Caproni Ca.165

Caproni

Industry	Aerospace
Founded	1908
Headquarters	Italy

The Caproni Ca.165 was an Italian biplane fighter developed in the period immediately preceding World War II. Only a single prototype was completed, as the competing Fiat CR.42 Falco was ultimately chosen for mass production.

Design

While Caproni was primarily recognized for its three-engine heavy bombers, the company also had a longstanding involvement with fighter aircraft dating back to 1914. Their early efforts included an interceptor monoplane armed with a single machine gun, which, despite being advanced for its era, did not achieve operational success—similar to many other fighter designs proposed in subsequent decades.

Italian manufacturers produced various aircraft models before World War II, some reaching limited production runs; however, the Ca.165 did not progress beyond the prototype stage after being submitted for a fighter competition. Its maiden flight occurred in February 1938.

The construction of the Ca.165 combined different materials: its fuselage featured a steel frame covered with lightweight metal alloys, while the wings were constructed from wood and covered with fabric. The tail assembly was metallic but also skin-covered with fabric.

The fighter had a slim fuselage design incorporating an enclosed cockpit. The landing gear was fixed and equipped with spatted wheels. A distinctive characteristic of the Ca.165 was its retractable radiator system, which the pilot could adjust based on flight conditions—fully extended during climbs for enhanced engine cooling and retracted during level flight or dives to reduce drag. This mechanism resembled that used on the Morane-Saulnier M.S.406. Deploying the radiator increased aerodynamic drag significantly but improved engine performance and reliability.

Power came from a V-12 Isotta Fraschini L.121 R.C.40 engine producing 671 kW (900 hp), coupled with a three-bladed electric propeller manufactured by Alfa Romeo. The aircraft’s maximum speed reached approximately 465 km/h (289 mph) at an altitude of 5,350 m (17,550 ft), with a service ceiling near 10,000 m (32,810 ft). Its operational range was limited to about 672 km (418 miles). The dimensions included an overall length of 8.1 m (26.6 ft), height of 9.3 m (30.5 ft), and wingspan measuring 2.8 m (9.2 ft), featuring a wing area of 21.4 m² (230.3 ft²). The empty and maximum takeoff weights were 1,855 kg and 2,435 kg respectively (4,090 lb / 5,368 lb), carrying a payload of approximately 570 kg.

Following several adjustments during development, modifications included enlarging the tail surfaces and lowering the rear fuselage to accommodate a canopy that offered panoramic visibility around the cockpit.

Testing and evaluation

During the evaluation at Guidonia, the aircraft underwent trials alongside numerous other fighters. However, its direct comparison was limited to the Fiat CR.42 Falco, the sole other biplane in the lineup. In simulated combat scenarios, the Ca.165 demonstrated superior performance over the CR.42, attributed to enhanced aerodynamics and greater engine power. Despite this advantage, the Ca.165 was ultimately judged inferior because the CR.42 exhibited better maneuverability and utilized a proven, dependable engine, whereas the Caproni powerplant was experimental and suffered from reliability issues. Nevertheless, the Ca.165 was declared the victor in these mock engagements, prompting General Valle to place an order for 12 units on 2 September 1939. This order was subsequently rescinded on 11 October 1939 and replaced with an order for 12 Caproni F.5s, a decision that incurred a financial penalty.

In terms of payload capacity (570 kg/1,257 lb versus 575 kg/1,268 lb) and armament (2 × 12.7 mm/0.5 in and 1 × 7.7 mm/0.303 in machine guns), the Ca.165 was roughly equivalent to the CR.42. However, it weighed approximately 200 kg (441 lb) more and featured less wing area, resulting in a wing loading of 113 kg/m² compared to the CR.42's 99 kg/m². This higher wing loading, combined with less effective control surfaces, reduced the Ca.165's agility. On the other hand, its stall speed was lower (114 km/h/71 mph versus 122 km/h/76 mph), which translated into shorter takeoff distances and marginally improved low-speed handling.

The Ca.165's fuselage was notably slender and compact but still heavier than that of the CR.42, likely due to differences in engine type and structural design. Rather than being a classic 'turn fighter,' it functioned more as an 'energy fighter,' emphasizing speed over tight turning ability—a characteristic highlighted by test pilots during evaluations. Although a variant aimed at enhancing maneuverability was conceptualized, development ceased prematurely. Constructed primarily from non-strategic materials such as steel and wood, it might have offered advantages regarding material availability during wartime production; however, its economic viability remained questionable given its engine choice.

Caproni pursued further enhancements for this robust biplane by experimenting with alternative powerplants: initially a 746 kW (1,000 hp) Piaggio P.XI radial engine and later a 746 kW (1,000 hp) Isotta Fraschini L.170 liquid-cooled engine, accompanied by redesigned sesquiplane wings under the designation Ca.173. These developments failed to generate significant interest from the Regia Aeronautica. Both engines suffered from reliability challenges and were never widely adopted by the Italian air force.

Cancellation

It is possible that Fiat's influence played a role in favoring the CR.42 Falco over the Ca.165 despite Caproni's prominence at that period. The decisive factors appeared to be that although the Ca.165's engine offered only a modest increase of 44 kW (60 hp), it was considerably less reliable and its airframe was about 200 kg (440 lb) heavier.

Although declared superior in mock combat exercises, the Ca.165 did not succeed in final evaluations. Test pilots were able to outperform their counterparts flying the Falco but generally expressed dissatisfaction with the aircraft itself. The emphasis on higher speed represented a more modern approach for fighters intended to intercept fast bombers like the Bristol Blenheim, which often outpaced the Falco. Speed became an increasingly critical design parameter during World War II aircraft development, but concerns over engine dependability negatively impacted production decisions.

Ultimately, only one prototype of the Ca.165 was ever built before it disappeared from operational consideration. Meanwhile, despite being largely outdated by later standards, the Fiat CR.42 emerged as Italy’s most extensively produced fighter aircraft during World War II, with nearly 1,800 units manufactured through 1944.

Further reading

• Green, William. "Facts by Request." Flying Review International, Vol. 24, No. 3, November 1968, p. 71.
• Lembo, Daniele I brutti anatroccoli della Regia(in Italian), Aerei nella Storia, Westward editions, No. 14.
• Punka, George. Fiat CR 32/CR 42 in Action (Aircraft Number 172). Carrollton, TX: Squadron/Signal, 2000. ISBN 0-89747-411-2.

External links

• 1000aircraftphotos.com