I do not know all of the restrictions to the application of the fluid
   coupling, but if you are looking for something that will absorb
   "chatter"
   and does not generate a lot of heat, have you considered the Dodge
   coupling
   that Molt Taylor used in the IMP and mini-IMP?

   http://www.dodge-pt.com/products/pt_components/flexidyne/flexidyne.html

   I had heard at one time the company was not "aviation" friendly
due to   liability issues.

   Just a thought.

   K. Carl Milbrodt PE

   As far as I can figure it out they are limited to 1800 RPM
   and they are very heavy. We need something that will survive 7500
RPM

   Paul Lamar
   --

   A Flexadyne is a centrifugal clutch.
   Bud Warren used a centrifugal clutch on his gear drives. A single
plate   with weights with ramps and rollers to clamp up instead of
the springs   in a   normal clutch.    Most centrifugal are drum
type rather than disc. Disc is likely better   for high rpm.  The
SGF coupling is the lightest, simplest, least   expensive   and
quickest way to deal with the drive line vibration.  Do you think   that
   Porsche, M-B, BMW, General Motors and the other car companies
that use   them   are guessing?

   Murry I Rozansky

   The rubber couplings really don't deal with low RPM aircraft gear
box   chatter.   Their real function is to mitigate the torque
pulses effect on the gears.   What we need is both but I have not
come up with a light weight   fluid coupling or a centrifugal clutch
yet. In the mean time we will   continue to idle the rotary at 1800
engine RPM or higher. After all the   prop is only turning 632 RPM.

   Paul Lamar

  The Molt Taylor flexidyne is a centrifugal dry fluid clutch by
  Dodge-PT.  They use a steel shot sandwiched between wavy housings/plates
  to transfer power.
  They are not light.
  Flexidynes apparently worked well for many folks using 0-200's or less.
  One Cirrus VK-30 owner mentioned a MTB Failure of a few hours with
an  IO-550?   I believe they are using an off the shelf Lord LCD
damper now  with many hundred successful hours.

  There are a lot of engineered industrial and marine dampers out
there to  choose from...

  Here is a viscous torsional damper redrive project I was involved with
  years ago.  The prototype was built and flown.
  Many additional variations and concepts were discussed.

   http://www.eaa245.org/Presentations/EA81Torsion/Torsion/sld028.htm
   http://www.eaa245.org/Presentations/EA81Torsion/Torsion/sld022.htm

  Cheers
  Cary

Cary,

Thanks for the Presentations. I have been thinking about building and
was really worried about the mechanical issues. That clears up many
doubts.

I do have a question for you. Since you are interested in Rotary, do
you know how much Torsional Damping will be needed for 13B 3 rotors?
In the presentation, it talked about Ross's PSRU failure. Do you know
what it looks like? Is it similar to the flex plate failure or it is
more like broken gears, etc. Thanks!

Henry Nee



How about using the magnetic fluid like they are using in some shocks to vary
the damping response. More magnetic field increases the stiffness. Could vary
with a rheostat on the panel. Might be possible with testing to use a PLC to
control it according to engine and flight parameters. Use in a housing like
Cary showed.

Dale Davies