Question $1$

$3$ Marks

Consider the airfoil shown below, mounted in the test section of a wind tunnel. The length of the model in

the flow direction is $0\mathrm{.}6$ m $,$ and its width across the flow $($wingspan$)$ is $1\mathrm{.}0$ m $.$ The air flow in the test

section of the wind tunnel at standard sea$-$level conditions, the profile drag on the airfoil at zero degrees

angle of attack is $29$ N $.$ Calculate the drag on the airfoil due to skin friction Df$.$

Renolds' number $=4{10}^6$

Density $=1\mathrm{.}225k\frac{g}{m^3}$

Viscosity $=1\mathrm{.}78910-5k\frac{g}{m}.s$