The Savoia-Marchetti S.M.81 Pipistrello (bat) was a development of the Savoia-Marchetti S.M.73 18-pagsenger airliner which had first flown in prototype form on 4 June 1934. Like the airliner from which it was derived, the S.M.81 was a three-engine cantilever low-wing monoplane with fixed tailwheel landing gear. First flown in early 1935, it was available in some numbers by the time that Italy invaded Abyssinia (Ethiopia) on 3 October 1935. Here in addition to its dedicated bomber role, it was used also for reconnaissance and transport. The next operational use of the type came during the Spanish Civil War, with S.M.81s being among the first aircraft provided in support of General Franco, and others served in Spain a little later as components of the Aviazione Legionaria.

By the time Italy became involved in World War II about 100 remained in service with the Regia Aeronautica, but although it was already completely outdated the S.M.81 was to be found wherever Italian forces were fighting. Because of its low speed and vulnerability to attack, it was used primarily for second-line duties, but with the protection of darkness many found important use as night bombers, particularly in North Africa. Some remained in service at the time of the Italian surrender, continuing in operation with the Aeronautica Cobelligerante del Sud, and a few survived the war to serve for five or six years with the post-war Aeronautica Militare Italiana. A total of approximately 534 S.M.81s had been built and flown with a variety of powerplants including the 650 hp (485 kW) Gnome-Rhôene 14K or similarly powered Alfa Romeo 125 RC.35, the 900 hp (671 kW) Alfa Romeo 126 RC.34, and the 700 hp (522 kW) Piaggio P.X RC.35. Under the designation S.M.81B a single experimental twin-engine prototype had been flown under the power of two 840 hp (626 kW) Isotta Fraschini Asso XI RC engines, but no production examples followed.

Savoia-Marchetti S.M.81 - The production version and flown with a variety of powerplants including the 650 hp (485 kW) Gnome-Rhôene 14K or similarly powered Alfa Romeo 125 RC.35, the 900 hp (671 kW) Alfa Romeo 126 RC.34, and the 700 hp (522 kW) Piaggio P.X RC.35 radial engines, with the latter being the most common (534 built).

Savoia-Marchetti S.M.81B - A single experimental aircraft using only two 840 hp (626 kW) Isotta Fraschini Asso XI RC engines. Performance was disappointing an no further development or production took place (1 built).

 (Savoia-Marchetti S.M.81 Pipistrello "Bat")

Type: Five or Six Seat Transport & Bomber

Accommodation/Crew: (Bomber) Pilot, Co-pilot/Navigator, Radio Operator/Gunner, Bombadier/Gunner and one or two beam gunners. (Transport) Pilot, Co-pilot/Navigator and Radio Operator/Gunner was the standard crew. Depending on the armament (if any) on the transport, additional gunners were crewed.

Design: Societa Italiana Aeroplani Idrovolanti (Savoia-Marchetti) Design Team

Manufacturer: Societa Italiana Aeroplani Idrovolanti (Savoia-Marchetti) with factories in Sesto Calende and Borgomanero.

Powerplant: (Typical) Three 700 hp (522 kW) Piaggio P.X RC.35 9-cylinder air-cooled radial engines.

Performance: Maximum speed 211 mph (340 km/h) at 3,280 ft (1000 m); service ceiling 22,965 ft (7000 m); climb to 9,845 ft (3000 m) in 12 minutes.

Range: 1,243 miles (2000 km) on internal fuel as a transport and 932 miles (1500 km) with full weapons/equipment and a 2,205 lbs (1000 kg) bomb load. Up to 4,410 lbs (2000 kg) of bombs could be carried when required, but this severely impacted the range of the aircraft.

Weight: Empty 13,889 lbs (6300 kg) with a normal combat take-off weight of 20,503 lbs (9300 kg) up to a maximum (overload) take-off weight of 23,040 lbs (10450 kg).

Dimensions: Span 78 ft 9 in (24.00 m); length 58 ft 4 3/4 in (17.80 m); height 14 ft 7 1/4 in (4.45 m); wing area 1,001.08 sq ft
(93.00 sq m).

Armament: This varied greatly but usually consisted of five or six 7.7 mm (0.303 in) Breda-SAFAT machine-guns (two in a powered dorsal turret, two in a retractable ventral turret and one or two manually aimed from each beam position) plus a bomb load of up to 2,204 lbs (1000 kg) carried internally. Some aircraft saw the dorsal turret fitted with a single 12.7 mm (0.50 in) Breda-SAFAT machine-gun.

Variants: S.M.81, S.M.81B (single prototype).

Equipment/Avionics: Standard communication and navigation equipment.

History: First flight (prototype) early 1935.