Design Car Wings: Aspect Ratio, Shape & Cross-Section

[hanson]

Hi all!
I am now working on a design project on car wings, but I don't even know where to embark on.
Our team is designing a race car. Could anyone provide information on what to design for a car wing?
I have searched in the internet and found several parameter like aspect ratio. Butwhat about the shape and cross-section of the wing?
Could anyone provide some reference?

 

[FredGarvin]

What level of schooling are you at?

 

[hanson]

I am jusy a sophomore~
I know that it is nearly impossible to design a real racing car.
But I think the project aims at enabling us to taste the design of a race car.

 

[FredGarvin]

A sophomore in high school or college? Sorry to keep bugging you with this question. It sometimes makes it easier to help if we know where we can go to in what we look at.

 

[brewnog]

What's a sophomore anyway?

 

[sid_galt]

Sophomore = second year

Sophomore in high school = 10th grade (In US school systems)
Sophomore in university = 2nd year

 

[FredGarvin]

Not to derail the post, but Brews! How the heck are ya?

 

[brewnog]

I'm good ta, just finished a week's ProE training, and started my placement in design on the dreaded cost-down. Been a bit car'ed out lately, the Citroen conked out, and it took them a week to trace it to a broken wire in the ECU, and then the exhaust fell off the Lotus, twice. Been avoiding the subject of automobiles for a while!

Ok, car wings. It would be helpful to know what sort of vehicle you're designing them for. You say a race car, but that's a bit vague. There's a chance you'll legally have to fully cover the wheels (so that viewed from above, no tyre is showing). You'll also need to make sure that you can achieve full suspension and steering movement without the wheels (or any running gear) fouling on the wings at all. Finally, there's the aerodynamic issue, - my Lotus has swept clamshell wings which catch a cushion of air beneath them at about 70mph, causing the front end to lift up. It's not a pleasant feeling losing front end grip at those speeds! Finally, you've got all the usual design parameters to think about; weight, stiffness, vibration, durability, manufacturing, cost.

There's your starter for ten, anyway.

 

[Cliff_J]

hanson, the wing creates downforce based on the amount of air deflected and the shape is largely responsible for the amount of drag experienced. It would seem in many racing circles that the level of drag is not as important as the sheer downforce generated. There are many charts on the lift/drag of many different wing cross sections available at different angles of attack, you should be able to use those to come up with a wing that fits the design requirements.

You likely also already know how the square of the velocity plays into the downforce generated and so on, but have you also factored in how it affects the chassis and handling?

Simplified, the wing applys a force to the near axle and will cause a lifting force to be applied to the far axle (obviously assuming the wing is outside the wheelbase). Thus the front and rear wings need to be balanced to ensure the handling does not change radically when the aero loading is present.

So now you have the balance of putting the wing in "clean air" as brewnog suggested above (no obstructions) and location on the car and size/weight and racing regulations.

And depending on the type of car and racing, like say the high-G contests for cornering forces, active downforce like McLaren used in Formula1 in the 70s with fans and a skirt to create a "reverse hovercraft" of sorts can accomplish a lot more downforce at low speeds.

 

[brewnog]

Ohhhhhhh, that kind of wing! Oops...!

 

[ray b]

And depending on the type of car and racing, like say the high-G contests for cornering forces, active downforce like McLaren used in Formula1 in the 70s with fans and a skirt to create a "reverse hovercraft" of sorts can accomplish a lot more downforce at low speeds.

that was first used on jim halls chaperal in can-am [unlimited sportscar]
and later on a brabham in F-1 racing not McLaren
and quickly banned under the moveable airo device rules
btw skirts are now banned too

there is a school base SAE program for uni's to build and race cars
thats most likely what he is up to
but consult the rule book as most good tricks are banned in most classes

a quick google at F-1 cars or lesser formula will show wing shapes used

 

[Cliff_J]

Thanks Ray - that all happened before my time...but I think I'd still love to see a Porsche 917 in action, those were seemingly the most brutal Can-Am car out there. And McQueen gets to drive one to make a movie!

Would have been wacky stuff to experience though, like some of the F1 cars with 2 pair of tiny front tires in the 70s, turbos that lasted for only a few years in the 80s, the active suspension in the early 90s and so on. I guess the current big changes are the (former?) domination by Schumacher and advances made in the tires, well for a couple more years anyways until Michelin bugs out.