banktoturn> There is really no benefit (that I know of) to an elliptical planform per se. An elliptical lift distribution gives the minimum induced drag, everything else being equal. An elliptical planform is one way of getting an elliptical lift distribution. The important thing to note is that induced drag is only important for a lifting surface (wing, stabilizer, ...) which is operating at high coefficient of lift.

This brings up another grey area for me, maybe more related to wing design. Does this eliptical planform / lift distribution relationship have any (unmentioned?) underlying airfoil assumptions? In other words, if you had 2 radically different root & tip airfoils, would an eliptical planform still be better (meaning minimized induced drag) than a trapezoid type planform of similar aspect ratio? Or is there some 1940's Spitfire folklore built in there & the advantage is only confined to constant airfoil family accross the wing panel? (Gee, I dont even know, did they blend airfoils on those eliptical warbirds back then?)


banktoturn> A good airfoil would have low CD at zero and low CL. It might make sense to have a slight inverted camber, as you mention, but certainly not much. I'm not sure about this tradeoff either. There are some sites on the web that list favorable stabilizer airfoils, and I don't know offhand that any of the URLs are. A Google search may turn them up. If I find any, I'll let you know. You definitely want a real airfoil shape, rather than a blunt flat plate.

Nope, the blunt plate was never an option! The Avionik D99 (F5D pylon rcer above) references a naca0006. The Ariane crowd (link = http://www.delago.de/ariane/EProfil.htm ) favours an HD800 & HD801 for similar application. From what I can see on the polars seem pretty comparable.

- Assuming the max thickness is defined, what about the high point placement? With the elevator proportion like shown in the D99 & maybe 10 deg max deflection, is there any pros/cons of the resulting polars by having the high point occur at 25% vs 30% vs 40% etc?