Savoia-Marchetti SM.78
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| SM.78 | |
|---|---|
| Type | Bomber/reconnaissance flying boat |
| Manufacturer | Savoia-Marchetti |
| Maiden flight | 1932 |
| Number built | 49 |
The Savoia-Marchetti SM.78 was an Italian bomber/reconnaissance biplane flying boat of the early 1930s.
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[edit] Development
The SM.78 first flew at the end of 1932, designed for the role of maritime reconnaissance-bomber. It was one of the many flying boats made by SIAI (Savoia-Marchetti), that in 1915 had started building foreign aircraft under licence, followed two years later by the first of its own designs.
The SM.78 was developed from the SM.62bis. The prototype, which carried the serial number MM222, made its first flight late in 1932 [1] and then transferred the next year to Vigna di Valle for evaluation. The SM.78 was the last biplane flying boat, built or used in large numbers by Italy; 49 were completed in all (32 by Piaggio and 17 by SIAI).
[edit] Technical description
The SM.78 was a single-bay biplane. It had a long and slim aft fuselage, with a tall welded steel fin and a wooden horizontal tail mounted centrally. The lower hull had two steps, to aid take-off from the sea.
This aircraft evolved from the SM.62bis, retaining practically the same unmodified wings, tail and fuselage, but with a different model of Handley Page flaps.
The hull/fuselage had poplar frames, and longerons made of ash. The plywood-skinned hull had a double-layered bottom, with an external layer of cedar, while the flanks were made from orthogonally-arranged laminates of cedar. The fabric-covered wings had spruce longerons and poplar ribs, utilising the low-weight and high-strength characteristics of these woods, and were painted to render them impermeable to water. Twin stabilising floats were mounted at mid-wing.
While the pilot and co-pilot were seated side-by-side in an enclosed cockpit in the prototype, this was replaced by an open cockpit in the production model. [1] A crew position mounting a 7.7 mm Lewis machine gun was situated in the nose, which also contained two cameras. This position was manned by the co-pilot when necessary, the aircraft having a three-man crew. A second, enclosed turret was fitted in the dorsal position, also armed with a Lewis gun, manned by the gunner/radio operator, who was also provided with an R.A.350 transmitter and an A.R.4 receiver. The aircraft was not fitted with an intercom, but the two pilots could communicate with the nose position using a "pneumatic message" system in which messages were passed through a tube. The forward machine gun had 564 rounds of ammunition in 12 magazines, while the aft machine gun had 470 in 10 magazines. Bombs were carried in a bomb bay within the lower wing, near to the fuselage. The weapon-load was 700 kg maximum. Typical combinations were: two x 250 kg and two x 100 kg bombs, six x 100 kg bombs, four x 70 kg depth charges, or six x 12 kg training bombs. Smoke generators could also be mounted on the inner hardpoints. A "Jozza" bombsight was located on the right in the cockpit, behind a glazed window.
The aircraft was powered by a single Isotta-Fraschini Asso 750 W18 engine, generating 900 hp at takeoff, arranged in a steel structure mounted between the two wings; and drove a four-blade propeller with variable pitch that could be set before takeoff. This, and the much refined hull of this aircraft bestowed a good performance for the time. A carbon dioxide fire extinguisher was mounted by the engine. A total of 2,200 l of fuel could be carried in six unarmoured Duralumin fuselage tanks, two aft, two central and two forward.
[edit] Operational history
The SM.78 was built between 1932 and 1935, with only 16 by SIAI and 32 from Piaggio. It equipped the 141° Squadriglia, based at La Spezia, the 144° based at Livorno, the 182° at Nisida and the 189° at Syracuse. It continued to serve until 1938,[1] being replaced by the Cant Z.501, a monoplane design with superior performance. Some aircraft remained in service during the early phase of the Second World War, performing in an air-sea-rescue capacity. Spain, which already operated SM.62s, tried unsuccessfully to acquire a licence to build the SM.78, leaving Italy as the only operator.
[edit] Operators
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[edit] Specifications (SM.78)
General characteristics
- Crew: 2
- Length: 12.26 m (40 ft 2½ in)
- Wingspan: 16.66 m (54 ft 8 in)
- Height: 4.34 m (14 ft 2⅞ in)
- Wing area: 69.5 m² (748 ft²)
- Max takeoff weight: 5,150 kg (11,354 lb)
- Powerplant: 1× Isotta-Fraschini Asso 750R 18 cylinder W configuration, 634 kW (850 hp)
Performance
- Maximum speed: 245 km/h (132 knots, 152 mph)
- Cruise speed: 220 km/h (119 knots, 137 mph)
- Range: 2,400 km (1,296 nm, 1,490 mi)
- Service ceiling 4,000 m (13,100 ft)
- Endurance: 11.5 hours
- Climb to 1,000 m (3,300 ft): 5 min 37s
- Climb to 2,000 m (6,600 ft): 14 min 30 s
- Climb to 3,000 m (9,800 ft): 29 min 43 s
- Climb to 3,800 m (12,500 ft): 53 min 40 s
Armament
- 4× 7.7 mm (.303 in) machine guns
- 6× 100 kg bomb load
[edit] See also
Related development Savoia-Marchetti S.59
Savoia-Marchetti S.62
[edit] References
- Notes
- Bibliography
- Donald, David, ed. The Encyclopedia of World Aircraft. London: Aerospace Publishing, 1997. ISBN 1-85605-375-X.
- Lembo, Daniele. "SM.78 (in Italian)." Storia Militare N.19, Westward editions, p. 43-49.
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