Elon;
I'd put one ruler horizontal and another one vertical to get a proper
scale in both axes, back off a ways and then use a telephoto lens. A
telephoto lens compresses the perspective so you can then use the
digital photo to get a reasonably accurate measure of frontal area.
Using the rulers, draw a grid pattern on the photo and count the
squares, estimate the % of non- filled squares and add everything up.
Voila! ....frontal area.
Regards, Neil Tucson, AZ
-----Original Message-----
From: owner-land-speed@autox.team.net
[mailto:owner-land-speed@autox.team.net] On Behalf Of Elon
Sent: Friday, November 11, 2005 10:43 PM
To: land-speed submit
Subject: Area, as in CdA
I am trying to figure the frontal Area on my car to use in CdA calcs. I
was
going to put a 1ft length of duct tape on the front bumper and a 1ft
piece
on the windshield. Then get as far back as I can and take a digital
photo.
I would print it out and then draw squares all over the picture using
the
duct tape as my calibration for the squares. The problem is the
perspective
will shrink the 1ft piece on the windshield and the squares will
"pinch-in"
toward the top. I.e., they won't be perfect squares but narrower at the
top
due to perspective. Is this the correct way to do all this? Is there a
more accurate way? -Elon
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