Pratt &amp; Whitney R-1830 Twin WaspPratt &amp; Whitney R-1830 Twin Wasp Pratt & Whitney R-1830 Twin Wasp The Pratt & Whitney R-1830 Twin Wasp is an American air-cooled radial aircraft engine. It displaces and its bore and stroke are both . The design traces its history to 1929 experiments at Pratt & Whitney on twin-row designs. Production began in 1932 and it was widely used during the 1930s. It was selected as the power plant for both the four-engined Consolidated B-24 Liberator heavy bomber and the twin-engined Douglas DC-3 transport, two of the most-produced aircraft. The production run of 173,618 R-1830 examples makes it the most-produced aviation engine in  history. A further developed version, the R-2000, was produced starting in 1942. The R-2000 was "bored-out" to and had a number of other minor changes to improve fuel economy and allow it to run at higher power ratings on lower-octane fuel. The primary user of the R-2000 was the Douglas DC-4. Mostly retired today, the R-1830 is still used on Douglas DC-3 and various museum aircraft and warbirds seen at airshows. It is not manufactured anymore, but spares are still available and there is still a market for second-hand engines and parts. Pratt & Whitney R-1830 Twin Wasp