A method and apparatus for controlling airflow with a gapped trailing edge device having a flexible flow surface. The airfoil can include a first portion having a first leading edge, a first flow surface, and a second flow surface facing opposite from the first flow surface. The airfoil can further include a second portion having a second leading edge and a trailing edge, with at least part of the second portion being positioned aft of the first portion. The second portion is moveable relative to the first portion between a first position and a second position, with the second leading edge separated from at least part of the first portion by an airflow gap when the second portion is in the second position. The second portion includes a flexible flow surface that has a first shape when the second portion is in the first position, and has a second shape different than the first shape when the second portion is in the second position.