The Savoia-Marchetti SM.81 Pipistrello was the first three-engine bomber/transport aircraft serving in the Italian Regia Aeronautica. When it appeared in 1935, it represented a real step ahead in Italian military aviation: it was fast, well armed and had a long range. It proved effective during the war with Ethiopia and the Spanish Civil War. Despite being too slow to remain competitive as a bomber in the later years of World War II, it was one of the most flexible, reliable and important aircraft of the Regia Aeronautica from 1935 to 1944, and adapted to second-line duties in a wide range of tasks.

A trimotor is a propeller-driven aircraft powered by three internal combustion engines, characteristically one on the nose and one on each wing. A compromise between complexity and safety, such a configuration was typically a result of the limited power of the engines available to the designer. Many trimotors were designed and built in the 1920s and 1930s as the most effective means of maximizing payload.