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Bernie,
The calculations for ratio of this kind is (ring
gear divided by sun gear). Using teeth numbers on the ring
gear divided by the teeth numbers on the sun gear; If you had 81 teeth on
the ring gear and 45 teeth on the sun gear i.e. (81/45=1.8).
Now if there were an intermediate gear as on the
planetary i.e. planetary gear - then the calculation for the planetary gear
teeth. is; ring gear minus sun gear divided by two i.e.( 81- 45)/2 = 18. As
a planetary runs with 3 gears, the prop runs the same way if the planetary
is held (in place) by the ring gear, the calculations are 1.85 +1 = 2.85:1
Ratio.
As the rotary runs anti-clockwise in out
orientation ( from the rear of the motor forward ) we have a clockwise prop
direction when using a planetary PSRU, with ring gear held. With the planet
housing held it would run anti-clockwise and would be 1.8:1
However we only have two gears (sprockets) in this
belt PSRU so ir must run in the direction
the motor runs i.e. anti-clockwise. The ratio is similar to the Ford planetary
which is 1.85:1.
I don't really know the numbers of the teeth on the
belt PSRU sprockets but used the numbers abovementioned as demonstration
only.
Hope that's clearer!?
George (down under)
"With the rotary, that would
mean an anti-clockwise prop rotation, view from
the cockpit, 1.8:1 is
right on the mark as compared to the Ford planetary
reduction which is
2.85:1 with clockwise rotation i.e. 1.85+1.
George (down under)."
I am totally confused about having two different ratios going from
clockwise prop rotation to anti-clockwise for the same engine speed and prop
speed. I am way out of my depth here. HELP!!!
Bernie
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