I never really thought about *why* a forward pointing control surface is so much more powerful, inch for inch, than a trailing surface.



I'm not sure the foil shape has the dominant impact on the leverage equation here, and here's my (slightly goofy) reason:



Mid century airplanes, the ones controlled by wires affixed to the steering column, with no hydraulic power assistance, used forward surfaces to balance their elevators - and if memory serves, those surfaces weren't foils! The larger horizontal stabilizers often were foils, but the hinged-on elevators weren't, I believe. And yet, visualizing it now, I do think the ratio of forward surface to aft was about 1 to 4-or-5; certainly nowhere's near 50-50!



So I'm liking Gary's point about where the highest pressure is located on the side of a deflecting surface, foil or no. If the highest pressure piles up pretty near the leading edge of the attack side, then you have to keep that awfull close to the fulcrum, or pintle-axis.



I can visualize it being about getting the same (leverage adjusted) amount of pressure on both sides of the pintle-axis.



I hope somebody who knows the actual answer jumps on this....