17 April 2015

The Last Savoia-Marchetti Airliner

Italian aeronautical engineer Alessandro Marchetti
The Italian aircraft manufacturer Savoia had a history dating back to its founding in 1915 by Umberto Savoia and after the end of World War I, it merged with SIAI (Società Idrovolanti Alta Italia), another firm known for its seaplanes. The company became Savoia-Marchetti (sometimes also referred to as SIAI-Marchetti) when the designer Alessandro Marchetti became its chief engineer in 1922 and quickly became famous for his work on the S.55 twin-hull flying boat. Many of Marchetti's designs during the interwar period would set speed and endurance records in flight. Most of what Alessandro Marchetti is best known for, though, was his line of three-engined aircraft that began with the SM.79 Sparviero that first flew in 1934 as a fast eight-passenger transport capable of air racing. With the storm clouds of war fast coming to Europe, the Sparviero became Italy's primary bomber aircraft and one of the few Italian designs produced in significant quantities during the Second World War. The trimotor layout of the Sparviero set the pattern for a whole seriesof aircraft from Savoia-Marchetti, In 1934 the Italian airline Ala Litorria asked Marchetti for a modern long range airliner to which the SM.75 Marsupiale transport resulted. The Marsupiale had its inaugural revenue flights with Ala Littoria in 1938 with the Italian air arm, the Regia Aeronautica, taking interest in the aircraft as a transport. 

With war embroiling Europe in 1941, Marchetti began work on a four-engined derivative of the SM.75 that accommodated 18 passengers on long-range flights. It was a departure from Marchetti's land plane designs which were nearly all trimotors save the obscure SM.74 of which only three were built of this pre-war shoulder-wing airliner. The new aircraft was designated the SM.95 and a prototype and two pre-production examples were built in 1942. In addition, work began on a long-range bomber version designated SM.95B. The original design called for either 14- or 18-cylinder Piaggio radial engines, but wartime availability meant that Marchetti had to settle for a 9-cylinder Alfa Romeo engine producing 780 horsepower. Typical for Marchetti's designs of the period, the SM.95 was of mixed construction with a welded steel tube fuselage with metal alloy skin for the nsoe section and underside and fabric covering for the rest of the fuselage. The wings were plywood-skinned with three wood wing spars. The mixed-material construction likely also made the aircraft much lighter given the fact that lower-powered engines were used instead of what was originally planned. 

The prototype first flew on 8 May 1943 and was immediately impressed into transport service by the Luftwaffe. The fate of the first pre-production aircraft is unknown but is believed to have also been impressed into Luftwaffe service. The second pre-production aircraft was stretched and designed SM.95GA for "Grande Autonomia", featuring increased fuel capacity and revised cockpit instrumentation. Work on the SM.95 was soon hampered by the Italian Armistice in September 1943, but work was completed on the SM.95B bomber prototype with had the wings, engines, and empennage of the transport variant married to a new fuselage that was deepened to allow a bomb bay below the wing spar carry-through structure. A glazed nose accommodated the bombardier with the flight deck moved forward with defensive armament consisting of 12.7mm Breda guns in a turret aft of the flight deck and lateral positions in the aft fuselage and a ventral position forward of the bomb bay. No known photographs of the SM.95B are known to exist though the bomber prototype did fly at least once in 1945. 

Alitalia's SM.95 I-DALL "Marco Polo"
The third SM.95, the SM.95GA, finally made its first flight on 28 July 1945. It and the next aircraft built were put into military service with the Aeronautica Militare. The stretched fuselage of the SM.95GA became the production standard, the nine-foot fuselage stretch allowing for the carriage of 30 passengers in three-abreast seating. The military transports entered operational service starting in May 1946. The new Italian flag airline Alitalia had just been established in September 1946 and orders for six SM.95s were placed. The first two were I-DALJ "Cristoforo Colombo" and I-DALK "Amerigo Vespucci", delivered at the end of 1947 to Alitalia and promptly put into airline service. The production SM.95s had upgraded 9-cylinder Alfa Romeo radials that had increased power output from 780 horsepower on the wartime prototypes to 930 horsepower to accommodate the increased weights of the increased fuel and stretched fuselage. The balance of Alitalia's order, though, was completed with British Bristol Pegasus engines that delivered 1,000 horsepower- these aircraft were I-DALL "Marco Polo", I-DALM, I-DALN "Sebastiano Caboto" and I-DALO "Ugolino Vivaldi". The first two Alitalia SM.95s were subsequently re-engined with the more powerful Bristol Pegasus. It was I-DALN "Sebastiano Caboto" that inaugurated Alitalia's first postwar services to Great Britain on 3 April 1948. 

One of LATI's three SM.95s, I-LATI "San Francesco"
Another Italian airline also ordered the SM.95- Linee Aeree Transcontinentali Italiane (LATI), which had operated air services between Italy and South America prior to the Second World War. LATI had ordered three SM.95s which were all delivered by 1949- I-LAIT "San Antonio", I-LATI "San Francesco" and I-LITA "San Cristoforo". When LATI ceased operations in 1950, their three SM.95s were assumed by Alitalia. Interestingly the only other airline operator of the SM.95 was SAIDE of Egypt, which operated three aircraft to connect Cairo with European capitals. While Alitalia configured its aircraft for 20 passengers, LATI flew shorter routes than Alitalia and configured its aircraft for 26 passengers but SAIDE operated even shorter routes and packed in 38 passengers on their aircraft. Both LATI and SAIDE's aircraft were powered not by the Pegasus radial engine but Pratt & Whitney R-1830 Twin Wasp 14-cylinder engines producing 1,200 horsepower. 

Only a total of 12 production SM.95s operated commercial services out of a total of 20 airframes built including the prototypes. The mixed material construction wasn't terribly robust with the rigors of scheduled passenger services and lacking pressurization also limited their usefulness. Compared to the Douglas DC-4 and the Lockheed L-749 Constellation of the time, the SM.95 was an outdated design. The last passenger flights took place in 1950 less than a year after the last production aircraft was completed. 

Interestingly, there was a plan by the Regia Aeronautica called "Operation S" prior to the 1943 armistice that would have used a modified SM.95GA to fly at very long ranges to bomb New York City. Benito Mussolini, however, would only allow the mission to drop propaganda leaflets as he didn't want to alienate the large population of Italian-Americans in the city. The mission was under preparation when the 1943 armistice occurred. 

Source: Air International "Plane Facts" Volume 10 Number 2, February 1976. Photos: Wikipedia, Alitalia, Air International

1 comment:

  1. 14 people were killed, among them a whole family on January on a "Ugolino Vivaldi" plane from London to Rome. Eerily, Ugolino Vivaldi was the first Italian pilot killed in an air accident, falling from his plane in 1910. Even more eerily, the pilot killed in the crash survived exactly the same type of incident with lightning hitting the wing area and igniting the plane, but successfully crash landed it near Lyon a year earlier!!