Caproni Ca.135

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Caproni Ca.135

A Ca.135 of the Hungarian Air Force, 1942.
Type Medium bomber
Manufacturer Caproni
Designed by Cesare Pallavicino
Maiden flight 1935
Introduced 1937
Primary users Regia Aeronautica
Hungarian Air Force
Peruvian Air Force
Produced from 1936

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 in 1937 in Peruvian Air Force and in January 1938 in Regia Aeronautica.

Contents

[edit] Design and Development

Regia Aereonautica searched, with the 'R plan' a quick and wide enhancement program. This plane, designed by Gen. Valle, aimed to have in service 3,000 war machines for 1940. In the fall of 1934 there was a contest for a bomber that should allowed the following performances: 330 km/h at 4,500 m and 385 at 5,000, climb to 4,000 in 12,5 min and a radius of 1,000 km with 1,200 kg, and finally a ceiling of 8,000 m. This latter and the range were practically not matched but the speed was superseded by almost all the machines presented.

At the end of the contest, the "winners" were: Fiat BR.20 (204 ordered), Ca.135 (204), Piaggio P.32s (144) and P.50s(12), with also 96 SM.79s and 49 CANT Z.1007s. All this array of 'winners' was already an incontrovertible proof of the incredible anarchy, clientelarism and inefficiency that affected all the Italian aviation industry, and the worse was the continuous waste of resources made by Italian airforce, that almost always gave some orders for these new machines, even if they were too obsolete or even too advanced (ex. P-32 and R.2000). The Caproni Ca.135 was surely not in the second of these two classes, but nevertheless had some interesting features. Finally, the winners of the contest not always were the best, and often were override by other projects, like happened with BR.20 declared winner of the 1934 bomber contest and lather, outclassed by S.79 that never took part to this contest.

The Ca.135 was not allocated a type number in Caproni-Bergamaschi's 300 series as it was to have been built at Caproni's main Taliedo factory. This is why the type had a designation in the main Caproni sequence rather than in the Caproni Bergamaschi Ca. 300 series. In any case the project was retained at Ponte San Pietro and the prototype, completed during a very long building (from late 1934 to all the 1935), was flown for the first time on 1 April, a day dedicated traditionally to the jokes, as was substantially, this aircraft in service. Project-chief was Cesare Pallavicino, historical projectist of CAB (Caproni Aereonautica Bergamasca).

The new bomber was so considered in the "century series" of Caproni aircraft, but it was not similar to those (ex. Ca.133) but rather to the 300 series. In fact, it resembled not marginally a sort of Ca.310, even if enhanced in a superior class: rounded nose, two engines, fuselage low and large, and a wing with very long chord. It had several 'incarnations' that were fitted with different engines and so have some noticeable differences also with the performances. The first, basic Ca.135 was those of the first 'batch', for RA.

As general data of this first Caproni bomber, it was powered by two 836 hp (597 kW)/4,000 m Isotta Fraschini Asso XI RC radial engines, the Ca.135 was initially built with 2 blades-wood propellers, and had a length of 14,5 m, wingspan 18,96 m, wing surface 61,5 m2. It had an a weight of 5,606 kg empty and 2,875 useful load.

Structurally, it was made of mixed materials, with a stressed-skin forward fuselage, and a wood and fabric-covered steel-tube rear section, the wing being of metal and wood, using fabric and wood as covering. The wings were with a very large chord, more than one third of the total length, and had two spars of wooden construction, covered with plywood and metal. The strength coefficient was 7,5. Also the tail's surfaces , doubled, were made with wood covered with metal and plywood. In addition, the production version had three-bladed metal propellers instead of the two-bladed wooden ones used in the prototype. As fuel system, in the inner wings there were two tanks for a total of 2,200 l.

The fuselage's shape of this machine was overall quite different than, as example, BR.20s. If these latter resembled quite well B-25, the Ca.135, with its fuselage low and aggressive resembled quite well a sort of B-26. Its nose was long, with a nacelle for the pointer and above him the defence front turret (as will happen for the Piaggio P.108 and some British bombers). The front nose was detachable to assure a quick escape from the aircraft, and also two roof doors were present in the cockpit, to allow the pilots the escape in emergency. The right of the two seats was foldable to assure the entry in the nose.

In the middle fuselage there was a 12.7 mm turret, served by second pilot, afther there was the flight engineer seat, and in the aft fuselage there was the 'marconist' cockpit with radio AR350/AR5 (the standard for Italian bombers), Radiogoniometer (P63N), an OMI AGR.90 photographic-planimetric machine or the similar AGR 61, and finally there was another machines, the APR 3 moveable by the crew and not fixed in the floor (with a small window dedicated). Finally, the marconist had also a 12.7 mm machine gun in the ventral position, that render him very busy (radio, radiogoniometer, photos and machine-gun) so the new bombers like this had often at least one man more on board. To help the tasks asked for, the aircraft had very wide glassed surfaces in the nose, the cockpit, the middle and the aft fuselage, much more than the usual for Italian machines, like the S.79.

All the machine guns had 500 cartridges except the front, that was a 7,7 mm but had only 350.

Over the defensive armament, there was also an offensive one. As usual for Italian bombers, the payload in terms of bombs was not impressive in total weight, especially with the normal bomb load, but there were many combination possibles to optimize it all exigences, from anti-ship to close air support:

  • 2x800 kg (the heaviest of Regia) plus 2x50 kg and 2x31 kg, for a total of 1,862 kg (not counting the total true weight, because the 50 kg weighter around 70).
  • 2x500 kg+4x100 (true weight 130) +2x31 kg, total nominal 1,462 kg
  • 4x250 kg
  • 8x100+8x50+4x31 kg, total 1,324 kg
  • 16x50+8x31 kg, total 1,048 kg
  • 24x31, 20, 15, 12 kg.
  • 120x1 or 2 kg bomblets
  • two torpedoes (never used, but there were the hardpoints)

Totally, this machine had a very heavy maximum load of bombs, as usually the Italian machines were not able to hold so many bombs (ex, S,79s had in alternative: two x 500 kg, five x 250 kg, 12 x 100 kg or 50 kg bombs, or 700 1-2 kg bomblets). The four crew were also fitted with three machine guns, two of them were heavy calibres, and two were in turrets (but they were not the same machine guns fitted in the turrets) and overall assured almost a 360 degree curvature.

All this was quite impressive, the bomber had around two tons of bombs, heavy machine guns with two turrets, two photographic machines, radio and radiogonyometer, and its engines despite being weak, but also inline ones, so the aerodynamic drag was reduced.

Even so, the Ca.135 was not really good nor acceptable in practice. The aircraft was underpowered, with a maximum speed of 363 km/h at 4,500 m. and a minimum speed, quite high (there were not slats and maybe not even flaps) of 130 km/h. The ceiling was only 6,000 m and the endurance, at 70% of throttle was 1,600 km. The weight was too high, with total of 8,725 kg and not 7,375 as expected.

The payload of 2,800 kg should been shared between crew (320 or more kg), military equipment (200 kg of weapons, over 100 kg radios and more other stuff), fuel (max. 2,200 l, 1,500 kg) oil, oxygen and bombs, so with the maximum bomb load there was almost not possibility to hold also fuel (the other Italian bombers were generally capable of 3,300-3,600 kg payload): around 500 kg with the maximum, modest fuel load (BR.20 and S.79 had 3,600 l.), or with the maximum bomb load, almost nothing was available with fuel, and the lack of power made not possible take-off over loaded, in fact it was problematic also take-off at normal load.

The machine began also quite late respect the others, like BR.20, and with a total unsatisfactory technology.

Despite this there was an order for 32 by Regia, in 19 June 1937. Only in January 1938 , over one year after BR and SM bombers, they started to enter in service.

Enhanced by Asso XI RC 40 with 900 hp at 4,000 m. they were more efficient machines, still on paper. This new engine, still inline liquid-cooled (so there were not great differences with 1,000 hp radial engines) gave a maximum speed of 400 km/h at 4,000 m., climbing to 2,000 m in 5,5', 4,000 m in 12,1' and 5,000 m in 16,9'.

Take-off and landing were 418 and 430 m. Range was good enough to assure 2,200 km with 550 kg and 1,200 km with 1,200 kg.

Despite this, the aircraft was rated still underpowered and so this gave the Ca.135Mod with Piaggio P.XI engines, 1,000 hp each.

This happened in 1939, but to make even more complex the history, the year before some aircraft were sent in Spain, or at least it was planned to do so, sending another type of Italian fast bomber in that theatre. They needed to be enhanced, so in 1938 the Tipo Spagna aircraft was fitted with Fiat A.80 RC.41, rated at 1,000 hp (746 kW).

To start the missions, crews of 11 Wings were sent to Taliedo to take the first seven Spain bombers Ca.135S. But already at take-off one was damaged. The other six landed at Ciampino, but here two aircraft suffered damages on landing operations. With the reparation of all the aircraft and some modifications, the seven machines were ready to take off for Spain. But this aircraft was really unfortunate, so not before the fall of 1938 (around six months after) this squadron was ready to fly over Spain, when the war was almost ended. This was a disaster, because two were forced by icing to return in Italy and three fallen in the sea. Two arrived at Palma de Majorca and there, they remained unutilized for six months.

The production of this bomber was initially only 32 machines, of them eight were Ca.135S (that were a total failure), some were transformed in Ca.135Mod, and finally, in 1938 were built the firsts Ca.135Bis. They were fitted with Piaggio P.XI RC.40, 1,000 hp, with Piaggio three blade propellers, metallic, of model P.1001. Length was 17.7 m, wingspan 18.8 m, wing surface 60 m2. Still there were 2x12.7 mm and one 7.7 mm, and the nose was different, more pointed.

Another 32 were ordered by Regia and built between 1939 and June 1940. They were not successful as well, with a rough judgment by the Italian aviators: unable to be operational used, so they were only sent to schools and then exported in Hungary. The Caproni bombers were not successful at all in Regia, and the first batch was phased out already in fall 1938 by 11 Wing. 25 were still available over Jesi airfield, only four ready to the use and the others probably in maintenance for the engine replacements. In 1940 there were at least 15 both Ca.135S and Ca.135Mod in Malpensa aviation school, in 1941 the bad conditions of these materials were so heavy that there was decided to demolish them until November 1941. So, with the demolition of the first batch and the sell of second, all the 64 Caproni vanished from service in Regia, without been able to perform a single operational mission. In the meanwhile, still in June 1940 there were five wings and several squadrons equipped with S.81s, theoretically much more obsolete.

A Hungarian Air Force Ca.135 with its bombs being loaded, 1942.
A Hungarian Air Force Ca.135 with its bombs being loaded, 1942.

In the 1938 Imperial Japanese Army Air Force competition 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.135's had Manfred Weiss WM K-14 engines in place of the Piaggio P.XI's, since Hungary used these engines in its version of the Reggiane Re.2000 and its version of 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.

A modified Ca.135 P.XI was also developed by Caproni by incorporating a dihedral tailplane and 1,400 hp (1,044 kW) 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 Ca.135 to more than 480 km/h (298 mph).

The final variant was a one-off, known as the Ca.135 Raid, a 'must' for the Italian aircraft of the time, all used to set records and win air raids. It had been built in 1937 to the order of Brazilian pilot de Barros, was powered by two 986 hp (736 kW) 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, another disaster for the image of that bomber.

[edit] Operational Use

The Hungarian Air Force operated, some sources says, 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 machines constituted practically the only heavy bomber of Hungary and were ordered in exchange of the Ca.310, that were rated really bad and then restituted to Caproni in exchange of these new aircraft, much more powerful. The second Ca.135 series rejected by Regia and a new one for 35 was delivered between 1940 and 1941 after an order made already in 1937, but perfected only in 1939, after the trial made by Hungarian pilots at Guidonia, that surprisingly found it satisfactory. Practically Hungary was almost all equipped with Italian aircraft at the beginning of the war. 4° Bombardment group had these machines until fall 1942, when survivors, worn out, were used as schools aircraft. Hungarians did not loved the Ca.135Bis but at the beginnings it was all they had and so they struggle to use it at best. Only one of the squadrons, the I/4, (originally armed with eight machines, one soon lost at landing and then replaced with other 4 Capronis) performed, until October 1941 265 attacks, 1,040 sorties and dropped around well 1,600 t bombs, evidently helped by the short range (200-300 km) that allowed to use the bombs at maximum capability. Two machines were downed, another two lost for accidents and 11 aviators lost as well. The average of these four months was over 8 missions and 14 t of bombs for each day.

Peru also ordered the Ca.135, and an initial delivery of six aircraft with 815 hp (608 kW) 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 900 hp (671 kW) Asso XI RC.40 engines in modified cowling, as well as revised gun placements. These aircraft were used by the Peruvian Air Force in the 1941 Ecuadorian-Peruvian War and proved somewhat successful against Ecuadorian ground units.

Overall, this machine was at least unfortunate. Despite the look and the power of the weapons this was utilized only by foreign costumers. Continuous changes in engines made the Caproni prototype (Asso, 830 hp), Caproni I series (900 hp), Caproni S (A.80, 1,000 hp), Caproni 135 Mod and Bis (P.IX, 1,000 hp) and still, the machine was rated totally unsatisfactory by RA and had some success only in Hungarian service.

[edit] Variants

  • Ca.135 Tipo Spagna :
  • Ca.135 P.XI : Medium bomber version, powered by two 1,000-hp (746-kW) Piaggio P.XI RC 40 radial piston engines.
  • Ca.135 Tipo Peru : Export version for Peru, fitted with two 815-hp (608-kW) Asso XI RC 45 engines.
  • Ca.135 bis/Alfa : One aircraft fitted with two 1,400-hp (1044-kW) Alfa Romeo 135 RC 32 Tornado radial piston engines.
  • Ca.135 Raid : Special long range version, fitted with extra fuel tanks. One built.

[edit] Operators

Flag of Hungary Hungary
Flag of Italy Italy
Flag of Peru Peru

[edit] Specifications (Ca.135 P.XI)

General characteristics

  • 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: 2× 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.

[edit] References

[edit] See also

Related development

Comparable aircraft

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