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Anyone have Aero questions?


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19 hours ago, Mazmarc said:

 

Image may contain: carwe have the CCP fastback.  and for a back window we are making louvers. 

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19 hours ago, Mazmarc said:

 

Thanks for the kind words. I will come up with some way to seal the back of the hatch.

 

So maybe two small NACA ducts reversed toward the rear of the "glass" for cabin flow?

 

Thanks for all the responses guys. Very much appreciated.

 

 

 

 

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Disclaimer: I have no formal aerodynamics training and most of this info I am going to share I have just picked up on the side for fun. Feel free to critique anything I am about to say.   I

one more before i hit the road.  not quite.  The air being directed over the top of the car does add downforce. It's not the temp to blame, it's the speed. So to make downforce, the general

Put a hole in the top of the fender above your control arm/spindle/whatever. Attach a rod to the top of your control arm that is long enough to protrude above the fender at full droop. Mark the rod at

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On 9/17/2019 at 10:31 PM, LAMR2 said:

 

A few questions about the analysis:

 

Was the road stationary or setup as a moving wall? 

 

How was the grid made? Automated in Fusion360? 

 

Do you know what the y+ is for the grid? Target/average/whatever

 

Euler or full Navier-Stokes? 

 

Thought these questions sounded familiar, then I looked at the user name and it made sense!

 

On 9/12/2019 at 1:41 PM, Davef_dci said:

Hey folks,  

 

at the risk of subjecting myself to the scrutiny of some folks that know what the hell they're doing I thought I'd share the analysis I did on adding Aero to our Neon.  

 

Here is a link to the analysis I did which tried to predict the impact on lift and drag to various Aero strategies. I used a purchased CAD model of our Neon combined with Fusion360's CFD package (the old Blue Ridge Numeric's CDDesign).  

 

I am NOT an aero engineer so caveat emptor.  I suspect Johnny C will find some deep flaws.  

 

https://drive.google.com/open?id=1SJUoOjb7sRXu9ehfUWbrHwP6xpzpRUxr

 

As for the impact - it's hard to say since we were changing other things on the car at the same time. I've tried running without the wing and the car seems quite a bit less stable but it's possible that's subjective and my butt-dyno at work.  Conversely - at Gingerman we ripped the chin off the car and went on to run our fastest lap without it - but again it's hard to say.  

 

Hope this adds value to someone.  I built the wing and splitter myself so if anyone want's plans let me know. 

 

Please be gentle with your analytical pitchforks!


Dave 

 

 


I was a little surprised that the front splitter more than doubled the drag, but looking a the last page it appears that it caused the separation in the rear window to move pretty far forward. That's probably a big part of the increased drag and keeping that flow attached could reduce the drag. Time for some VGs? Be good to verify where the separation actually is with some tufts.

 

A few more questions: Are these time accurate simulations? There looks to be shedding vorticies in some of the simulations, but not all of them. Are you averaging the forces over the last few oscillations, or just getting forces from the final iteration?

 

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I've got a question about ducting for brakes.  I am working on them right now.

My research shows the brakes are cooled by the vented rotors work like turbines and suck in air and spit it out the edge of the rotor, 

and then that air goes out the wheel.

The commonly done approach is to add brake ducts to the front of the car and route them into the center of the brake rotor to force more cooler air through the rotor vents.

I was doing calculations on how much airflow you get with ducts at what size and speed.  My thoughts were you get tons of airflow on the straights at top speed when you don't need it,

and less in the slower turns where brakes are the hottest.  While true,  the cars are still going pretty fast in turns, there is still plenty of flow to cool them.

 

The brake ducts are going to create drag, so I have this idea to route the air going through the radiator to the brakes instead of another duct.  Sure that air is warmer, but it is still way  cooler than brake temps.  And that radiator air drag is required to cool the engine already, and the flow is much greater than smaller brake ducts.  And otherwise, a lot (??) of that air is exiting under the car. 

 

Every 'better idea' I have that nobody is doing, there is some reason why people don't do it.  Is it because the wheels can't keep up with the radiator flow?   The path from radiator to wheels is too contorted to flow sufficiently?   Has anyone tried it?  

 

 

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On 10/26/2019 at 4:02 AM, NimbleMotorsports said:

I've got a question about ducting for brakes.  I am working on them right now.

My research shows the brakes are cooled by the vented rotors work like turbines and suck in air and spit it out the edge of the rotor, 

and then that air goes out the wheel.

The commonly done approach is to add brake ducts to the front of the car and route them into the center of the brake rotor to force more cooler air through the rotor vents.

I was doing calculations on how much airflow you get with ducts at what size and speed.  My thoughts were you get tons of airflow on the straights at top speed when you don't need it,

and less in the slower turns where brakes are the hottest.  While true,  the cars are still going pretty fast in turns, there is still plenty of flow to cool them.

 

The brake ducts are going to create drag, so I have this idea to route the air going through the radiator to the brakes instead of another duct.  Sure that air is warmer, but it is still way  cooler than brake temps.  And that radiator air drag is required to cool the engine already, and the flow is much greater than smaller brake ducts.  And otherwise, a lot (??) of that air is exiting under the car. 

 

Every 'better idea' I have that nobody is doing, there is some reason why people don't do it.  Is it because the wheels can't keep up with the radiator flow?   The path from radiator to wheels is too contorted to flow sufficiently?   Has anyone tried it?  

 

 

You would end up with less flow through that portion of the radiator (reducing its effectiveness) and subsequently very little flow through the brake duct. To match the cooling of a normal duct you would need a much larger one.

 

Much better to run the normal style duct and then tape off the radiator down to optimal size. 

 

Also, you don’t need to cool the brakes during a braking zone, you just need them to have cooled enough from the last braking zone that this current one doesn’t heat them beyond their temp limit.

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Is it worth anything to seal off the area behind the driver on both side floor to roof 

keeping a pressure in the cabin area so air does not want to go in the side windows 

or is air going to still want to cross from side window to side window 

 

also so thought of this hard top 

lexan closed off 3/4 of rear window 

 

I know the cones are killing me was for theme in other series 

gonna get serious with the car in 2020 

5FA504DC-C5BA-4958-8197-AA7CFD3BC63B.jpeg

C39909B5-DC01-4E64-B9A7-F66FD8FF49CB.jpeg

DF0A622B-5B7A-46FD-B520-E8197F3E963E.jpeg

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On 1/12/2020 at 5:25 PM, Steve Peterson said:

Is it worth anything to seal off the area behind the driver on both side floor to roof 

keeping a pressure in the cabin area so air does not want to go in the side windows 

or is air going to still want to cross from side window to side window 

 

also so thought of this hard top 

lexan closed off 3/4 of rear window 

 

I know the cones are killing me was for theme in other series 

gonna get serious with the car in 2020 

5FA504DC-C5BA-4958-8197-AA7CFD3BC63B.jpeg

C39909B5-DC01-4E64-B9A7-F66FD8FF49CB.jpeg

DF0A622B-5B7A-46FD-B520-E8197F3E963E.jpeg

themes are over-rated. We race in the other series and couldn't care less about our "theme".  

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On 1/12/2020 at 5:25 PM, Steve Peterson said:

Is it worth anything to seal off the area behind the driver on both side floor to roof 

keeping a pressure in the cabin area so air does not want to go in the side windows 

or is air going to still want to cross from side window to side window 

 

also so thought of this hard top 

lexan closed off 3/4 of rear window 

 

I know the cones are killing me was for theme in other series 

gonna get serious with the car in 2020 

5FA504DC-C5BA-4958-8197-AA7CFD3BC63B.jpeg

C39909B5-DC01-4E64-B9A7-F66FD8FF49CB.jpeg

DF0A622B-5B7A-46FD-B520-E8197F3E963E.jpeg

  You will be accessed material points for anything beyond factory top dementions.  You may have a 10 point spoiler on the end also, that area would not count on to your material points.

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5 hours ago, Ray Franck said:

  You will be accessed material points for anything beyond factory top dementions.  You may have a 10 point spoiler on the end also, that area would not count on to your material points.

 

Uh.  That is a factory top.  That's a Solstice Coupe.....

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4 minutes ago, SonsOfIrony said:

 

Uh.  That is a factory top.  That's a Solstice Coupe.....

  Well so it is and would not be beyond factory dimensions and 0 points even with the little lippy thing at the back. Never seen one before, I seem to learn something every day...

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6 hours ago, Ray Franck said:

  You will be accessed material points for anything beyond factory top dementions.  You may have a 10 point spoiler on the end also, that area would not count on to your material points.

E69BBB39-A3CC-45E3-BCFE-63F2D222E303.thumb.jpeg.bfd0aa6e4579ccc93191ec2d15b17653.jpeg

It’s a factory copy

how could it get points 

just asking not trying to being smart 

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57 minutes ago, Ray Franck said:

  Well so it is and would not be beyond factory dimensions and 0 points even with the little lippy thing at the back. Never seen one before, I seem to learn something every day...

 

I remember thinking they were neat looking when they came out, but I've yet to see one IRL.

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3 minutes ago, Steve Peterson said:

Was wondering about blocking off the rear cabin area floor to roof

I was think this may keep air from coming in side windows or does this just make the air want to cross from window to window 

You cannot block pass through vision and a lexan upper portion would not be considered a point free bulkhead .

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12 minutes ago, Ray Franck said:

You cannot block pass through vision and a lexan upper portion would not be considered a point free bulkhead .

I understand it would be points for lexan was just wondering if it would be worth anything aero wise I air stays out of the cabin area 

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 Opinions vary but look around  if it worked it would be everywhere .  Don't get me wrong aero is important even at our speeds , though some say not, I believe it is. Far more can be gained outside the car than inside I would work there first. Most all of the cars I drive are amazingly calm inside at speed so there is that.

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17 minutes ago, TiredBirds said:

"Aerodynamics are for people who can't build engines"  - Enzo Ferrari 

 

We're not allowed to build engines.

 

He also said that about 50 years ago when most designers had no understanding of the subject.

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1 hour ago, SonsOfIrony said:

 

We're not allowed to build engines.

 

He also said that about 50 years ago when most designers had no understanding of the subject.

with the current "points"  system I can build a 400hp+ small block and have points left over for aero. P.S. I was just having fun. we are all aware how much aero plays a part...track depending. 

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1 hour ago, TiredBirds said:

"Aerodynamics are for people who can't build engines"  - Enzo Ferrari 

I Love this quote because it's so "Ferrari" and demonstrates what is Italian racing pronounce. I say this because this quote is from 1960 (about the 250TR) and at the time, Ferrari was crushing everyone with their aerodynamics. they had the slipperyist car made. I can assume Enzo wanted you to look under the hood rather than what was actually giving them the wins.    It's the quintessential 'don't look behind the curtain the great OZ is before you'
Image result for 1960 le mans

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36 minutes ago, @NineLivesJohnny said:

I Love this quote because it's so "Ferrari" and demonstrates what is Italian racing pronounce. I say this because this quote is from 1960 (about the 250TR) and at the time, Ferrari was crushing everyone with their aerodynamics. they had the slipperyist car made. I can assume Enzo wanted you to look under the hood rather than what was actually giving them the wins.    It's the quintessential 'don't look behind the curtain the great OZ is before you'
Image result for 1960 le mans

On a side note, I was close to buying one of these.. it is clone based on a 240z 

ferrari-250-gto-1962-replica-tribute-clone-other-makes-1.JPG

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