To add to this answer (about how an airplane behavs during turns), most
airplanes are designed with dihedral. This means that the wings point up a
little bit. If you looked at a plane from in front of the nose, the wings will
form a slight V shape. This makes the "lift" that each wing produces point a
little bit inward, towards the center of the plane, rather than straight up.
Now, if the plane goes into a shallow bank, the wing that is lowered will
become more level, and the lift will point straight up, while the wing that is
raised will become more tilted, and the lift will point more towards the center
of the plane. More of the lift on this "tilted" wing is "wasted" (in the sense
of not holding the airplane up). So, since the other wing exerts more upwards
force, it causes the plane to return to level flight. This is one of the
things that makes an airplane inherently stable in flight.

Separate from this, when an airplane is banked in coordinated flight and
turning, the outer wing (which is the one that is raised to bank the plane to
make the turn) is actually travelling faster than the inner wing. It has to,
because that wing is further from the center of the turn. (to see this,
imagine the plane turning so sharply that it's just about pivoting on one
wingtip) The faster wing will produce more lift, and cause the airplane to
bank in the direction of the turn. This is called "overbanking tendency".

So, there are two opposite tendencies. Dihedral is more important with shallow
banks (and gentle turns), and the overbanking tendency is more important with
steeper turns and banks. Somewhere in the middle, they cancel out.

Jose

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