i´ve designed a horizontal tail and ran vortice lattice method in order to get induced angles on it. Then I corrected the lift coefficient with wind tunnel data (MS excel) and calculated the induced drag coefficient, by having induced angles and the corrected lift coefficients on each station.

The values i obtained are "exactly" double of the ones I got from XFLR5. So I started to look for what made both values different.

I´ve found out that the calculation of the Cdi, when using the whole wing area instead of only half-wing (which seems correct, because I´m calculating only half-wing), returns pretty much the same values of XFLR5.

Is that correct? I´m running XLFR5 4.02Beta.

If that is correct, the only thing that must be changed is the area by which the sum of all spanwise stations induced drag coefficients is divided.

thanks... =)