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 Although it was quickly superseded as a front-line bomber, the SM.81 continued to serve as a transport by virtue of its wide fuselage, which allowed it to accommodate a wide range of loads.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 aircraft. Since the engines were quite small, the fuselage did not blend well with the nose engine, even less so than the SM.79. Many windows were present to provide the fuselage interior with daylight, giving the impression that it was a passenger aircraft. The all-wooden wings had three
spars to provide the necessary support, whereas the semi-elliptical tail surfaces were fabric-covered metal. The pilot and co-pilot were seated side-by-side in an enclosed
cockpit, with separate cabins for the flight engineer and the radio-operator/gunner behind the cockpit. The bomb bay was behind the cockpit, together with a passage which linked the mid and aft fuselage, where there were three further defensive positions. The
bombardier's position was located just below the cockpit, in a semi-retractable gondola, ==Fuel==