The Pratt & Whitney R-1830 Twin Wasp is a fourteen-cylinder air-cooled radial arranged in two rows of seven cylinders. It became one of the principal American aircraft engines of the 1930s and Second World War, powering transports, bombers, flying boats and fighters. The nominal displacement is 1,830 cubic inches.[1]
Introduction and power growth
The US Air Force museum dates introduction to 1932, with early versions producing 775 or 825 horsepower at 2,400 rpm depending on compression ratio. Improved fuel allowed output to rise first to 1,000 and then to 1,200 horsepower. The need for high-octane gasoline was important to this development: the engine's potential depended on the fuel available as well as mechanical changes.[1]
Two-row development
The Twin Wasp extended Pratt & Whitney's radial range beyond the capability of its earlier single-row designs. The Smithsonian records certification in 1933 and subsequent work with single-stage, two-stage and turbo-supercharging arrangements. Its account also notes that fuel requirements could be a disadvantage for airlines, contributing to development of the larger R-2180 Twin Wasp.[2]
Military applications
Major installations included the Consolidated B-24 Liberator, Douglas C-47 and Grumman F4F-4 Wildcat. British-operated aircraft included Catalinas, Sunderland Vs, Marylands and Beauforts. The R-1830-90C was especially associated with the C-47; the museum lists a 1,200-horsepower maximum rating and a weight of 1,467 pounds for that version.[1]
Production and variants
Wartime production involved firms beyond the original designer. The Smithsonian preserves a cutaway R-1830-43 manufactured by Buick, part of General Motors. That variant powered several B-24 models and related transports, including the C-87. The preserved engine illustrates both the scale of the wartime manufacturing effort and the way one basic engine family was adapted to bomber and cargo-aircraft installations.[2]