Caproni Campini N.1

During 1931, Italian aeronautics engineer Secondo Campini submitted a report to the Regia Aeronautica (the Italian Air Force) on the potential of jet propulsion; this report included his proposals for one such implementation, which he referred to as a thermo-jet. That same year, Campini established a company, with his two brothers, called the "Velivoli e Natanti a Reazione" (Italian for "Jet Aircraft and Boats") to pursue the development of this engine. In April 1932, the company demonstrated a pump-jet propelled boat in Venice, Italy. The boat achieved a top speed of 28 knots (32 mph; 52 km/h), a speed comparable to a boat with a conventional engine of similar output. The Italian Navy, who had funded the development of the boat, placed no orders but did veto the sale of the design outside of Italy.[2][3]

During 1934, the Regia Aeronautica granted approval for the development of a pair of prototypes, along with a static testbed, for the purpose of demonstrating the principle of a jet aircraft, as well as to explore potential military applications.[3] As his company lacked the necessary industrial infrastructure for such endeavours, Campini formed an arrangement with the larger Caproni aviation manufacturer, under which the latter provided the required material assistance for the manufacturing of the prototypes.[4] Under this relationship, Campini developed his design, which later received the official Italian Air Force designation of N.1.[5]

Historian Nathanial Edwards has contrasted the relative openness of Italian early jet development work against the high levels of secrecy present within other nation's programmes, such as Britain and Germany.[6] He speculated that this was due to desire of the Italian government to be perceived as possessing a modern and advanced aviation industry, being keen to acquire national prestige and renown for such achievements. Edwards went onto claim that the practicality of the N.1 design was undermined by political pressure to speed the programme along so that Italy would be more likely to be the first country in the world to perform a jet-powered flight.[6]

The first two stages of the compressor of the C.C.2

The Caproni Campini N.1 is an experimental aircraft, designed to demonstrate the practicality of jet propulsion and its viability as an engine for aircraft. It was a monoplane built entirely out of duralumin, with an elliptical wing. The initial aircraft lacked elements such as a pressurised cabin; however, these improvements were featured on the second prototype. However, flight testing quickly revealed that, due to the excessive heat output of the propulsion system, the canopy had to be left permanently open as a mitigating measure.[7]

The engine of the N.1 differs substantially from the later-produced turbojet and turbofan engines. One crucial difference in Campini's design is that the compressor – a three-stage, variable-incidence one, located forward of the cockpit – was driven by a conventional piston engine, this being a 900 hp (670 kW), liquid-cooled Isotta Fraschini unit.[8] The airflow provided by the compressor was used to cool the engine before being mixed with the engine's exhaust gases, thus recovering most of the heat energy that in traditional piston-propeller designs would be wasted. A ring-shaped burner then injected fuel into the gas flow and ignited it, immediately before the exhaust nozzle, to further increase thrust.[5][9]

In practice the engine provided enough thrust for flight without activating the rear burner, making the design somewhat similar to a ducted fan coupled to an afterburner.[7] Campini referred to this configuration as being a thermojet, although it has since become commonly known as motorjet.[10] However, despite the elaborate design, the relatively small size of the duct limited the mass flow and thus the propulsive efficiency of the engine. In modern designs this is offset through high overall pressure ratios, which could not be achieved on the N.1, therefore resulting in relatively low thrust and poor fuel efficiency.[11] Ground tests performed with the static testbed produced a thrust of around 700 kgf (1,500 lbf).[4]

The C.C.2 during a ground test, with the tail section removed. Note the lit burner within the airflow from the compressor.

The N.1s first flight was made on 27 August 1940 by test pilot Mario De Bernardi at Caproni's facility in Taliedo, outside Milan. He would conduct the majority of the N.1's test flights.[12] The first flight lasted ten minutes, during which de Bernardi kept the speed below 225 mph (362 km/h), less than half throttle.

Although the first flight of the jet-powered Heinkel He 178 had been made a year before to the day, it had not been made public, so the Fédération Aéronautique Internationale recorded the N.1 as the first successful flight by a jet aircraft.[4]

Flight tests with the first prototype revealed several issues with the engine. It did not produce sufficient thrust to achieve the anticipated performance if it was matched to a strengthened airframe to withstand the high loading pressures.[5] The engine generated considerable heat, which forced the pilot to fly with the canopy open throughout the flight, which although effectively venting the heat, increased drag.[7] According to aviation author Sterling Michael Pavelec the N.1 was "heavy and underpowered" and the conventionally-powered Caproni Vizzola F.4 was faster which he attributed to limited national resources which left development programs underfunded.

N.1 over Rome

On 30 November 1941 the second prototype was flown by de Bernardi, with Giovanni Pedace as a passenger, from Milan's Linate Airport to Rome's Guidonia Airport, in a highly publicised event which included a fly-past over Rome and a reception hosted by Italian Prime Minister Benito Mussolini. It was the first cross-country jet flight. The flight included a stopover at Pisa, possibly to refuel, and was made without using the rear burner.[4][9]

A Soviet aircraft design bureau, TsAGI, obtained some details of the motorjet, and developed their own.[13] Campini later formed a partnership with another Italian aircraft company, Reggiane, and with Roberto Longhi, modified the Reggiane Re.2005 to create the Re.2005R with a motor jet. Speed could have been increased to 750 km/h (470 mph) but fuel consumption would have reached nearly 1,000 L/h (61 imp gal/ks), almost four times the normal consumption of the Re.2005, at full throttle.

Testing of the two N.1 prototypes continued into 1943; however one of the N.1s was partially destroyed when the Caproni factory was bombed, and the collapse of the Fascist government following the Allied invasion of Italy hindered the programme. After the defeat of Italy, the damaged prototype was transported to the United Kingdom for study at the Royal Aircraft Establishment (RAE) in Farnborough. The aircraft was later scrapped at RAF Newton in 1949.[4]

The surviving C.C.2 at the Italian Air Force Museum

The surviving example is now on display at the Italian Air Force Museum at Vigna di Valle, near Rome, while the ground testbed, consisting of only the fuselage, is on display at the National Museum of Science and Technology in Milan.[14]

Data from Illustrated Encyclopedia of Aircraft [15]

General characteristics

• Crew: 2
• Length: 13.1 m (43 ft 0 in)
• Wingspan: 15.85 m (52 ft 0 in)
• Height: 4.7 m (15 ft 5 in)
• Wing area: 36 m² (390 sq ft)
• Empty weight: 3,640 kg (8,025 lb)
• Max takeoff weight: 4,195 kg (9,248 lb)
• Powerplant: 1 × motorjet , 6.9 kN (1,600 lbf) thrust consisting of a 670 kW (900 hp) Isotta Fraschini L.121 R.C.40 piston engine driving a three-stage, variable-pitch axial compressor with an afterburner

Performance

• Maximum speed: 375 km/h (233 mph, 202 kn)
• Service ceiling: 4,000 m (13,000 ft)

Aircraft of comparable role, configuration, and era

• Mikoyan-Gurevich I-250
• Sukhoi Su-5

Related lists

• List of jet aircraft of World War II

Wikimedia Commons has media related to Caproni Campini N.1.

• Photographs and a cutaway drawing of the N.1
• Caproni Campini test flight on YouTube
• Jet Propulsion pg 50, Life, November 27, 1944