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 Kaman's K-125 synchropter, which used a Boeing T50 turboshaft engine to power it on 11 December 1951. Compared to turbofans, turboprops are most efficient at flight speeds below 725 km/h (450 mph; 390 knots) because the jet velocity of the propeller (and exhaust) is relatively low. Modern turboprop airliners operate at nearly the same speed as small regional jet airliners but burn two-thirds of the fuel per passenger. However, compared to a turbojet (which can fly at high altitude for enhanced speed and fuel efficiency) a propeller aircraft has a lower ceiling. The most common application of turboprop engines in