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Caproni Ca.135

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The Caproni Ca.135 was an Italian medium bomber designed at Bergamo in Italy by Cesare Pallavicino. It flew for the first time in 1935, and entered service with the Peruvian Air Force in 1937, and with the Regia Aeronautica (Italian Royal Air Force) in January 1938.

Origins

General Valle (Chief of Staff of the Regia Aeronautica) initiated the "R-plan" - a program designed to modernize Italy's air force, and to give it a strength of 3,000 aircraft by 1940. In late 1934 a competition was held for a bomber with the following specifications:

The ceiling and range specifications were not met, but the speed was exceeded by almost all the machines entered. At the end of the competition, the "winners" were the Ca.135 (with 204 aircraft ordered), Fiat BR.20 (204), Piaggio P.32 (144), Savoia-Marchetti SM.79 (96), CANT Z.1007 (49) and the Piaggio P.32 (12).

This array of aircraft was proof of the anarchy, clientelarism and inefficiency that afflicted the Italian aviation industry. Worse was the continuous waste of resources by the Aeronautica Militare (Italian Air Force). Orders were given for aircraft that were already obsolete. The winners of the competition were not always the best - the BR.20 was overlooked in favour of the SM.79, an aircraft which was not even entered in the competition.

Design

The Ca.135 was to be built at Caproni's main Taliedo factory in Milan, which is why the type had a designation in the main Caproni sequence, rather than in the Caproni-Bergamaschi Ca.300 series. However, the project was retained at Ponte San Pietro and the prototype, completed during 1934-35, (a long construction time for the period), was first flown on 1 April. The project chief was Cesare Pallavicino of CAB (Caproni Aereonautica Bergamasca).

Although the new bomber was in the "century series" of Caproni aircraft, it resembled the Caproni Ca.310, with its rounded nose, two engines, low-slung fuselage, and wings with a very long chord. Several versions were fitted with different engines and some had noticeable performance differences.

The prototype was powered by two Template:Convert (at 4,000 m/13,123 ft) Isotta Fraschini Asso XI RC radial engines initially fitted with two bladed wooden propellers. It had a length of Template:Convert, a wingspan of Template:Convert, and a wing surface of Template:Convert. It weighed Template:Convert empty, and had a Template:Convert useful load. Structurally, it was built of mixed materials, with a stressed-skin forward fuselage, and a wood and fabric-covered steel-tube rear section, the wings being of metal and wood, using fabric and wood as covering. The wings were more than ⅓ of the total length, and had two spars of wooden construction, covered with plywood and metal. The strength coefficient was 7.5. The tail surfaces were made with wood covered with metal and plywood. The fuel system, with two tanks in the inner wings, held a total of 2,200 L (581 US gal).

The Ca.135's fuselage's shape was quite different than, for example, the Fiat BR.20. If the latter resembled the B-25, the Ca.135, with its low fuselage more resembled the B-26. Its long nose accommodated the bomb-aimer and a front turret (similar to the Piaggio P.108 and later British bombers). The front part of the nose was detachable to assure a quick escape from the aircraft. It also had two doors in the cockpit roof, to allow the pilots to escape in an emergency. The right-hand seat could fold up to assist entry to the nose.

In the mid-fuselage, there was a 12.7 mm (0.5 in) gun turret, manned by the co-pilot. A seat for the flight engineer was later fitted. The wireless operator's station, in the aft fuselage, was fitted with the AR350/AR5 (the standard for Italian bombers), a radiogoniometer (P63N), an OMI AGR.90 photographic-planimetric machine or the similar AGR 61. The aircraft was also equipped with an APR 3 camera which although not fixed, was normally operated through a small window. The wireless operator also had a 12.7 mm (0.5 in) machine gun in the ventral position. All this equipment made him very busy; as a result, an extra man was often carried. The aircraft had very wide glassed surfaces in the nose, cockpit, and the central and aft fuselage; much more than was usual in other Italian aircraft.

The aircraft was fitted with three machine guns, of 12.7 mm (0.5 in) calibre in the turrets, and a 7.7 mm (0.303 in) calibre gun in the nose. All had 500 rounds, except the 7.7 mm (0.303 in) which had only 350.

The bombload, like most Italian bombers, was less than impressive in terms of total weight, but was relatively flexible, depending on the role - from anti-ship to close air support:

  • 2 × 800 kg (1,760 lb) bombs (the heaviest in the Regia Aeronautica) plus 2 × 50 kg (110 lb), and 2 × 31 kg (68 lb), for a total of 1,862 kg (4,105 lb)
  • 2 × 500 kg (1,100 lb) + 4 × 100 kg (220 lb) + 2 × 31 kg (68 lb), total nominal 1,462 kg (3,223 lb)
  • 4 × 250 kg (550 lb)
  • 8 × 100 kg (220 lb) + 8 × 50 kg (110 lb) + 4 × 31 kg (68 lb), total 1,324 kg (2,919 lb)
  • 16 × 50 kg (110 lb) + 8 × 31 kg (68 lb), total 1,048 kg (2,310 lb)
  • 24 × 31 kg (68 lb), 20 kg (40 lb), 15 kg (33 lb), or 12 kg (26 lb).
  • 120 × 1 kg (2 lb) or 2 kg (4 lb) bomblets
  • 2 × torpedoes (never used, but hardpoints were fitted)

The aircraft had a better bomb capacity than most of its contemparies (the SM.79 could carry: 2 × 500 kg/1,100 , 5 × 250 kg/550 lb, 12 × 100 kg/220 lb or 50 kg/110 lb bombs, or 700 × 1–2 kg/2-4 lb bomblets).

Performance

The aircraft was underpowered, with a maximum speed of Template:Convert at Template:Convert, and a high minimum speed (there were no slats, and maybe not even flaps) of Template:Convert. The ceiling was only Template:Convert and the endurance, at 70% of throttle was Template:Convert. The weight was too high, with total of Template:Convert and not Template:Convert as expected.

The total payload of Template:Convert was shared between the crew (320+ kg/705+ lb), military equipment (200 kg/441 lb of weapons, over 100 kg/220 lb of radio and other equipment), fuel (2,200 L/581 US gal), oil (1,500 kg/3,307 lb), oxygen and bombs, so with the maximum bombload there was almost no possibility of carrying a full load of fuel (the other Italian bombers were generally capable of 3,300-3,600 kg/7,275-7,937 lb payload): around 500 kg (1,102 lb) with the maximum, modest fuel load (the BR.20 and SM.79 had 3,600 l/951 US gal), or with the maximum bomb load, almost nothing was available with fuel, and the lack of power made take-offs when over-loaded impossible, in fact take-offs were problematic even with a normal load.

Take-off and landing distances were Template:Convert and Template:Convert. The range was good enough to assure Template:Convert with 550 kg (1,210 lb) and Template:Convert with 1,200 kg (2,650 lb).

The production version was fitted with inline liquid-cooled Asso XI RC 40 engines, giving Template:Convert at 4,000 m (13,120 ft), so that aerodynamic drag was reduced, and three-bladed metal propellers, and were theoretically more efficient machines. This new engine gave the aircraft a maximum speed of Template:Convert at 4,000 m (13,120 ft), and could climb to 2,000 m (6,560 ft) in 5.5 minutes, 4,000 m (13,120 ft) in 12.1 minutes and 5,000 m (16,400 ft) in 16.9 minutes.

Despite this, the aircraft was still underpowered, which lead to the 1939 Ca.135Mod, fitted with Template:Convert Piaggio P.XI engines.

Operational service

The aircraft arrived late in respect to the others (like the BR.20), and with a totally unsatisfactory technology. Despite this there was an order for 32 aircraft by the Regia Aeronautica on 19 June 1937. In January 1938, over a year after the BR and SM bombers, they started to enter into service.

Spanish civil war

In 1938 seven aircraft were earmarked for the Aviazione Legionaria to serve in the Spanish Civil War. These Tipo Spagna ("Spanish Type") aircraft were refitted with Fiat A.80 RC.41 engines, rated at 746 kW (1,000 hp).

Crews from 11 Wing were sent to Taliedo (just outside Milan) to take the first seven aircraft - designated Ca.135S - to Spain. One was damaged on take-off, and the other six landed at Ciampino near Rome, where two suffered damage on landing. After repairs and some modifications, not until late 1938 were all seven aircraft ready to leave for Spain. During the flight two were forced by icing to return to Italy, and three crashed into the sea. Only two arrived at Palma de Mallorca, and there they remained unused for six months.

Italy

Production of the aircraft was initially of only 32 aircraft, of which eight were Ca.135S's, and some were converted into the Ca.135Mod. In 1938 the first Ca.135Bis were built. They were fitted with 746 kW (1,000 hp) Piaggio P.XI RC.40 engines, with Piaggio P.1001 three-blade metal propellers. Length was 17.7 m (58.1 ft), wingspan 18.8 m (61.7 ft), and wing surface 60 m² (646 ft²). Armament was still only two 12.7 mm (0.5 in) guns and one 7.7 mm (0.303 in), but the nose was redesigned to be more aerodynamic. Another 32 aircraft were ordered and built from 1939-June 1940.

They were not successful aircraft, being heavily criticized by the Italian pilots. Unable to be used operationally, they were sent to flying schools, and then exported to Hungary. The first batch of Ca.135s flown by 11 Wing were phased out by late 1938. 25 were still available at Jesi airfield, though only four were in flying condition, while the others were probably in maintenance for engine replacement. In 1940, there were at least 15 Ca.135S and Ca.135Mod at the Malpensa flying school, though the poor condition of these aircraft meant that they were scrapped in November 1941. With the scrapping of the first batch and the selling of the second, all 64 Ca.135s left the service of the Regia Aeronautica without performing a single operational mission.

Hungary

File:Ca.135 being armed.JPG
A Hungarian Air Force Ca.135 with its bombs being loaded, 1942.

In the 1938 Imperial Japanese Army Air Force evaluation, the Ca.135 P.XI had lost to the Fiat BR.20, but the Hungarian Air Force nonetheless ordered the aircraft. It is likely that these Hungarian Ca.135s had Manfred Weiss WM K-14 engines in place of the Piaggio P.XI's, since Hungary used these engines in its versions of the Reggiane Re.2000 and the Heinkel He 70. Both the Piaggio P.XI and the Manfred Weiss WM K-14 were licensed versions of the French Gnome-Rhône 14K Mistral Major.

The Hungarians operated up to 100 Ca.135s with some success against the Soviet Union in the Eastern Front in 1941 and 1942 once Hungary had committed its forces in that sector during during World War II.

These aircraft constituted almost the entire heavy bomber force of Hungary and were ordered in exchange for the Ca.310, which were rejected and returned to Caproni in exchange for these new, more powerful, aircraft. The second Ca.135 series, rejected by the Italians, and a new one of 35 aircraft was delivered between 1940 and 1941 after an order originally made in 1937, but only confirmed in 1939, after a trial was made by Hungarian pilots at Guidonia, that surprisingly found it satisfactory. Hungary was almost entirely equipped with Italian aircraft at the beginning of the war. The 4° Bombardment Group operated these aircraft until late 1942, when the survivors, worn out, were used as training aircraft. The Hungarians did not love the Ca.135Bis, but it was all they had, and so they did their best. One of the squadrons, the I/4, (originally equipped with eight aircraft, one soon lost on landing, and then replaced with another four aircraft) performed, up to October 1941, 265 attacks, 1,040 sorties, and dropped around 1,450 tonnes (1,600 tons) of bombs, evidently helped by the short range (200-300 km/120-190 mi) that allowed them to use the aircraft's maximum bomb load. Two aircraft were shot down, another two lost in accidents, and 11 aviators lost. The average over these four months was over 8 missions flown and 13 tonnes (14 tons) of bombs dropped each day.

Peru

Peru also ordered the Ca.135, and an initial delivery of six aircraft with 608 kW (815 hp) Asso XI RC.45 engines was followed by a contract for 32 others designated the Ca.135 Tipo Peru ("Peruvian Type"). The later order had 671 kW (900 hp) Asso XI RC.40 engines in a modified cowling, as well as revised gun placements but the planes were never delivered. The original six aircraft were used by the Peruvian Air Force in the 1941 Ecuadorian-Peruvian War and proved somewhat successful against Ecuadorian ground units.

Modified aircraft

A single Ca.135 P.XI was modified by Caproni by incorporating a dihedral tailplane and 1,044 kW (1,400 hp) Alfa Romeo 135 RC.32 Tornado radial engines, and given the designation Ca.135 bis/Alfa. The newer and more powerful engines pushed the maximum speed of the aircraft to more than 480 km/h (300 mph).

The final variant was also a one-off, known as the Ca.135 Raid, it was used to set records and win air races. It was built in 1937 to the order of the Brazilian pilot de Barros, was powered by two 736 kW (986 hp) Asso XIs and provided with additional fuel capacity for a greatly extended range. While attempting a flight from Italy to Brazil in 1937, de Barros and the Ca.135 Raid disappeared over North Africa, in another disaster for the image of the aircraft.

Variants

  • Ca.135 Tipo Spagna : Seven aircraft fitted with Fiat A.80 RC.41 engines for service in Spain.
  • Ca.135 P.XI : Medium bomber version, powered by two 746 kW (1,000 hp) Piaggio P.XI RC 40 radial piston engines.
  • Ca.135 Tipo Peru : Export version for Peru, fitted with two 608 kW (815 hp) Asso XI RC 45 engines.
  • Ca.135 bis/Alfa : One aircraft fitted with two 1,044 kW (1,400 hp) Alfa Romeo 135 RC 32 Tornado radial piston engines.
  • Ca.135 Raid : Special long range version, fitted with extra fuel tanks. One built.

Operators

Template:Country data Hungary
Template:Country data Italy
Template:PER

Specifications (Ca.135 P.XI)

General characteristics

  • Crew: 4 (sometimes 5)
  • Length: 14.4 m (47 ft 3 in)
  • Wingspan: 18.8 m (61 ft 8 in)
  • Height: 3.4 m (11 ft 8 in)
  • Wing area: 60.0 m² (645.86 ft²)
  • Empty weight: 6,050 kg (13,340 lb)
  • Max takeoff weight: 9,550 kg (21,050 lb)
  • Powerplant:Piaggio P.XI-RC40 14-cylinder radial engines, 746 kW (1,000 hp) each

Performance

Armament

  • 3 × 12.7 mm (0.5 in) dorsal Breda-SAFAT machine guns in nose, dorsal, and ventral turrets.
  • 1,600 kg (3,527 lb) internal bomb load.


See also

Related development

Comparable aircraft

Designation sequence
Ca.132 - Ca.133 - Ca.134 - Ca.135 - Ca.140 - Ca.142 - Ca.146Related lists

References

it:Caproni Ca.135 pl:Caproni Ca.135

This article is licensed under the GNU Free Documentation License.
It uses material from the Wikipedia article "Caproni Ca.135".