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Savoia-Marchetti SM.84 Medium Bomber / Torpedo Bomber (1941)

Authored By Staff Writer | Last Updated: 1/19/2015

The Savoia-Marchetti SM.84 three-engined bomber was developed to replace the SM.79 series in service with the Regia Aeronautica - it failed in its goal.

Picture of Savoia-Marchetti SM.84
With the arrival of World War 2 in September 1939, many existing aircraft of all types were pressed into wartime service and the resulting actions often showcased obsolete approaches to both design and doctrine. Additionally, aviation technology began a quickening pace of evolution which rendered many prewar mounts expendable or useless in the coming years. Such was the case with the Italian Air Force's (Regia Aeronautica) Savoia-Marchetti SM.79 "Sparrowhawk" tri-engine bomber series. It was introduced in 1936 and some 1,350 were produced from then until the end of the war in 1945. However, by 1940, a newer, more modernized bomber form was sought.

Savoia-Marchetti engineers took the basic three-engine design with its low-set monoplane wings and modernized it in the hopes of a better product. The fuselage was revised and uprated engines installed. The original wings were retained and the cockpit flightdeck remained in stepped position over the long nose assembly. The tail unit consisted of a dual-vertical tail fin arrangement and the undercarriage was of a "tail-dragger" configuration. Armor protection for the crew and systems were improved over that of the "softer" SM.79 series and self-sealing fuel tanks were used. Construction included a steel tube understructure with metal skin and fabric at the fuselage while the wings were of wood. The fuselage housed an internal bomb bay.

A prototype was developed and this recorded its first flight on June 5th, 1940. After the requisite flight testing phase, the aircraft was ordered into production by December and formally introduced during 1941 as the "SM.84". It was intended to succeed the aging SM.79 series in full.

The three-engine concept allowed for additional pulling power without a major disruption of the overall design. Several well-known tri-engined aircraft were used throughout the war including Ford's famous Tri-Motor as well as the recognizable contribution by Junkers with its Ju 52.

As completed, the SM.84 featured a crew of up to six - pilots, radioman, engineer, bombardier, and machine gunners. Dimensions included a length of 18 meters with a wingspan of 21 meters and height of 4.6 meters. Empty weight was listed at 19,500lbs with a loaded weight nearing 29,330lbs. Power was served through 3 x Piaggio P.XI RC 40 14-cylinder, air-cooled radial piston engines - one fitted at the nose and the other two along each wing leading edge as normal. Output was 1,000 horsepower each which allowed for a maximum speed of 270 miles per hour with a range out to 1,140 miles and a service ceiling of 25,920 feet.

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Specifications for the
Savoia-Marchetti SM.84
Medium Bomber / Torpedo Bomber

Focus Model: Savoia-Marchetti SM.84
Country of Origin: Italy
Manufacturer: Savoia-Marchetti - Italy
Initial Year of Service: 1941
Production Total: 309

Crew: 6

Length: 58.83 ft (17.93 m)
Width: 69.23 ft (21.10 m)
Height: 15.06ft (4.59 m)
Weight (Empty): 19,511 lb (8,850 kg)
Weight (MTOW): 29,321 lb (13,300 kg)

Powerplant: 3 x Piaggio P.XI RC 40 14-cylinder air-cooled radial piston engines developing 1,000 horsepower each.

Maximum Speed: 268 mph (432 kmh; 233 kts)
Maximum Range: 1,137 miles (1,830 km)
Service Ceiling: 25,919 ft (7,900 m; 4.9 miles)
Rate-of-Climb: 0 feet-per-minute (0 m/min)

Hardpoints: 0
Armament Suite:
1 x 12.7mm Scotti machine gun in dorsal position.
1 x 12.7mm Scotti machine gun in ventral position.
1 x 12.7mm Scotti machine gun in left beam position.
1 x 12.7mm Scotti machine gun in right beam position.

4,409lbs of conventional drop bombs OR 2 x torpedoes.

SN.84 - Base Series Designation; initial production models;

SM.84bis - Improved variant; limited production and limited operational service.

SM.84ter - One-off prototype; refined model of 1944; fitted with 3 x Piaggio P.XII engines of 1,500 horsepower each; lost to crashin 1946.

Italy; Nazi Germany; Slovakia