# Find the coefficient of lift of the wing- body combination of an airplane.

Consider wing- body combination of an airplane. Find the coefficient of lift of this wing body if the coefficient of moment about the center of gravity and the coefficient of moment about aerodynamic center is \(0.006\) and \(-0.015\). Aerodynamic center is forward of the center of gravity at \(0.035\) chord length.

For a wing-body combination of an airplane

\[{C_{M,cg}} = {C_{M,ac}} + {C_L}\left( {h – {h_{ac}}} \right)\]

Here, \(h – {h_{ac}}\) is difference of distances of center of gravity and aerodynamic center in terms of fraction of chord length from the wing’s leading edge .

Therefore,

\[0.006 = – 0.015 + {C_L}\left( {0.035} \right)\]

\[ \Rightarrow {C_L} = \left( {0.006 + 0.015} \right)/0.035 = 0.6\]