamic than the competing SM.79. The Z.1007 had three engines, with one engine in the nose and two in the wings. The trimotor design was a common feature of Italian aircraft of the Second World War. The aircraft had a slim fuselage as the two pilots sat in tandem rather than side-by-side as in most bombers of the period. Visibility was relatively good and the aircraft was almost a three-engine fighter. This slimness reduced drag but also somewhat worsened the task of the two pilots. Both pilots' seats were offset to port to allow a passageway for the bombardier to enter his compartment below the pilot's feet (directly behind the central engine), by ducking through an opening under the starboard instrument panel. Both front and rear instrument panels contained flight and navigation instruments, while the engine monitoring gauges were located to starboard where the rear pilot could see them past the front pilot's shoulder. Although the rear pilot's view was limited, he was capable of landing or taking off if needed. However, his primary purpose was to allow the forward pilot to rest, and to add some "muscle" to the controls when needed, as well as acting as an extra set of eyes to notice problems and to monitor gauges while the other was occupied.
There were five crew members: the pilot, the copilot, a bombardier/navigator/ventral gunner, a dorsal gunner/radio operator, and waist gunner/flight engineer. The radio equipment was located in the center section between the dorsal turret and the waist position. Like most tri-motor Italian aircraft of the period the Z.1007 suffered from poor defensive armament, although it was no worse than many other contemporary designs, many of which had no rotating dorsal turret, no waist guns, or no ventral gun, or various combinations of such. Other issues were poor engine reliability and a weak power-to-weight ratio due to low powered engines (the three 1,000 hp engines of the Z.1007bis were equivalent to twin engines of 1,500 hp each, but this was slightly offset by the added weight of the third engine). The Z.1007 also suffered longitudinal stability problems that were partly rectified later by the adoption of a twin tail arrangement. The Z.1007's wooden structure suffered cracks, separations and surface delamination due to the inhospitable climatic conditions in North Africa and Russia, but allowed the aircraft to float in case of ditching. The surface delamination and deformation greatly added to the aircraft’s drag. A total of 660 "Alciones" were built.
Armament.
The Z.1007 had a defensive armament of four machine guns: two 12.7 mm (.5 in) and two 7.7 mm (.303 in). The main defensive weapon was a Caproni-Lanciani Delta manually powered Isotta Fraschini dorsal turret armed with a 12.7 mm (.5 in) Scotti or Breda-SAFAT machine gun. The turret had a good field of fire, although it had blind spot behind the tail (as did all turreted aircraft without rear gunners or twin vertical stabilizers). The 12.7 mm (.5 in) Breda was a standard weapon for Italian bombers and the field of fire was improved by the twin-tail configuration on later models. An electrically powered Breda V turret carrying a similar armament was substituted in late production aircraft. Another 12.7 mm (.5 in) was in the ventral position behind the bomb bay, with a field of fire restricted to the lower rear quadrant of the aircraft. There were also two waist position 7.7 mm (.303 in) Breda machine guns, with 500 rpg. Only one of the waist guns could be used at a time since the gunner for this position manned both guns (a practice common with other aircraft, such as the He 111, B-25 Mitchell and G4M Betty). Simultaneous attacks from both sides were generally rare, and waist guns are generally the least effective armament on an aircraft, mostly intended to improve morale and provide a deterrent effect. Allied reports stated that armour was better than usual for an Italian bomber, with the dorsal gunner receiving a large .76 m × 1.1 m (2 ft 6in x 3 ft 6 in) armor plate, plus a small head protection plate of .36 m × .20 m (14 x 8 in), as well as an 8 mm (.31 in) thick curved plate which rotated with his turret. There was rear armor plate 5 mm (.20 in) thick for side gunners, with other 6 mm (.24 in) all around the machine guns, and 6 mm (.24 in) armor for ventral machine gun position, which meant that all defensive positions were reasonably protected against light enemy fire and fragments. The pilots were protected with 5 mm (.20 in) roof and lateral armor, 6 mm (.24 in) around the seats, 5 mm (.20 in) overhead, and a 6 mm (.24 in) armored bulkhead behind them.
The Z.1007 had a lengthy and shallow horizontal bomb bay which could carry 1,200 kg (2,650 lb) of ordnance. Many other Italian aircraft had bomb bays which carried the ordnance vertically, tip pointing up, which limited the size and variety of bombs which could be carried internally, a problem shared with the German He 111 bomber. There were also a pair of under-wing hardpoints which could carry up to 1,000 kg (2,200 lb) of bombs, giving the Z.1007 a potential 2,200 kg (4,900 lb) payload and a maximum range of 640 km (400 mi), but the standard payload was 1,200 kg (2,645 lb) and 1,000 km (621 mi) range. The Z.1007's external hardpoints were a rarity in the bombers of the "Regia Aereonautica". The Z.1007 could also carry two 454 mm (17.7 in), 800 kg (1,760 lb) torpedoes slung externally under the belly in an anti-shipping role, an option never used operationally. The bombardier's position was just below and ahead of the pilot, behind the central engine (he could look up at the rudder pedals and see the pilot's face). This improved the layout compared to the SM.79, which located the bombardier in the ventral casemate under the rear fuselage, which meant that it was difficult to man the ventral gun while the bombardier was in position, since space was limited. The forward location of the bombardier's compartment provided somewhat better forward visibility, but was still cramped as well as being relatively loud and subject to considerable vibration, largely due to it being directly behind and very close to the central engine.
Operational history.
Introduction.
The first Asso-powered Z.1007s were used to equip the 50° "Gruppo" of the 16° "Stormo" from May 1939. These Asso-powered aircraft, despite being designated as bombers, were not considered suitable for operational use as a result of their engines being relatively unreliable as well as the aircraft's high maintenance requirements and their defensive armament being considered to be inadequate. Accordingly, they were typically used as trainer aircraft instead.
The 47° "Stormo" was equipped with some of the first production aircraft at Ghedi. Production of the type was relatively slow, only fifteen aircraft were being completed every month at most. Gradually, Z.1007s were delivered to a number of different "Stormi", such as the 9°, where it substituted the SM.79 and BR.20. Upon Italy's entry into the Second World War on 10 June 1940, "Regia Aeronautica" had two "Stormi" equipped with the "Alcione". One was the 16°, with 31 aircraft, equipped with the Isotta Fraschini engine and so declared "non bellici" ('not suitable for war'). The 47° "Stormo" had just received four CANT Z.1007bis.
Second World War.
The Z.1007 Asso replaced the Savoia-Marchetti SM.81s of 16° "Stormo" while 47° "Stormo" was equipped with Z.1007Bis, but operational readiness was only attained in August, when around thirty machines were sent to Sicily to attack Malta. "Stormi" 16°, 12°, 35°, and 47° operated over Greece with some losses. 175a "Squadriglia da ricognizione" (reconnaissance squadron), and later 176a, were deployed to Africa. The British destroyer was sunk by an explosion caused by a Z.1007 bombing during 1941. 35° Stormo was dispatched to Africa in the bombing role; these three-engine aeroplanes were used occasionally in Russia too. During 1942, Z.1007s were used by four groups and two wings in the Mediterranean theatre, in anti-ship role and against Malta, often escorted by Italian and German fighters.