EVOlutionary

iTrader: (38)

SORRY - I NEED SPELL CHECK. Topic supposed to be AERODYNAMICS. Don't know where that stupid 'T' came from . . .


Hello All,

Just need some input regarding aerodynamics/physics and a general concept I am trying to understand.

If you have a wing in the front of the car, it adds downforce to the front (F1).
If you have a wing in the rear of the car, it adds downforce to the rear (EVO).
If you have a wing mounted to the top of the roof in the center of the car the downforce should be spread approximately evenly from front to rear.

Ok, now, what if you had a wing mounted so that the wing body was over the roof of the car, but the wing supports angled back so that the base was mounted to the rear decklid/trunk area.

Thinking back many years to my physics class and Vectors and such - when the air flowing over the wing tries to push it down, is that downforce applied at the attachment point (trunk), or because the wing is in essence mounted to a big lever is that downforce applied at the location of the wing body?


EVOlutionary

Varrius

iTrader: (1)

If you had it over the roof of the car, it would apply more downforce then being on the rear. However, the roof isn't trying to get off the ground. The rear-end is. So the downforce isn't needed on the roof. Not only that but the wind pushing the wing down on the roof would create more "technical" weight on the roof of the car, lowering its handling performances. In the Evo's case, the rear-end probably doesn't try to get off the ground as much as a rear-wheel drive car.

ez

iTrader: (15)

The force is transmitted through the attachment point(s). The location of the wing merely changes how the force is applied.

In your scenario, the vertical force still applies but you introduce a horizontal torque on the mount which will try to pry the mount off the car. It the wing is big enough and the mounting is strong enough, this scenario would also transmit torque forward along the horizontal axis of the car resulting in measurable downforce applied to the front wheels as well.

There quite a few variables of course...

Ahnospell44

well, to see a good explination of your front wing rear wing go take a look at the audi S1, there has never been another car *short of ricers* that has had as many aerodynamic wings, of course it was a B-Class rally car but still. If you added a Wing to the roof it would infact create more problems then it could be useful. You could instead put aero guides over the car like the vortex fins, that would achive the same thing to keep the car true with enough force being generated to keep the car to the ground, that is your wing over your roof.

DaWorstPlaya

iTrader: (31)

+1 well said ... as ez said there will now be a vertical and horizontal force applied to the point of attachment that can be measure using the cos or sin of the angle depending on the angle measured. But if the wing is big enough I would think all the down force would be applied to the rear and not the front because I think of the rear axles as a fulcrum point, ofcourse this will depend on whether the point of attachment. If it is in front of the rear axles then what ez said will be true but if it is behind the rear axles then what I said would apply ... Hope that helps
Ps: I hope you meant aerodynamics

kingleh@GSC

iTrader: (3)

all cars have a wing that makes dowforce that spreads throuout the car.... its the entire body of the car.....


why wing front and back?..... increase overall downforce... and to Tune with.......


on a car like a evo..... the car itself should make the downforce and the wings be used just to tune.....

x838nwy

Should, being the word there.
I think the evo actually creates lift without the wing.

EVOlutionary

iTrader: (38)

Nice!
http://www.audianer.de/audi/historie/his_rallye_03.jpg


Thanks for the help guys. Didn't even think of the fulcrum point being behind the rear axle and all. Sounds like unless the forwardmost attachment point is in front of the rear wheels it will pretty much just push the rear down. Don't need that. I'm trying to brainstorm some ideas to get more downforce on the front wheels and working within a specified rule set. I can add or modify a rear wing, but it must attach at the trunk/rear deck.

Grafting an F1 style wing into the front bumper might help, but it might be considered a "tortured interpretation" of the rules (unless it resembled a "body kit").

EVOlutionary

EVOlutionary

iTrader: (38)

Next question - thinking of the rear wheels as a fulcrum point for the downforce created by the rear wing (stock location), if you had enough downforce would it in effect try to lift the front of the car?

So if you took off the rear wing, or heaven forbid created lift in the rear with an inverted wing, would that trasfer more weight to the front tires? This is all just theoretical, of course!

mayhem

iTrader: (9)

You could put that wing on the top of the car and create additional downforce, but at the price of additional drag. Benefits of the rear wing is more downforce and less drag, not in all cases, but in ours with the OEM wing.

ez

iTrader: (15)

The placement is a factor, yes, but the torque will certainly be applied along the entire horizontal axis.

But Playa's point is a good one because a placement behind the rear axle will mean the torque would have to compress the rear suspension in addition to the front.

So this means the wing and lever/mount would have to transmit a great deal more force to be measurable at the front than if placed ahead of the rear axle...

ez

iTrader: (15)

Yes, because the fulcrum is pushing against the ground which cannot move...

Not necessarily, because the rear tires are not solidly connected to the ground. So the lift will bear some weight and lighten the rear end...and the net effect is a lighter car. However, you *could* move more weight to the front if the process shifts the center of gravity any distance forward...which would likely happen if lifted enough.

trinydex

iTrader: (12)

wings are placed where they are largely for the fact that airflow must be accessible.

you wouldn't wanna put a wing on your roof because although the airflow is pure there it would cause an additional trail of turbulance which would effectively double your drag because you now have 'two' shapes moving through one flow as opposed to having one shape moving and creating one birdtail flow.

as far as increasing front downforce this is usually done with splitters canards and the like.

since you're limited by rules you'll do well to look into "bodykits" that include large splitters in the front integrated into the bumper. such kits include the voltex, veilside, varis, valdisport/test service, sumopower, etc. these bumpers have huge splitters on them and while looking very ugly they will give you a basis for additional downforce.

of course after getting one of these bumpers you'll have to seal off the bottom with an undertray of some sort so that you don't lose the air flow and high pressure zones.

https://www.evolutionm.net/forums/sh...d.php?t=201056

hotrod2448

Let's see he rules and we'll figure out a way around them. I do that for a living.

EVOlutionary

iTrader: (38)

That's what I'm trying to do. So far a front body kit similar to that crazy Audi looks like my best option.

Thanks Trinydex for the info. BTW, I just added a front splitter/undertray. Dramatic improvement is all I can say. More testing to follow, but I really never thought it could make this big of a difference at moderate speeds!

https://www.evolutionm.net/forums/sh...d.php?t=215186

Car now handles like a RWD car in the corners. Get on the gas and the rear end comes out! Before it would just push if I tried accellerating too early coming out of a turn.

EVOlutionary