I haven't looked at the illustration but what happens is that if the a/c
rolls to the left, it will begin to slip to the left. The left wing
will have a greater angle of attack than the right, therefore more lift
and it will tend to correct the roll.

By the same token, if it is yawed the left it will begin to skid to the
right. The right panel has a higher angle of attack and it roll left.
That's how rudder-only model a/c manage to roll and turn.

You fly enough models - especially free flight - and the value of
dihedral for stability becomes quite evident. Dihedral produces
stability in roll. Most full size a/c don't have enough to produce what
I guess would be called static roll stability. Left alone, they go into
a spiral and either hit the ground or break up. Free flight models
have enough dihedral (or polyhedral) to remain stable in roll.
Typically they are set up for stable circling flight. Take too much
dihedral out and they will spiral in.

Dihedral was key to controlling early RC models. With a properly setup
rudder-only non-proportional control model, you could not only turn, but
climb, dive, and even loop. I wonder what Jepp says about that?

Dallas wrote:
Would anyone care to comment on the accuracy of this illustration of how
wing dihedral works from a 1981 Jeppesen Sanderson book.

http://makeashorterlink.com/?B25A35DCC

The accompanying statement reads:
"When an aircraft with dihedral rolls so that one wind is lower than the
other, the lower wing will have more effective lift than the raised wing
because it is not tilted from the horizontal as much. The imbalance in lift
tends to raise the lower wing and restore level flight."


Dallas