Douglas DC-6

While the DC-3's and DC-4's civilian careers were interrupted by WW2, the opposite applies to the DC-6, which started off in response to a military airlift requirement, and went on to become Douglas' most successful four engined piston airliner. During the latter stages of WW2 Douglas began work on a developed DC-4 for postwar commercial use. However the improved DC-4 (which would feature a 2.11m/6ft 11in fuselage stretch and P&W R-2800 Double Wasp engines) soon attracted the attention of the US Army Air Force, which devised a requirement which the new transport was developed against. A prototype was built, designated XC-112, but it did not fly until February 15 1946, by which time the war was over and the military requirement no longer stood. Instead Douglas continued development of the type as a long range airliner, resulting in the DC-6. The XC-112 served as the prototype for the DC-6 program. US airlines had already shown strong interest in the new transport, with launch orders for the DC-6 placed in September 1944. The first production DC-6 first flew in June 1946 and service entry, with United Air Lines, occurred on April 27 1947. However early service was not smooth with the fleet grounded for four months from November that year after two internal fuselage fires in flight, one being fatal, caused by fuel venting entering the cabin heater ram air intake. The availability of the more powerful R-2800 engines with water/methanol injection prompted Douglas to develop the further stretched DC-6A Liftmaster freighter (first flight September 29 1949) and the equivalent passenger DC-6B (first flight February 2 1951). The DC-6C, the last DC-6 model to be developed, was a convertible passenger/freight version of the DC-6A. Meanwhile renewed military interest in the DC-6 was sparked by the Korean War, with the result that large numbers of USAF C-118s and USN R6D-1s were built. Many of these were later sold to civilian operators.

The backbone of this section is from the The International Directory of Civil Aircraft by Gerard Frawley and used with permission. To get your own copy of the book click here.