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. Variants R-1830-1: R-1830-9: , R-1830-11: R-1830-13: , , R-1830-17: R-1830-21: R-1830-25: R-1830-33: R-1830-35: Fitted with GE B-2 turbosupercharger R-1830-41: Fitted with GE B-2 turbosupercharger R-1830-43: R-1830-45: R-1830-49: R-1830-64: , R-1830-65: R-1830-66: , , R-1830-72: R-1830-75: R-1830-76: R-1830-82: R-1830-86: R-1830-88: R-1830-90: R-1830-90-B: R-1830-92: R-1830-94: R-1830-S1C3-G: , R-1830-S3C4-G: R-1830-S6C3-G: R-1830-SC-G: R-1830-SC2-G: , R-1830-SC3-G: same engine built in Sweden as STWC-3G by SFA company for Swedish J 22, B 17 and B 18. Applications DAP Beaufort – Australian-built variants of Bristol Beaufort Bloch MB.176 Boeing XB-15 Budd RB Conestoga Burnelli CBY-3 CAC Boomerang – Australian "emergency fighter" CAC Woomera Consolidated B-24 Liberator Consolidated PBY Catalina Consolidated PB2Y Coronado Consolidated PB4Y Privateer Curtiss P-36 Hawk Douglas C-47 Skytrain Douglas DC-3 Douglas DB-7 – early variants only Douglas TBD Devastator FFVS J 22 – "emergency fighter"; built in-house by the Swedish Air Force Grumman F4F Wildcat I.Ae. 24 Calquin Laird-Turner Meteor LTR-14 Lioré et Olivier LeO 453 Lockheed Model 18 Lodestar Lisunov Li-3 – a Yugoslav version of the Lisunov Li-2 Martin Maryland Martin M-130 Republic P-43 Lancer Saab 17 Saab 18 Short Sunderland V Seversky P-35 – Finnish "emergency fighter" Vickers Wellington IV VL Myrsky Vultee P-66 Vanguard Engines on display Model R-1830-65 on display at the Museo Nacional de Aeronautica, Buenos Aires, Argentina Model R-1830-86 on display at the