How to start designing a multi-element wing?

[weis]

Hi all,
i have figure out how much downforce i need in front and rear. i have search many websites and books. I did find some useful websites which provides the airfoils profile. However there's no CL provided for the profile.
I do not know which naca series to use for my multi element wing design. does it mean that i have to run the analysis myself to get the CL of the series?
I read from the previous post that naca23012 are commonly used in motorsports. Are the airfoil profiles in multi element wing usually the same?and only AOT and height are different?
Please forgive me for my ignorancet, this is my first attempt in aero design. i promise will share my analysis result/design in near future.

Thousand Thanks again!

"competition car downforce" - Simon Mcbeath

Like Simon points ou in his book on a first simplistic approach though you have 2 alternatives!

First - figure out the amount of downforce you want (don't look at drag now)...grab the wing width you want....through a simplistic calc you can figure out the CL of the wing.....then grab a airfoil profile catalogue and take a look at the profiles there....and choose the one that best suits you.

Second - if you have the the Hp of the engine...you can determine the amount of Hp you're willing to sacrifise for drag (hp at the wheels not at the flywheel...so consider the losses)...with this info you can calculate the Cd of the wing.....and going to the catalogue once again.....

You can also include the weight distribuition in order to know what the diference of downforce is between the front and back to maintain an aproximatly the same amount of diference between downforce at the front and rear, and weight dist front-rear.

After this I'd say.....go to a 3D design software....and after that start CFD testing....untill you find reasonable/expected values! Then tweek with the wing shape...position....kinds of profiles.


The first approach actually is my own approach (didn't read it)....the second one came from the book! I prefer to start with the downforce even if it compromises drag and then try to eliminate drag....

[Monstrobolaxa]

Well I like the 23012 at least as a start it seems relativly good!....an it is very good with 2 flaps....

The answer...about the other question....yes probably you'll have to run through a few catalogues to find a airfoil....and do the math.

[ah_chu80]

Hi... i am a university student from Tokyo. I am interetsted paticulary in the arodynamics of front wing. i am wondering, is there any aerodynamic consideration behind utilisation of the spoon-shaped front wing? or merely to meet the new regulations? or other structural considerations? Are there any effects on the front wing characteristics and the rear part behind the front wing? what is the merit of using a spoon-shaped front wing compare to a flat one. Your infomation and guidance will be appreciated. Thankyou.

[Guest]

Race car aerodynamicists do not use aerofoil sections from catalogs. As mentioned by one of the guys here, design your own aerofoil section. It should be noted that when you optimise your wing section for maximum downforce and minimum drag in say free stream, you will need to optimise it again when it is with close proximity to the car etc.

The books mentioned before are quite good and I believe you should use them to design your initial design.

Hope this helps and good luck.

[Monstrobolaxa]

Well that is true in F1....but the 23012 is used in Champ Cars....

Another kind of airfoil widely used in Formula 1 are the Be airfoils.....Be as in Benzing....

I contacted Benzing (the creator of these airfoils) a while back and he mentioned at least 10 Be airfoils that are still used in F1! But he mentioned there are a whole lot more!

Most top end racing categories that have free development employ aerodynamicists that spend their time developing airfoils! In the lower formulae, in controlled development categories and in single make categories NACA airfoils are widely used.

The Benzing airfoils can only be found in a book called: "Ali/wings" - Enrico Benzing....but it's out of print!

So you can try: "Dall'aerodinamica alla potenza in Formula 1" - Enrico Benzing.

Mr. Benzing mentioned that there won't be an english version...but the most comunlly Be airfoils used in F1 are in the this second book. Though not all the airfoils are published in this new book.

You can find more info on the airfoils on the following site:

http://www.benzing.it/enrico.profili.htm

[Guest]

Indeed, Benzing aerofoils are used by different teams with low budgets, however it is worthwhile mentioning that most teams try to optimise Be aerofoils. Most of the Be aerofoils are designed for laminar flow at the tips avoiding turbulent boundary layer at the aft region of the aerofoil. As a result it produces attached flow allowing more downforce to be generated.

As a starter I would prefer using the Be aerofoil sections.

[pranav]

Hi guys!!!

I need some urgent help. I want to design a rear wing (airfoil) for f1 car. My professor has told me to look at the following things.." explain how you determined the size and profile of your wing.. Presumably you looked at things like required downforce, required wing performance (as opposed to that from the underbody etc), the constraints etc. From this you presumably derived wing profile and size". can anyone tell me exactly what I need to do to meet the above requirements? which calculations need to be performed. and what equations need to be followed? if any....
Can someone please help me out with this as currently I dont have access to any aerodynamics related books.

[machin]

Can you get hold of the excellent book "Competition Car Downforce" by Simon McBeath? (NOT the follow on "Competition car aerodynamics" by the same author). I'm sure Amazon can deliver very quickly if you need it..... It has a step by step process to follow, and example wing charts to use too.....

In short (from memory!):

1.Select the top speed you want the car to have.
2.Determine the power required to achieve this speed
3.Subtract engine maximum power from the power calculated above. This is the power you have available to overcome the drag from the wing.
4.Start off looking at a single element wing (this is cheapest and simplest to manufacture). Set the width to the maximum you are allowed (or physically fits on the car!)
5.Determine the wing area required for this wing to absorb the power calculated in step 3.
6. Determine the chord required to achieve this area with the span you've already set. I forget the ideal ratio, but you don't want the chord/span ratio to be too big as the wing will be less efficient. If the span/chord ratio is too big, or the required angle of attack is so high that it is near its stall point then go back to step 4 but this time look at a two element wing (then 3 element and so on), until you have a wing which absorbs the power you have available, whilst still having a low chord/span ratio and is at an angle of attack away from the stall point.
6. Use this area and the CL to determine the downforce available.
7. ideally you want to run modelling software to determine the best trade-off of downforce to top speed against lap time.
If you can't do any modelling then you'll have to run the car and see what wing angle setting gives you the lowest lap time, which is why its sensible to make sure you're not operating near the wing's stall point.... (as you don't want to find that your lap times will come down if your wing gave you just a little bit more downforce, but you can't do this as its too near its stall point).

[pranav]

thanks a lot machin. really appreciate it.

[Conceptual]

Here is an excellent little java applet that will calculate a NACA airfoil profile for you according to the pareameter you choose (max camber etc.)

http://www.pagendarm.de/trapp/programmi ... NACA4.html

Now if they only had a direct import to CATIA, I would be all set!

[Monstrobolaxa]

I imported over 400 points for each of the 5 airfoils I tested...had to put the x and Y measure.
There are some macro/excel direct importers but most of them don't work too well!

[Zweeper]

A question from my side is the following:

what is the best way to determine the angle of attacks from the different airfoils?

Should i start with the main wing, then with the flap and at last the lower third wing? (three wing profile)

Or are there other and better ways to get started with this deal?

Kind regards,

Zweeper

[ringo]

There is a program called X foil. It calculates Cl, Cd an Moments charts for any profile and any reynold's number provided you have the profile's coordinates.
Good luck finding it; but you can also google search for provili , it's basically x foil with a more user friendly interface. X foil runs in MSDOS or command prompt.
These are very helpful.

[rDynamic5]

I would definitely recommend you read Competition Car Aerodynamics. That gives some good guidelines for you to start out with for both single and multi-element wings. After that, Race Car Aerodynamics is a good second book to read, it is slightly more technical and it covers a lot of things CCA doesn't. Although I have to say that CCA actually covers some areas better in my opinion. Those two books should give you a good foundation and research papers along with the references should help round out a basic understanding of race car aerodynamics.

[smak]

Well that is true in F1....but the 23012 is used in Champ Cars....

Another kind of airfoil widely used in Formula 1 are the Be airfoils.....Be as in Benzing....

I contacted Benzing (the creator of these airfoils) a while back and he mentioned at least 10 Be airfoils that are still used in F1! But he mentioned there are a whole lot more!

Most top end racing categories that have free development employ aerodynamicists that spend their time developing airfoils! In the lower formulae, in controlled development categories and in single make categories NACA airfoils are widely used.

The Benzing airfoils can only be found in a book called: "Ali/wings" - Enrico Benzing....but it's out of print!

So you can try: "Dall'aerodinamica alla potenza in Formula 1" - Enrico Benzing.

Mr. Benzing mentioned that there won't be an english version...but the most comunlly Be airfoils used in F1 are in the this second book. Though not all the airfoils are published in this new book.

You can find more info on the airfoils on the following site:

http://www.benzing.it/enrico.profili.htm

What do the numbers of these be airfoils mean like 122-155 and 153-175
NACA four digit series has a particular meaning like camber and chord percentage. So what do these numbers mean.

P.S. This is such an amazing post. Helping me immensely