What is the purpose of aileron droop used in some commercial airliners?
The purpose of aileron droop is to use the ailerons as wing flaps. Wing flaps increase the lift generated by the wings at low speed. They occupy a good part of the trailing edge of the wing, except for the outer part, where the ailerons are. By deflecting both the ailerons downwards, they change the wing camber and act like simple plain flaps. They can still act as ailerons, by normal differential deflection.



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