Aero rear wing Why not over the rear wheels?

[Breck]

Hey

I can't think of any cars/vehicles (with the exception of dirt track sprint cars, huge wing mounted in the center.. well maybe dragsters) who's rear wing is mounted directly over the rear wheels.  F1 cars rear wings (for example/ a car with a front wing) are mounted in the far aft, and the front wing is put there primarily to balance the car.  The downforce of the rear wing, mounted behind the axles would make the front end lighter, wouldn't it?  Wouldn't there be less lift on the front of the car, if the rear wing was mounted on top of the rear wheels?  Is that about maximizing down force with less drag (using leverage and smaller wings) and if it is, wouldn't there be less drag if the racecar didn't need a front wing to balance out the rear downforce?

Or.. Is it mostly about getting the Cp behind the Cg for stability?


Breck

[Tman]

Dude, you think too much, go cut and weld some metal

[maguromic]

The rear wing on modern race cars are designed to work with the under tray.  I personally liked the way  that McLaren (and eventually some others) used to duct the air from the cockpit to stall out the rear wing on the high speed straights  last year.  It was so simple that it was diabolically clever. Tony

[kiwi]

Most racing classes limit the height of the rear wing (for sedans this is quite often no higher than the roof). So the wings are placed rearward to try and get clean air.

[RidgeRunner]

Breck

I did a quick scan of the 39 pages that came up on your strangeholiday link you posted on the powered aero thread earlier today, very interesting.  My quick take is, like so many other subjects, the combinations of various components makes the differences.  In this case the various wings can be made to work in different ways when they are located to work with different body parts and styles of cars.  I will study the link and some of the referenced material more in depth when I get a chance, thanks for posting it.

TMan

A big weakness of mine as well, projects don't progress while I'm studying a subject beyond reason.....'puters don't help - far easier to sit where its warm rather than tug a cold wrench.....

                 Ed

[Breck]

Dude, you think too much, go cut and weld some metal

Maybe.  I am just Itching to build something.  Still trying to figure what that ought to be.

So the wings are placed rearward to try and get clean air.

Make since.

I personally liked the way  that McLaren (and eventually some others) used to duct the air from the cockpit to stall out the rear wing on the high speed straights  last year.  It was so simple that it was diabolically clever. Tony

F duct.  Pretty cool.
http://www.racecar-engineering.com/category/technology-explained/

Breck

I did a quick scan of the 39 pages that came up on your strangeholiday link you posted on the powered aero thread earlier today, very interesting.  My quick take is, like so many other subjects, the combinations of various components makes the differences.  In this case the various wings can be made to work in different ways when they are located to work with different body parts and styles of cars.  I will study the link and some of the referenced material more in depth when I get a chance, thanks for posting it.

TMan

A big weakness of mine as well, projects don't progress while I'm studying a subject beyond reason.....'puters don't help - far easier to sit where its warm rather than tug a cold wrench....

                 Ed

Ain't all that the truth.

Breck

[DocBeech]

Do you mean like this?






I have been looking into how to make a good set of front and rear canards for years. The only issue I have is not enough money for testing the design. You could start with Vortex Generators and move forward from there?

But I still need to test a front splitter, front canards, and vortex gen placement before I can move to rear canards.

[Breck]

Do you mean like this?

Actually more like these on the North American Eagle

http://www.landspeed.com/images/ras09/ras09f.jpg

link to the photo album
http://www.landspeed.com/gallerylist.html

Canards usually reffer to the little wings up front on airplanes, on DTM cars like the one you posted they reffer to the pieces that are rapped around the bottom corners of the fenders in front, maybe in back as well. Canard means Duck in french, although I have no idea how this type of wing got it's name.  I have never seen a duck with wings on it beak.  : ]

Breck

[DocBeech]

I found your origin: http://en.wikipedia.org/wiki/Canard_Voisin

It was because the first plane to utilize "Canard Wings" was said to resemble a duck in flight.

"Some early fixed-wing aircraft such as the Brazilian Santos-Dumont 14-bis and French Canard Voisin had tail-first configuration which were seen by observers to resemble a flying duck — hence the name."

[hotrod]

I would refer to those as "strakes" rather than canards.

http://en.wikipedia.org/wiki/Strake_%28aviation%29

Larry

[Blue]

The biggest reason to have an aft wing/spoiler vs. locating this above the rear axle is to take advantage of the forward weight of the chassis to weight the rear axle.  If the rear wing pushes down aft of the axle, then the physical weight forward of the axle is added to the wing downforce by the factor of the leverage of the forward mass distribution. 

Many of the current ALT and CC record holders use this to their advantage.  They're smart racers.  Look at the downforce distribution of the record holders based on their spoiler angles vs. vehicle configurations.

[Howard]

  :-)Just a comment that you probably already know. Nothing is free. Rear wings came to be to resolve traction problems under acceleration on high powered sports cars. Anytime you stick something out in the wind and try to create downforce, you are also creating drag.
In our sport sometimes it is necessary to make the car go fast but it is a bandaid to hide an inefficient car.
My opinion,
Howard

[manta22]

Locating a wing behind the rear axle increases downforce at the rear but in so doing, it creates a force on the front axle that is lifting it.

Regards, Neil   Tucson, AZ

[John Burk]

The height of top fuel wings turns drag into down force as long as the front wing is functioning . Sprinter wings do the same on the straights and in the corners the spill plates transfer weight to the inside tires . In a spin a tall fin on a lakester or streamliner could offset the resistance of the tires to keep it upright the way the body does on a roadster .