Roof spoiler effectiveness

[Eatoniashoprat]

Originally Posted by beetle1303

Just to add something to what Eatoniashoprat said, the vorteces at the back of a car MUST EITHER merge to the back of the car OR hit the road and stay attached to it at some point. only then u have a higher efficiency. if they dont attach to either they just swirl around increasing drag/ allowing the one behind to get into slipstreaming...

If you're not concerned about slipstreaming the lip will still reduced lift though correct? It will not be as efficient if it doesn't meet the road and stay attached but you're still decreasing the area that the flow is not attached therefore decreasing lift.

Originally Posted by beetle1303

On the combined use part... i think that if u investigate/research/design a roof spoiler and a wing u can achieve maximum downforce by directing the vortices leaving the roof spoiler to be at a small angle to the wing. so u get rid of the laminar flow at he back, only to direct it onto the wing.

Chris

Kind of like the 2007 STi? I can't find a good pic to post

[effvee]

One day I'll have mine running. I hope it helps, my cay to hold the road.

I'm told the Remmele one does a good job, however I don't like the ideal of have something glued to my car, which add safety.

[beetle1303]

I feel the need to make smthng straight for the ease of everybody understanding:

Imagine, a wing mounted somewhere and air flowing through it. IF the wing's plate is flat (not the profile) ie is straight, like the ones in the pics in this post, the air leaving the trailing edge will flow straight, evenlt across the wing's width.

Vortices will be generated between the side plates and the wing's plate, and around the corners of the side plates. IE rule of thumb, vortices need edges, protrutions to be generated.

Eatoniashoprat,
you got it the other way round, lift is generated, by attached flow, or low pressure cavities...

Now, a lip may reduce local lift, and disrupt the attached air flow ( to the car's body), but how effective it will be depends on the angle of the lip, and its height,

effvee, am i silly asking or it is facing the front of your car???

Chris

[effvee]

Hi, its facing forward. I have seen many of us (including myself) trying to get it right. When I installed that lip (which is 1" or 25.4mm) height) my attempt is to force the air passing over the roof (heightest point on the roof) to not so much to cause drag, but rather push on the lip. I'm hoping for the force to aid in a down force, yes it will deflect upward, but push on the lip. I don't know what the out come will be, however I'm this works in con-junton with a front air dam. I did not like the ideal of have something glued on at 120mph weather it worked, worked good or just caused drag, go flying off and hit something. If I ever get that car running, I will post what it feels like at 120 going to Vegas.

Not only that, I heard somewhere that as air pass over the deck lid area at high speeds, there is lift of the rear deck lid, something like how a shirt lift up on the back of a motocycle rider. So I reversed louvered my deck lid to catch air and release it into the engine compartment and below the license plate.

[Wally]

I really like the deck-lid idea , but not so much the roof lip

[effvee]

Walter hi, well concerning the roof spoiler, I hope it works. If not, I'm down alot of labor and body work. Hay concerning the front spoiler, the one you modded from I beleive a Rabbit. How well did it work? I sure wish someone were to make a front spoiler some-watt less in width (ground clearence). I know the roof spoiler won't fly off though

[SilverBullet]

Anyone doing a flat plate under the car?

[Wally]

Originally Posted by effvee

Hey, concerning the front spoiler, the one you modded from I beleive a Rabbit. How well did it work?

It did look cool, but only worked a little compared to the Kamai front air dam.
Like you predicted, that really does work extremely well, even at lower speeds!