Aero/wing question...with a twist...and my name is not Hyper
12-10-2009, 04:30 AM
#26
I wouldn't discount feel. Setting up a car is both what makes the fastest car and how the driver feels about the car.
Decent wings will have downforce spec sheets, such as the GTC-300 that Emillio sells (link here APR Performance - GTC-300 - CFD Data & Analysis ) and that is the best way to get information. I'd generally say, if the manufacurer of the wing doesn't put out drag/downforce numbers, don't count on it being more than a styling choice.
Decent wings will have downforce spec sheets, such as the GTC-300 that Emillio sells (link here APR Performance - GTC-300 - CFD Data & Analysis ) and that is the best way to get information. I'd generally say, if the manufacurer of the wing doesn't put out drag/downforce numbers, don't count on it being more than a styling choice.
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12-10-2009, 09:36 AM
#27
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One minor detail I seem to have forgotten. I would be using a large wing/spoiler like Chris's car and am looking to get as much as I can in downforce in the 20-55mph range and I figure catching the air right off the slope of the top (top would be up obviously), I would be able to get as much air as possible over the wing.
As for mounting the wing, I would mount it right on top of the ridege that holds the trunk seal which would keep trunk flex to a minimum and transfer of downforce to the body efficently.
Now, I do plan on eventually getting a different wing for track days...one that will sit as far back as possible and as high as possible....because there are no rules on track days.
See, on a nice sloped back car (like if I somehow got my hands on one of those new autokenexion fastbacks), a wing mounted far back works well with minimal AOA because the wing is forsing a lot of air over its top and the air going under isn't really turbulant.
*warning awesome picture*
Attached is a pic of a NC in a wind tunnel and a description of the area in question.
As for mounting the wing, I would mount it right on top of the ridege that holds the trunk seal which would keep trunk flex to a minimum and transfer of downforce to the body efficently.
Now, I do plan on eventually getting a different wing for track days...one that will sit as far back as possible and as high as possible....because there are no rules on track days.
See, on a nice sloped back car (like if I somehow got my hands on one of those new autokenexion fastbacks), a wing mounted far back works well with minimal AOA because the wing is forsing a lot of air over its top and the air going under isn't really turbulant.
*warning awesome picture*
Attached is a pic of a NC in a wind tunnel and a description of the area in question.
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12-10-2009, 11:07 AM
#30
The GTC wings are 3 dimensional airfoils. That means they are shaped to accomodate the airstream as it comes over the hardtop. In autocross, I don't have a top on my car.
I also think the dual element wings are capable of creating more down force than a single element wing given the same square inch surface area. I think 5 is the point of diminishing returns with regard to the number of elements. SSM limits you to two unfortunately, which I have never understood given the area limit.
I also think the dual element wings are capable of creating more down force than a single element wing given the same square inch surface area. I think 5 is the point of diminishing returns with regard to the number of elements. SSM limits you to two unfortunately, which I have never understood given the area limit.
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12-10-2009, 11:10 AM
#32
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Btw, these folks are popular among the SCCA autocrossers:
Wing Shop home page
Some of their airfoil data:
Wing Shop aerofoil facts page
Looks like at 50mph their dual element one at 20 degrees angle of attack is making 84 lbs downforce for the penalty of 2.5 hp
Wing Shop home page
Some of their airfoil data:
Wing Shop aerofoil facts page
Looks like at 50mph their dual element one at 20 degrees angle of attack is making 84 lbs downforce for the penalty of 2.5 hp
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12-10-2009, 12:24 PM
#33
EDIT- Found it... http://autospeed.com/cms/A_3059/article.html
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12-10-2009, 12:57 PM
#34
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It would really depend on what type of air you wanted to catch with the wing. If you wanted to catch air that has already been introduced to turbulence moving the wing forward would help. However, if you wanted to catch clean air which is more linear in flow, the rearward mounting would be better. The flow that is seen in the NC can be helped with the use of vortex generators at the roof-line drop off to direct the air more linearly up and over the rear window and trunk lid but flow under the wing. This would be ideal... I will try to find the article where I saw the CFD's of before vortex generators and after...
EDIT- Found it... Browser Warning
EDIT- Found it... Browser Warning
But I don't think VGs will work all that well at autoX speeds :( Not to mention I would need a hard top to use them, and to use a hard top I would need to remove my roll bar for one that is HT compatable...too much work.
The question I am wondering is, for lower speeds (autoX), will it be a viable option to catch the air coming off th eroof line just before it's about to become turbulant along with catching clean air? Might there be any benifit?
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