• Segment length (L segment.)
• Root chord (Corde E).
• Tip chord (Corde S)
• leading edge sweep (Flèche).
• twist.
• Diehedral (optional).
• Leading edge thickness.
• Trailing edge width
• skin thickness.
• Spar(s) position.
• Spar(s) dimensions.

Recul E = tan Alpha * Decalage E ---> Definition of the root starting point.

Recul S = tan Alpha * Distance

tan Beta = (Corde E - (Corde S + Fleche)) / L segment

Course E = Corde E + Recul E + (tan Beta * Decalage E)

Course S = Course E - (Recul S + (tan Beta * Distance))

RBA = epBA / cos Alpha

Trailing edge withdrawal (RBF) .

RBF = epBF / cos Beta

Slope = (Yb - Ya) / (Xb - Xa) = tan Gamma

For EXTRADOS

X = X0 + ep * sin Gamma

Y = Y0 - ep * cos Gamma

For INTRADOS

X = X0 - ep * sin Gamma

Y = Y0 + ep * cos Gamma

L : spar width

H : spar height

P : Position of the spar(s) axis over the chord ( mm or  % of chord)

If 1 single spar Extrados and/or Intrados:

From X = (P - (L'/2) one realize Yl = Y - H at Extrados up to X = P + (L/2)

From X = (P - (L'/2) one realize Yl = Y + H at Intrados up to X = P + (L/2) 

r = sqaure root(X² + Y²)

Teta = arcsin (Y/r)

X' = cos(Teta + Alpha)

Y' = sin(Teta + Alpha)

 
• The initial thickness is given from the airfoil section : Epr.
• The medium line (Yligne) is determined as:

 
• Epr2 : desired thickness.

For any  X the new intrados point is Yinf ' = (Yinf + Yligne) * Epr2 / Epr