Metro aerodynamics

[Silveredwings]

Originally Posted by MetroMPG

rubber bands, or a sheet of teflon plastic on the back of the skirt where the tire would contact.

i'll add "wheel skirts: all or nothing" to the things-to-test list. (i'm going to have to quit my work and go into testing full-time.)

i was wondering if there would be some complimentary dynamic in covering all 4 wheels vs. just the rears or just the fronts. e.g. the rears improved FE approx 2.8% at 95 km/h. maybe the fronts will be similar on their own. but maybe the net effect of front + rear skirts will be greater (or less) than simply summing their individual effects.

I think the back skirts are effective because they are more likely to disturb an otherwise smooth flow past the wheels than the front ones where air is rushing around the front corner around the front wheels (I certainly will defer to your imperical measurements). My gut intuition tells me that you are much closer to a point of diminishing returns for front wheel skirts as opposed to the bigger drag you're prpbably getting from turbulent air underneath the car. Prefered remedies seem to include lowering the car, a front air dam, and a belly pan (probably in that order). Just a thought.

[MetroMPG]

Originally Posted by Silveredwings

I think the back skirts are effective because they are more likely to disturb an otherwise smooth flow past the wheels than the front ones where air is rushing around the front corner around the front wheels

your reasoning sounds good

[Silveredwings]

Originally Posted by MetroMPG

this is why tuft testing would be useful.

Yes, that would be interesting. I assume you're using the poorman's wind tunnel: someone else drive the test car down a multi-lane road while you observe from a chase car. You could video tape it at different driving speeds in real-time and review the tape in playback. You could also more easily compare test runs. If only one side of the car has your mods, you could compare the difference in a single run. What fun. Too bad we have to work.

Of course if you have two drivers and a closed course, I've also seen the observer use a smoke generator connected to a long pipe extended by hand from the chase car or pickup truck bed. Maybe too many safety issues to manage though (don't try this out on the road or at high speeds).

[XFi]

I know this thread has been 'asleep' for a month, but I thought that this would be best here.

Check out this 75mpg Metro http://www.1989geometro.com/index.html


(Edit: added image)

[Matt Timion]

Originally Posted by XFi

I know this thread has been 'asleep' for a month, but I thought that this would be best here.

Check out this 75mpg Metro http://www.1989geometro.com/index.html

That thing is so freaking cool!

They actually have working front wheen skirts too! Sweet.

[Compaq888]

all that for 75mpg????

AHAHAHAHAHAHAHAHAHAHAAHA

I'm sorry to **** on the party but 75mpg can be achieved without hacking a car.

[MetroMPG]

Awesome find, XFi - thanks!

[MetroMPG]

XFI - just out of curiosity, how did you come across that page?

[Matt Timion]

Originally Posted by Compaq888

all that for 75mpg????

AHAHAHAHAHAHAHAHAHAHAAHA

I'm sorry to **** on the party but 75mpg can be achieved without hacking a car.

Go ahead and show us how then.

[XFi]

Originally Posted by MetroMPG

XFI - just out of curiosity, how did you come across that page?

Did a search using 'geo metro fuel mileage'. On the first page.

Your site comes up under 'geo metro mpg'