Aircraft Ailerons and Adverse Yaw

Ailerons

• Ailerons are control surfaces on the trailing edge of wings
• Located from the wing midpoint to the tip
• Function in opposite directions
• Moving one aileron up, moves the other down
• Operated by the cockpit control wheel
• Left aileron up/right aileron down = turn left
• Right aileron up/left aileron down = turn right

Aileron Drag (Adverse Yaw)

• Aileron displacement creates undesirable aileron drag
• Downward-moving aileron generates more lift and drag
• Wingtip drag pulls the aircraft's nose in the opposite direction of the turn (adverse yaw)
• A significant issue during turns
• During a bank to the right, additional drag from the down- moving left aileron causes a nose-dive to the left.

Differential Ailerons

• Minimises adverse yaw effect
• Upward-moving aileron travels further than the downward-moving aileron
• Creates extra parasite drag to balance induced drag

Frise Ailerons

• Another method to mitigate adverse yaw
• The up-going aileron's leading edge extends below the wing's underside
• Increases parasite drag to counteract induced drag

Roll Spoilers

• Hinged surfaces located above the flaps on the upper wing surface
• Usually flush with the wing surface, having no impact on the airfoil's performance
• Connected to aileron controls; aileron movement triggers spoiler deployment
• Deploy to reduce lift on the lowered-wing side
• Generate additional parasite drag to counteract adverse yaw
• In large aileron movements, account for about 80% of the roll rate
• Employed in transport aircraft for secondary flight control

Elevators

• Horizontal control surfaces on the aircraft tail
• Cause rotation about the lateral axis (nose-up/nose-down)
• Elevator movement is directly linked to control wheel input
• Pulling back the control wheel moves the elevator up, lifting the nose
• Pushing the control wheel forward moves the elevator down, lowering the nose.

Stabilator

• A type of horizontal tail surface (all-movable tail)
• No fixed stabiliser, features an anti-balance tab on the trailing edge
• Anti-balance tab reduces excessive sensitivity
• Controlled by the control wheel in the cockpit
• Pulling back the control wheel causes the leading edge of the stabilator to move down and increases the downward force from the tail, generating a nose-up turn.
• Pushing the control wheel forward moves the stabilator leading edge up, lowering the tail load and resulting in a nose-down turn.

This text describes ailerons, control surfaces on the trailing edge of wings that function in opposite directions to control an aircraft's roll. Aileron drag can create adverse yaw. Differential ailerons and Frise ailerons are methods to mitigate adverse yaw.