Douglas DC-7 DC-7

The DC-7 was born of a scheduling constraint. American Airlines wanted an aircraft able to cross the United States nonstop in about eight hours, because the Civil Air Regulations then limited domestic flight crews to eight hours' flying in any 24-hour period. Douglas was reluctant to build it until American's president, C. R. Smith, ordered 25 aircraft for a total of $40 million, covering the development costs.

The wing comes from the DC-4 and DC-6, with the same span; the fuselage is 40 inches (100 cm) longer than the DC-6B's, through a plug inserted behind the wing. The decisive difference is the engines: four 18-cylinder Wright R-3350 Duplex-Cyclone Turbo-Compounds instead of the DC-6's Pratt & Whitney Double Wasps. The prototype flew in May 1953 and American received its first DC-7 in November, inaugurating the country's first nonstop coast-to-coast service — unrealistically scheduled just under the eight-hour limit — and forcing TWA to answer with its Super Constellations.

Those engines were also its undoing. Both types suffered frequent in-flight engine failures and many flights were diverted; the blame fell on the high power settings needed to keep to the schedules, which overheated and destroyed the power recovery turbines. Pratt & Whitney offered no effective larger engine apart from the poorly regarded Wasp Major, so Douglas turned to Wright: the Duplex-Cyclone had troubles of its own and they marked the DC-7's service record. Carriers operating both DC-6s and DC-7s usually retired the newer DC-7s first once jets arrived; some withdrew them after little more than five years.

105 DC-7s were built, all for US carriers, within a series total of 338 aircraft. The basic price of a new one was around $823,308 (£570,000).