Thanks for the interesting insight.

This is exactly where I'm coming from while helping my son trimming his Spark pattern ship. As one post above written the subject of trimming is much of a black art. There isn't much written stuff on the subject and a few sources including semi official sites could be quite confusing on this subject.

Recently I came across an interesting approach by Bryan Hebert (Triangulation Trimming, http://www.hebertcompetitiondesigns....tion.aspx?id=8)
That is supported by some known F3A champions. His approach sounds very promising to me in the sense that once you follow his approach accurately you may get rid of most radio mixes of your model by manipulating only CG and incidences.

My problem is currently that I find it difficult to apply a recipe of this kind that I can't understand each step to its exact rational and expected effect on the model's flying qualities.

Would appreciate clarifications on the following specific points:

1. Why an increase of wing incidence may cure a model tendency to pull to the canopy on verticals? Is there any difference (in this sense) between up and down lines?
2. Suppose your verticals are now perfect. How can a plane be trimmed to both verticals (wing is unloaded) and level flight (wing loaded)?
3. The tendency of an airplane to go to the belly on knife-edge is taking care of by moving the CG forward. Is there any difference between left or right KE in this sense?


Thanks,

Yoav