PURPOSE: To prevent the generation of flow breakaway around a rudder face provided rotatably behind a wing body by providing movable skirts extended from the rear edge of the wing body toward the rudder face, and interlocking these skirts with the movement of the rudder face.

CONSTITUTION: The wing (a general term for a main wing, a horizontal tail and a vertical tail) of an aircraft is provided with a wing body 6, a fixed part forming the most part of the wing, and a rudder face 1 rotatable around a rudder face rotational center 2 is provided behind the wing body 6. An upper and a lower movable skirts 3, rotatable around hinges 4, extended backward toward the rudder face 1, are fitted to the rear edge parts of the upper and lower faces of the wing body 6. The rear ends 43 of an upper and a lower rudder face rods 8, 8' are pivotally fixed into the upper and lower positions in the vicinity of the front edge of the rudder face 1. The respective rudder face rods 8, 8' are extended frontward inside the wing body 6, and their front ends are connected to an actuator. The movable skirts 3 are driven interlockingly with the movement of the rudder face 1 so as to diminish a gap between the movable skirts 3 and the rudder face 1 and thereby to prevent the breakaway of flow around the rudder face 1.