Quote:
Originally Posted by NewBModder
So, how much of the aerodynamic drag on a car can be attributed to the bumper parachute effect?:
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Only your friendly neighborhood windtunnel engineer could say for sure... I'd guess it's some small contributor. But the small things all add up, an mpg here, an mpg there, pretty soon you pull in for your weekly gas fillup, open the cap and fuel spills out!
ok, that was just silly, but it's late in the day, working with spreadsheets and our contracts department all day has me loopy...
Quote:
Originally Posted by NewBModder
Or is that a separate drag and not really part of the 'cd'? (Yes, I'm displaying the depths of my lack of knowledge and/or understanding  |
Remember that a car's total drag is cd x frontal area.
Just like a blunt nose or poorly designed roof section, by definition that rear facial's drag component is included in the vehicle's advertised cd number.
What is uneffected by shape is the 'frontal area' part of the equation.
Whats the difference? (paraphrasing a famous drag racer) "Drive a car into a mortorless brick wall, and count how many bricks fell out the otherside. Adding up the number of bricks x (brick length and width dimension), would roughly give you the car's frontal area. cd is much harder to figure out"
