Douglas DC-6 DC-6

The baseline DC-6 is a pressurised DC-4, stretched by 2.0 m and re-engined with four 18-cylinder Pratt & Whitney R-2800 Double Wasp radials, an engine the Second World War had refined thoroughly in combat aircraft. It flew on 29 June 1946 and Douglas kept the first aircraft for testing; the first airline deliveries — to American Airlines and United Airlines — took place on 24 November 1946.

It was built in two versions distinguished by range: the domestic DC-6-1156, seating 53 to 68 with 2,400 hp (1,800 kW) R-2800-CA15 engines, and the trans-ocean DC-6-1159, seating 48 to 64, with extra crew, fuel capacity increased to 4,722 US gallons (17,870 L), take-off weight raised to 97,200 lb (44,100 kg) and R-2800-CB16 engines.

Its career began badly. A series of in-flight fires — one of which caused the fatal crash of United Airlines Flight 608 — grounded the whole fleet in 1947. The cause was a fuel tank vent next to the cabin cooling turbine intake; every DC-6 was modified and the fleet returned to service after four months on the ground.

By April 1949 United, American, Delta, National and Braniff were flying DC-6s within the United States; United took them to Hawaii, Braniff to Rio de Janeiro and Panagra flew Miami-Buenos Aires, while KLM, SAS and Sabena crossed the Atlantic. BCPA linked Sydney with Vancouver and Philippine flew Manila to London and to San Francisco. A new DC-6 cost between £210,000 and £230,000 in 1946-47 and £310,000 by 1951; by 1960 a used one was around £175,000.