ORIGINAL: Top_Gunn
Just a word of warning. Dihedral may be ''your friend,'' but only up to a point. Too much dihedral and aileron turns become difficult or impossible because the adverse yaw makes the plane turn the wrong way. Lanier used to make a plane called the ''Super Trainer 40.'' A guy in my club won one in a raffle and gave it to the club to use as a club trainer. I thought it had way too much dihedral, but built it per the plans on the assumption that Lanier had tested it and knew what they were doing. Mistake. If you didn't coordinate turns it would turn the wrong way. This is not what you want in a trainer. So I built another wing, with a lot less dihedral. Plane still sucked (much too fast for a trainer, for one thing), but at least you could turn it with ailerons.
It wasn't the dihedral that was causing the adverse roll problem that the Lanier Super Trainer 40 was experiencing. The problem is known as adverse roll and its cause is improper aileron differential. You can have the same problem without any dihedral at all.
Too much dihedral in a wing makes the model less fun to fly than when it has the proper amount of dihedral, which is seldom zero.
Dihedral's job is to keep the wings level. This takes a lot of work off of the pilot and lets the pilot relax a bit and steer the model mostly with rudder. Ailerons are for adding the proper amount of bank when using the rudder to turn the aircraft.
Ed Cregger