Theory and Preliminary Flight Tests of an All-Movable Vertical Tail Surface

An improved type of all-movable tail surface has been developed and tested in flight. The surface is pivoted behind the quarter-chord point and is provided with a plain flap that deflects in the same direction as the main airfoil. This arrangement provides control-free stability and a stable variation of the control forces during maneuvers. Flight tests made with the Fairchild XR2K-1 airplane showed a vertical tail surface of this type to be satisfactory in all the maneuvers attempted, including those that involve complete stalling of the surface. The all-movable tail was found to be more effective than the conventional type and offers the possibility of a reduction in the size and the drag of tail surfaces.