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Aircraft control surfaces 3, Fig. 1, are pivotally attached about forwardly convergent axes to wing or tailplane 2 and are arranged to constitute overlapping tips thereto and are each movable to operative positions in which they extend above and below the level of the wing or tailplane as shown in Fig. 3. Conjoint operation of the flaps causes them to act as airbrakes whilst on turning the flap on the inside of the turn only is operated. The flaps may be differentially operable when in adjusted position and may substitute either ailerons or elevators.