wind tunnel meassure wing lift=5000N
frontal area is 2m2
planform area is 15m2
if we use frontal area Cl = 1.66
if we use planform area Cl=0.22
So choosing different reference area we have different results.That mena Cl and Cd are dependent of reference area.. So ARIBITRARY area does not make sense to me ,because than Cl and Cd can be any number.
So wich lift coefficient is corret,also if arbitray area change Cl and Cd value is it impossible to compare it with other type of wings?
So my conlusion is that we cant compare coefficients if reference areas are different,for example one is frontal area and one is planform area (car vs airplane).