The Pratt & Whitney R-1830 Twin Wasp is an American air-cooled radial aircraft engine. It displaces 1.830 cu in (30,0 L) and the bore and stroke are both 5,5 in (140 mm). The design originated from 1929 experiments at Pratt & Whitney with two-row designs. Production began in 1932 and it was widely used in the 1930s. It was selected as the engine for both the four-engine Consolidated B-24 Liberator heavy bomber and the twin-engine Douglas DC-3 transport aircraft, two of the most produced aircraft. With a production run of 173.618 R-1830 units, this is the most produced aircraft engine in history. Power: 1.200 hp (890 kW) at 2.700 rpm for takeoff 700 hp (520 kW) at 2325 rpm cruise power at 13.120 ft (4.000 m) Specific power: 0,66 hp / cu in (30,03 kW / L) Compression ratio: 6,7:1 Specific fuel consumption: 295 g/(kW•h) Power-to-weight ratio: 0,96 hp / lb (1,58 kW / kg)