The turn occurs because as you roll into bank, the lift vector now
has a horizontal component which will pull you in the direction of
the bank. Think of a string suspending the wing straight up (the
lift vector for level flight). Now think of the string being pulled
sideways slightly as well as up. This will pull the aircaft in the
direction of the pull... or lift vector... which now has a horizontal
component.

The rudder is used to coordinate the turn only.

You could fly along level with a slight bank angle with no turn
(aka a "slip") if you applied opposite rudder... enough to counteract
the horisontal lift component. This will only work for a limited bank
angle however.

Ramapriya wrote:

Hi guys,

Unlike the elevators and rudder that change an aircraft's pitch and
yaw with no other secondary effect, why does the banking of wings by
the use of ailerons not just roll an aircraft but also produces a turn
(yaw)? Logically, one would expect an aircraft to keep going straight
ahead even if the pilot banked the aircraft left or right. Where does
the turning effect come from?

Is there a website you know of that can teach me such basics, without
having to bug you?

Cheers,

Ramapriya