aerodynamic drag and body style

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David Redszus
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Re: aerodynamic drag and body style

Post by David Redszus »

Rick brings up an important aspect that is often overlooked...wind effects.

The drag forces of a vehicle are a function of airspeed, not ground speed.
Therefore, wind velocity must be taken into consideration.

A race car with a frontal area of 30 sqft and a Cd of 0.45 will produce the following drag forces:

133 mph = 604 lbf
140 mph = 669 lbf
147 mph = 738 lbf.

If the vehicle ground speed with no wind is 140 mph, the effects of a 7 mph headwind
and tailwind can be seen as substantial.

But we often encounter cross winds or angled wind direction; and the plot thickens.
Fastvette94
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Re: aerodynamic drag and body style

Post by Fastvette94 »

I raced a 3rd gen camaro in the 1/8, 406CID TH-350. Trap speeds were 100ish. At those speeds aero dynamics arent a big deal. The F3 is sleek to begin with.

Spend your efforts elsewhere unless you plan on running sub 5s.

I made a simulator years ago and aero changes in FA and Cd did not impact 1/8 times significantly.

As far as headwind/tailwind, just simply add or subtract it to your speed for the equivalent resistance. In a 20 mph headwind at 100 mph vehicle speed it will feel like 120 to the car.

There is more to aerodynamics such as body lift vs speed, body pitch, center of aerodynamic drag, suspension response to a cross wind (bumpsteer), wings. Going off from your stated 80mph in the later half I have surmised that we aren’t talking extreme speed and light weight.

Good luck.
David Redszus
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Re: aerodynamic drag and body style

Post by David Redszus »

Fastvette94 wrote: Wed Mar 10, 2021 6:53 am I raced a 3rd gen camaro in the 1/8, 406CID TH-350. Trap speeds were 100ish. At those speeds aero dynamics arent a big deal.

Quite correct. The following data support your observation. What is the average speed for 1/8 mile?
While chasing aero drag reduction is not a significant factor at lower speeds, wind speed does have an effect
on times.

A race car with a frontal area of 30 sqft and a Cd of 0.45 will produce the following drag forces:
60 mph = 123 lbf
80 mph = 218 lbf
100 mph = 341 lbf

120 mph = 492 lbf
133 mph = 604 lbf
140 mph = 669 lbf
147 mph = 738 lbf.
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