A civil, non-aerobatic aircraft has a wing loading of 2,400 N/m^2 and ∂CL/∂a = 5.0/rad. If n1 = 2.5 and F = 0.715, calculate the cruising speed for the gust case to be critical.

Question

A civil, non-aerobatic aircraft has a wing loading of [latex]2,400 N / m ^{2}[/latex] and [latex]\partial C_{ L } / \partial \alpha=5.0 / rad . ext { If } n_{1}=2.5 ext { and } F=0.715 ext { , }[/latex] calculate the cruising speed for the gust case to be critical.

Accepted Answer

From Eq. (13.33),

[latex]n=1+\frac{\frac{1}{2} ho_{0} V_{ E }\left(\partial C_{ L } / \partial \alpha ight) F u_{ E }}{w}[/latex] (13.33)

[latex]n=1+\frac{\frac{1}{2} imes 1.223 V_{ C } imes 5.0 imes 0.715 imes 15.25}{2,400}[/latex]

giving [latex]n=1+0.0139 V_{ C }[/latex], where the cruising speed [latex]V_{ C }[/latex] is expressed as an EAS. For the gust case to be critical,

[latex]1+0.0139 V_{ C }>2.5[/latex]

or

[latex]V_{ C }>108 m / s[/latex]

Thus, for civil aircraft of this type having cruising speeds in excess of 108 m/s, the gust case is the most critical. This, in fact, applies to most modern civil airliners.

Question 13.7: A civil, non-aerobatic aircraft has a wing loading of 2,400 ...

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