# Design lift coefficient of an airfoil

I have the design lift coefficient of the plane during the cruise condition. Now, I want to calculate the lift coefficient required by the airfoil which makes up the wing, taking into account the Aspect Ratio, Sweep, etc. Is there a formula for that? I have seen formulas that give the slope of the lift curve for a wing using the slope of the lift curve of an airfoil.

I need the design lift coefficient of the airfoil for choosing an appropriate airfoil.

• Okay, that can be done. I had one more doubt. At each span location, will the lift coefficient (of the airfoil at that location) be different or will it be the same? As we move in the spanwise direction, the lift will decrease and the chord also decreases. Therefore, can we say that lift coefficient will be same cross the span? Apr 27 '20 at 14:43
• Oh, I see. I forgot about the downwash and spanwise flow. Then how can one chose an airfoil if one has design lift coefficient of the wing? Apr 27 '20 at 14:47
• Then, I will add another question. Apr 27 '20 at 14:51

For straight tapered wing, you can use the lifting-line, which computes the downwash angle at the discrete spanwise locations, which you can use to easily back-out local $$C_l$$. For swept wing, your easiest solution is to use a vortex-lattice method, such as AVL. AVL directly outputs the section lift coefficient at the corresponding control points.