The Savoia-Marchetti SM.81 Pipistrello (Italian: bat) 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. Design and development The SM.81 was a militarised version of Savoia-Marchetti's earlier SM.73 airliner, having cantilever wings, three engines and a fixed undercarriage. The origins of this version were in pursuit of the interests of Italo Balbo, a brilliant exponent of the Fascist regime (but nevertheless "exiled" in Libya by Mussolini), who required a fast and efficient aircraft that was capable of serving the vast Italian colonies in Africa. The SM.81 had wings that were roughly similar to those of the double-fuselage S.55, and identical to those of the S.73, but had a much simpler fuselage. Around six months after the SM.73s first appearance, the SM.81 prototype (MM.20099) first flew from Vergiate, near Varese, on 8 February 1934, controlled by test pilot Adriano Bacula. The first serie, ordered in 1935, was for 100 aircraft and was quickly put into production as a result of the international crisis and the embargo caused by the war in Ethiopia. The first examples were sent to 7 Wing at Campo della Promessa airbase near Lonate Pozzolo. Although it was quickly superseded as a front-line bomber, the SM.81 continued to serve as a transport by virtue of its wide fuselage, which allowed it to accommodate a wide range of loads. Apart from its speed, it was generally superior to the SM.79 Sparviero as a multirole aircraft. Overall characteristics The SM.81 was a robust, three-engine monoplane, with a fixed tailwheel undercarriage, with the mainwheels enclosed by large spats to reduce drag, and had a crew of six. The aircraft was of mixed construction: the fuselage had a framework of steel tubes with a metallic-covered aft portion, while the rest was wood- and fabric-covered. It had a relatively large fuselage, an unnecessary characteristic for a bomber, which determined its future as a transport