Windtunnel Experiment: Calculating Drag Force on Airplane Body

[Nitewolf96]

I am going to be doing an experiment for science fair that will be using a wind tunnel to calculate drag force on the body of an airplane. I can't tell the independent variable because of that, but I need to know what to use. I looked at force sensors and load cells, but they are expensive and I don't know how to use them. Any ideas? Thanks in advance.

 

[Nitewolf96]

And if possible I need a way of measuring lift as well.

 

[RandomGuy88]

You can obtain the drag by measuring the pressure in the wake of the body and then integrating the pressure deficit. The body extracts momentum from the flow and this results in drag on the body. The flow in the wake has less momentum and this can be measured by measuring the pressure in the wake which will be less than the pressure in the freestream. In order to do this you could need a Pitot Static tube, some way of moving the the probe throughout the flow and a pressure transducer, you could use a manual manometer.

This method works very well for 2D bodies such as airfoils but it is significantly more difficult for 3D bodies like an entire airplane model. This is because of the induced drag. If you are not able to simplify your experiment to an airfoil instead of an entire plane then you will have to do it the old fashion way. You could probably just get away with a decent digital scale instead of a load cell.