When the world's first jet airliner, the De Havilland Comet, was introduced in 1949, Douglas held a commanding position in the aircraft market. Although Boeing had pointed the way to the modern ... all-metal airliner in 1933 with the 247, it was Douglas that, more than any other company, made the promise a reality. Douglas produced a succession of piston-engined commercial aircraft through the 1930s, 1940s and 1950s: 138 DC-2s, 10,928 DC-3s (mostly for military service in World War II), 1453 DC-4s, 537 DC-6s and 226 DC-7s.
Given the success of their designs, Douglas took the view that there was no reason to rush into anything new, as did their rivals Lockheed and Convair. Most air transport manufacturers expected that there would be a gradual switch, from piston engines to turbines and that it would be to the more fuel-efficient turboprop engines rather than pure jets.
In contrast, Boeing took the bold step of starting to plan a pure jet airliner as early as 1949. Boeing's military arm had gained extensive experience with large, long-range jets through the B-47 Stratojet (first flight 1947) and the B-52 Stratofortress (1952). With thousands of their big jet bombers on order or in service, Boeing had developed a close relationship with the U.S. Air Force Strategic Air Command (SAC), and could count on having preference when the time came to replace SAC's fleet of piston-engined KC-97 Stratotankers. For Boeing, this was an opportunity to build a jet aircraft for air-to-air refueling that could be turned into a commercial transport.
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