Ah, hunting! As in the model hunts for a steady direction to resolve conflicting inputs?
Seen that and down thrust seems to cure it.
Thanks Serge.
Though 0,0,0 is the standard that can always be trimmed out to work some what acceptably, here seems to be a lot of fiddling with the controls, and handle to cure hunting, and other unwanted inputs.
I've found, after reading Bob Whitley's post, "Things that always work", is that if I set my planes up as Bob recommends, I have a much easier time trimming the plane out for proper flight. Seldom, if ever, is there any hunting. as well as other more subtle problems.
Bob suggests 1-2 degrees of down thrust, just enough out-thrust to make sure there is no in-thrust, and 1/2 to 1 degree of positive stab incidence.
It's easiest to use a pair of incidence meters. First establish the wing at 0 incidence, and block the fuselage so that wing incidence is maintained while you work on the thrust line, and the stab incidence. I leave the incidence meter attached to the wing. This allows me to refer to the wings meter, to get the proper down thrust line. To establish the stab incidence, keep the fuse blocked up where the wing remains at 0 degrees, and move the second incidence meter back to the stab, set it up for 1/2 to 1 degree positive. I most often use about 1/2 degree positive, at the stab. Crank in enough out-thrust, towards the out side of the circle.
I have found that I seldom, if ever, have hunting problems, and the plane seem to fly truer with this set of incidences. Of course, this all is based on CCW flying with standard prop rotation. I've not flown CW, or with a pusher prop to have an opinion.