Ground Clearance vs Aerodynamic Drag

[aerohead]

I went back to the original post and added the different ground clearances covered in the investigation.Up at top.

[aerohead]

I culled some additional data for the Probe-IV and added it to the original post below the images of the PROBE.Ford was very comprehensive in their attack on drag.
P.S. Oddly enough,if we add conventional mirrors to the 1985 PROBE-V,Cd 0.137 Concept,and allow 0.015 as with the FUSION 999,we get Cd 0.152!

[Cd]

I was thinking aboat contacting Ford about the testing on the Fusion.
Some information is considered 'industrial secrets' though.
It's worth the effort though, eh ?
Personally, I think one of you engineers on this site with better credentials would have more 'pull' than me though.

I was also going to try and find out the Cd on the LSR Prius I posted on page one.

[aerohead]

Originally Posted by Cd

I was thinking aboat contacting Ford about the testing on the Fusion.
Some information is considered 'industrial secrets' though.
It's worth the effort though, eh ?
Personally, I think one of you engineers on this site with better credentials would have more 'pull' than me though.

I was also going to try and find out the Cd on the LSR Prius I posted on page one.

In the past I've had good success going through corporate information officers.I would just call corporate headquarters.Very nice and helpful all around the globe.A specific request makes it easier for them to locate press kits and the like.
GM sent a video of the EV1 land speed record runs handled through a public relations firm they'd contracted.
They may not want to give free advertising to MOON Equipment Company.I'd understand that.
I don't think it matters if you're an individual.If you do have a business card,you can tape that to the request envelope as your return address.I did this as Independence Technological Works.

[skyking]

My new truck does not have any good lowering options, and it is about as tall a stock truck can get. I will put it back on stock sized tires. Am I looking at the best air dam returns when I can no longer see the differentials and suspension components? One would figure those items are a part of the frontal area.

[aerohead]

Originally Posted by skyking

My new truck does not have any good lowering options, and it is about as tall a stock truck can get. I will put it back on stock sized tires. Am I looking at the best air dam returns when I can no longer see the differentials and suspension components? One would figure those items are a part of the frontal area.

Feysal Ahmed's Masters Thesis reported that a 6" clearance was good.
Drag would increase if it went lower,unless you took it down to 3" clearance,but that would only be for racing applications.
At 3" the airdam would have an 1% drag advantage (1/2% mpg).

[BabyDiesel]

Aerohead, what effect do you guesstimate the decklid extension had on Cd reduction? I find it odd that it was not included in the report Cd posted in post #3.

[freebeard]

My guess would be zero. A Bonneville spoiler is supposed to aid downforce without increasing drag.

[Cd]

Originally Posted by freebeard

My guess would be zero. A Bonneville spoiler is supposed to aid downforce without increasing drag.

But in the case of that car, it allowed the airflow to reattach out back as well.
The slope is nearly flat on that spoiler.



We talk about it at length here : http://ecomodder.com/forum/showthrea...34-0-a-85.html

[BabyDiesel]

Ah ha! Thank you freebeard, I didn't know it was a specific spoiler.

It seems to me that if the length was optimized for streamlining, it would decrease Cd.



Very close.

Maybe the spoiler needs more angle in order to create a vortex so the air "rides" over the trunk?

Sorry if this is off-topic

Edit: Cd, thanks for the info and link posted above
That is what I was attempting to show.