History of Cubana de Aviación of its fleet, opting to replace its long-range piston-prop Super Constellations with turboprop aircraft, and to expand its existing Vickers Viscount turboprop fleet in the immediate future. Cubana placed orders for four long-range Bristol Britannia (Model 318) and four Vickers Super Viscount (VV-818) aircraft, all turboprops, for its international services (which included Madrid, New York, Mexico City, Miami, Montego Bay, Nassau, Port-au-Prince), and for some of its domestic routes (Camagüey, Santiago de Cuba, Varadero). The first Bristol Britannia (CU-T668) was delivered in late 1958, and was placed in service in the airline's New York route. The new Britannias and Super
Turboprop in the experimental Consolidated Vultee XP-81. The XP-81 first flew in December 1945, the first aircraft to use a combination of turboprop and turbojet power. The technology of the Allison's earlier T38 design evolved into the Allison T56, with quartets of the T56s being used to power the Lockheed Electra airliner, its military maritime patrol derivative the P-3 Orion, and the widely produced C-130 Hercules military transport aircraft. One of the most produced turboprop engines used in civil aviation is the Pratt & Whitney Canada PT6 engine. The first turbine-powered, shaft-driven helicopter was the Kaman K-225, a development of Charles