Erwan, the sweeper is just the flat part at the bottom/tack of the main, just straightens the stream lines (blue) and reduces the turbulence.
Rolf, yes its XFLR, and yes the 2.5D algorithm is a problem, but the example was just to see the differences due to geometry.....in the full up CFD run I did the differences are markedly smaller but still there. The L/D delta varied markedly over the wind range, just showed the 20 knot case as it high lighted the differences best.
Cheers
RG