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The Savoia-Marchetti S.73 was an Italian three-engine airliner that flew in the 1930s and early 1940s. The aircraft entered service in March 1935 with a production run of 48 aircraft. Four were exported to Belgium for SABENA, while seven others were produced by SABCA. The main customer was the Italian airline ''Ala Littoria''. ==Design and development== The aircraft was developed in only four months, thanks to the use of the S.55 wing, combined with a much more conventional fuselage. Developed in parallel with a bomber version (the SM.81 ''Pipistrello'') the prototype S.73 first flew on 4 July 1934 from Cameri, with Adriano Bacula as test pilot. The prototype had a four-blade wooden propeller on the central engine, and two-blade wooden propellers on each wing engine. Later all aircraft were fitted with three-blade metal propellers. The S.73 was a mixed-construction (a skeleton of steel covered by wood and fabric for the fuselage, wood for the three-spar wing) monoplane with a braced tailplane and fixed undercarriage. There were two generators, one in each side of the fuselage; the batteries were 24 V and were rated at 90 A. The pilot and co-pilot were seated side-by-side in an enclosed cockpit, with a compartment for a radio operator and a mechanic. A passenger compartment could house 18 passengers in two rows. It had eight metallic fuel tanks, all in the wings, with a total capacity of 3,950 L (1,044 US gal). The prototype had French Gnome et Rhône Mistral Kfr engines, but further aircraft had 522 kW (700 hp) Piaggio P.X Stella, 574 kW (770 hp) Wright R-1820, 544 kW (730 hp) Walter Pegasus III MR2V and Alfa Romeo AR 125 and 126. Propellers were three-blade, aluminium-steel variable pitch (only adjustable on the ground). It could be used from small airports and had reliable handling controls, and was not too costly. The power on board was incremented with the latest types of engines, including Piaggio P.X, 522 kW (700 hp), Wright R-1820, 574 kW (770 hp), Walter Pegasus, 544 kW (730 hp), and Alfa AR.125/126. With the R-1820 engine it had 1,723 kW (2,310 hp) and a speed cruise/max of 270/340 km/h (170/210 mph), 1,000 km (620 mi) range, and 6,300 m (20,670 ft) ceiling. Interestingly, with the less powerful AR.126 it had 1,678 kW (2,250 hp), 345 km/h (214 mph), 1,000 km (621 mi) range, and 7,000 m (22,970 ft) ceiling. The SABCA license-produced aircraft had 671 kW (900 hp) Gnome-Rhône engines for a total of 2,013 kW (2,700 hp), comparable to the last models of S.79s or the CANT Z.1018. This aircraft was from the start a valid project, and few modifications were recommended by Regia Aeronautica. It was easy to fly, rugged, and easy to operate on the ground, including the ability to fly from short airfields and with bad terrain conditions, in spite of its relatively underpowered propulsion system and the lack of leading edge slats. Its mixed construction and fixed landing gear were its main shortcomings, when in the USA and Germany there were already full metallic aircraft. Some of these were faster or had better performance, but the S.73 was competitive with them for some years. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Savoia-Marchetti S.73」の詳細全文を読む スポンサード リンク
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