Problem 3: The airfoil NACA 2418, considering a chord-based Reynolds number of: Re = 5. 105, has a lift coefficient of: CL = 0.25 at zero angle of attack. Assuming the C - a slope of the first-order approximation, calculate the lift coefficient at 5. For the same airfoil in the same conditions, at C = 0.15 the drag coefficient attains a minimum equal to 0.009, while the drag coefficient at zero angle of attack is 0.01. Assuming a parabolic approximation of the CD (C) curve, calculate the drag coefficient at 5. Finally, calculate the efficiency at 5.