$4$

Problem $05\mathrm{.}006-$ Estimate maximum value of L$/$D from a graph

$11\mathrm{.}11$

points

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References

The ratio of lift to drag, L$/$D$,$ for a wing or airfoil is an important aerodynamic parameter. Indeed, it is a direct measure of the aerodynamic efficiency of the wing. If a wing is pitched through a range of angle of attack, L$/$D first increases, then goes through a maximum, and then decreases. Consider an infinite wing with an NACA $2412$ airfoil. Estimate the maximum value of L$/$D$.$ Assume Reynolds number is $\backslash (9\backslash$times $10^\{6\}\backslash ).$ Refer to the Appendix graph given below for standard values.