Guys,

Just wanted to start a discussion on the concept of Initial Trim.

So, you get an RTF, assemble an ARF or even scratch build a model. You fix all your gear on the model and check and adjust the CG. Now what? How does one determine whether or not any of the controls require a trim or a sub trim? What are the steps?

Pankaj

http://www.rcindia.org/self-designed-diy-and-college-projects/scratch-build-cub-trainer/msg9751/#msg9751

http://www.rcindia.org/self-designed-diy-and-college-projects/scratch-build-cub-trainer/msg9758/#msg9758

That thread has some good pointers.  Launching into (or in front of tall grass/plants) is a great idea if your flying skills have room for lots of improvement.

Anwar,
I remember those pointes from you and Astha very well, but still there room for understanding.
Let us say that in general a flight pattern of a tail heavy model is well documented - It will climb steeply, stall, nose dive, recover - repeat.... But what about the others?

Say, I launch the model in the air and it turns - this can be attributed to
a) the engine mounting - as advised, the electric motor to have a 'slight' angle to down and right - so define 'slight'
b) wind/turbulence - very difficult to get a 'no-wind' situation
c) the rudder trim - if the rudder or the tail fin is not aligned perpendicular with the wing
d)uneven lift between left and right half of the wing
e) CG? (one wing heavier than the other)
f) etc....

The problems can be many and equally there can be multiple solutions. This is important because each time we make an adjustment, we need to launch the bird in the sky to see the result. So for a newbie this can become challenging and expensive (crash/repair).So how does one go about eliminating each one of these?

More importantly, when do we require a trim and when is sub-trim required?

Pankaj