The
mean camber line of an
airfoil is the
line from the
leading edge to the
trailing edge, of which each point lies exactly halfway between the upper and lower surfaces. For an airfoil with zero
camber (i.e., the
wing is
symmetric about the
chord line), the
mean camber line is straight and corresponds to the
chord line. In other cases, the mean camber line is curved.
upper surface
_____
-- --------_______
/ _----________ -----...
(------------------------------->
\ _____--------_______-----'''
--
lower surface
The chord line is the dotted line through the center; the mean camber line is the dotted and flat line just above it, and the dotted line where only that exists.
Sorry for the horrible ascii art; for a better picture, see http://www.grc.nasa.gov/WWW/K-12/airplane/geom.html.
Indirectly inspired by a look at my nodeshells.