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.

Every geared engine passes through this range several times on a given
flight, but rarely loiters there.

Even in ground ops.. you are pushing.. or pulling.. but rarely
straddling the fence.

Dave

Morgans wrote:
"Dave S" wrote in message
nk.net...

Wouldn't you have this "effect" ANY time you went from a thrusting to a
braking action with regards to thrust generated?

If I pulled power back, set the pitch to flat, and pushed the nose over,
wouldn't the prop be "driving" the engine in the manner you describe?

All of this is able to be done without a specific Beta range.

Dave


Actually, no. Kinda. g

When the engine is using HP to turn the prop, all is well, be it forward or
reverse thrust. The only difference the gearing sees is the thrust on the
shaft goes from pulling the shaft out, to pushing the shaft in, but the load
on the gears is the same. (all for tractor applications, in this case)

When the possible chattering comes in, is when you are gliding, and at a
very low power setting, and the *windmilling* prop is trying to turn the
engine, thus the prop is "making" HP to try to turn the engine- opposite
from normal.