Pratt & Whitney initiated design and development of the R-2800 Double Wasp, America’s first 18-cylinder radial engine, in 1936. With water injection and turbo-supercharging, the R-2800 produced more than 46 kW/L (1-horsepower/cubic inch). Even though smaller, it was more powerful than the Gnome-Rhone 18L, the world’s only other modern eighteen cylinder engine, but required advanced cooling fins to dissipate the accompanying heat. During World War II, it powered the Grumman F6F Hellcat, Vought F4U Corsair, Republic P-47 Thunderbolt, and other combat aircraft. After the War, it powered the Douglas DC-6 and other airliners.
This R-2800-CB-16 was a commercial engine powered the Douglas DC-6A/-6B, Martin 202A, Martin 404, and Convair 340. By the time production ended in 1960, more than 125,000 R-2800s had been manufactured by Pratt & Whitney and its licensees, one of the largest production runs of any single aircraft engine model.