Drag coefficeints

[David Pozzi]

This was posted over on Team Camaro reciently, a new square foot number for a 69 Camaro. I thought it would be good to reference it here for our archives.



QUOTE
"Camaro CD info: http://www.camaros.net/forums/showthread.php?t=16452
Hi, I'm new to this message board, I am bringing this post back from the dead (7 years, is this a record maybe? heheh) to bring you guys some useful information regarding 1969 Camaro aerodynamics. The biggest error I've seen published is in frontal square feet. Most figures people are finding is 25 sq. ft. This is incorrect...

The flat square of the width x height = 25.85 sq. ft. Now all the empty space must be subtracted to get the true frontal area.

The method I used was a basic silhouette using a bright light a large distance from a 1:25 model set at stock ride height with a sheet of paper directly behind it taped to the wall. The light was a single source LED placed parallel to the wall inline with the car and centered to the geometric middle of the car. My recordings are accurate to +/- 5% as I used a 1" real size grid to measure it.

These numbers include two stock side mirrors and all use 245 section width tires front and back.

STOCK: 19.64 sq. ft.
1" drop: 19.50 sq. ft.
2" drop: 19.36 sq. ft.
3" drop: 19.22 sq. ft.

Our cars are actually very good for this measurement, ranging from 76 down to 74% of full square. (lower is better)
Oh, with this good news comes the bad: CD is at a minimum, 0.4x."