Problem $2$:

Consider an airfoil that is a half cylinder shape with radius $R=2ft.$ The airfoil is in a free$-$stream

velocity of $100$ knots in an atmosphere at standard sea$-$level conditions. The velocity on the upper surface

of the airfoil varies in the same way that it does over a circular cylinder. The velocity on the lower

surface is the same as the free$-$stream velocity. Determine the lift per unit span for the airfoil.

Hint: ${\displaystyle \underset{\phantom{}}{\overset{\phantom{}}{}}}si{n}^{3}d=\frac{1}{3}co{s}^3-cos+$CConsider an airfoil that is a half cylinder shape with radius R $=2$ ft$.$ The airfoil is in a free$-$stream

velocity of $100$ knots in an atmosphere at standard sea$-$level conditions. The velocity on the upper surface

of the airfoil varies in the same way that it does over a circular cylinder. The velocity on the lower

surface is the same as the free$-$stream velocity. Determine the lift per unit span for the airfoil.

Hint: $331$

sin cos cos

$3$

d