‘Flight is not merely a technical achievement,
but the subjugation of space to the audacity of human thought.
Gianni Caproni
In the historiography of aviation, accounts of the origins of jet flight are often marred by chronological inaccuracies or by interpretations dictated, at the time, by the conflicting demands of wartime propaganda.
To guide the reader towards the true historical record, it must be stated at the outset that the Campini-Caproni of 27 August 1940 was not, in absolute terms, the first jet aircraft to take off; that distinction belongs to the secret German Heinkel He 178 in August of the previous year.
However, the Italian feat boasts two historic and indisputable world records, officially recorded by the Fédération Aéronautique Internationale (FAI): that of the first jet-powered flight carried out in daylight in front of the public and the press, and that of the first inter-city flight carrying airmail. This essay aims to explore the origins of this record, giving due scientific credit to the designers and the valiant pilot who led this epic endeavour.
Introduction
The late 1930s represented a period of profound technical identity crisis for global aeronautical science and, at the same time, a formidable pioneering drive. The paradigm of the aircraft propelled by a conventional powerplant – the combination of a reciprocating piston engine and a propeller – was inexorably reaching its insurmountable physical limit, dictated by the phenomena of air compressibility occurring at the tips of the propeller blades as the speed of sound was approached (the transonic barrier). International research, whilst conducted in a climate of extreme military secrecy due to pre-war geopolitical tensions, moved in the same direction: the abandonment of the propeller and the exploitation of the principle of action and reaction.
Against this backdrop, aviation historiography has often focused on the successes of Nazi Germany with the Heinkel He 178 in August 1939, and of the United Kingdom with the Gloster E.28/39 in May 1941, both of which were equipped with pure turbojet engines. However, the Italian experience with the Campini-Caproni holds a position of absolute uniqueness and scientific significance. This essay aims to analyse, through a rigorous examination of archival documentary sources—including the technical records of the Regia Aeronautica’s Experimental Centre in Guidonia and the certification reports of the Fédération Aéronautique Internationale (FAI)—the development, technical architecture and operational performance of the Campini-Caproni C.C.2 aircraft.
The analysis will not be confined to a cold, thermodynamic examination of the engine, but will seek to situate the project within its historical and political context, highlighting the role of the national industry and the irreplaceable contribution of key figures such as test pilot Mario De Bernardi.
The case of the Campini-Caproni represents, in the final analysis, the swan song of an autarkic engineering tradition capable of visionary leaps, yet structurally hampered by the country’s industrial and metallurgical limitations on the eve of the Second World War.
The insight and technical expertise of Secondo Campini
Born in Bologna on 28 August 1904, the engineer Secondo Campini belonged to that generation of designers who came of age amidst the feverish technological renewal of the 1920s. From his university days onwards, Campini distanced himself from the orthodox schools of thought in internal combustion engine design, focusing his research on the fluid dynamics of ducts and jet propulsion. In 1931, at the age of just twenty-seven, Campini filed a patent in Italy (Italian Patent No. 289762) and subsequently abroad for a ‘jet aircraft’, laying the theoretical foundations for the establishment, in Milan, of the ‘Società Veneta Campini per Velivoli e Battelli a Reazione’.
Unlike his contemporaries across the Alps, such as Hans von Ohain (1911–1998), who intended from the outset to couple a gas turbine to the compressor, Campini chose a middle ground, dictated both by his personal theoretical convictions and by a pragmatic awareness of the state of the art in the national metallurgical industry, which was unable to supply special alloys capable of withstanding the extremely high temperatures and centrifugal stresses of a turbine’s blades. Campini’s patent envisaged a conceptual separation between the component generating mechanical power and the component generating fluid-dynamic thrust.
The concept of the ‘thermoreactor’ (or motorjet)
The propulsion system devised by Campini, scientifically defined as a ‘motorgetto’ (or motorjet, or thermoreactor), was based on a hybrid thermodynamic cycle. At the heart of the system was a conventional reciprocating piston engine: in the case of the second prototype, a powerful Isotta Fraschini Asso L.121 RC.40 12-cylinder V-engine, capable of delivering around 900 cavalli at a type-certification altitude of 4,000 metres.
This traditional aero-engine was not, however, connected to an external propeller. Its kinetic power was entirely harnessed to drive, via a drive shaft and a reduction gearbox, a large three-stage tubular axial compressor, fitted with blades featuring variable pitch adjustable on the ground. The cycle’s operation was divided into the following theoretical phases:
- Intake and Compression: Outside air entered through the large ogival air intake at the nose of the aircraft, flowed over the Isotta Fraschini engine (which was cooled by the airflow itself) and was compressed by the three-stage fan.
- Static and dynamic heating: The compressed air flowed into the wide duct encircling the fuselage, undergoing an initial rise in temperature due to the radiant heat released by the piston engine and its exhaust ducts.
- Combustion (Afterburner): At the rear of the duct, before the exhaust nozzle, the air encountered a system of ring burners. Here, fuel (kerosene or petrol) was injected; as it ignited, it caused a violent thermal expansion of the gas, increasing its exit velocity.
- Expansion: The high-temperature, high-pressure gas expanded into the rear Venturi nozzle, the outlet cross-section of which was adjustable via a long movable cone (known as the ‘Campini needle’), generating, by reaction, the dynamic thrust necessary for motion.
Thermodynamic limitations, weight considerations and propulsive efficiency
Whilst, from a theoretical point of view, Campini’s thermoreactor appeared to be a masterpiece of engineering, its practical application revealed intrinsic and insurmountable thermodynamic limitations. The main flaw lay in the system’s overall efficiency coefficient.
In a pure turbojet, the energy to drive the compressor is extracted directly from the exhaust gases via the turbine, minimising mechanical losses. In the Campini system, the installation of an entire 900 CV piston engine within the fuselage resulted in a deadweight that was disproportionate to the actual thrust generated. The weight of the power unit, combined with the coolants, radiators and compressor, adversely affected the thrust-to-weight ratio of the entire aircraft.
Furthermore, the heat generated in the rear combustion chamber tended to spread by conduction and radiation to the duraluminium structures of the fuselage. During testing, the burners’ efficiency proved unsatisfactory at low speeds and at lower altitudes, where the jet engine’s performance was significantly inferior to that of a good contemporary propeller-driven fighter (such as the Macchi C.200 or the Fiat G.50). The estimated maximum thrust never exceeded 700–750 kgf, limiting the aircraft’s actual maximum speed to less than 380 km/h – a far cry from the theoretical expectations of the designer, who had anticipated speeds approaching 500 km/h. The jet engine was, by its very nature, a dead end in the evolution of propulsion: a fascinating technological bridge, but one destined to be superseded by the formidable rise of the gas turbine.
The partnership with Caproni and the birth of the C.C.2
Secondo Campini’s theoretical insight would have remained confined to the records of the Patent Office had it not been for the far-sighted intervention and industrial clout of Giovanni Battista Gianni Caproni. The renowned Trentino-based manufacturer, whose company dominated the national aeronautical scene with a widespread network of factories and a well-established international presence, took notice of the young Bolognese engineer’s project, recognising its revolutionary potential – if not in terms of immediate military applications, then certainly in terms of technological prestige. In 1934, following the signing of a formal agreement, Società Veneta Campini was absorbed into the Caproni group, and the thermoreactor designs were transferred to the state-of-the-art laboratories at the Milan-Taliedo plant.
The transition from the drawing board to the actual airframe required years of complex research into internal fluid dynamics, a field that was almost entirely unexplored at the time. The General Directorate of Aircraft Construction of the Ministry of Aeronautics decided to fund the construction of two prototypes and an airframe for static testing, officially registering the project under the designation “C.C.2”. From a purely aerodynamic point of view, the Campini-Caproni airframe was an elegant low-wing cantilever monoplane, constructed entirely of duralumin.
The fuselage, however, had to meet structural requirements that were the antithesis of those for conventional aircraft, as it was not merely an aerodynamic shell intended to house the crew and payload, but constituted in itself the complex forced-flow duct for the engine.
The fuselage is not merely a skin, but a single, immense aerodynamic duct. The entire longitudinal section of the fuselage was designed as a huge Venturi tube. The cockpit for the two pilots, seated in tandem, was housed within a pressurised superstructure positioned above the main duct; a solution which, whilst ensuring excellent visibility, created considerable problems with acoustic and thermal insulation due to its proximity to the internal combustion engine below.
Coordination between Campini’s technical department and Caproni’s workforce focused on achieving millimetre-level tolerances for the fuselage’s internal walls: even the slightest roughness, protruding rivet or imperfection in the sheet metal would have generated harmful turbulence, drastically reducing the already critical thrust of the compressed air flow.
The Making of the Ace: the military prowess of Mario De Bernardi
To understand the exceptional skill demonstrated at the controls of the Campini-Caproni, one must look back to the origins of Mario De Bernardi’s career, a life story that is intertwined with the very birth of the Italian Air Force. Born in Venosa on 1 July 1893, the young De Bernardi showed an early aptitude for flight, which led him to enrol on pilot training courses even before the outbreak of the First World War. When Italy entered the Great War, he was already serving in the ranks of the Royal Army’s Aeronautical Service, destined to become one of the leading figures in the aerial duels over the Italian front.
Assigned to frontline fighter squadrons, including the famous 91st Squadron – known as the ‘Squadron of Aces’ due to the presence of legendary figures such as Francesco Baracca, who was already the undisputed leader on the front in terms of number of victories and tactical daring – De Bernardi immediately distinguished himself through a boldness underpinned by exceptional composure. In the turbulent skies over Veneto, Friuli and Trentino, piloting the fragile Nieuport and SPAD biplanes, he engaged in epic dogfights against the Austro-Hungarian air force. His manoeuvring skills and marksmanship led him to achieve numerous confirmed aerial victories, a record that rightfully elevated him to the select ranks of the Aces of the Great War.
The valour he demonstrated in these combat missions was recognised through the award of the highest honours. He was awarded the Silver Medal for Military Valour for an epic mission in which, upon spotting a large and formidable formation of enemy aircraft attempting to bomb the Italian lines, he set off alone in pursuit. Despite being vastly outnumbered and facing heavy defensive fire, De Bernardi managed to disperse the enemy patrol, shooting down one aircraft and forcing the others to flee, demonstrating an extraordinary disregard for danger and a sense of duty beyond the ordinary. This first high honour was followed by a Bronze Medal for Military Valour, awarded for the perseverance, courage and spirit of self-sacrifice he demonstrated during countless low-altitude escort and reconnaissance missions behind enemy lines, often returning to base with his aircraft severely damaged by anti-aircraft fire.
This wealth of heroism and profound knowledge of aircraft was not lost with the signing of the armistice. In the post-war period, his move to the newly formed Regia Aeronautica was the natural culmination of a life spent in the air. It was precisely his exceptional ability to push aircraft to the limits of their structural integrity that propelled him to the top of the High-Speed Unit at Desenzano del Garda. Here, De Bernardi linked his name to the epic story of the Schneider Trophy, the world championship for high-speed seaplanes which represented the ultimate technological showdown between the world’s major powers. In 1926, on the waters off Norfolk in the United States, piloting the legendary Macchi M.39, De Bernardi secured a historic victory by breaking the 396 kilometres per hour barrier and snatching the record from the Americans. The following year, in 1927, he broke the world record once again, exceeding 475 kilometres per hour – a speed which, for the time, placed almost intolerable physical strain on the human body.
So when Gianni Caproni and Secondo Campini had to entrust their revolutionary but unstable jet-powered aircraft to a pilot, they realised that no man in Italy possessed the combination of scientific courage and geometric intuition that Mario De Bernardi did. His was not merely the daring of a fighter pilot, but the informed audacity of an aviation scientist, capable of translating the vibrations of a duralumin fuselage and the delayed responses of a thermal jet engine into valuable engineering analyses, confirming right up to his final day the mettle of a hero decorated for valour. [1 – to be continued]
Photo by Bergfalke2 CC 4.0 sa by
