Edward Klepeis wrote:

Dear Paul
      Take alook at this drive system it's made by Jerrie Barnett
of olivehurst Ca. It is made up now for the subaru eng but I
don't see why it could not be fitted to the rotary with the
changing of the mounting plate.
            Regards
            Ed

Sure looks cool. I hope that is not the diameter of
the output shaft I see sticking out of the front flange. There are high
bending loads on prop shafts due to gyroscopic forces. This requires
a shaft around two inches in diameter or larger.

It is obviously not a planetary.

The thing you have to keep in mind about any gear box
is gear mesh line length. The capacity of a set of gears to handle
torque is directly related to this line length. For a given width
of gears a planetary with six pinions has six times the line length
and therefore six times the torque capability.

A second big factor is the separating force between gears. When
gears mesh they tend to force themselves apart. This puts
high loads in the shaft bearings and in the gear box housing.
This adds weight. In a straight cut planetary these loads are
self contained by the ring gear. In the Ford case the gears are
helical so we need to deal with the resulting gear thrust loads.

A third factor is heat expansion of a spur gear box tends to
increase the back lash. In a planetary all the gears expand at
the same rate so the mesh never changes.

These factors are what makes planetary gears hard to beat on a torque

capacity

to weight ratio.  Most geared aircraft engines (with a few notable
exception) wound up with planetary gearing during and after WW II. This
includes all turbo prop engines.

Paul Lamar

-> Mr. Klepeis:

Super nice pictures, by chance do you have any more that show the engine
mount just a bit more? Thanks, Bob Boberrorusa.

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