Obtaining drag force from pressure distribution

[IrishAlex]

I'm trying to obtain the drag force acting on a smooth cylinder at the exit plane of a wind tunnel. I took measurements of pressure at regular degree intervals around the cylinder.

The pressure readings are in inches of water, and I know the freestream velocity and the stagnation pressure. I just don't know what to do with the data I have to obtain a value for drag force.

 

[IrishAlex]

Thanks for all your help. I found Cp at all the points of pressure measurement, multiplied by cos of the angle of rotation, plotted the product versus angle of rotation and integrated from 0 to pi.

Turns out the drag coefficient for the large cylinder is about 0.71 and 1.07 for the small cylinder.