Douglas DC-4E

The design originated in 1935 from a requirement by United Air Lines. The goal was to develop a much larger and more sophisticated replacement for the DC-3 before the first DC-3 had even flown. Such was the initial interest from other airlines, that American Airlines, Eastern Air Lines, Pan American Airways and Transcontinental and Western Air (TWA) joined United, providing $100,000 each toward the cost of developing the new aircraft. As cost and complexity rose, Pan American and TWA withdrew their funds in favor of the Boeing 307 Stratoliner, which was anticipated to be less costly. ==Operational history==

The prototype (NX18100, s/n 1601) first flew, without incident, on June 7, 1938 from Clover Field in Santa Monica, California, piloted by Carl Cover. Testing issues, however, delayed the Approved Type Certificate until May 5, 1939. It was used by United Air Lines for in-service evaluation during 1939. On June 9, 1939, when the DC-4 was in Dayton, Ohio, along with Carl Cover, Orville Wright was a passenger on a flight over the city. Although the aircraft was relatively trouble-free, the complex systems proved to be expensive to maintain and performance was below expectations, especially with an increase in seating to 52 and gross weight to . ==Operators==

; • Imperial Japanese Airways ; • United Airlines ==Specifications (Douglas DC-4E)==