Patent ID: 7992825

Claim:
Control surface ( 1 ) for an aircraft lifting surface ( 2 ) that comprises a primary control surface ( 6 ) that comprises a hinge axis ( 10 ), and a secondary control surface ( 7 ) that comprises a hinge axis ( 11 ), with the secondary control surface ( 7 ) rotating by means of its hinge axis ( 11 ) relative to the primary control surface ( 6 ), said secondary control surface ( 7 ) only partially occupying the span of the primary control surface ( 6 ), characterized in that the length of the secondary control surface ( 7 ) along its hinge axis ( 11 ) is significantly less than the length of the primary control surface ( 6 ) along its hinge axis ( 10 ), and moreover the width or chord of said secondary control surface ( 7 ) narrows significantly along the direction of its hinge axis ( 11 ) towards the tip of the lifting surface ( 2 ) according to a law of narrowing designed expressly for adapting the distribution of torsional stiffness along the span of the lifting surface ( 2 ) to the distribution of aerodynamic load thereon, whereas the distribution of effective curvature due to the deflection of said control surface ( 1 ) is such that it increases the stalling angle of the lifting surface ( 2 ).