In xflr5,how is the value of Fz calculated? I am building an conventional plane with AR=6 and I find the wing area,A.So I have selected an airfoil  for building my plane that is sd7062. Using xflr5 I got a cl vs alpha graph and I took the cl value at 4 degrees . using this cl value I calculated my lift and equated to the weight of my plane which is 2kg*9.81=19.6N .now equating L=W I find the area ,A and using this area and aspect ratio 6 or 7 I  calculate the span and chord .Now when  I do an analysis for the wing dimensions I got and plot a graph between Fz(lift) and alpha graph and find that at 4 degrees the Fz value is 13.078N ....why is there a decrease in my lift.....if there's a decrease then are the calculations I have done wrong?..please help me out]1
When you have taken the Cl of the airfoil concerned, the Co-efficient refers to an infinite wing. You have to compute the CL of the wing, which refers to a finite wing, taking into consideration the 3D nature of the flow.