Area of application
The Pratt & Whitney R-1830 Twin Wasp (TWC3) was an American engine that was very widely used in various aircraft models in the 1930s and 1940s. In Sweden the engine was used in aircraft types SAAB-B17, SAAB-B18A, J 9 Seversky, FFVS J 22, TP 47 Catalina and TP 79 (Douglas DC 3).
In 1940 there were orders with P&W in the USA for a large number of TWC3 engines for the B17 and B18A aircraft. Exports to Sweden were hampered because of the war situation and negotiations for licensed production of the engines were started. In the autumn of 1940 the USA imposed export bans and Sweden could not obtain a license to manufacture either. It was then decided to copy the engine and start production at Svenska Flygmotor AB in Trollhättan. There were many problems and delays. The first Swedish-produced engines were only delivered at the end of 1943 and were given the designation STWC3.
One of the subcontractors was Bolinder-Munktell who manufactured crankcases, pre-compressors and inlet valves for the engine and also assembled complete engines in its bomb-protected mountain workshop in Ärna between Eskilstuna and Torshälla. A total of 135 STWC3 engines were assembled in Eskilstuna.
In total, worldwide production was 173,618 units of the R-1830 engine, which makes it the most produced aircraft engine even today.
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Pratt & Whitney R-1830
Engine 14-cylinder, 2-row air-cooled radial engine
Engine output 1 200 hp, 2 700 r/min
Cylinder bore 139,7 mm
Stroke 139,7 mm
Displacement 30 dm³
Compression ratio 6,7:1
Weight 567 kg
Serial number 828