Wing Profile Recommendations

I plan to make a rear wing for my crapcan/Lemons/BMW CCA E36. Does anyone have any good recommendations on profile (NACA number) width and chord?

Thanks

Joe

Sprint car swap meet?

I have ordered foam wing cores to cover in fiberglass as big as 72" long, 12" wide, and cut to E423 profile. Hope this helps. T

There was a wing profile called out in one of the LeGrand updates.

Gasoline has it--E423 is a wing profile that works best under 100mph....pretty draggy with high downforce.

Kind of a neat site is: Airfoil Investigation Database.

http://www.worldofkrauss.com/foils

You can pull up sectional wing profiles to your heart's content. Go to Browse, E, and you can see what E423 looks like.

T

Per Schroeder wrote: Gasoline has it--E423 is a wing profile that works best under 100mph....pretty draggy with high downforce.

Per - Any opinion on if it would have been easier / cheaper / more of a PITA / less of a PITA / etc. to skin the foam cores with thin aluminum?

Hmm--that's certainly do-able, but you would still need to bend the aluminum to conform to the concave portions of the profile--especially on a highly-cambered profile. If it was a more traditional symmetric shape, then I'd think it would be pretty easy.

DILYSI Dave wrote: Per - Any opinion on if it would have been easier / cheaper / more of a PITA / less of a PITA / etc. to skin the foam cores with thin aluminum?

In my humble opinion, it would have been more of a pain in the ass to skin the foam in aluminum.

The trick with skinning a wing in any metal is connecting the ends. Engineering to Win has an entire section solely dedicated to this. If done improperly, really strange things can happen.

If skinning in Carbon Fiber is too rich for your blood, I'd look to fiberglass. Just make sure your foam core is reasonably braced internally. Also, if the supports for the wings aren't space appropriately (or made correctly) the fiberglass will stress fracture pretty rapidly.

And fwiw I would use E216 w/ a gurney flap for any speeds higher than 100mph. There are many other good profiles, but E216 is a good balance between lift/drag.

A more efficient profile is MH 115 11.06% (An L/Dmax of 85) but it requires a more aggressive angle of attack. I would also use a gurney flap with it. The reason MH115 is tricky is because it's best at the very limit of stall. So local airflow makes a big difference.

E216 should be mounted between 4-6 degrees (w/ gurney). Where MH115 should be mounted between 6-8 degrees (w/gurney). Without a gurney, the max angle is the lower of the two suggested values.

Also, their angle of attack is with reference to local airflow...not with the ground.

Call me old fashioned, but I still like the Clark Y.

Gasoline wrote: I have ordered foam wing cores to cover in fiberglass as big as 72" long, 12" wide, and cut to E423 profile. Hope this helps. T

From?

flyingfoam.com

Per Schroeder wrote: flyingfoam.com

After reading, you have inspired me to try bagging one in carbon fiber.

I had planned on using a medium cure and Peel Ply/absorber cloth, but you did not. Any reason I should avoid the PP/cloth method? All I can think of is the vacuum pull on the absorber cloth may distort the long fragile wing foam shape? Over thinking?

In the end, I'm hoping the Peel Ply finish may require less sanding/finishing......

From what the engineer that designed my wings told me if the profile is right adding the gurney flap is a step backwards.Same goes for the multi elements,with a monkey see/monkey do attitude I asked him to work up a multi element set-up and he flat refused.With the right profile a single element will provide at least equal downforce with far less drag. Not my words,just restating what a guy that designs wings for living shared with me.

We just made a fiberglass wing with a foam core for the Wreck Racing miata for the Ultimate Track Car Challenge. The S1223 airfoil profile is what we selected and is pretty good for low-ish reynolds number applications like you'd see in a Lemons application. It's a recent favorite in the heavy lift model airplane competitions for this reason. However, the deep camber can make this profile more difficult to fabricate.

For something like Lemons where there's no restriction on the size of the wing, you should design a very large single-element airfoil. You can use a less aggressive (less cambered and lower angle on attack) wing that will give you lower drag. You'll take a hit on your lift coefficient but you can make up for that with a larger surface area (bigger wing).

Also, if you properly design and constrain the struts for the wing you can make them very small and light.

Agressive wing shapes like E423: So I was on Ebay and no one bid on these carbon fiber "Wings". I contacted the seller and purchased them for a little more than shipping. F1 Benneton and Williams wings about 1994?/95ish.
When you look at them, I was suprised that they have very little "wing" look about them. There is very little or no upper camber. It is all about scooping the wind for downforce. They get alot done in a little width. I had expected a more slippery shape on a 200mph car. Anyway I feel pretty good with E423 and less wondering about a more slippery profile. My 2 little cents.

Thanks guys this is great help, I will post my final creation when completed.

Joe

In reply to JohnyHachi6:

What chord size did you go with and width?

I should've shown my wing in foam.Excuse the messy shop please.

We used a 14" chord and I believe it was a 62" span.

Thanks!