NukeC5

Now and then I toss around the idea of trying to reduce drag behind the vehicle. Does anyone know if one of the stick on lip style spoilers a lot of vette owners get help in any way? Or does it have to be a wing to have this effect? Seem like I've seen dragsters use long flat lips off the back on various old school muscle cars. But I know a wing high up is what really changes the air flow over the vehicle.

I know areo is a difficult concept for a lot of people. But anyone with anything intelligent to say, I'd like to hear your insight.

frsr06

As i understand it, spoilers on the rear of a car are not intended to reduce the drag - its too late as most of the air has already passed the car. Rear spoilers provide a downward force keeping the rear of the car on the ground for better traction. The normal force of air will cause an uplifting reaction on the car. Look to the front spoiler and shape of the car to reduce the drag.

road pilot

Reducing drag is a good thing. Increasing downforce is a better thing.
The stick on spoilers can increase down force. But unless there has
been some R&D it's probably just to look pretty. The problem with wings is that they can increase drag rather than increase down force.
A wing has to be above the disturbed air coming off the roof. That's
why you see them high (and above the roof line) on many cars.
When I drag race I take the wing off because of the drag. When I
track race I reinstall the wing for downforce esp.. going around
curves. Just to make things more complicated--depending on the
length and how tight the track is I change the degree of the wing
from flat to as high as 10% off center. Why, for more down force.
It depends on what your car is being prepared for. Drag race, track,
autocross.
Another down force product is a diffuser and cunards. All to
increase down force, more grip is good.
Start reading aero literature , there is a lot to learn. Good luck.

NukeC5

I have a decent understanding. The car is a dragster. I'm not necessarily concerned about down force, and I don't want to sacrifice top speed for down force in this type of racing..

But as I understand it, the drag behind vehicles in effect holds the car back a little right? So if I was able to basically "cut" through the air with less drag, the car would theoretically go faster right? Now I'm not sure a spoiler would help at all.. But if a simple lip off the back could help with this, I'd be interested. I'm not the type to do wings and body accents unless it's functional. So if I can justify a spoiler, I don't mind doing it..

3sACROWD

As I understand it, the long flat spoiler is to reduce drag by moving the point of intersection of the air from above and below the car to a point further rearward and less turbulent due to the air from under the car having a chance to "straighten" out.

NukeC5

This is my logic as well, but I'm no expert. A lip type spoiler would probably be minimal, but any little bit pointing slightly up an back must have some kind of effect.. Maybe I'll take some time and look into some custom designs. See if there's any drag specific designs out there. The long flat type I have in mind.

NukeC5

Here we go.. just what I have in mind

http://www.fastracecars.com/categori...rvette-10.html

http://funny-pictures.picphotos.net/...Bcorvette.jpg/

Corvette_Ed

I'm not as well-versed as some here on the aerodynamics, but I believe this type of rear wing is used to cut down on the drag from the chute assembly. I might be wrong, but I can't recall seeing any car without a chute using that type. If you have a chute, however, this would be the perfect thing for you.

4DRUSH

Ed Quay makes nice spoilers

http://www.edquay.com/spoilers/FBW1/index.html

NukeC5

The one they make for the C5 is pretty awesome. I'd rock that on the street too haha.

Can anyone verify that those are specifically for parachutes? Seems like shoot or not, the drag should be reduced with something coming off the back like that.

LSOHOLIC

I'd start with the huge amount of air that gets trapped under the hood at speed. Look at any pro racing vette program...all run a vented hood of some type and I'm willing to bet it aint for looks. Lots of wind tunnel time, if your going to imitate....imitate the best.

A good yarn test with a gopro can show you a bunch.

NukeC5

That's true too. Do you think sticking on a common aftermarket hood like the ZR 2 edition would have this effect?

StatmanRN

Some pretty fast pro-mod guys have said the long flat spoilers are more to do with keeping the car staight at speed. The flat angle minimizes drag and the lenght provides leverage for the downforce. How much of that is based on wind tunnel testing or on hearsay I dont know.
The factory had a wing type spoiler option availible for a while, which is copied by someone in the aftermarket. [ACI?] I wonder if GM did testing did testing on that.
Really? for most of us its about the look if we are honest. Serious racers excepted of course.

NukeC5

Well I have a hypothesis that I want to test. And I think it can be done without wind tunnels. It's simply that you can see the effects of drag by the dirt build up these cars seem to get a lot of. I've never had a car that gets so much dirt build up in the back and below the tail lights and license plate area. This shows clearly that there is quite a force pulling back towards the car. The dirt is the left overs from this direction of flow.

If putting on a long flat spoiler brings the point that the air from the top and bottom meet far enough back that it doesn't have a chance to suck up to the back of the vehicle.. Won't that mean it's cutting through the air better?

The point of this of course is to have a lower coefficient of drag down the drag strip. But if I can see less dirt build up or possibly a difference in instant fuel economy read outs after some testing, then it would be a safe bet that the car is now more aerodynamic right?

Corvette_Ed

The added weight might cancel out any fuel economy benefits.

The GoPro and yarn sounds like a good idea to me.

NukeC5

I wanted to see your opinions on this wing. Its an APR-GTC-200 drag specific wing. Though its mostly for sport compacts, it should do good on the coupe because of what it says about a low roof and gradual slope to the rear.

APR is a pretty good company and has wind tunnel results to back up their claims if you search around the site. This one in particular is designed to reduce drag, not so much for down force, which sounds perfect for a dragster. It's of course a light weight carbon fiber design.

I know the GTC-300 and 500 are popular road race wings for the C5 and C6. But I just dont need a high rise wing, and the cost is a lot more.

Wing:
http://aprperformance.com/index.php?...d=51&Itemid=44

Data:
http://www.aprperformance.com/index....sk=view&id=342

wcsinx

Spoilers, strictly speaking, increase drag. They do not reduce drag nor are they intended to. They're converting some of your forward energy into down force. And the C5 already has a very low coefficient of drag ... lower than both the C6 and C7.

The big flat things you linked aren't actually spoilers. They're more "deflectors" really meant to keep the chute junk from creating turbulence and/or messing up the laminar flow.

NukeC5

I appreciate the insight. However, they claim that this wing reduces drag. Do you have a way to verify that that is incorrect? I would defiantly not be into buying one if it was simply impossible to do so.
But theoretically, if the wing is set to 0 AOA, it's not going to hold the car back much from top speed and allow it to pass through the air with less turbulence behind the vehicle. I don't know the facts, just the basics, that in effect, there's a force that's kind of pulling (I guess that's the drag) that's like several pounds of holding back force that the vehicle is dragging and that increases with the speed.

Supposedly the wing is designed to make the air travel over the vehicle in such a way that it reduces the effect of all the force that's behind the vehicle. So you would be faster with less drag right? Obviously to maximize the effects, a front splitter and ideally a rear diffuser would be used in conjunction. I'm not ruling them out. But interested in starting with the wing.

That's if it really does make sense to do so..

wcsinx

Think of it this way. If you want to create a down force, where does that energy come from? You don't get something from nothing. The energy that a spoiler redirects to create down force manifests as drag on the vehicle. It's just like sticking your hand out the window and then angling the leading edge down. Your hand gets pushed down, right? But it also gets pushed backwards, and you have to fight to keep it in the same position. That's drag.

So if you angle a spoiler as such to minimize drag then it begs the question why do you have a spoiler in the first place if you're not generating any downforce with it?

Now bear in mind I'm still talking about spoilers. The things you linked really aren't spoilers. I would be curious to see their data which substantiates their claims. Without a lump of equipment back there, I can't see that such a device would help anything.

NukeC5

Hmm that makes sense, but what if the stock design is creating enough drag that a wing like this, though you are physically adding something, is simply redirecting the air so that it actually makes the entire car have less drag? I know anything on the car will have some drag, including the wing, but what if the wing's little bit of drag is compensated by fixing the drag for the entire top of the car, windshield base and up for example.

Like I said I'm defiantly not up to speed on all this nor am I arguing this. It just seems like the theory behind it. Looking for as much insight as I can find.