I'm by no means an M-14 expert, but
spend quite a bit of time behind a geared 1340 Pratt & Whitney. Just wanted
to verify a couple of things on reduction gearing and hopefully an M-14 expert
may reply. The reduction on the geared 1340 is 3:2 or .667, similar to the M-14,
I believe. But the gearing reduces the propeller RPM, not the crank speed i.e.
the crankshaft makes 3 revolutions while the propeller makes just 2. This
allows the engine to turn a much larger propeller slower (gives a lot more
thrust and a heck of a lot less noise on the 1340). While I have never had
the nose case off of an M-14 I believe it has a similar type planetary
reduction system which reduces the prop RPM similar to the Pratt. This lets it
turn that big 3-blader so well. Hope this helps.
© Dr. Günther
Email Guenther Eichhorn