When Wright engineers began R-3350 development in January 1936 they
incorporated as many of the established Cyclone engine attributes as possible
into the new engine following the design and construction details of their
successful R-2600. The R-3350 was an air-cooled, duplex engine that had
18 cylinders with two radial rings of nine cylinders positioned around
the crankshaft. (Author/Pima ASM)