Gordon,
I was under the impression the bearings won't hold up in direct drive and
I've always thought along the lines of PSRU with dampening for the torque
pulses - that's how it's been with the two rotor and Tracy has done a good
job with the damper design, simple and effective.
The single has greater torque reversals that a 4 cylinder  so may require a
different damper, perhaps something like the BMW damper.
I'm unfamiliar with the long drive shaft resonance problems, but with a good
design that may eliminated or dampened out ?
Just some thoughts on the subject as I don't think the single rotor has been
fully utilized to date.
There area few of us still working on regardless!
George ( down under)



There's no reason the bearings won't hold up spinning a small fan direct
drive. Spinning a big prop is a different matter.


That previous discussion you are alluding to about a direct drive 13B
engine, was where I proposed supercharging the engine to make the same
power at 3500 rpm as it makes at 6000 with a redrive. That's where the
problem with the bearings comes in because the much higher combustion
pressures at low rpm would be hard on the bearings.

With a fan engine you have a completely different scenario. You are
spinning the engine at 6000 rpm or more just like you would in a car and
driving a little fan with small mass moment.

When you asked about the single-rotor engine in the mini-imp I assumed
you were thinking ducted fan, in which case I think it would work just
fine. But if you are thinking propeller and long driveshaft, Paul is
right, it's going to run into vibration problems big time.


Regards,

Gordon.




George ( down under) is referring to the thrust bearings
in the 13B. Perry Mick destroyed a set after a few years
with his direct drive set up. They are not designed to withstand
continuous thrust.

Charley Airseman did extensive experimentation with a shaft
direct drive and eventually abandoned it and went with a very large
diameter composite prop extension.

Paul Lamar ...No rotor no motor.

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