Keith Holm wrote:

Hi Paul,  I talked with a Cozy Pilot at AirVenture who has had failures of
two Ross drives in under 200 hrs. the nature of the failure was not
specified, only the disgust!  I believe that Dave Atkins has performed all
the prescribed thrust bearing and oiling mods, and is on his third drive,
at relatively low power levels.  Dave has ordered a Powersport reduction.

Keith Holm [at Power Sport]

Well Keith pardon me for being a bit skeptical but when you guys get
500 hours on one of those things let me know :-) Jim Mederer and I
talked about mounting the redrive pinion on the end of the e-shaft and
he too was a bit skeptical. It is not as if this has never been tried before
in aircraft engines. Allison did a lot of work on this arrangement
as did Rolls Royce back in the 30's and they were both six power pulses
per rev V12 engines. Rolls wound up using a quill shaft to isolate the
torsional vibrations. You guys need to get a lot more hours before I will
be totally convinced.

Paul Lamar

Paul - The Powersport drive sounds a lot like the Marcotte (sp), is
there any relationship ? - Vance

They are both internal spur gears but the Marcotte, as you can see, has
a torsionally isolated spur gear pinion mounted with a separate bearing.
The rear main does take some side load but it is much reduced due to 
leverage effects. Still not ideal but much better.

Paul Lamar
 
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