Presented by Nine Lives Racing
Johnny_at_NineLives
Johnny_at_NineLives New Reader
6/10/19 12:47 p.m.

All,

As the owner of Nine Lives, I will be making posts that give us a "Free" way to test aerodynamic items. Feel free to post comments and questions.  

This Img was sent to us over the weekend. the details. Corvette Zr1, Nine lives wing, dual element kit, on a Grid life Corvette that won its class. 

 

As you can see he has some smoke. the driver reported a rear-main leak,  it was cooking on the exhaust and thus the smoke. The smoke is coming from the underside of the car.  Normally the air over the top of the car will push down and try to fill behind the rear of the Corvette. in this picture, we are seeing the smoke not being pushed down, but instead being pulled up. This is telling us that the wing, although on top of the car is affecting the air under the car.   The way we make downforce is Slow under - Fast over. With the air being pulled from under the car this can speed up the air under the car and will increase overall downforce. not just rear. 

Setting your car on almost-fire isn't an ideal way of testing, it is helpful to see the movement. We can use water mist from a rainy day as well. 

 

bentwrench
bentwrench SuperDork
6/10/19 1:04 p.m.

Strings or ribbons taped to the car will show airflow.

There is a special "paint" that can be applied to the car which will "flow" and indicate airflow.

 

Regarding the picture. There is a low pressure area under the wing and behind the car, air exiting the underside will tumble behind the car.

I'll bet there was oil on top of the rear bumper too...

wvumtnbkr
wvumtnbkr UberDork
6/10/19 1:32 p.m.

That car looks like it has a diffuser.

 

That paint can be made easily with 3 in 1 oil and bright powder paint.  

 

We call it ghettoviz.  Works pretty well.

sleepyhead the buffalo
sleepyhead the buffalo Mod Squad
6/11/19 4:55 a.m.

Assuming you’ve got your own level, relatively smooth, stretch of closed-off pavement... I’ve seen some use of ground up ‘hand chalk’ laid out on the ground to drive over which should show similar info to your ‘inadvertent oil smoke’ visualization.

One draw back to these is it’s a bit more difficult to ‘measure’ change in downforce due to setup alterations?.

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