How Does Wind Speed and Surface Area Affect the Drag Force on a Car?

This experiment was conducted to determine how wind speed and surface type affect the drag force on a car. To successfully perform the experiment we constructed three different car replicas using cardboard for the frame and different grits of sandpaper for the surface type. These replicas were then placed on a force cart, which was then attached to a force sensor. To produce the wind the replicas were placed in a model wind tunnel that had three speed settings: low, medium, and high. The wind was turned on for each trial and the data was collected for ten seconds. The average drag force over ten seconds was then documented. After a total of 21 trials, or three two factor Design of Experiments (DOE), we found that the lowest drag force, at an average of 0.015 N, was recorded when wind speed was low and surface type was smooth. These results show that a smooth surface is what produces a low drag force, not a rough surface.

Research Done By:

John Jason DiMambro
Cousino High School

David Rulestead
Cousino High School