In 1945 Pan American World Airways requested a DC-7, a civilian version of the Douglas C-74 Globemaster military transport. Pan Am canceled their order shortly afterward; that DC-7 is unrelated to the later airliner.American Airlines revived the designation when they requested an aircraft that could fly the USA coast to coast non-stop in about eight hours. Robert Rummel (at the time head of engineering at TWA) stated that pilot union rules limiting flying time to eight hours per day influenced American"s request to Douglas. Douglas was reluctant to build the aircraft until American Airlines president C. R. Smith placed a firm order for 25 at a price of $40 million, thus covering Douglas" development costs. The DC-7 used the DC-4"s wing with a fuselage 3 feet longer than the DC-6. The engine was the eighteen-cylinder Wright R-3350 Turbo-Compound. The prototype flew in May 1953 and American received their first DC-7 in November, inaugurating the first non-stop east-coast-to-west-coast service in the country (optimistically scheduled just under the eight-hour limit for one crew) and forcing rival TWA to offer a similar service with its Super Constellations. Both aircraft frequently experienced in-flight engine failures, causing many flights to be diverted.The DC-7 was followed by the DC-7B with slightly greater power and, on some DC-7Bs (Pan Am and South African Airways), fuel tanks added in longer engine nacelles. South African Airways used this variant on their Johannesburg to London route. Pan Am"s DC-7Bs started flying transatlantic in summer 1955, scheduled 1 hr 45 min faster than the Super Stratocruiser from New York to London or Paris.