Here is another possible approach to reducing gear chatter [attached file]
  which would be located forward of whatever flex plate we end up with?.
  the red drive gear is coaxial with the eshaft, which drives the green
  internal gear directly, and the power is transmitted to the outer purple
  gear via the black-colored rubber bushings.  Of course this is only a
  representation of a concept where rubber bushings are placed as close
  as possible to the source of gear chatter, which is difficult to do with
  planetary gears.  Also, the purple gear would not have to necessarily be
    outside the green gear, but it could be placed forward of the green
  gear,
  and its 'fingers' could extend between the rubber bushings in an axial
  direction instead of the radial direction shown in my crude drawing.  This
  would be analogous to the products shown in the attached Centaflex file.
  [So have we agreed that Rhino2 is as good as any?  Anything cheaper?]

  This concept could be used to raise the prop thrust line, allowing more
  room over the engine to consider using stock Mazda components such
  as water pump etc.

  Gene Kahn

  Excellent idea Gene!!!! Good work. All we need is a new ring gear holder
  and slots milled in the PSRU housing. I think chunks of round
  silicone rubber rods will work.

  What is shown is an internal spur gear but it will work fine with
  a planetary. Much simpler than what we are trying to do now,
  Will require a new PSRU housing but that is no real problem.

  I think we can saw off Tracy's box and weld on a new aft section.
  Will stiffen the motor plate in the bargain.

  I will draw it up.

  I like Rhino but it is up to 4.

  Good work Gene. Why to think.

  Raising the trust line is not the way to go. Not needed and less cowl volume
  for the cooling system. The RX8 water pump is no higher than the rotor
  housing.  Been there done that.

  Paul Lamar


   Hi, a soft mount for the ring gear is an excellent idea,  I thought of it
  years ago. Found out that R-R used it in their Eagle of 1918.

  Murry I Rozansky

  Here is a Rhino 3D dwg hot off the press.
  The advantage over the R-R is silicone rubber.

  Paul Lamar


I was looking around for possible sources of gear chatter, and wondered
if those little needle bearings might not cause some chatter:  as the needle
bearings roll around their circular path, their inner ends travel a shorter
distance than do their outer ends, and therefore pure rolling cannot occur,
but considerable sliding has to accompany the rolling.  Perhaps tapered
roller bearings might be better?  Every bit of the thrust from the propeller
must be born by these thrust bearings.

Gene Kahn

No it is not the needle thrust bearings. All  different design gear boxes
with a high polar moment of inertia prop on the output end do
the same thing when driven with an intermittent combustion engine.

Putting the rubber inside will not solve that problem.
Apples and oranges. All we hope to do is reduce the shock load
to the gears.

In order to solve the low RPM chatter problem the engine must be disconnected
from the gear box.

Here is a completely differently designed gear box and rotary engine that would
chatter below the same 1800 to 2000 RPM range. Not even a planetary.

Paul Lamar