RaNGVR-4

iTrader: (4)

Im no engineer (anymore, lol) but this is just what I have read. its still creating drag, but it keeps the fast moving air thats farther from the surface of the car away. used right, it keeps the smooth laminar flow away from the surface of the car, while still having airflow attached. but its mostly for keeping that higher pressure, smooth flowing air out from under the car via the "barrier" effect. lower pressure under car=more downforce. Canards are, on race cars, used for fine tuning. very incremental adjustments. Thats why its odd so many people run them on the street

aeroweenie

iTrader: (5)

Attached laminar flow gives the lowest skin friciton drag. But it is very prone to breaking away from a surface creating a separated region with lots of drag. There is enough junk on most cars and/or the flow is disturbed enough that the flow is turbulent, which creates more drag than a laminar boundary layer but is much more resistant to separation. Vortices from the canards can add energy to the boundary layer further increasing resistance to separation, at some cost in drag.

That being said, I doubt that the canards are used to control separation on the sides of the car. Also, I don't know if they affect the underside of the car at all - I doubt it. I would agree that they are probably used for downforce tweaking. Also, by creating a low pressure zone (vortex), they may help extract flow from the wheels (brakes) but I would think this is a minor effect.

EVOlutionary

iTrader: (38)

Doesn't the vortex generator at the rear of the roof create vortices that then keep the air more attached to the rear window area, allowing more clean air to get under the wing. . . ?

I read Mitsu's paper describing the exact effect of the VG, but I can't remember if it reduced drag or not. I know it made more downforce at the rear. . .

EVOlutionary

RaNGVR-4

iTrader: (4)

I think that is correct evolutionary, and I think its along the same lines of what I and aeroweenie said.

I think aeroweenie is just describing what I am trying to, but better.


as for evacuating the wheel wells, canards may help, but flat outcroppings in-front of the wheel wells create a far better low pressure zone to evacuate the wheel wells, which is where allot of the air under the front of a race car is moved to. you can see it in this picture of a ford WRC car:

nothere

iTrader: (23)

nm

griceiv

iTrader: (2)

getting back on topic, you could probably figure out most of the data you want to test for less money by just putting some shock pots on the car and spending a couple hours on an empty road. You'd end up with shock pots and the end of the testing as a bonus.

sscottttt

iTrader: (4)

This seems like a great idea, it would be nice if some companies would step in and donate some parts for you to try. I'd like to see how big an effect the vortex generator has on rear downforce with stock or other wings. Other than that I'm looking forward to seeing your results.

nothere

iTrader: (23)

I thought I'd log suspension via some string pots. Best I could figure there are too many variables and too little actual movement from aero changes to make a telling statement.
As an example the before moving and the after shut down height differences were about .5" different. So that was a variable in spring behavior. A half inch was the most I ever could possibly attribute to an aftermarket wing. Measuring from a slow period directly in front of, and the midst of a high speed run. Then again, how much interference was I getting from acceleration, suspension bindings... .

Then again, just because you see smoke doing X, that doesn't always mean Y.

IOW a tunnel will tell you how crazy the airflow gets... which you MIGHT attribute to downforce. I might just tell you you are distorting the natural order.

Which brings me to the notion, put some suspension scales under the tires.

EVOlutionary

iTrader: (38)

I just re-read the VG study from Mitsu - decreased Cd and Cl by 0.006 (less drag and less lift/more downforce). From looking at the CFD and other data it looks like even with a taller wing you would still get the reduction in Cd, but the Cl effect would be less. The taller the wing gets the less effect the VG will have on it as the air naturally gets cleaner and faster the higher you go. . .

toovira

iTrader: (2)

http://www.mulsannescorner.com

http://www.mulsannescorner.com/vortexlift.html

http://www.racecar-engineering.com/ - Great magazine. Always have an aero section.

jid2

iTrader: (62)

I think you should plan a baseline with a stock EVO, without data on a stock EVO it's going to be difficult to gauge the overall effect of the added parts. I think it's important to know the changes over stock to front and rear downforce. Maybe find a stock body work car to go with you, that's faster than changing parts out.

I assume you will have scales under each wheel. That's the only way to know what going on in terms of downforce/lift. A stock EVO will create lift, if you're lucky all your aero may get you neutral.

EVOlutionary

iTrader: (38)

Well I'm bringing this thread back from the dead. I still would like to get the car in the tunnel this spring to get some numbers - especially now that I'm getting a DHP V3.0 front splitter built for the car!

Here is a revised test pattern. I think it will be easier to test in a reverse manner - taking things off rather than installing parts . . .


- test car as-is with DHP V3.0 splitter, Voltex bumper, Voltex canards, Voltex side skirts, custom side-skirt extensions, 0.5" wicker on hood vent, DHP wing @ 12* AOA, DHP flat underpan, taped off all front end vents, wing 3" higher, front and rear ride height 1" higher than race height (similar to a "standard" lowered car)
- lower front of car 1" to test with front rake
- lower rear of car 1" to get back to standard race height
- remove front end tape
- remove 3" wing height extension to run at regular height
- remove gurney
- remove flat undertray (between front and rear wheels)
- re-run test @ 40mph wind speed
- re-run test @ 60mph wind speed
- remove custom side-skirt extensions
- test low AOA on wing = 8*
- test high AOA on wing = 15*
- remove DPH splitter - install VOLTEX undertray
- remove Voltex undertray, install air dam to 1" off ground
- remove airdam
- remove Voltex skirts - install stock side skirts
- remove Voltex canards
- remove DHP wing, install stock wing
- install stock front bumper with no undertray
- install stock front undertray
- remove stock wing (final iteration - stock bumper and undertray with no wing and stock side skirts, lowered to my race ride height)
- and then as a baseline I would have a local with a stock VIII RS and stock IX with zero lift kit throw their cars on. . .

That is 22 different combinations if I counted correctly. I think that is about as thorough of a test as one individual can do. It will give us a good idea of how much downforce changes when you have:

- a taller vs. a shorter wing
- higher or lower AOA on the wing
- 3-D splitter vs stock undertray vs airdam
- front raked ride height
- canards vs. no canards
- low side skirts
- winged or wingless?
As well as the question - just what does that stock under-tray/pain-in-the-a$$ do?

All of this testing will cost somewhere between $3000-$4000. I don't have the budget this year to cover all these costs myself, so I am looking for some partners to share in the knowledge gained as well as the cost. Although I like to keep a few secrets to myself - I really like to help out the greater EVO community by sharing knowledge I've learned. Each person who participates in this test will agree not to share the information learned publicly, but we will decide as a group what to share for the good of the community. . .

Additional parts I would be interested in testing include a full Voltex Cyber edition splitter/bumper package (assuming no one can get ahold of VOLTEX's wind tunnel data. . . ahem, Driveline are you listening ), any APR or other brand wing, any rear diffuser/bumper combo, small side mirrors. . . . any piece that you think may give a measureable aero advantage.

Cost sharing will be $150 for full access to all the data. Anyone or any company wishing to sponsor a part to be tested will be $450 per hour for actual testing time for that part (or A2's going rate at that time), plus the $150 if you want access to the full data to compare your part vs. other setups. No information for paying vendors will be shared with ANYONE except that vendor unless authorized. I will sign a confidentiality statement if needed.

Anyone interested please let me know and I will add you to the list. No payment will be taken until the actual test is scheduled. Also - if there are other variations of parts you want to see tested let me know and I will work them into the mix. . .

NOTE TO MODERATORS AND ADMIN - I am not taking any profit from this. In the case that I have more paying parties than the total cost of the testing, the difference in cost will be refunded to each paying party. I don't see that happening though. . .

Also - any shop or company who is interested in sponsoring part of this test please PM me. Your shop will get the full results and also be highly promoted as a sponsor to the EVOlutionary EVO IX Project. . .

EVOlutionary

jid2

iTrader: (62)

The Voltex wind tunnel info is available. I have all of it...
http://www.youtube.com/watch?v=kqjKxDFEK98

Read every page of this blog.
http://voltexsuzuka.blog12.fc2.com/

I also have a white paper on the stock undertray, it's pretty seriously designed.
http://www.myevo.com/Lancer%20evo%20VIII.pdf

I also think my v2.0 for chassis data logging is going to be able to measure downforce with resolution in the1-5 lbs range.

EVOlutionary

iTrader: (38)

I have seen the video and translated the #'s from that - but the other two are great reads!! Thanks for pointing me in the right direction!

DaveK

iTrader: (21)

Pics of V3.0? I'm assuming this is different from the 3d setup I ran last year, and David and I had chatted about different options for this go-round. I'm just curious if you've already got a setup in hand? I'd be more than willing to send out what we used last year, but I think his new stuff will be superior, so not sure if its worth testing.

I'm on a tight budget, but I may be able to contribute to help get you into the tunnel. I was just planning on heading out to the track and making changes to the stuff I've got, and just basing my final settings on what yielded the quickest lap.

Thanks!

Dave