Science Buddies: "Ask an Expert"

Hi,

I want to build a simple wind tunnel and try to measure the drag of a styrofoam cone object. I would like the cone to represent a rocket, and to see if a cone with dimples carved, verses lines, versus smooth would have less drag and therefore use less fuel in takeoff when launching into space. I have done a lot of research on aerodynamics, and know how to build the wind tunnel, but am confused how to measure drag. Someone suggested using a tachometer - would I attach it to the styrofoam cone or measure the fan (which I am planning to use to PULL air into the tunnel). Or would I use a wind measure to see how wind moves around the device? Or should just measure lift by using a digital scale under the device and seeing if the weight changes? I can't find any answers on the internet, please help.

A lot of experimenters measure drag by attaching the front of the object to a spring scale. As the wind pushes the object backwards it exerts a force on the spring scale. https://www.youtube.com/watch?v=sGEnKtTiYj0 is a short video someone made of their solution. The spring scale is mounted below the wind tunnel and has a string and pulleys to attach to the front of the object - in their case a cart.