By the way, I'm beginning to realize that it only takes one force to
turn an object, as long as that force is not acting through the centre
of gravity.

That's not quite true (unless by "turn" you mean "yaw"). A single force
not through the CG will cause the object to rotate about the CG. To get
an airplane to actually =turn= however requires also a change in
direction, else the airplane would simply skid sideways the rest of the
flight.

Let's say you are flying straight and level, due North, and simply stomp
on the (left) rudder pedal. The first thing is that the tail will swing
to the right, because the force from the rudder is not through the CG.
But then other things happen. As the tail swings, the right wing ends
up going faster and the left wing slower through the air. So the right
wing provides more lift, and the aircraft banks to the left. Since the
airplane is still going due North, but pointing slightly west, the
airflow on the side of the plane will push the airplane somewhat to the
left, and the propeller (now pointing slightly west) will also help pull
the airplane west. The bank also introduces some net leftward force.

So, there's a lot going on. (and no, stomping on the rudder pedals isn't
usually the best way to turn).

Jose
--
The monkey turns the crank and thinks he's making the music.
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