As good as computer radios are, they still have some short comings.
Fortunately, they can usually be overcome. The described problem occurs
whenever you have two servos moving mirror image control surfaces. ie
ailerons or flaps. The problem is always there, sometimes its so small you
aren't aware of the problem, sometimes its obvious.
Assuming the servos are matched and the programming does not contain a
problem, flaps move differently because the mechanical linkage of the two
flaps are different. SERVO OUTPUT IS NOT LINEAR. The programming may be
linear but the servo arm is rotary. Maximum movement occurs when the servo
arm is 90 degrees to the pushrod connecting the servo arm and the control
horn. In other words, the system we use builds in reverse exponential
output.
Typically, the flap servo arm is pointed towards the rear of the model in
normal flight mode. In this extreme position (for the control linkage, at
the extreme end of movement) even small differences can result in very large
differences at the other extreme.
The two mechanical control systems must be identical. ie angle and length of
servo arm in normal flight mode, the height and positioning of the control
horn relative to the hinge line etc.
If your still problems, send me a copy of your template to verify you don't
have any programming problems. You can do the same by removing the servos
from the wing, placing them face to face and compare servo arm movement
through the arc.
Nine times out of ten, when someone shows me a problem like this one at the
field, its not a problem with the radio but one with the mechanical set up.
I Sand a small balsa block to match the angle of the servo arm when held
against the bottom of the wing. Then use the block to set the other servo
arm.
Good Luck
Sherman Knight
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