RNAS Caproni Ca.4s
A number of sources agree that six Caproni Ca.4 triplane bombers were used by the RNAS in Italy and were later turned over to the Italians. However the details of the machines and how they were used is difficult to piece together.
The Ca.4 first flew in July 1916, but it did not enter operational service with the Italian air force until February 1918, when the first bombing raids were made on targets in Austro-Hungarian controlled territory.
Evaluation
The RNAS appears to have begun considering the Ca.4 in the first half of 1917. The idea was to use these heavy bombers to attack Austro-Hungarian naval bases on the Adriatic (such as Pola and Cattaro) with a view to hampering U-boat operations.
RNAS personnel evaluated and trained on the triplane bombers in 1917 at Gallarante, near Milan. Since the British pilots and Italian instructors could not understand each other, all the training was conducted using hand signals! The Ca.4 triplanes were found to be slow and poor climbers, leading to fears that they would be vulnerable to enemy fighters. There then appears to have been a switch of emphasis to night bombing.
Sub Lt Harry Laurence Nunn flew Caproni triplanes with RNAS no. 6 wing, no. 2 squadron from July 1917 to December 1917 in Brescia in northern Italy (see extracts of his logbook here). This appears to have been a training/evaluation posting. The last entry of his logbook for his time in Italy (11th December 1917) was a flight in Caproni Ca.4 N527, with the following remark:
The flight lasted 35 minutes to an altitude of 4500 feet, the crew are listed as O.S.L. Ashworth (presumably the second pilot) and "3 gunners". Since the short flight could not have reached the front lines from Brescia in this time, this must have been a test bombing trip, presumably at night, given the mention of flares.Bombing trip and using parachute flares and landing flares. Testing same.
Part of the confusion surrounding these machines is the designation. The Italian air force referred to all triplane bomber variants as "Ca.4". After the war the Caproni company retrospectively applied designations to its wartime designs, but during the war they generally referred to each variant by the amount of horsepower developed by its engines. Thus a Caproni triplane with Isotta Fraschini V5 engines would be a Caproni 750h.p., but could also be called a Ca.41 (using the later designation). The RNAS Ca.4s (given serials N526-N531) are variously described as Ca.42 or Ca.52, but this nomenclature was not used at the time.
The RNAS Ca.4s all had Fiat A12bis engines, although the first two machines (N526 and N527) appear to have initially had Isotta Fraschini V5 engines, which were then swapped for the more powerful Fiats before delivery. The aircraft were armed with twin lewis guns in the nose gun position, as opposed to the Italian variants which had a single Fiat-Revelli gun in the nose. The rear gunners probably had single lewis guns, but twin guns may have been used. The RNAS aircraft also had a modified bomb nacelle, tailored to British bombs, which would not fit the standard nacelle.
Delivery
Training, flight testing and evaluation were conducted by RNAS personnel in the second half of 1917, but the aircraft were not handed over to the RNAS until early 1918. Acceptance testing for the final RNAS machine, N531, began on 13th March 1918. The plan to carry out long range raids on Adriatic U-boat bases using these heavy bombers never came to fruition, but the aircraft were delivered and were probably based at Pizzone for a short time.
The RNAS stations in Southern Italy were initially unable to strike at Austro-Hungarian U-boat bases on the far side of the Adriatic Sea due to the limited range of the Short seaplanes with which they were equipped. However by 1918 the RNAS had D.H.4s based in Southern Italy with Sopwith Camels for protection. They were later joined by D.H.9s. These aircraft were used for anti submarine patrols but were also capable of striking at enemy bases on the far side of the Adriatic. Such was the situation when the six Caproni triplanes were finally delivered. Furthermore the RNAS was absorbed into the newly formed RAF on the 1st April 1918, the Caproni Flight becoming 227 squadron RAF.
In view of the above the Caproni triplanes were probably seen as a burden rather than an asset - their performance was less than had been hoped for and the task for which they had originally been ordered was now being fulfilled by the tried and tested D.H.4. The new 227 squadron RAF inherited the Caproni triplanes, but they did not last long. In mid-1918 at least some of the machines were given to the Italians, where they were flown by 181a Squadriglia. 227 squadron appears not to have become operational before the end of the war.
With multiple engines and a high endurance, the Ca.4 had potential to be a good machine for anti submarine patrolling. There is some suggestion that the British Ca.4s were used in this role for a short time, but this seems to be based on speculation rather than evidence.
Fate
By mid-1918 at least some of the RAF Ca.4s had been given to the Italians. 182a Squadriglia (formed in July 1918) received some of the former RNAS machines. British bombs were also given to the Italians, presumably because Italian bombs would not fit the specialised nacelles used in the British machines. By the end of the war there were no Ca.4s in British service.
Interestingly, one of the ex-RNAS Ca.4 aircraft features in Flight of the Giants (see link below). The 181a Squadriglia card is based on the former British aircraft N526. The winged head nose art visible in photos of this aircraft in British service is depicted on the card.
Pictures
Profile of an RNAS Ca.4
N526
Original artwork for Flight of the Giants card - N526, after it was transferred to Italian Squadriglia 181a - note the winged face on the nose (visible in the photo above)
N527 with RNAS markings, probably prior to delivery
N528 showing twin lewis guns (aerodrome account required to view this image)
N528 after the war, with the bomb nacelle converted for passengers
N529 with Italian officials
Line up of 4 RNAS Ca.4s, N531 in the foreground
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