# 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 C₂ - a slope of the first-order approximation, calculate the lift coefficient at 5°. а For the same airfoil in the same conditions, at C₁ = 0.15 the

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## 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 C₂ - a slope of the
first-order approximation, calculate the lift coefficient at 5°.
а
For the same airfoil in the same conditions, at C₁ = 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 (C₁) curve, calculate the drag coefficient at 5°. Finally, calculate the
efficiency at 5⁰.