Originally Posted by
Chris Scott
Hi Marcus,
You haven't stated your source for a 16:9 engine-to-prop reduction-ratio. Mine, from Janes for 1957/8, giving an engine : prop ratio of 8:3 (i.e., 16:6), would give a prop RPM only two-thirds of yours.
Pratt and Whitney manufactured a whole bunch of different radial engines with 2800 cubic inches of displacement. Some models are pretty dissimilar with no interchangeable parts The engines installed on the Convair were almost certainly either CA series or CB series engines, both of which had a drive ratio of 9:20 or .45:1 Reference is the Type Certificate Data Shees for the respective engine series.