What Are Ailerons and What Do They Do?

Ailerons are primary flight control surfaces that areAilerons come in several forms. They may be:
mounted on the outboard trailing edge of the wings.Differential Ailerons - The upward moving aileron is
They control roll (bank) about the longitudinalraised a greater distance than the other one is
axis.They are connected by cables, bellcranks, pulleys,lowered. This produces more drag on the wing which
and/or push-pull tubes to the control wheel or controlis lowered. Frise-Type Ailerons - When an aileron is
stick. When one aileron is deflected upwards, thedeflected upwards, the leading edge of it projects
other one moves down. The one that movesdownwards beneath the wing. This creates drag and
upwards is always the one in which you point the tophelps to equalize the drag created on the lowered
of the control wheel towards. When you move thewing. Coupled Ailerons and Rudder - Ailerons and
control wheel to the right, the right aileron isrudder are linked by interconnect springs. These
deflected up and the left is deflected down. Whensprings automatically deflect the rudder appropriately
you move the control wheel to the left, the leftwhen the ailerons are deflected. Flaperons - Ailerons
aileron is deflected up and thus the right is deflectedand flaps are combined. When a pilot wants to roll,
down.flaperons function in much the same way as ailerons.
When an aileron is deflected up, it decreases camber,When the same pilot wants to add flaps, they
which then decreases lift. When it is deflected down,function accordingly. All four of these types of
it does the opposite.ailerons are designed to reduce the effects of
So when you turn the control wheel to the right, theadverse yaw. Adverse Yaw is the tendency of the
right aileron goes up and decreases lift on that side.aircraft to yaw towards the outside of a turn. When
The left one goes down, increasing lift on the leftthe descending aileron increases lift, it also produces
side, which then causes the plane to roll to the right.more induced drag as a by-product. This drag creates
An exercise you can do to understand this better isthe tendency for the nose to want to move
to put your hand out the window while you aretowards the opposite direction of the roll. This should
driving. Pretend your fingertips are the hingebe corrected when turning by applying rudder on the
connecting the aileron to the wing. When you tiltside of the turn.
your hand up (aileron deflected down), you can seeWhen you turn right, adverse yaw causes the
how lift and drag is increased - your hand moves upairplane to yaw left, so add right rudder. When you
and back. When you tilt your hand down (aileronturn left, add left rudder.
deflected up), your hand moves down and forward.