This page computes the lift, moment, inviscid drag, and Cl distribution for wings with chord extensions.
Note that in the above program the wing area (sq. ft.), aspect ratio, and taper ratio are defined based on the trapezoidal area (ignoring the chord extensions).
Sweep is in degrees and is measured at the quarter chord of the trapezoidal wing.
The trapezoidal wing root chord is given by: croot_trap = 2 WingArea / (Span*(1+Taper)) and the span is related to the aspect ratio by: span2 = AR*WingArea
The leading edge and trailing edge chord extensions (LEX and TEX) are optional and extend the leading edge at the root by a distance of LEX*croot_trap and the trailing edge at the root by a distance of TEX*croot_trap. This larger chord tapers away linearly out to a distance of ExtensionSpan times the semispan. Experiment with these 3 parameters to see their effect on the planform shape.
The incidence at the root and tip may be specified in degrees. The incidence at the break is the incidence at the end of the chord extensions (at a spanwise position of ExtensionSpan times the semispan). If there is no chord extension the break incidence may still be used to produce a nonlinear twist distribution. If ExtensionSpan is set to 0, the wing is trapezoidal and the break is at the root, so the program ignores the root incidence value. Note also that changing the incidence at root, break, and tip together is (essentially) the same as changing the angle of attack, so you may set the angle of attack to zero and change incidence to change lift.
Finally note that the dimensionless forces and moments are based on the trapezoidal area and geometric mean chord. The moment is given about the root quarter chord point of the trapezoidal wing (ignoring chord extensions). To translate the moment coefficient to a point at a distance x aft of this reference point, we simply add CL*x/c to the moment given here. (Recall that c is the trap mean geometric chord -- Area/Span -- in this code.) CDi is the induced drag coefficient and e, the span efficiency is just (CL2/pAR)/CDi. The maximum is about 1.0 (although may be 1% to 2% higher due to numerical error with this model).