Problem 4 In a wind tunnel, velocity profiles are measured at the upstream end (surface 1) and at the downstream end (surface 2) of the control volume which encloses an airfoil of chord length c as shown in the Figure. The flow is incompressible, two-dimensional, and steady. If surface 3 and 4 are streamlines and the pressure is p. (constant) over the entire surface of the control volume, a. Calculate the vertical length of the upstream station (2H) in terms of c. b. Calculate the drag coefficient for the airfoil. HU -Streamline Hp=0.025c =U_₤1-0.5 cos 5 2H Streamline