[2] 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.

[2] 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.

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.

[3] 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.

[citation needed] 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.

[4] 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.

[citation needed] The aircraft, having a large wing and robust undercarriage, was reliable and pleasant to fly, and could operate from all types of terrain.

Once retracted, only the upper part of the turret was visible, with the gun barrels positioned vertically, one aft of the other to reduce drag, giving the impression that the aircraft had additional antennae.

The SM.81's bomb bay was divided into two parts with a passage linking aft and mid fuselage between, and could accommodate a wide range of ordnance up to a total of 2,000 kg (4,410 lb) over short ranges, with individual bombs of up to 500 kg (1,100 lb), arranged either horizontally or vertically:[5] The bomb-release mechanism was located on the right side of the bombardier's position.

SM.81s also fought in the Spanish Civil War with the Aviazione Legionaria and were among the first aircraft sent by the fascist powers to airlift aid to Francisco Franco.

[7] A further flight was concurrently deployed against Anglo-Rhodesian defensive positions in British Somaliland immediately before the decisive Battle of Tug Argan, presaging a limited role as a tactical bomber.

[8] Its low speed and vulnerability to fighter aircraft meant that during daytime the SM.81 was restricted to second line duties, finding use as a transport.