Racing car aerodynamic optimization

[sierra4000]

Hi All,
some suggestions for aerodynamic optimization?

for more downforce and reduce drag

http://vunebenzinu.cz/images/aktuality_2013_C/i.jpg

https://fbcdn-sphotos-c-a.akamaihd.net/hphotos-ak-frc3/460957_374376452593682_922518243_o.jpg

thanks for ideas
Radek

 

[GregLocock]

Fit narrower tires and lose the wheel arch extensions.

Oh you don't want to do that, well, you need to tell us what your limitations are.

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

http://eng-tips.com/market.cfm?

 

[MikeHalloran]

Fastest cheapest aero thing that comes to mind is a fairing over each pair of tubes supporting the rear wing.

Mike Halloran
Pembroke Pines, FL, USA

 

[rb1957]

more down force ? more incidence for the rear wing, bigger rear wing, more elements to the rear wing (like F1). what's the undertray look like (how well controlled is the outlet ?)

like greg says, how do your class rules limit things ?

Quando Omni Flunkus Moritati

 

[sierra4000]

Thanks for answers,

Greg Locock - I certainly do not narrower tires !!!
I have not any class rules limitations


MikeHalloran - what exactly do you mean ?"fairing over each pair of tubes supporting the rear wing"
closed profile support?



rb1957- rear Wing is two element with gurney flap,
undertray is flat aluminum plate begins under transmission and ends under the rear axle axis

Radek

 

[MikeHalloran]

What I mean is, there is some parasitic drag associated with each of the support tubes on each side of the car, because they are (apparently) round, and because there are two of them. The after tube just has to interfere with the vortex street trailing behind the forward tube.

So, fold a pizza box in half, slap it over both tubes, and staple the loose ends behind the tubes, so you end up with a sorta streamlined 'pant' over the two tubes.

At least put a streamline sleeve over each tube.


Also, the plate that attaches the tubes to the wing and the flap; that's aero-ugly, and probably bigger than it needs to be structurally.


Mike Halloran
Pembroke Pines, FL, USA

 

[sierra4000]

OK Mike,
I understand now

 

[MikeHalloran]

Additionally, the forward tube could be smaller in diameter (and not stressed in bending) if you added a third tube extending toward the forward end of the decklid, so you end up with a structure looking like the letter 'N', and fully triangulated. Skin the whole thing of course.


Also, the secondary airfoil is not strictly a Gurney flap.

http://en.wikipedia.org/wiki/Gurney_flap

It might be more effective as a downforce device if moved up a little so it's out of the primary foil's boundary layer but still in the pressurized area.





Mike Halloran
Pembroke Pines, FL, USA

 

[rb1957]

i'd just cover the space between the tubes (rather than fairing each one).

is the undertray vibrating any ? i hear that F1 gains alot in the careful management of the airflow under the car.

how about a 3rd rear wing element ?

Quando Omni Flunkus Moritati

 

[rb1957]

there might be a little drag reduction fairing the front bumper edge and maybe fairing the front of the engine bay (the hood fwd edge, yes?)

Quando Omni Flunkus Moritati

 

[sierra4000]

rb1957 - ???? fairing the front bumper edge and maybe fairing the front of the engine bay -the hood fwd edge
I do not understand


Here small gurney flap:

 

[rb1957]

front bumper ... the top edge looks pretty sharp (in your first pic) ... consider adding a radius block (to fair in the edge) ... it might reduce drag (a very little).

hood fwd edge ... again, your first pic shows the fwd edge of the hood, doesn't look smoothly faired into the front panel (in front of the radiator).

i understand two elements in the rear wing ... why not three ? (like F1)

Quando Omni Flunkus Moritati

 

[sierra4000]

I could replaced rear wing tubes vertical support plates
yes,
probable vibration is seen at the first image
(undertray bend before the rear wheel)


is a replaceable curtain for reducing pressure under the hood (entry restrictions cooler)
look what hood does (lift) without curtain

https://scontent-b-vie.xx.fbcdn.net/hphotos-ash4/999127_537169156353716_1756769260_n.jpg

 

[sierra4000]

Of course, I can give big rear wing or 3nd wing element.
But how do you reach more downforce on the front end for aerodynymic balance?

Thanks for Your any more ideas

 

[MikeHalloran]

Downforce on the front?
Jack up the after end of the hood, like the car told you it wants, or just truncate the after end, leaving a big slot for the air to get out.

Maybe you can take it far enough to turn the hood into a huge front wing.


Mike Halloran
Pembroke Pines, FL, USA

 

[sierra4000]

Mike,
You can to specify?
just to make sure that I understand correctly.

 

[MikeHalloran]

Instead of trying to hold down the after end of the hood, raise it until it doesn't try to lift off anymore, or until you can just barely see over it, whichever comes first. ... and if you can, then raise it more to generate some downforce.

Think of it this way: If you ignore the presence of the engine and the radiator, the space between the front wheels would make a decent aero tunnel, with a wing mounted upside down at the top where the hood is, and a clean air passage from the radiator intake going back and then up to the base of the windshield. Now just mentally put the engine and radiator back in place, and figure out the tinwork to maintain the airflow under the hood/wing. Probably easier with a Subaru as the substrate.




Mike Halloran
Pembroke Pines, FL, USA

 

[sierra4000]

OK Mike,
I understand now -this good idea ( hood rear end helping engine air evacuation)

also me interested aero elements used for japanese silhouette car(pictures)
as strips on the sides of the windshield or rear panels behind the rear wheels
that can work well

http://www.speedhunters.com/wp-content/uploads/2008/11/race4_0LlJ_0.jpg

http://www.speedhunters.com/wp-content/uploads/2008/11/race2_JY76_0.jpg

 

[MikeHalloran]

The vertical panels behind the rear wheels are clearly intended to help the rear undercar diffuser do its thing, by restricting flow from the side into that area, inducing better flow from under the car.

The strips at the windshield corners I'm not sure about. If there's a gap under them, they would tend to direct some of the pressurized air stacked up in front of the windshield around the A pillar in a relatively orderly manner, just as some station wagons are equipped with anti-spoilers(?) that direct the roof boundary layer down over the rear window.
... for different reasons, I think.
If there's no gap under them, I haven't a clue.



Mike Halloran
Pembroke Pines, FL, USA

 

[sierra4000]

I think-these cars did not have rear diffuser
panels probably restricting flow from the side into that low pressure area (diffuser effect substitute)

The strips at the windshield If you do not have the space could increase the pressure in windshield