Trimming Help

[BUDDYonRC at aol.com]

Paul
I am no aerodynamics expert, but I have learned some basic's over the years 
that work for me.
1. The wing must have a positive angle of attack to create lift.
2. the stabilizer and elevators steer the pitch attitude of the airplane 
resulting in more or less lift.
3. Balance can change the angle of attack which will change the pitch 
attitude.
4. Aileron's up or down will change the pitch attitude .
5. Up or down thrust will change the pitch attitude.
Therefore:
A. Increasing the positive wing incidence will cause the airplane to climb, 
which will require down trim to achieve level flight.
B. Likewise adding tail weight will cause the airplane to climb and require 
down trim to achieve level flight.
C. Added weight does not alter the vertical down line BUT elevator trim added 
to maintain level flight because of the added weight will effect the down 
line. Tail weight will require down trim which will steer the airplane more to 
the belly in a down line, and added nose weight will require up trim which will 
steer the airplane to the canopy.
D. In the vertical up line elevator trim and the engine thrust line will 
effect the vertical and/or yaw direction   
All of the above will effect the knife edge flight of the model.
Combinations of adjustments to any or all of the above trim items done at the 
same time will leave you confused and frustrated.
Most models will require some mixing to achieve near perfect lines in all 
flight attitudes in order to minimize / eliminate control inputs by the pilot to 
maintain a perfect course.
I have yet to see the perfect airplane should such an animal exist, but I 
keep looking and building since I truly believe that nothing is impossible.
When trimming an airplane make a written log of every change no matter how 
small so you don't have to start over when changes are not correct.
Buddy
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