RAH'er has forced landing

On Fri, 24 Dec 2004, Stealth Pilot wrote:

6 years isnt too informative though.
how many hours were accumulated in those years?
how much work had the gearbox done before finding a home in your
aircraft?

The gearbox was used, over 80,000 miles when I got it, I installed new
bearings. It flew 415 hours in the six years. I suspect that the bearings
may have worn enough to disturb the gear lobe fit (but I don't know).
In hindsite, I wish that I had replaced the bearings at annual.

To share my understanding on other issues raised on RAH:

The Mazda Wankle has very low amplitude (strength) power pulses, since the
power stroke is over 130 degrees of the output shaft.

The frequency of power pulses is the same as a four cylinder four stroke
as there are two per revolution. However, if it starts on one rotor,
then every other pulse is removed, which lowers the frequency by one half.
That is not likely to happen on any other engine.

If you know the moment of inertia of each component, and the rate of
spring of the revolving mass, then you can compute the frequency during
which torsional resonance is likely. In my setup, that is 200 to 300 rpm
with both rotors running (double that on one rotor). The forces generated
by resonnance, approach infinity, so no "stronger" gears help much.

I did use an elastomeric dampener (clutch hub), and a quill shaft on
the tranny input (came with it).

Thanks for all of your kind words, I'm off to retrieve my airplane today.

George Graham
RX-7 Powered Graham-EZ, N4449E
Homepage http://bfn.org/~ca266