Differential ailerons - radio controlled aircraft
Radio controlled aircraft with ailerons can benefit from
differential throws of ailerons. Aileron differential means that the aileron that moves upward needs to be
deflected by a larger angle, and the one that moves downward is being deflected by a
smaller angle. This results in a more coordinated roll of the aircraft because
if the aileron throws were the same, the equal angle of downward deflection causes
more drag than lift for the upward moving wing, slowing the wing down and causing the aircraft to yaw in
the direction opposite to the desired direction of turn (if any).
To use the charts, first make a note of the deflection angle you need and of
what percentage of the upward deflection angle you want the downward deflection
angle to be (the differential). Next critical parameter is servo arm travel.
This parameter is what you can change by placing the aileron linkage in the
different holes in the servo arm.
For example, we want maximum upward deflection angle of 50º and downward deflection angle that is 60% of the upward deflection. Checking the charts for 5 mm linkage travel (see examples of angle and differential charts marked accordingly), we find a suitable combination of clevis height (10 mm) and control horn offset (5 mm). Other options would be 12 mm and 8 or 9 mm (or one can try 12 mm and 6 mm with the 7 mm linkage travel, or 7 mm and 4 mm with the 4 mm linkage travel). From these options, higher clevis would be better because that setup is less sensitive to imprecise installation.
The calculations presented on the plots are based on the kinematics similar to these:
If something is not quite clear, or you have questions or need a chart for
some parameters not listed above,
free to drop us a message.