No, not quiiiite correct. NASA's Glenn Research Center has a good website on introductory aerodynamics with a special section devoted to dispelling that myth, as well as some others, about what actually generates lift.

This is the page dispelling that particular incorrect theory: http://www.grc.nasa.gov/WWW/K-12/airplane/wrong1.html

The page with the correct theory: http://www.grc.nasa.gov/WWW/K-12/airplane/right2.html

The simplest and most accurate way to think of it is that the airflow is turned. Because of the net initial vorticity created by the turning, this theory was effectively proven correct when Ludwig Prandtl was able to photograph the counter-rotating shed vortex, described here: http://www.grc.nasa.gov/WWW/K-12/airplane/shed.html

The aerodynamics index for the GRC has a lot of good pages, if anyone is interested in reading: http://www.grc.nasa.gov/WWW/K-12/airplane/short.html

-Adrian

 

to simply evacuate air from the wheel well, the primary benefit is increased front grip by making the splitter more effective. there are secondary benefits as well such as brake cooling but the front grip thing is the real reason

it would depend on the car's particular areo package to determine which style is most useful it could also be a rules thing, generally speaking you want to pull as much air out from under the front of the car as possible after the splitter (unless you have a full underbody in which case a great percentage, but not all, is channeled all the way through to the rear diffuser). Changing the percentage allows the team to adjust the aero balance of the package.

 

gotta' get me some of those (great on a summer day )

 

this is very good... so the turning of hte fluid then turns the wing which sort of acts as your hand under a broom stick (upright) type thing yeah?

 

wow...I really feel stupid now.

 

Ok, after reading most of this thread, I only really have one comment...

From testing MYSELF on the track, (Road America to be exact), I picked up 5-6mph on the top end without changing ANY other equipment in similar temperature environments just by adding the new APR rear diffuser... (135mph vs 140-141mph)



This proves that the "parachute" effect on an Evo is rather large. These values were datalogged and recorded, so it wasn't a glacing at the speedo/tach thing. Fixing this problem helps with drag on the top end.

Now, I can't say that it helped with any amount of "downward force" at all, it felt roughly the same through the high speed turns.

I will ALSO admit, that the Evo has the aerodynamics of a brick. I can be FASTER than the Corvettes in the turns, but they will pull on me in the straights if I am next to them. Now, if I'm in the draft, I can usually slingshot around them without any problems. I've topped out well past 145mph just by using one of their drafts.

So, how do we make the Evo slippery-ier? I am not too concerned about downforced, persay... you have to remember, most Evos are not going at crazy speeds where downforce is really needed, but more to help with speeds past 100mph.

 

data??? just cuz i figure others will ask.

 

This is an awesome thread.

 

Interesting stuff...

What i would do to reduce drag? Your APR diffuser apparently works, and i'd add fender louvers, a decent front lip/splitter, lower side skirts, and some creative underbody panels. Might look funny, but there's not much else you can do.

A big front splitter would be tempting for a track car, and IMO would be worth the drag penalty, which wouldn't be too bad if designed correctly.

Tape up the seams on the front of your car too. Hood, headlights, fenders etc.


- Andrew

 

any data? i just wanna see some logs...