I am curious for those of you using this wing which angles do you find work best and at which speeds. The track that i will be racing has a top speed around 130 with the technical sections around 60-80. Also i am curious about angles for autocross as well. I imagine more extreme angles will be necessary to generate any downforce in autocross. The magazine racecar engineering did an article a few years ago where downforce could be generated at autocross speeds and i believe their results. One last thing that i've noticed is that i have almost maxxed out my wing adjustments and my wing is about parallel with the ground which doesn't seem right. Thanks guys.

 

http://www.gotuning.com/product_info.php?f...products_id=237

 

Which direction did you max them out? What part of the wing is parallel to the ground (it has a both twisted chord and a cambered airfoil, what are you defining the parallel plane as)?

A CFD analysis of the GTC-200 is available here.

Unfortunately, they only take the analysis up to 15 degrees Angle of Attack, at which point the wing has not stalled yet. It also is done in a freestream, when the wing is purposely designed with a chord twist to take advantage of the air coming off the roof of the car at a different AoA than that coming around the sides.

That being said, I wouldn't try much more than the 15 degrees they give data for. Keep in mind this 15 degrees is measured from their reference plane from that link to the freestream. Given that the twist on the GTC-200 is 14 degress, this could very well mean your center section looks parallel to the ground. In fact, if you set the wing less than that max (which I might for a 130mph top speed course), your center section could have a positive angle relative to the ground (though it will still be negative relative to the air flow over the car).

 

I played around with mine at the last track event...
125ish max speed with one 95mph turn and 3 80-85 mph turns (summit point main)

I had an aggressive AOA, a medium and basically flat (measured from the leading edge to the rear) With it flat the center portion was positive.
Honestly, I didnt notice much difference.... Leads me to believe the majority of the downforce is coming from the edges...
I did take the hardtop off for one session and noticed a HUGE difference.

My wing is mounted on normal S2000 GTC200 mounts... I bet if I had it higher the center section would do more. But honestly, my car is still understeering slightly at highspeeds (nonstaggard RA-1s, gendron front sway on a softer setting) so im not too worried about more rear downforce

 

What did you notice? less grip?

 

I just picked up the APR angle indicator tool and just measured my AoA on my GTC 200. The guys at APR have told me to place the indicator in the center of the wing to take my measurements and I am only showing 5 degrees. I don't know about anyone else, but if I try to adjust the wing to be more aggressive, I will be running out of adjustment bolt on the adjusters. Any ideas???

 

They should not have told you to measure from the center. The center of the wing is getting air flow coming down down from the roof, so the real AoA is 5 degrees plus whatever that angle is. Since there is no easy way to measure that, just use the sides. They are in the free stream (or as close as you're going to get) which will be parallel to the ground (which is where you tool is measuring from).

The GTC-200 has a chord twist of 14 degrees, so you are really at 19 degrees AoA. This seems consistent with what I remember from seeing your wing at RTA. This is way too much AoA, you are most likely stalling the wing out, creating extra drag and actually losing downforce relative to a shallower angle. I wouldn't go with much more than the 15 degrees they provide CFD data for.

 

I was also told by APR to measure AOA from the center of the wing. Not to mention, as you go farther out on the edges the angle gets steeper(from what I remember). No two people would measure at the same spot. How would you get a reliable starting point?

I measure mine with a camber guage, while the car is set on scales that are level. The adjusters are crap(IMO). Both of mine stripped the bottom screw the very first time I turned them. So, I can only adjust so much, using the top screw.

From what I'm reading here, I'd need to get the wing at the same angle as the rear window, in order to be at 0 degrees? I don't think it'll adjust that far.

 

Hi, actually apr website tells us to measure from the centre of the wing as below

http://www.aprperformance.com/index.php?op...ask=view&id=181

well i guess thats how so much downforce is generated at relatively low AOA since the left and right parts of the wings are already aggressively angled.

although i wish they had thats for voltex wings

 

[QUOTE=9kI4,Jul 24 2008, 09:24 PM]I was also told by APR to measure AOA from the center of the wing.