Douglas C-74 Globemaster - Design and Development

Design and Development

A contract worth more than $50 million was signed 25 June 1942, for 50 aircraft and one static test article. There were no XC- or YC-74 models produced.

The Douglas Aircraft Company began studies at their Santa Monica division towards developing a transport capable of fulfilling the needs of the U.S. military. The 'C-74 Project Group' used their company's DC-4 as a basis and concentrated on extending its capabilities. This new model number aircraft became the Douglas Model 415. Their design philosophy was to build a "no-frills" aircraft that was able to accommodate much of the Army's large equipment. This included tanks, 105 mm Howitzers with transporting vehicles, angle bulldozers, and smaller utility vehicles like jeeps.

This first flight of a C-74 occurred on 5 September 1945. The first C-74, 42-65402, was airborne just two months after it rolled off the assembly line. At the time of its first flight, the C-74 was the largest landplane to enter production, with a maximum weight of 172,000 lb (78,000 kg). It was able to carry 125 soldiers or 48,150 lb (21,840 kg) of cargo over a range of 3,400 mi (5,500 km). Perhaps the most notable feature of the C-74 was its cockpit arrangement with separate canopies over the pilot and copilot; the same arrangement was used for the XB-42 Mixmaster. This arrangement was unpopular with flight crews, however, and the aircraft were retrofitted with a more conventional arrangement. During the life of the aircraft, the radial engines were also upgraded to 3,250 hp (2,424 kW) Pratt & Whitney R-4360-49 engines. The aircraft was 31 feet longer than the C-54 Skymaster, and would be 24 feet longer than the proposed C-118 Liftmaster.

The second built, 42-65403, c/n 13914, crashed during flight testing on 5 August 1946 at Torrance, California when it lost a wing during an overload dive test. All four crew bailed out successfully. The fourth aircraft was diverted to a static test article at Wright Field, Ohio and virtually every component was tested to destruction between August 1946 and November 1948. This was done in order to determine the individual components' ability to withstand design loads. The fifth C-74 built was modified to be a prototype for the Douglas C-124 Globemaster II, which used the same wing as the C-74, but used a much larger fuselage. This newer aircraft quickly superseded the C-74 in service.

Douglas had every intention to adapt the aircraft into a civil airliner once the war ended. Pan American World Airways began negotiations in 1944. Their civilian model would be dubbed a DC-7 by Douglas (Model 415A) and the 'Clipper Type 9' by Pan American. Pan American intended to use the 108-passenger aircraft for international travel between New York, Rio de Janeiro, and other cities. The major difference between the military cargo aircraft and the civil airliner was the non-pressurized fuselage of the military C-74 and the pressurized DC-7. The passenger compartment was to be outfitted with a lounge bar, dining area and sleeping cabins for night flights. In June 1945, an order was placed for 26 DC-7 aircraft.

With the need for military aircraft greatly reduced by the end of World War II, the order for 50 military aircraft was canceled in January 1946 after production of only 14 aircraft. Only construction numbers 13913/133926 (AAF serials 42-65402/65415) were built. Construction numbers 13927/13962 (AAF serials 42-65416/65451) were canceled. This cancellation also ended plans to build an airliner version of the C-74 for the civilian market, as the limited military production run increased the cost per civilian aircraft to over $1,412,000 and Pan American canceled its order. Douglas then canceled the DC-7 designation. The DC-7 designation was later used for a completely different civilian airliner project in the early 1950s, having no relationship to the C-74.