John,
Good question!
....
I suppose you could try for more planet gears with a smaller diameter with
the bigger sun gear ( reduced ratio) - but the speeds would then be the
killer.
Hope that helps!?
George (down under)

George,
Just to clarify things.
At the same output speed of the planetary, meaning at the same propeller
speed, the velocity of all the gears is the same when using  the same
size Ring gear.
It matters not what the ratio is and at what speed the engine turns. All
three gears, sun gear, the planet gears, and the ring gear have the same
pitch line velocity at the same output rpm, provided the diameter of the
ring gear is the same.

Rolf Pfeiffer

Rolf,
Point taken Rolf - how do you explain that a smaller gear rotates it's
diameter more times than the bigger gear at the same speed, perhaps 'duty
cycle' OR could we say that the circumference of the smaller gear repeats
itself faster than the bigger gear, proportional to the number of teeth.
However your right speed isn't the right word here, speed would be correct
if different sized wheels were independently driven by the same source, but
gears are interlocked so speed is the same but (duty)cycling is faster on
the smaller gear.

Then again if bearings were placed at the inside of the sun gear and the
outside of the ring gear, wouldn't the hearings themselves be running slower
than the smaller planet gear, maybe, maybe not, but the number of bearings
are less, the surface is less and the duty cycle is still greater - can you
shed some light on this for future reference.

I have probably been thinking 'speed' as an over simplification!
George ( down under)


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