EVOlutionary

iTrader: (38)

DHP Composites contact is DHPComp@gmail.com (no website)

I'll let you read up on undertrays and aero on your own. It's just physics. Works the same way as a diffuser or wing on the rear of the car, creating an area of high speed/low pressure air and using flow turning to apply a force on the car. . .

Depending on the shape of the underside of the splitter/undertray, it also helps direct air out the front wheelwells, keeping that air out from under the center of the car. This has benefits also. . .

Saying you're having a hard time being convinced that flat is not best, well . . . that's like saying you're having a hard time being convinced that the stove burner is hot when it's red. I can tell you all I want to, but you either have to experience it first hand (burn yourself), or read up on it and understand WHY the red stove burner is hot and believe it.

http://www.mulsannescorner.com/
http://www.grc.nasa.gov/WWW/K-12/airplane/bga.html
http://www.grc.nasa.gov/WWW/K-12/airplane/presar.html

RaNGVR-4

iTrader: (4)

^ This is the main reason you dont want a flat bottom splitter. if you direct air under the nose to the wheel wells, and the wheel wells are somehow vented or have a place for the air to get out, then there will bel lower pressure under the front. less air=lower pressure. its a miniscule pressure difference, but the actual downforce it creates is suprising.


As for the "standing" on the splitter, its a saying, its not a do-or-die rule. if you have a honecomb core carbon splitter like race cars, you would break it by standing on it, but it could hold 5-10 times your weight sprea out over the front. All its saying is, a properly designed splitter/tray can generate more downforce than you weigh, and should be able to hold that "weight".

dhpcomposites

No official website yet, but you can check out some additional pictures on the photo page below:

http://www.flickr.com/photos/dhp_composites/

If you have any questions please let us know.

Thanks!

griceiv

iTrader: (2)

I hate to rain on your parade, but your DHP splitter is not making any more downforce then an otherwise flat undertray would at your ride height. The exit area of the your splitter is only marginally larger then your throat area, the exit flow is highly restricted and thus the exit pressure is going to be higher then the base pressure at the rear of the car, and it's installed at a negative rake angle so is likely creating positive pressure on the underside of the splitter.

I give it full credit for sticking out farther then any other splitter i've seen on an evo though.

EVOlutionary

iTrader: (38)

Rain doesn't bother me. That's what I have a set of Hoosier Radial Rains mounted on the stock wheels for!

Please feel free to comment further on what does or does not work after you've spent hours testing aero parts in a wind tunnel. Or burned up many tanks of gas testing different bumpers and splitters and undertrays. David at DHP has been there, done that. I've been there, done that. Voltex has been there, done that. (granted, they're in a whole other league)

As for my "ride hight" - the front splitter barely scrapes the ground (on the front outside edge) when trail braking into a hard corner. The side skirts barely scrape the ground when the car sees nearly 100% weight transfer to that side. How much lower do you want me to go??

griceiv

iTrader: (2)

You mean something like this?


or like this?
Wind Tunnel testing?

heeltoer

1. This site is the awesome. http://www.mulsannescorner.com/ Thanks for sharing!

2. Lets not confuse similar shape and design with actual knowledge.
Sure, there is precedent for using shaped underbellys and underbody vanes to direct air from underneath the car into the wheel wells (actually more likely the shaped areas behind the wheel wells).
e.g. http://www.mulsannescorner.com/audir8-01-3.html

Show us a windtunnel video or a CFD study on an EVO and everyone will be the wiser.

3. With that said, a shaped splitter will be something I'll be looking to test for next season.

-yang
Team Lee Myles Transmission

P.S. Usually someone with superior knowledge does not resort to overtly ambiguous analogies. By the reasoning presented, I should just as readily believe the stove top is hot when green.

oneguy

iTrader: (23)

Here is a pretty good read on the basics and some graphs thrown in with it:
http://engineering.union.edu/~brunob...rodynamics.ppt

heeltoer

good info, for those that don't have Powerpoint.
http://www.slideshare.net/heeltoer/m...-presentation/

Here is another pretty detailed doc about the Evo vortex generator.
http://www.mitsubishi-motors.com/cor...004/16E_03.pdf

Interestingly the optimum combined drag and lift reduction was achieved and tested at 50 m/s or 112 mph!

EVOlutionary

iTrader: (38)

Nice video Marshall! I didn't know you were on your school's FSAE team. So what did you guys learn from testing the aero package on that car. How does it compare with what UTA has been running the past couple years?

I know a couple years ago they ran something much smaller and compact than what you have on the car above, but they said that idea didn't really pan out. That rear wing element is pretty huge. Did the front end make that much grip that you needed that much downforce in the rear to balance it out?

How does what you learned in FSAE transfer over to the EVO?

Jeff_Jeske

iTrader: (66)

KazzEvo8

iTrader: (2)

Absolutely in awe here with the content of the thread. Thanks, all!

griceiv

iTrader: (2)

We learned that we could make a crap load of drag. UTA's aero package had a far superior build quality and weighed a lot less. We were probably fairly close downforce wise though.

the tricky part is that with the huge wing we could run it a lower AOA and reduce the amount of drag it made for a given amount of downforce. The front wings are very much in ground effect and make a suprising amount of downforce. Also the rear wing was mounted almost directly over the CG and the front wings were way out in front of the CG, long story short, yes they balanced.

Honestly? I learned that there isn't much to be gained performance wise (at normal autox speeds) for the amount of weight you can add in aero devices, but that speed dependent stability augmentation is a good thing.

Oh and you can spend a lot of money fixing broken carbon parts when you hit cones.

EVOlutionary

iTrader: (38)

Speed dependent stability augmentation? What do you mean by this?

I know for my car we set it up with no aero to rotate pretty well and be a little loose in the rear end. I added the splitter and the thing turned into a snap-oversteering b!tch. About the 3rd cone into a slalom, if you were pushing it, it would just come around on you. We had to slow down to not spin out. Then I added the wing and now you can take a slalom as fast as your hands can move the steering wheel . . .

Jeff_Jeske

iTrader: (66)

^ I just find that hard to believe.... what kind of speed are you slaloming at?