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Caproni Ca.4

Triple-Engine Heavy Bomber Triplane Aircraft

The Caproni Ca.4 triplane heavy bomber proved itself a heady performer for the Italians during World War 1.
Authored By: Staff Writer | Edited: 5/31/2017
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Year: 1918
Manufacturer(s): Caproni - Italy
Production: 50
Capabilities: Ground Attack; Navy/Maritime;
Crew: 4
Length: 42.65 ft (13 m)
Width: 98.10 ft (29.9 m)
Height: 20.67 ft (6.3 m)
Weight (Empty): 14,793 lb (6,710 kg)
Weight (MTOW): 16,535 lb (7,500 kg)
Power: 3 x Liberty L-12 V12 water-cooled inline engines developing 400 horsepower each.
Speed: 87 mph (140 kph; 76 kts)
Ceiling: 9,843 feet (3,000 m; 1.86 miles)
Range: 435 miles (700 km; 378 nm)
Rate-of-Climb: 410 ft/min (125 m/min)
Operators: Kingdom of Italy; United Kingdom; United States (evaluation only)
Giovanni Caproni was a prolific Italian aircraft designer of the 20th Century with his contributions seen throughout both World Wars. His initial venture was the Ca.1 experimental biplane of 1910 which led to the line of large aircraft seen in World War 1 (1914-1918) - the Ca.2, Ca.3 and Ca.4 heavy bombers all emerged during this time. The Ca.4 was a progressive development of the earlier, successful Ca.3 and led to production of some 50 or so aircraft. The product achieved a first flight in 1917 and was formally introduced during 1918, the last year of the war. It was eventually taken into service with the forces of Italy and Britain while United States evaluated three examples.

For its Ca.4 product, Caproni took the Ca.3 as a starting point and retained the twin-boom / center nacelle arrangement. The twin-boom configuration resulted in triple-rudders at the tail. Drive power was from a single engine installed at the rear of the center nacelle in a "pusher" setup while the forward sections of each boom structure housed an engine in a "puller" setup. All three engines were Liberty L-12 series V12 liquid-cooled powerplants of 400 horsepower output (each). The undercarriage, fixed during flight by a network of struts and cables, were multi-wheeled to help support the aircraft when on the ground. The crew numbered four and consisted of two pilots, a forward machine gunner and a rear machine gunner, the latter also doubling as an in-flight mechanic. Standard armament centered on four 6.5mm FIAT-Revelli machine guns while up to 3,200lb of conventional drop stores could be carried.

Unlike previous Caproni bombers, the Ca.4 was given a triple wing arrangement for improved lift and control.

The initial prototype was known under the company designation of Ca.40 and this was followed by the production-quality Ca.41 which numbered 41 total aircraft - these powered by FIAT A.12 inline engines of 280 horsepower (each). The Italian air service tested the platform during 1917 before formal operational service was granted in 1918. The heavy bombers were used along the Italian-Austro-Hungarian Front where it proved itself a relatively fast, robust and reliable product that held a considerable bomb load.

With its sound design and triple-engine layout, the aircraft could reach a maximum speed of 87 miles per hour and range out to 435 miles while flying at altitudes up to 9,845 feet. Rate-of-climb was listed at 410 feet-per-minute.

Then came twelve of the Ca.42 model which introduced the 400 horsepower Liberty engines mentioned above. The Ca.43 served as a "one-off" flying boat derivative and the Ca.48 marked post-war passenger airliners converted from wartime bombers. The Ca.51 became another one-off form powered by FIAT A.14 series engines of 700 horsepower (each) and featured a new tail assembly. Ca.52 marked British Ca.42s and numbered six aircraft. The Ca.58 sported either Fiat A.14 or Isotta Fraschini V.6 series engines and the Ca.59 became its export designator.


4 x 6.5mm FIAT-Revelli machine guns

Up to 3,200lb of conventional drop ordnance.

Graphical image of an aircraft medium machine gun
Graphical image of an aircraft conventional drop bomb munition

Variants / Models

• Ca.40
• Ca.4 - Base Italian Military Designation
• Ca.40 - Prototype model
• Ca.41 (Caproni 750hp) - Definitive production form; fitted with 3 x Fiat A.12 engines of 280 horsepower; 41 examples.
• Ca.42 (Caproni 1200hp) - Fitted with 3 x Liberty engines of 400 horsepower; 12 examples.
• Ca.43 - One-off flying boat model
• Ca.48 - Airliner form converted from wartime Ca.42 bombers.
• Ca.51 - One-off example with new tail and 3 x Fiat A.14 engines of 700 horsepower.
• Ca.52 - British Ca.42 models; six examples.
• Ca.58 - Ca.48 bombers completed with Fiat A.14 or Isotta Fraschini V.6 engines.
• Ca.59 - Export designation of Ca.48 aircraft.
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