Drag Coefficient:
By connection the cylinder pressure tapping to one leg of the manometer and rotating the cylinder to successive angular positions, it is possible to determine the variation in static pressure around the circumference of the cylinder. The maximum positive pressure is at a point about 70 from the center of the upstream face, a region of pressure recovery is downstream of the point of minimum pressure, and a nearly uniform negative pressure exists over the downstream of the cylinder.
The drag coefficient is the force exerted by the air stream upon an object and is defined as: