Here is more about the Pratt and Whitney Wasp series engines, which were manufactured from 1925 through 1955 and powered such iconic aircraft as the DC-3/C-47, B-24, Grumman F6F Hellcat, P-47 Thunderbolt, DC-6, and B-36.
A total of 173,618 engines of the R-1830 Twin Wasp model were manufactured starting in 1932, and it remains in service today on vintage DC-3 aircraft.