Savoia-Marchetti SM.92 – The Italian P-38

The Savoia-Marchetti SM.92 stands out as a unique and fascinating aircraft. Developed during the late stages of the Second World War by the Italian aircraft company Savoia-Marchetti, the SM.92 was an experimental fighter that showcased innovative design and engineering. Its development was part of Italy’s efforts to create superior aircraft to compete with the advanced fighters of the Allies.


The SM.92

The SM.92 was designed by the renowned engineer, Ing. Alessandro Marchetti. It was a twin-engine, twin-boom aircraft, a design that was quite radical for its time. The twin-boom configuration is similar to that of the P-38 Lightning by Lockheed. This design offered several advantages, including improved pilot visibility and a concentrated burst of firepower.

The SM.92 design although unusual, wasn't completely radical.
Marchetti’s design although unusual, wasn’t completely radical.

For its powerplant, the SM.92 utilised two Fiat RA.1050 Tifone engines. These engines were chosen for their reliability and power, aiming to give the SM.92 impressive speed and manoeuvrability.

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The development process, however, faced several challenges. World War II was a period of turmoil and resource scarcity, which inevitably impacted the progress of the SM.92’s development. Moreover, Italy’s changing political situation, particularly the Armistice of Cassibile in September 1943, further complicated the project. This armistice led to Italy switching sides in the conflict, creating a chaotic environment for continued development and testing.

Despite these challenges, the SM.92 did reach the prototype stage and undertook its maiden flight in late 1943. The initial flight tests showed promise, indicating that the aircraft had good stability, control, and potentially competitive performance. However, due to the aforementioned challenges, the SM.92’s development was never fully completed, and its capabilities were not exhaustively tested.

The SM.92 was intended to be equipped with a formidable array of weapons, including three 20 mm MG 151 cannons and two 12.7 mm Breda-SAFAT machine guns, all concentrated in the nose.
The SM.92 was intended to be equipped with a formidable array of weapons, including three 20 mm MG 151 cannons and two 12.7 mm Breda-SAFAT machine guns, all concentrated in the nose.


Alessandro Marchetti was an influential Italian engineer and aeronautical designer, renowned for his significant contributions to the field of aviation. Born on May 4, 1884, in Sesto Fiorentino, Italy, Marchetti’s career spanned a crucial era in aviation history, witnessing the transition from rudimentary flying machines to advanced aircraft.

Marchetti’s journey in aviation began with his education, where he developed a strong foundation in engineering principles. His passion and skill for aircraft design quickly became evident. In 1922, he joined the SIAI (Società Idrovolanti Alta Italia), which later became known as Savoia-Marchetti, a company that would become synonymous with Italian aviation.

Alessandro Marchetti
Alessandro Marchetti

At Savoia-Marchetti, Marchetti’s talents flourished. He was instrumental in designing several successful aircraft, most notably the S.55, a double-hulled flying boat that gained fame for its transatlantic flights. This aircraft was a testament to Marchetti’s innovative approach to design, combining practicality with the boldness of engineering.


Marchetti’s design philosophy often revolved around versatility and performance. This is exemplified in his work on the SM.79, a three-engine bomber that became one of the best-known Italian aircraft of World War II. The SM.79 was versatile enough to be used in multiple roles, including as a torpedo bomber, and was appreciated for its speed and agility, unusual for a bomber of its time.

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Throughout his career, Marchetti’s contributions were not just limited to individual aircraft designs. He played a pivotal role in advancing the aeronautical engineering field in Italy, pushing the boundaries of what was possible in aviation technology. His work influenced several other designs, including the SM.92.

Despite the challenges of working through two World Wars, Marchetti’s dedication to his craft never waned. His work continued to evolve, demonstrating a keen understanding of the changing dynamics of aviation and warfare.

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Flight Performance

The two Fiat RA.1050 Tifone engines, Italian-built versions of the German Daimler-Benz DB 605 engine, were anticipated to give the SM.92 a high top speed and good climbing performance. These engines were among the most powerful available to the Italian aircraft industry at the time, and their inclusion in the SM.92’s design was a strategic choice aimed at ensuring the aircraft could compete effectively with contemporary Allied fighters.

A closeup of the Italian DB605 engine.
A closeup of the Italian DB605 engine.

Initial flight tests, which began in late 1943, indicated that the SM.92 had promising performance characteristics. Reports suggested that the aircraft exhibited good stability and control, important factors for a fighter aircraft. Pilots noted that the SM.92 was responsive to control inputs, a crucial aspect in dogfight scenarios.

However, the comprehensive performance capabilities of the SM.92, such as its maximum speed, service ceiling, rate of climb, and manoeuvrability under various combat conditions, were not fully documented.

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The ongoing war, resource limitations, and Italy’s changing political circumstances, including the Armistice of Cassibile, significantly hindered extensive testing and development. Consequently, the SM.92’s performance in combat situations remained largely untested and speculative.

Due to the difficulties of the war, the SM.92 was never fully tested.
Due to the difficulties of the war, the SM.92 was never fully tested.

Challenges and Limitations

The twin-boom design of the Savoia-Marchetti SM.92, while innovative and promising in several respects, also presented a unique set of challenges and limitations. This design, featuring two separate fuselages (booms) with a central nacelle for the pilot and armament, was a distinctive approach to fighter aircraft construction during the Second World War.

One of the primary challenges with any twin-boom design is related to aerodynamics. The presence of two booms created additional drag, which could potentially reduce the aircraft’s top speed and agility – critical factors for a fighter aircraft.

The twin boom design did have significant advantages. But also quite a few drawbacks.
The twin-boom design did have significant advantages. But also quite a few drawbacks.

Managing this drag required careful aerodynamic design and engineering to ensure that the performance advantages of the twin-boom configuration were not negated by increased air resistance.

The twin-boom configuration also introduced increased structural complexity. Connecting the two booms with the central nacelle and the wing assembly required a robust and intricate structure to maintain the integrity of the aircraft.

This complexity not only added to the weight of the aircraft but also presented challenges in terms of manufacturing and maintenance. Ensuring structural strength while keeping weight to a minimum was a significant engineering challenge.

Synchronising the two engines mounted in separate booms was another challenge. The performance and response of the aircraft depended heavily on the precise operation of both engines. Any discrepancy in engine power or response could lead to handling issues, potentially making the aircraft difficult to control, especially in combat situations or during high-performance manoeuvres.

The SM.92 was bigger than the P-38. A fairly large fighter already.
The SM.92 was bigger than the P-38. A fairly large fighter already.

Road to Nowhere

The Savoia-Marchetti SM.92, although a less-known chapter in Second World War aviation, represents an intriguing blend of innovation and ambition in aircraft design. Its development during a tumultuous period of Italian history reflects the challenges faced by engineers and designers in war times.

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Today, the SM.92 is remembered by aviation enthusiasts and historians as a symbol of Italy’s advanced engineering capabilities and as a fascinating “what could have been” in the history of military aviation.