Real rear wings

[da9jeff]

Just looking for any information about efficient wing profiles that have been successfully used and tested in motorsport. Websites with actual profiles and general theory would be great. Are there any wings available in australia that are proven to be worthwhile ie. wind tunnel tested?

Im interested in making my own wing in either cf or frp and would mainly be a interesting project (researching, designing, manufacturing, then testing) rather than a "how to look like a tool for $150" kind of thing.

Ive tried google but turns up mainly shit.

Thanks,
Jeff Scanlan

[PLAYA]

At a guess you would want to start with a search for sae papers etc, use a good journal library like compendex. If you know someone at a uni they have access to it on their computers.

[GTSBoy]

http://www.google.com.au/search?clie...=Google+Search

[Zac]

Books are still the best for this. I have just had a quick look in Katz for you but there are no simple 4/5 digit NACA examples with heavy camber. If you want an uncambered one then i can give some examples and then you can just give them angle of attack to produce downforce. The NACA 23012 is popular.
GTSBoy recommends them because they are quite well in the public domain (I'm guessing). Here is a calculator for 4 and 5 digit:
http://www.ppart.de/programming/java...les/NACA4.html
http://aa.nps.edu/~jones/online_tools/panel2/naca/

Here are some other profiles known to be used in motorsport, this time with cambered profiles and pressure distribution graphs:
http://www.benzing.it/enrico.profili.htm

[da9jeff]

thanks for that.. shit there are alot of profiles!

ive looked here: http://www.ae.uiuc.edu/m-selig/ads/coord_database.html

and these aerofoils:
e421.dat \ Eppler E421 high lift airfoil \ e421.gif\ \ \
e422.dat \ Eppler E422 high lift airfoil \ e422.gif\ \ \
e423.dat \ Eppler E423 high lift airfoil \ e423.gif\

The words "high lift" made them look interesting, is this anywhere near the mark?

Ive heard of people using chopped up helicopter blades as car wings but i would have thought the profile would be designed for much higher speeds than a car would achieve - or is it more to do with angle of attack?

edit: THanks zac, yeah i reckon ill buy or borrow some sort of book. my interwebs just aint up to scratch

[Billzilla]

Ive heard of people using chopped up helicopter blades as car wings but i would have thought the profile would be designed for much higher speeds than a car would achieve - or is it more to do with angle of attack?

They'd suck badly - too heavy and too symmetrical to make enough downforce without having quite an angle of attack on them.
Take the time to work out a proper profile and make one, it'll be worth the effort. Also put some effort into designing the end plates, there's a bit in that as well.

[Zac]

I guess you could say there are an infinite number of profiles!

[Billzilla]

and these aerofoils:
e421.dat \ Eppler E421 high lift airfoil \ e421.gif\ \ \
e422.dat \ Eppler E422 high lift airfoil \ e422.gif\ \ \
e423.dat \ Eppler E423 high lift airfoil \ e423.gif\

Yeah something like one of those would be good.
I like the e420 myself.

Also look at Gurney flaps for trimming the downforce - When we first put the wing on the back of my racer (re: rule change that allowed them for the first time) the front of the car had little downforce and the car understeered extremely badly. For that days testing we had to keep on reducing the angle of the rear wing until it was nearly flat - I suspect the only downforce we were getting was the weight of the wing!
But the front end is now much better and we've actually run out of angle on the rear wing and I'm thinking of adding the small gurney to it that it used to have before we removed it.

[Zac]

Also what car do you have and what rules do you have to adhere to?

[da9jeff]

They'd suck badly - too heavy and too symmetrical to make enough downforce without having quite an angle of attack on them.
Take the time to work out a proper profile and make one, it'll be worth the effort. Also put some effort into designing the end plates, there's a bit in that as well.

thanks. how would i go about working out which profile? is there an easy calc where i can enter dimensions, lift target, aoa range etc and get a profile spat out? or is it just research?

Zac: that comment made me feel a bit silly

[da9jeff]

Also what car do you have and what rules do you have to adhere to?

dont laugh.....the honda. But after this process i would hopefully have the knowledge to apply this to any future, far more serious racing endevour.

Aero is something ive wanted to try for a while, who cares if the car isn't fast enough to really need it. And if I get any measureable benefit to my lap time or even just the ease of driving (which should equate to lap times) It would be a great bonus

[Billzilla]

thanks. how would i go about working out which profile? is there an easy calc where i can enter dimensions, lift target, aoa range etc and get a profile spat out? or is it just research?

It'll be a bit of hit & miss at first - if only because you probably don't know how much downforce you want on the rear.
The reason I say that is bcause on a car like mine, the front is made so that the downforce increases at pretty much the same rate as the rear so that the car doesn't start to do strange things at different speeds.
So, if you've got a conventional sedan-type car with naff-all downforce on the front then you're not going to be needing much from the rear.

If that's the case then I'd suggest just a small wing, and play with it from there. Just make a cheapie and experiment .... You won't really feel any difference much under about 100km/h odd. Use a heap of cotton thingies to see what the airflow is doing; it's quite possible that if the wing is too low that the airflow off the back of the roof will be flowing over it nicely at low speed (where there's not enough airflow to make it work well) but then start to break away off the top of the roof at high speed and so still not work.
There's a lot of fiddly shit to know.

[da9jeff]

"quite possible that if the wing is too low that the airflow off the back of the roof will be flowing over it nicely at low speed (where there's not enough airflow to make it work well) but then start to break away off the top of the roof at high speed and so still not work."

do the things on the roof of a 07 wrx work? or are they just boy racer crap?

[Zac]

ah a Honda, I forgot that i had turned signatures off!

[Nero]

Not the next but the issue after of Race I will have a DIY wing section. I am making wings for a Sports sedan at the moment.
E423 is excellent for a single element wing.
What do your rules allow and how much excess power do you have?