Flightcrew of three, standard passenger seating for 44, max seating for 86. Most surviving aircraft configured as freighters.
Total DC-4 production comprised one DC-4E, 78 commercial DC-4s, 1162 military C54 Skymasters and 42 Canadair developed Merlin powered derivatives. Almost 80 remain in commercial service, most as freighters.
Piston engined airliner and freighter
The history of the DC-4 dates back to when United Airlines devised a requirement for a four engine long range airliner.
United looked to Douglas to fulfil the requirement, who devised the highly ambitious DC-4E (where the E stood for experimental). This four engined behemoth was flight tested in 1939. It was roughly three times the size of the DC-3 (its wingspan was 42.17m/138ft 3in, and length 29.76m/97ft 7in), had triple tail surfaces, tricycle undercarriage, was pressurised and potentially could fly nonstop from Chicago to San Francisco.
However all the ground breaking new technology on the DC-4E meant that it was costly, complex and had higher than anticipated operating costs, so Douglas thoroughly revised the design, resulting in the smaller and simpler definitive DC-4.
The new DC-4 was developed under the darkening clouds of WW2, and upon the USA's entry into war all DC-4s then on the production line were requisitioned for the US military. The result was that the first DC-4 flew for the first time on February 14 1942 in military markings (as the C-54 Skymaster). The DC-4 was found to admirably suit the USAAF's requirement for a long range cargo transport, and 1162 were built through the war years.
As was the case with the DC-3, the end of war meant that much of that number were surplus and sold to the world's airlines. Further to this Douglas built an additional 78 DC-4s to new orders. Over the years the survivors have been passed down to charter and freight airlines, and today small numbers survive in service as freighters.
Notable developments of the DC-4 include Aviation Trader's much modified Carvair freighter (described separately) while Canadair built a number with RollsRoyce Merlin engines and pressurised fuselages. The DC-4 also formed the basis for the larger DC-6 and DC-7 which are described separately (the DC-4 was the first airliner to introduce a circular section, constant diameter fuselage which made stretching the basic aircraft relatively simple).