Yes, the structural spar tends to sit closer to the leading edge than the trailing edge of the wing. The mechanical importance of this for bending and torsional resistance is well understood, and it does not apply if the leading edge is only slightly shorter than the trailing surface.
If this is so, what other advantage does asymmetry have? For if there were no advantage to a slightly asymmetric feather, it seems difficult to envison the evolutionary path to full asymmetry. (And no, I dont accept "display function" as an answer here :-) ) Martin. Priv.-Doz. Dr. Martin Bäker Institut für Werkstoffe Technische Universität Braunschweig Langer Kamp 8 38106 Braunschweig Germany Tel.: 00-49-531-391-3065 <=== NEW phone number! Fax 00-49-531-391-3058 e-mail <martin.baeker@tu-bs.de> http://www.tu-braunschweig.de/ifw/institut/mitarbeiter/roesler1 http://www.scienceblogs.de/hier-wohnen-drachen