GATE 2026 AE – Question 63
Thin airfoil theory predicts the zero-lift angle of attack $\alpha_{L=0}$ of NACA 2412 airfoil as $-2.1^\circ$. The corresponding prediction of $\alpha_{L=0}$ for NACA 5410 airfoil is ________ degrees (rounded off to 1 decimal place).
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Correct answer: -5.23 to -5.17
Explanation
NACA 2412 and 5410 both have the maximum camber at 0.4 of the chord. In thin airfoil theory $\alpha_{L=0}$ is proportional to the camber, which is 2% for NACA 2412 and 5% for NACA 5410 (the thickness has no effect). So $\alpha_{L=0} = -2.08^\circ \times \frac{5}{2} = -5.2^\circ$ (using the unrounded $-2.077^\circ$ for 2412).