7. Wing pitching-moment coefficient about its aerodynamic center ${{C}_{{{m}_{AC}}}}$ \[{{C}_{{{M}_{ac}}}}=\] \[\frac{2}{S\bar{c}}\left( \int_{0}^{b/2}{{{C}_{{{m}_{ac}}}}\left( y \right){{c}^{2}}\left( y \right)dy-\int_{0}^{b/2}{\left[ {{C}_{{{l}_{\alpha }}}}\left( y \right)\left( {{\alpha }_{{{0}_{wing}}}}+\varepsilon \left( y \right)-{{\alpha }_{0}}\left( y \right) \right)\left( {{x}_{ac}}\lef..