Rolf,

Unlike the discussion above I will fix the ring gear and take power out of
the planetary cluster. The cluster would be attached on the prop shaft and
be supported front and back on bearings.  How would I calculate the load the
planetary gears will be seeing?  Total torque divided by the total tooth
contact area?   My engine will be putting out over 200 ft/lbs of torque at
max rpm. With a supported prop shaft  I believe the loads on the bearings
will be from torque transmission and the centrifugal force of the planets
themselves, right?

Also if I understand it correctly the gear line velocity is circumference
times rpm.   Calculating it from  the Bell sun gear in feet that is 377mm /
304.8mm = 1.24 ft.  1.24' X 8200 rpm = 10,168 ft per min?

Mistral's unit  at a 8000 designed redline with a slightly larger sun gear
would not be far off this figure.  You mentioned maximum line speeds of
5,000 ft/ min.  Is that figure for light duty gearboxes?

Thanks

Doug,



You have a fixed ring gear and rotating planets. Give me the dimensions
of all the gears, DP and pitch diameter and we can calculate it
together. As already mentioned, it is pitch diameter times pi times rpm
/12. Pitch diameter in inches, pitch line velocity in fpm.


Since the pitch line velocity of all gears is the same, one need to
calculate just one. Best is the ring gear and the output speed or
propeller speed. The gear ratio is thereby irrelevant. The torque load
is also the same on all gears. The load per tooth is divided by the
number of planets.


The bearing loads are essentially torque divided by radius. The
centrifugal force of the planets only need be considered on the planet
bearings, for the output shaft they cancel each other out through equal
spacing around the circumference.

Rolf

The centrifugal load of the rotating planet assemble is
contained by the ring gear and the separating tooth forces.

Paul Lamar ...No rotor no motor.

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