United Airlines had approached Douglas in 1935 to start development of the DC‑4. In 1936, it became a cooperative project among five airlines (UAL, EAL, TWA, PAA, and AA).
From the beginning, the intention was to make the DC‑4, “Skymaster,” a different plane. It took advantage of the requirements generated by the success of the DC‑3. The public wanted larger and faster equipment, so Douglas invested three million dollars in the DC‑4, their first four engine, 42 passenger (30 berth), commercial airliner.
Arthur Raymond said, “We designed the first DC‑4 by committee. Before this, we worked with one airline, like American or TWA. Five airlines were in on the DC‑4 design, and everyone wanted something special on their version. The crowning blow came when they all said it had to fit in the DC‑3 hangar. This meant we had to put five tails on it. We had to take the control surface area under engine out conditions, and spread it over the five tails (three above and two below) to squeeze it in the DC‑3 hangar. That was its downfall. We had a terrible time working out the stability and getting it licensed.”
In May 1939, following its first flight and a year of factory testing, United Airlines took tentative delivery of the experimental DC‑4. For three weeks they tested it and found it met some but not all the specifications. They decided not to purchase it. The other airlines followed United’s lead, and as previously agreed, each paid Douglas Aircraft $91,250 to cover partial engineering and development costs.
“When we got it to the point of flying,” said Raymond, “it had gained so much weight (65,000 pounds) and was so ungainly that Doug junked the whole thing. He knew it was a lemon. Then we redesigned it the way we wanted it, with a single tail, not so heavy, and it was a success.”
“We sold the original DC‑4 prototype to Japan and it later crashed with some high ranking military officers aboard into Tokyo Bay. We like to think that helped hasten the conclusion of the war. We then called it the DC‑4E for ‘Extinct.’”
The Japanese did use the DC‑4 prototype to fashion their own version of a four engine bomber, and transport, the G5N‑2 and the G5N‑L, which the Allies designated “Liz.”Modifications included changes in the wing spar and a slight extension in the nose. Both aircraft were equally unsuccessful.
Douglas started the second DC‑4 version in 1940. United Airlines was still interested in a redesigned DC‑4, so Douglas modified and trimmed the original design down to 48,000 pounds.
World War II interrupted its civilian destiny. On the production line the 40 machines ordered by the airlines, and already in airline livery became the C‑54, military transport, and never delivered to the airlines.
“The original design of the DC‑4 was to have included a pressurized cabin but we delayed that until we grew the fuselage into the DC‑6,” said Malcolm Oleson.
(Note: the aerodynamic shape of the DC‑4 wing and fuselage is identical to the later DC‑6 and DC‑7.)The C‑54 became the Army’s long range transport during the war and proved transoceanic air service was practical by land based planes. Between 1941 and 1945, C‑54s successfully completed 79,642 transoceanic flights with only three ditching, one of which was a test. Douglas manufactured 1,162 DC‑4s.