Aerodynamic panels, questions/ideas for improving CD and mpg of 6g Options

[ricochet1490]

Has anyone ever heard of addition panels to improve the coefficient of drag (cd) of our cars? Sites like ecomodder have all the people making stupid looking stuff to gain mpg, but imo our cars look too good for that to happen. So I was thinking, what if we made panels that either A) looked good on the car, or B) couldn't be "readily seen" - aka made out of lexan or something.

Any Thoughts, ideas? I think if we could shape some clear panels to deflect air around our bucket head lights, and some to keep the air off the spoiler (but still using the spoiler for mounting/looks), we could probably gain at least a few mpg. It might be worth looking into if some cheap lexan could be found.

[ricochet1490]

^^ now see that's what I was talking about. The headlight covers I bet would be a worthwhile investment as far as aerdynamics is concerned. But the thing of it is, right now I AM doing a lot of highway driving. 1000miles every ten days with about 85% highway.
But I was thinking about some sort of air dam, again made so that it looks good, but my fluid mechanics class is screaming in my ear right now lol. I have to think that the aerodynamic changes would HAVE to be worth at least 1.5-2 mpg. If we reference the mythbusters episode (not where the idea originated but a good example) of when they added clay to the car and then dimpled the clay. They saw a jump in mpg from something like 26 to 29. Now obviously they did the whole car with the exception of the underside, this would just be the underside, but the point is the same.

Using the equation Fd=.5*p*v^2 * A * Cd found here http://en.wikipedia.org/wiki/Drag_equation - And assuming this page is correct http://en.wikipedia.org/wiki/Automobile_drag_coefficient , our cars have a Cd of .32.
And then knowing how Cd is calculated from the drag equation wiki and the Moody diagram found here http://en.wikipedia.org/wiki/Moody_chart . The Fd COULD be significantly affected I think.

If we take for instance the frontal area of our car, estimated to be about 18.84 sq ft. - found here http://www.newcelica.org/forums/showthread.php?t=263442
a velocity of 55 mph, the p(density of air) at 72 deg F with a .32 Cd........ 55mph =24.59 m/s...... 18.84sq ft = 1.75 sq. met. .......... 72F = 20C so p = 1.204 kg/m^3

Fd = 203.845 N at 55mph If we reduce the Cd by even .02 so our new Cd is .3 our new Fd is 191.1. This may not seem like much but it's a difference of 6.25%. Which SHOULD correspond directly to the car not having to work as hard to push through the air. does this mean a 6.25% increase in mpg? maybe, maybe not, but even at 3.125% increase at a standard of 30mpg means a 1mpg increase to 31. All 6.25% gives us nearly 32 mpg. Anything beyond a .02 change could be really significant. Significant enough to pay for itself in a year? who knows- i don't really care to do the calculation right now.
To me the reduction in weight only serves purpose for accelerating type driving. If on a FLAT highway, your car doesn't care if the back seat and speakers are in the door or not. (also proved by Mythbusters episode on dimpling with clay.... that car gained 400 lb because of the clay and on flat ground got better mpg)

Sorry if I went over anyones head, but my engineering brain was screaming

Also I kinda want to relate this to the other topic, of which you may or may not have seen, hence my reference of the weight. http://www.6gc.net/forums/index.php?showto...mp;#entry928916


This post has been edited by ricochet1490: Aug 15, 2011 - 4:43 PM