Looks like I screwed up on the second stage ratio.
It may be 2:75 to one. 

I scaled the drawing as the ring
gear being 3.5 inches and the sun gear being two inches
with gives me a ratio C/A of 1.75.

Machinery's Handbook says the ratio of driver to output shaft
is ring gear dia. (C) over sun gear dia. (A) plus one. The PT6 uses 
configuration Fig 10. in the chart for the second stage gear reduction.

D is the reduction ratio. C is the ring gear diameter and A is the sun 
gear diameter. 

Adding one gives a ratio of 2.75 to one which is ideal for our
purposes.

Does this look right to you guys?

Archie will you please rotate that secondary sun gear and note how many revs
the prop shaft makes? :-)


Paul Lamar
 
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