Poly-hedral means many planes, for example. Like in polyhedron.
Di-hedral means two-planes. Thus, dihedral wings are at an angle (when seen from the front). This
confers stability to the vehicle when rolling (the vehicle centers itself if you release the stick).
Dihedral wing. The tips are
higher than the center of the wing.
An-hedral, strictly speaking, means no-planes. I've seen old books (in spanish) that use that term for flat wings. All the english speaking books I've seen use the term for
negative angled wings, that is, the tips are lower than the center of the wing.
So, in english books, anhedral means the wing has a downward angle (while in spanish this would be called negative dihedral wing).
Anhedral wing. Tips lower than center.
Anhedral (in its english meaning, or negative dihedrals, in spanish)
takes away some stability from the plane. It is used in planes that have a high wing. The center of gravity of those planes is below the wing, so you have stability by what is called the "keel effect". In many combat planes you don't want to have
too much stability, so you use an anhedral wing, to make the plane more agile.
Most formula one front wings, at least the late ones that I can remember, are polyhedral, that is, they have many angles.
I suspect those angles are to improve the interaction of the flow of air with the body, but I'm not sure at all.
Rear wings have no angle (by regulations, I think, but I'm not sure either), thus they're called "anhedral" where I live and "zero-angle wings" in UK/US (and heavens knows in how many countries more).
How these angles in the front wings interact with the car when turning, perhaps to improve rolling stability, beats me. I'm sure other members can help us here.
Take in account that
racing car wings work "inverted", thus, when seen from the front, what seems to be an anhedral is a dihedral and viceversa.
So, if you see a downward wing, thinking in reverse and concluding that it is a dihedral, you would think it would help the car to "counter-roll" a bit (or maybe a lot, I don't know) in curves.
I have no idea if dihedral angles create larger tip vortexes in the wings or maybe a larger drag. I would think that they diminish the "effective" span of the wing, because (I imagine) the lift forces they create are at an angle to the body.
So, my
amateur conclusion is that, unless rolling is a problem (and I can think of more efficient mechanisms in a car to counteract rolling), I don't know why would you use them in a car for stability only.
Please, take in account that all this blah, blah, comes from my years of building airplane models and what I've learned as airplane pilot.
