Camber

The camber of an aerofoil is the maximum displacement of the mean camber line from the chord. The mean camber line is the locus of mid-points of lines drawn perpendicular to the chord. In other words, the camber line is the bisector of the aerofoil profile thickness distribution from the leading edge to the trailing edge. The camber line is given by:

Camber = 2 (Пи + Пі)

Making this nondimensional, by dividing with the chord, the camber can be expressed as a fraction of the chord:

Percentage camber = ^^u + ^l max x 100 %• 2 chord

By Equation (4.8b), we have:

Пи = 2be(1 + cos 9) sin 9 + 2bfi sin2 9 nl = 2be(1 + cos (-9)) sin (-9) + 2bji sin2(-9) = —2be(1 + cos 9) sin 9 + 2be sin2 9•

Thus:

(Пи + Пі)max = 4b в (sin2 9)max – The chord of the aerofoil is c = 4b. Therefore:

4b в (sin 9)max

2 x 4b

In this relation, sin2 9 is maximum at 9 = n/2, that is, at the mid-chord. Therefore:

в

Percentage camber = — x 100 %•

From the above discussions it is evident that the vertical shift of the circle center is responsible for the camber of the aerofoil, and the horizontal shift determines the thickness-to-chord ratio of the aerofoil.