DOUGLAS DC-4E WIND TUNNEL MODEL
The parallel stories of the Douglas DC-4E and its wind tunnel model are both of interest.
Designed between 1935 and 1937 to United Air Lines specifications, the Douglas DC-4E (‘E’ for experimental) was first flown on 7 June 1938, more than six months before the Boeing 307. As such, it was the world’s first pressurized airliner, much larger and more luxurious than its successor, the DC-4/C-54. It also had a completely different airframe than the DC-4, and preceded it by nearly four years. Ultimately deemed too expensive and too complex to operate profitably, with its cabin air conditioning, full pressurization and hydraulic controls, the entire program was canceled after only 500 hours of flight.
The one and only DC-4E was purchased on 29 September 1939 by Dai Nippon Koku KK (which later became Japan Air Lines) allegedly as their flagship VIP transport. In reality, the DC-4E was disassembled, reverse-engineered and used as the development template for heavy, four-engine bombers. As an example, the entire wing assembly of Nakajima’s G5N1 ‘Shinzan’ is an exact copy of the DC-4E’s wing assembly. Japan had not built any heavy, four-engine aircraft prior to this and, by some estimates, the DC-4E gave them a two-year head start. It also gave Japan the potential capability of bombing the U.S.
The DC-4E made its trip to Japan by boat, accompanied by a team of Douglas technicians and all engineering data files. Also on board was the sole DC-4E wind tunnel model, which showed evidence of the airplane’s development. For example, when United Air Lines President William Patterson requested an increase in capacity from 46 to 52 passengers, back in 1937, a fuselage plug was added ahead of the wing box. That fuselage plug still exists on the wind tunnel model today.
Rather than custom-build a DC-4E display model, Dai Nippon Koku simply painted up the wind tunnel model in their commercial livery scheme – emerald green with a silver cheat line – and suspended it at their Tokyo headquarters, to further the deception. In the spring of 1940, a news bulletin describing the crash of the DC-4E in the Bay of Tokyo was circulated, as a means of explaining the disappearance of Nippon’s flagship airliner.
The wind tunnel model somehow managed to survive the intense fire bombing of Tokyo and resurfaced fourteen years later, when it was recognized at the back of a Japan Air Lines hangar by a Douglas technician, who was training Japanese DC-7 mechanics. This information was passed along to Donald W. Douglas, who arranged to have the model returned to Santa Monica for the Douglas museum, then in the planning stages. The Dai Nippon Koku paint was removed for the most part, though some work still needs to be done in that area, to restore the model back to its original condition. Interestingly, the side instrumentation access panel was taken off during the paint removal process. Its 1939 emerald green paint, silver cheat line and one metallic blue window are still present.