Savoia-Marchetti SM.74

Savoia-Marchetti SM.74
Type:	Airliner
Design country:	Italy
Manufacturer:	Savoia-Marchetti
First flight:	1935
Number of pieces:	37

The Savoia-Marchetti SM.74 was a transport and airliner for Italian airlines that broke another world record and was also called the “millipede” because of its versatility.

history

The increased need of the airlines for improved passenger aircraft and the need of the Regia Aeronautica for larger transport aircraft made a new project at SIAI necessary. With the SM.74, Alessandro Marchetti wanted to close this gap and secure market shares. The prototype started on March 26, 1935 for the first time with four Piaggio P-XR engines, each with 700 hp and an adjustable three-blade propeller made of metal. The test flight ran without any problems and showed particularly good flight characteristics. All results of the test flight were kept top secret; the competition from Fokker and Douglas was fierce and they wanted to sell. The only customer for the SM.74 was Ala Littoria and he threatened to drop out, the customer had to be convinced of the advantages of the SM.74. For this purpose, two further prototypes with Bristol Pegasus III engines with 845 hp each were built. The tests started on December 13, 1935. On July 18, 1936, Ala Littoria opened the Rome – Paris line with the SM.74. Nevertheless, in 1937 the engines of the SM.74 were converted to the Italian Alfa Romeo 126RC34 engine with 780 hp each, and all 37 machines received this engine. On December 22, 1937, another world record was broken with an SM.74, transporting 10 t payload at 322.089 km / h over a distance of 1100 km.

Because of the war preparations, the SM.74 were confiscated by the Regia Aeronautica and used as a transport aircraft to and from Africa. On April 9 and 10, 1941, the planes transported fuel and food deliveries between Ajdabiya and El Mechili for the Italian-German counter-offensive, especially for the armored division "Ariete" . On July 30, 1941, the heavily loaded machines were attacked by the British Bristol Blenheims , but the experienced pilots and crews were able to save the machines. From then on, the SM. 74 only used for transport purposes at night. On October 2, 1941, the Castel Benito airfield was bombed and some SMs were lost. Another SM.74 crashed on October 23, 1941 in the mountains of Licodia Eubea Goda with 26 soldiers on board. The last remaining SM.74 was destroyed on July 19, 1943 in an American bomb attack on Rome.

technology

The SM.74 had welded steel frames and was partially clad with duralumin sheets. The wings were made of reinforced plywood and some were covered with linen. The tail unit was designed similar to that of the large flying boats. The cockpit of the SM.74 was laid out above the wings so that the crew could monitor the engines during the flight. The first prototype was made with four Piaggio P-XR engines with 700 hp each. At the customer's request, two more received Bristol Pegasus III engines with 845 hp each, which were later exchanged for Alfa Romeo 126RC34 engines with 780 hp each. The undercarriage of the SM.74 was equipped with shock absorbers to protect the fully loaded aircraft from damage on landing.

Technical specifications

Parameter	Data
crew	4th
Passengers	up to 27
length	21.36 m
span	29.68 m
height	5.50 m
Wing area	120 m²
Empty mass	8900 kg
Takeoff mass	14,000 kg
drive	4 × DD Alfa Romeo 126RC34 with 575 kW (780 PS) each
Cruising speed	278 km / h
Top speed	322 km / h
Service ceiling	7000 m
Range	2000 km

literature

• Brotzu, Casolo: Dimensione Cielo. - Ed. Gonzo
• Evangelists: Gente Dell'Aria. - Ed. Olimpia
• Bignozzi, Heiden: Aircraft SIAI (1915–1935). - Ed. Italian Air Force
• SIAI: Ali in History - and Italian Air Forces.
• Curami, Gambarini: Catalog of the Regia Aeronautica Freshmen (1923-1943).
• Dunning system - courage alone - publisher aircraft construction company
• Arena: Regia Aeronautica (1939-1943). - Ed. Personal Aviation
• Brogiotti, Gori: The Air Warfare in North Africa (1940/41 and 1942/43). - Ed. Stem Mucchi.
• Emiliani, jargon, vineyard: Aeronautica Militare.
• Thompson: Italian civil and military aircraft (1930–1945). - Ed. Aero Publishers

Web links

Commons : Savoia-Marchetti p.74  - Collection of images, videos and audio files

• Documentation of the SM.74 with pictures (Italian)
• Documentation of the SM.74 with pictures (Russian)