Principles of Flight - Adverse Yaw

Have you ever heard of "Adverse Yaw"? When I was studying, I was confused by the difference of adverse yaw and the secondary effect of roll.

First of all, they are DIFFERENT !!!

By definition, adverse yaw is the yaw opposite to the turn ; while the secondary effect of roll is the yaw into the turn.

Still remember how we enter a roll? Take below diagram as an example. The aircraft is rolling to the right. The lift generated at the left wing is greater than the right. However, the left wing also produces more drag than the right at the same time. 

This additional drag pull the left wing backward. The aircraft yaw to the opposite direction of the turn. This is known as Adverse Yaw.

So will the adverse yaw and the secondary effect of roll counteract each other? Well, I would interpret the situation is this way :

E.g. Suppose we are conducting a left turn.

1.  Turn the control wheel to the left
2.  Left aileron up (less lift) and right aileron down (more lift)
3.  Initial effect: adverse yaw to the right
4.  Side-slip to the left continued
5.  Airflow hits the left body and weather-cocking takes place
6.  Secondary effect of roll : yaw to the left eventually