My Guillows 28" electric PT17 nearly beat itself to death until I:
1. Removed positive incidence on top wing , now close to zero.
2. Added more down-thrust.
3. Reduced control surface throws ( use dual rates/expo). Plane is very sensitive to rudder, don't have ailerons.
4. Try a smidge of down trim for take off and adjust trim for level cruise.
5. Be ready for pitch up after take off ( keep nose down when at full throttle).
6. I wouldn't mess with elevator incidence, mine is around zero.
Sounds like you have eliminated tail heaviness, make sure it isn't way noseheavy.
I notice that my little PT17 needs elevator trim changes for fast medium or slow flight to fly hands off. Rudder must be at neutral, no right trim for takeoff with right thrust, sometimes needs a little rudder trim after take off. Bipes handle strangely but sure look great in the air and not.
