Which statement, about an aeroplane leaving ground effect at constant angle of attack, is correct?

I. The lift coefficient C_{L} remains constant.

II. The induced drag coefficient C_{DI} decreases.

Refer to figure 1 and figure 2.

In figure 1 you can see the effect of downwash on the effective angle of attack and therefore the induced drag of a wing profile.Now the question is asking what will happen to the induced drag coefficient and the lift coefficient when **leaving** ground effect:

- Induced drag coefficient: Using figure 1, and knowing that when
**leaving ground effect**the downwash increases, we know that our induced angle (α_{i}) will increase, therefore increasing the induced drag (D_{I}). This means an increase in C_{DI}, hence**statement 2 is incorrect!** - Lift coefficient: Using figure 1, and knowing that when
**leaving ground effect**, the effective angle of attack (α_{e}) decreases because of the increased downwash, we can see in figure 2 that a decrease in effective angle of attack will decrease the coefficient of lift of the wing. Therefore we can say that**statement 1 is incorrect!**

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