The Pratt & Whitney R-2800 Double Wasp is an eighteen-cylinder, two-row air-cooled radial engine. Developed from 1936, it became a major powerplant for American combat aircraft during the Second World War and for commercial transports afterwards. Its name distinguishes it from the smaller fourteen-cylinder Twin Wasp.[1]
Development and cooling
The engine was publicly displayed at the 1939 New York World's Fair. Its high output created a demanding cooling problem, addressed through thin, closely arranged fins machined directly from the cylinder-head forging. With water injection and turbo-supercharging in appropriate installations, the family exceeded one horsepower per cubic inch of displacement. This combination of compact dimensions and high output helped make it valuable for both fighters and larger aircraft.[2]
Wartime aircraft
The Double Wasp powered the Grumman F6F Hellcat, Vought F4U Corsair and Republic P-47 Thunderbolt. It also served in twin-engine aircraft. The R-2800-43 was fitted to Martin B-26 variants and the Curtiss C-46, showing that its role extended beyond single-engine fighters. Different installations used different engine versions and associated boosting equipment.[2]
Commercial development
After the war, the family powered the Douglas DC-6 and other airliners. The Smithsonian's commercial R-2800-CB16 has a gear-driven, single-stage, two-speed supercharger and a rating of 2,400 horsepower at 2,800 rpm. Its displacement is 45.9 litres, with a bore of 5.75 inches and a six-inch stroke. Applications of that version included the DC-6A and DC-6B, Martin 202A and 404, and Convair 340.[1]
Production legacy
Pratt & Whitney and its licensees manufactured more than 125,000 Double Wasps before production ended in 1960. Its transition from wartime combat aircraft to postwar airliners made it one of the defining large piston engines of that period. The surviving military and commercial examples also demonstrate the breadth of development within the family rather than a single universal rating.[1]