|DC4 N406WA rests between firebombing contracts at Ryan Field near Tucson, Arizona, USA|
|The designation DC4 was first used by Douglas when
developing the DC4E as a large, four-engined type to complement its
forthcoming DC3 design.
The DC4E emerged as a 40-passenger airliner with a fuselage of unusually wide cross-section for its day and a triple fin tail unit, similar to that later used by Lockheed on its Constellation.
This DC4 first flew on June 7, 1938, and was used by United Air Lines for some proving flights. But the type proved to be ahead of its time - it was complicated to maintain and uneconomical to operate. The sponsoring airlines, Eastern and United, decided to ask instead for a smaller and simpler derivative but before the definitive DC4 could enter service the outbreak of the Second World War meant production was channelled to the US Army Air Force and the type given the military designation C54.
The DC4 was truly innovative in many ways: its nosewheel landing gear was a novelty and it introduced a fuselage of constant cross-section, which allowed for easy stretching into the later DC6 and DC7. The original DC4 entered production in 1941 and more than 1,000 were ordered by the US services.
Nine military versions were produced but Douglas continued to develop the type in preparation for a return to airline services when peace returned. But the type's sales prospects were hit by the offloading of 500 wartime C54s, and R5D US Navy, machines on to the civil market.
Douglas built just 74 new build aircraft before production switched to the upgraded DC6. All were unpressurised, as were the DC4s built by Victory Aircraft, later Canadair, in Canada with Rolls-Royce Merlin engines. Canadair did build the pressurised DC4M Argonaut for BOAC.
The DC4 proved to have longevity, with humerousl airlines operating the type as a freighter and sprayer into the 21st century. Today, Buffalo Aiways of Canada remains as one of a handful of operators.