How can I use the "control hinge-moment coefficient due to tab" for sizing a trim tab on an elevator?
The trim tab is sized first, and then the tab hinge moment is computed. The trim tab is sized to the conditions required for maximum trimmed position of the aircraft at:


low speeds;
all relevant CG positions;
all relevant flap settings;


The contribution of the trim tab to the elevator hinge moment is tiny, see the right hand graph which is measured data from the F-27.