When I first saw Bud Warren's centrifugal clutch something  in
 the back of mind was trying to tell me he did not build it.
 The parts looked too slick and too finished to be custom made.

 I think I figured it out. They are stock parts out of Center Force
 clutches. Of course Bud never talked about that.

 http://www.centerforce.com/clutches.tpl?subsection=clutchtypes#

 Ironically I have one in my my RX8. I love it. It works great.

 This will solve the gear box chatter problem if set up properly.

 The question is how thick must be the flywheel? That will
 affect the over all weight.

 BTW I don't think it was the cause of Bud's fatal crash.


 Paul Lamar


Confusing pics though....  it seems you've got a few pics of
subaru/eggenstein's --  did they use
bud's drives?

 William Mason

Yes. He sold several.

--------------------------------------------------------------
Center Force also make a compatible aluminum flywheel for the 13B.

Paul Lamar


   There is another way to eliminate the gear chatter.  Throw the
gear box
  out.  Mount an alternator on the eshaft,  a prop on a direct drive
electric
  motor and all the drive line problems go away. Like a diesel electric
  locomotive. Any remaining problems can be handled in the software of
the
  controller. The option of adding batteries would exist if you want
to be
  way trendy.

  Murry I Rozansky

  As I said many times before on here electric drives of that type
suck big
time.  This is a recording :)

  The motor is 85% times the alternator is 85% the over all effciency is
  .85 times .85 = .72% over all. You are wasting 30% of your fuel.
  Locomotives do it for one reason and one reason only. High starting
  torque.

  Paul Lamar

  Hi Paul,  was meant to be a humorous.  If there are no torque
reversals,
it must be drive line resonance.  What else could it be? Has any one
tried
running with a solid shaft connection, no flexible element?  A soft
enough
coupling should work. A disconnect will of course and a Bud type is
simple
and compact enough to fit. If it does not cause operational or safety
problems to idle the engine above the chatter speed, why is  gear
chatter
getting so much attention?  Some of the couplings have a surprising
amount
of wind up at their rated torque.  I think some were over 10 degrees.
If
chatter at idle, when there are very low loads does not damage anything,
maybe the problem is of a more psychological or esthetic nature.
Tracy's
damper design just seems overly massive to me.



  Murry I Rozansky

Tracy's rubber bushings are so stiff for all practical purposes it is
locked
up. I suspect there would be no difference. Same gear box chatter.
It is not unique to the rotary either. That is why Bud attempted to deal
with it.  You have this huge flywheel on the out put end of the gear
box called
a prop :) Could be caused by a combination of many things. Slop in the
splines or gear back lash. You will never get away from some wear or
slop.
Molt Taylor was the first to deal with it by using a centrifugal
coupling.
It was noticed by Allison on the shaft drive P39 back in the 1930's.


The down side would be prop wind milling which would increase the power
off stall speed. In fact that could have killed Bud if he did not
realize it. It was a low altitude stall spin crash. You must land faster
with a wind milling prop. If you do a wing over to turn around the
prop might stop. Then again if it did not stop you would lose
a lot of altitude.

--------------------------------------------------------------

This last chart shows for certain pitch ranges the wind milling
prop is less drag than a fixed pitch prop. It may turn out
to be that way if you have a fixed pitch cruise or top speed prop.

I think one must test for this at altitude where is is possible
to restart the engine or make the runway regardless.
Since the prop must drive the gear box backwards wind milling may
not occur using Tracy's gear box.

Slipping is a similar high drag situation so by all means practice
slipping on final. IMHO I would never try to make a conventional
approach with a dead engine unless I was so far down wind and so low
I had no other choice. In my opinion slipping is under rated.

Paul Lamar


I believe that Paul is correct is suggesting a free-wheeling windmilling
prop is relatively low drag. Some of the X-plane users could probably
give us a good analysis of the drag. The charts shown presume the prop
is turning an engine, which represents a considerable load, increasing
the drag. A lot of the drag from a loaded windmilling prop comes from
spoiling the airflow over the wing in the wake of the prop.

Victor Roberts



Hi all, I just had a thought.  The low rpm chatter may be from the prop
going forward when the mass of Tracy's damper is trying to go the other
way. Chatter is typical when the gear teeth change sides through the
clearance between the teeth in mesh.  Taking as much rotational inertia out
of the damper plate or going to a much lower flywheel effect coupler may do
the trick. Is there a simple way to test for the natural freq. of the
prop-gearbox-damper system without it being connected to the engine? That
will be the chatter freq. that can be excited by firing impulses even if
there are no torque reversals.


Murry I Rozansky

I want to emphasize for the new guys that chatter is not a real show
stopper and we have learned to idle above the chatter RPM.
There are some certified airplanes out there where you cannot
run the engine in certain RPM ranges due to prop vibrations.

Paul Lamar