A mean camber line with a reflexed trailing edge must have a point of inflection, and, therefore the simplest equation that can describe it as a...

A mean camber line with a reflexed trailing edge must have a point of inflection, and, therefore the simplest equation that can describe it as a cubic. Four boundary conditions are required to determine a cubic. Two of them are the condition of zero camber at the leading and trailing edges. Therefore, if a reflexed mean camber line is represented by a cubic, the equation will contain two arbitrary constants and may be writted in the dimensionless form :

z/c = a[(b-1)(x/c)3 - b(x/c)2 + x/c]

What are the values of b and cmac if the angle of zero lift of the airfoil is zero?

What is the value of b that makes cmac equal to zero?

(Use cos2Theta= (1+cos2*Theta /2 to help you find and derive dz/dx = a[(b-1)/8 + [(3-b)/2cos*Theta + [3(b-1)/8]cos2*Theta]