Jim Mantyla wrote:

Hello Group,(paul?)

Regarding the observations with my drive design, I do agree with the taper
idea and did consider it, but found that the skill required to match the
tapers properly might be beyond the average person.My testing to date has
shown no troubles in this area.It is a lot easier to match two diameters
with accuracy.

One of the considerations in designing my drive was to make it as short as
what could be considered to be reasonable.Should someone wish to increase
the bearing spacing it would be a simple thing to do.For the horsepower and
prop sizes i am using the bearing spacing has proven to be adequate.This was
designed in conjunction with the SKF engineering staff.

Hope this gives some insight ito my thought proccess when I was designing
this drive.

Jim Mantyla

I took a closer look and I would not fly it with a rotary engine like it is. 
Sorry to be so blunt Jim but that is how I see it.
The threads from the large bolt holding the flange on and the diameter 
of the shaft extension in that area lead to the possibility of the prop 
departing the engine. The highest torque and bending load on
the whole shaft is right in that area yet that is the weakest part of the
original shaft design. It does not pay to fool around there.

Send the shaft out and have a taper and provisions for a flange retaining
nut machined on the shaft. Damn the cost. The resulting taper would be
similar but larger in size than the one holding the flywheel on the e-shaft
in the Mazda rotary engine.

Those internal threads act like the start of a fatigue crack and it
is nearly impossible to magna flux down in that hole. One would probably 
have to have it X-rayed.

Here are the two drawings. The original and my suggested modifications.
there is no increase in length of the PSRU but there is more distance
between the bearings. I don't think those SKF engineers understood the
prop gyro bending forces on a prop shaft subjected to one radian per 
second or more precession.
 
The rest of it looks OK. 

Paul Lamar
 
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