U.S. Patent Specifications

In a body adapted to travel through a fluid medium, the combination comprising: a control surface; hinge means for hinging said control surface to said body for controlling the movement of said body; a tab connected to said control surface for up and down movement at the trailing edge of said control surface; spoiler means connected to said control surface for movement up and down to project respectively above and below said control surface at a given point spaced between said hinge means and said trailing edge to leave an area of said control surface aft of said spoiler means over which a negative pressure is developed establishing a hinge moment that overcomes the hinge moment established by positive pressure in front of said spoiler means and by drag forces caused by said spoiler means; and means inter‐connecting said tab to said spoiler means to move said tab down when said spoiler means is moved up, and to move said tab up when said spoiler means is moved down, whereby the net hinge force moment acting on said control surface as a result of fluid flow thereover is increased over a given range of control surface deflexions as compared to the hinge force moment available over said same given range in the absence of said spoiler means.