Hi AIRWAY,
Regarding aileron drag:
This is a product of the movement of ailerons as in a turn, for example. If the pilot wishes to effect a left turn the ailerons move such that the right aileron will move down and the left will move up. The affect of the right aileron moving down will increase the lift over that wing, whilst the left aileron in moving up will have a net affect of reducing lift on that wing. This then, is essentially going to start the roll (to the left in this case).
There are some secondary affects of this. The right wing, in generating more lift will also generate more drag! The opposite will happen with the left wing. So, we now have a situation where there is a yawing tendancy as the right wing generates more drag. So although we are effecting a left bank we have a right yaw - which would need to be countered by applying left rudder. This situation can be dangerous at or near the stalling angle!
To overcome this situation aircraft can be designed with a number of features which include:
Frise ailerons: A patented device that when an aileron is deflected up (to reduce lift) there is a lip protrusion into the airflow. This increases drag on that wing. In the case of a down-going aileron the design is such that it is smooth and flush so as to reduce any drag.
Differential Ailerons: These are designed so that the down-going aileron moves through less of an angle that the up-going aileron.
Spoilers: These panels which can be raised on the upper wing surface. They can be designed to operate on the down-going wing in conjunction with a bank - again increasing drag on that wing to counter the "adverse yaw".
There are others.
Regards,
df1