DevelopmentAfter World War II the major airlines of the United States realized that they had to have a modern airliner to serve the secondary, or feeder routes which supplemented the trunk systems. The Consolidated-Vultee and Martin companies, both wartime manufacturers of flying boats, competed for the market. Martin was actually in the lead at first, its Model 2-0-2 going into service in November 1947. But it was unpressurized, and there was also a structural deficiency which led to its withdrawal from service. United withdrew its support for a later variant, the Model 3-0-3, and even though T.W.A. and Eastern started service with the vastly improved (and pressurized) Model 4-0-4 in October 1951, most of the airlines turned to Consolidated Vultee, or Convair, as it became known, for its fine series of twin-engined airliners.
The Convair 240 first flew on 3 July 1947, by which time American Airlines had reduced its unprecedented order, placed in 1945, from 100 to 75. Altogether 553 Convair-Liners were sold, and they were popular in Europe, as well as in the U.S.
An Interesting FamilyDifferences in the various Convair models were not too easy to detect, as the table shows. The Model 340 was more popular than the basic Model 240, yet the Model 440, known as the Metropolitan, was more popular in Europe than at home. Later on, stimulated by the threat of the British Viscount, launched in the U.S.A. by enterprising airlines such as Capital and Continental, Convair produced successful conversions to turbine power of all models of the Convair-Liner.
Of these, the most popular was the Allison-powered Model 580, whose performance was superior to the Rolls-Royce-engined Models 600 and 640. In 1960, Allegheny Airlines put into service the Model 540, with British Napier Elands, and initiated a no-reservation commuter route; but Napier abruptly cancelled the project thus terminating a promising line of development.