Model Forum / Radio Controlled / Air Models / January 2009

The dihedral has two main functions:

1: Roll stability. When the plane rolls to the right, the right wing
effectively becomes slightly longer, and the left one slightly
shorter, causing a lift difference that opposes the initial movement.

2: Allow the rudder to cause roll. When you apply right rudder, the
left wing is pointed slightly forwards and the right one slightly
backwards. As a result, the left wing will have a slightly larger
angle of attack, and produce more lift, rolling the plane to the
right.

If you build both dihedral and ailerons, your ailerons would be less
effective and your rudder would cause the plane to roll. An expert
pilot would say it flies like a dog. For a total newbie, this setup
might not be all bad, but since you can handle your 3-channel with
reasonable confidence, I recommend going for zero dihedral. You can
fly it just fine using aileron and elevator only (forget about the
rudder at first, except on the ground), and it will be much more fun
to fly when the ailerons work the way they should.