I was always under the impression that in most light a/c, the dominate
rolling effect from 'inside' rudder is the result of dihedral (or
alternatively, sweep back). RC modelers are pretty adept at setting up
aircraft for 'pure' yaw from rudder input - no dihedral, symmetrical layout,
etc. Or setting up aircraft to bank and turn without ailerons - lots of
didedral.

Though I'd agree that the "forward motion of the outside wing" explanation
accurately predicts the rolling effect from rudder input that occurs on most
a/c - which is ok for training purposes.

"Dudley Henriques"
snip
If complimentary yaw (inside rudder) is used with no aileron, the speed
difference between the retreating inside wing and the forward moving
outside wing will cause bank, which will be a direct secondary result of
the complimentary yaw being produced.
In other words, insider rudder will most definitely produce bank as a
secondary effect and as such will produce turn...assuming no anti turn
control input is present.
Dudley Henriques
International Fighter Pilots Fellowship
for email; take out the trash