Consider two flat plate airfoils as lumped "lifting elements" in a tandem arrangement, where the second airfoil is located at some distance downstream from the first airfoil. The chords and attack angles of both airfoils are the same. Find the circulations of these airfoils in terms of the free-stream velocity U , attack angle  , chord c , and the distance between the airfoils’ leading edges d . Which airfoil generates higher lift force and why? Discuss the effect of the distance between the airfoils on their aerodynamic interaction.