smale@ncinternet.net wrote:
Several years ago I speculated about a lighter and stronger

reduction

unit.

This is near what I suggested. May I suggest an alternative ? On the

prop

ned of the shaft use a roller bearing all the prop loads but thrust

can

be

taken by the roller bearing. On the gear end use a tapered roller

bearing

taking the thrust of the prop plus locating the gears also with both

axial

and radial location . Since the shaft is located on only one end

axially,

the machining of the case is a noncritical item. I like one bearing

doing 2

jobs. The bearing can be reversed for pusher or tractor

applications.

This

makes for a less expensive job. Also the prop flange needs to have a

large

flat surface to transfer torque loads to wooden props. 6 inch

diameter

prop

flange is marginal. 8 inches @ 59 lb/ft bolt torque for the prop

bolts

is

more than adequate margin to carry the engine torque to the prop.

This

statement comes from the canard world. A 6 inch flange must be

frequently

checked to remain tight and if good wood or fiberglass is not used

the

wood

next to the prop will crush. An 8 inch will not crush.

smale@ncinternet.net

With one roller bearing and one tapered roller you are only opposing

thrust

in one direction. At flight idle in descent, your prop is producing net

drag

(negative thrust). What opposes this force?

Mark Wrathall
http://members.aon.at/wrathall/rotary/

I apologize for not making myself clear. 2 back to back bearings are needed.
having
the regular roller bearing at one end of the shaft and the taper roller
bearings at the other end solves
a host of problems including maching tolerances, expansion with heat and
sizing for load.
of course if an adjustment for preload of the taper roller bearings can be
done,usually by a compression tube
or a threaded end of the shaft the prior point becomes moot.

smale@ncinternet.net

 
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