"Dave S" wrote

And after discussing it with the rotary engine gang, the consensus is..
that you pass through this area of "chatter" fairly quickly.. either you
are engine driving prop.. or prop driving engine... but from a practical
matter you are not loitering in the power/thrust range that is teetering
between the two.

All very true. You get pressure of the opposite side of the gears from
normal, but it would indeed be rare for it to get to the RPM where it is so
closely balanced, as to go from one to the other, rapidly.

All of this is reason to make the gears tight fitting, with little lash.
More lash gives time for the motion to set up with a "head start", providing
more force to break things. Broken things = bad. g
--
Jim in NC
--
Jim in NC