I think that is an unsubstantiated claim, unless there is specific proof or someone has done testing. It could be, it might not be, but unless someone really has tested it, we will just say it doesn't have evidence. I asked Kognition for some downforce numbers, I believe he might be the only person who supplies these.


This is for a 67" wing and the left column is the degree of the rear wing. I am not sure a trunk lid is the ideal spot for someone that requires heavy downforce, I guess this is why we decided to sell the rear wings.

Also the GST Subaru runs this wing, 1:38.967 got my attention.

 

Look at the underside of the Kognition vs a Voltex type 7, not just the underside but even the transition from the front edge leading to the underside. I'm comparing to a Type 7 due to it being a 2d like the Kognition, but the underside says a lot about the differences in terms of drag and airflow.

I'm not trying to favor either one, just stating some visual differences.

 

I had the Kogniton wing. Maybe I didnt get a chance to run different angles but that wing created a lot more drag for me....like too much lol. Ive run a lot of wings too (APR, Voltex Type 2,3,7, and 1S)
Seems like all the guys using them are 500+HP but maybe at the right angel, it works well for NA s2000.

 

That is completely irrelevant to Bullwings post which said that, while it admittedly produces a lot of downforce, it also produced a lot of drag.

Huge hp time attack cars don't give a shit about drag (to a point) because they can overcome it with hp and the downforce is worth it. An N/A s2k does NOT have that luxury.

If someone wants an inexpensive 2D wing for an s2k, I'd recommend the APR GT-250 -- which was designed by someone with a ton of experience and has proven effective on numerous platforms at numerous power levels.

 

I think the Kognition is definitely a wing you'd want for a high HP car and the GTC-250 looks realy nice for NA but looking at the numbers provided Kogntion vs the GTC-200 the Kognition looks fine for NA also:


Comparing a GTC-200 at 10AOA to the Kogniton at 6 AOA the Kognition makes more DF with a about the same drag:

MPH DF APR 10AOA DF KOGN 6AOA DRAG APR DRAG KOGN

80 115 149 13 12.7
100 180 233 20.3 19
120 259 335 28.8 28

10AOA is a realistic point for the GTC-200 I always tried to run my GTC-200 at low AOA and mostly the center section would be flat or a few degrees off flat which corresponds to about 10AOA, I'm basing this off the outside section would be about 11AOA with the central section near to flat.

The tracks I run your usable downforce for an NA car is between 80-100mph 4th gear stuff but it won't hurt more on the straight either.

I am going to try to run the Kognition bellow 6AOA they said it will work but theres no numbers.

 

I currently run a chassis mounted kognition wing that is 70 inches wide. I don't know if it produced more drag then another wing from real world on track driving. Dan uk and I both reached the same mph mark at road atl (130) while he has a apr 200. I'm a fan of them and I think it's the wing I'll be keeping for awhile. I also plan on making 400-420whp this year. This wing creates a lot of downforce, I'll put it this way with a gtc300 my car was neutral with out a splitter. With the kognition it pushed...A LOT so now i have a massive splitter to balance it out.

I always tell my buddies who ask to go with a gtc250 if you don't want to run a splitter. There is also another local guy that runs a kognition chassis mount in nasa ttc.

 

[attachment=75887::]

Best photo I have I can get photos of how it mounts if you need op, but it's simple to bolt in the trunk but you have to be good at cutting your trunk which I was not lol

 

You must love an insanely pushy setup if you think the GT-250 doesn't need a splitter.... It absolutely requires a splitter to be even remotely neutral.

 

I ran the kognition wing at roebling which is my local track and has 2 fast 100 mph corners you realy use the wing on. Apart from switching from the GTC-200 to the Kogition chassis mount I made a few changes to bent things and put a new set of fender liners so there are other factors that could affect the handling/drag.


Initially I ran the Kogntion nearly flat with maybe 1degree AOA - the rear of the car felt amazingly planted but way much more so than the front.
I was on fairly old DZII tires and I tried to flatfoot turn 9 which is something I've only been able to do on R compounds but I understeered off the track!

I definitely felt like I had more rear grip in the slower corners and overall did not feel a lot of drag the car felt realy sharp, and top speed at the end of the straight was good.

For the second session I dialed back the wing to about +1 aoa so the leading edge was slightly higher than the rear vs the ground - which was the most adjustment I could get. So the car still had some understeer and I softenned the front shocks and just about found a balance (still pushy) I could work with.Towards the end of the day with the adjustments and the track getting slower I just about had it so I could flatfoot T9 (with a passenger!) on street tires which I
couldn't realy do before. I was still hitting 128mph+ at the end of the straight and the car was more planted in the slower corners.

I need to adjust the balance of the car a bit and I know the car will be flat in the high speed corners where it wouldn't go before without losing anything down the straight so its going to be consistently faster for sure.

Looking at how the wing is the hardtop must be bending the flow and increasing the effective AOA but the sides maybe in free stream. I think I am going to leave it where its at and just adjust the springs/bars to deal with the balance.

The fender liners could be helping with the drag also I have a new BBK. I couldn't realy go much deeper on the brakes so I don't think it was affecting the straightline speed much but thats a factor. The other thing I changed was a bent steering rack and my front knuckles/bearings i think one knuckle was slightly bent and the bearings could have been hurting the straightline speed as well.

 

Everyone please read and understand Dan's posts. You cannot set an APR GTC-200 or GTC-300 or any other chord twist wing to the same "Angle of Attack" as a constant chord wing. You are comparing apples to oranges.

The chord twist wings do a better job maximizing you L/D when placed in an environment where the angle of attack is varying over the span of the wing. And the angle of attack is defined as the angle between the local airflow and the airfoil chord, NOT the angle between the chord and the ground or some other static reference. That's a very important difference to keep in mind if you want to use the CFD data Gruppe-S posted for Kognition or APR's data for their wings. The posted AoA is relative to the local airstream, not the ground.

If you take a constant chord wing (like the Kognition) and set it so that the angle of the end of the airfoil is the same as your APR twisted wing used to be, there is a very good chance you will be STALLING THE CENTER SECTION (looking at you, f20kills...). Stall actually reduces downforce while increasing drag exponentially. You can see this in APR's CFD dataL




You can see the stall happening around 13 degrees AoA. Unfortunately they've done themselves a disservice by running their twisted airfoil in a uniform stream (doing CFD for a non-uniform flow would be much more complicated analysis), so the sides of the airfoil are actually at a higher AoA and causing the wing to exhibit stall a bit prematurely. An airfoil cross section probably stalls somewhere more like 15-20 degrees. Let's put it this way...I don't believe it's an accident that Kognition's CFD data stops at 18 degrees AoA. I would not set it so that any part of the airfoil exceeds that local flow angle.

The angle of the air coming of the roof is much steeper than you think, probably at least 10-15 degrees (depending on location).



For those paying attention at home, that means the center of the Kognition wing probably stalls if set steeper than about 3 degrees down relative to the ground (which would put it about 18 down to the local airflow).

The lower pressure areas behind the rear of the car and rear of the cabin change the direction of the air, even above the roofline, drawing it down. Even if you mounted a wing behind the car and at the roofline of a fastback, you'd still have a different angle of attack behind the cabin than around the sides:



Further more, all of these wings (APR, Voltex, Kognition) actually use a cambered airfoil. This means it's not symetric top to bottom and the shape itself generates downforce through pressure differentials/flow turning. Even if you had it set to 0 AoA or positive AoA relative to the local airflow, you could be making downforce.

This is all explained in APR's tech section, if you want to know more:
http://aprperformance.com/tech/
Or the wing setup section:
http://aprperformance.com/racing-pro...ustable-wings/
Click to expand the "CFD DATA & ANALYSIS FOR THE GTC-300 ADJUSTABLE WING (CLICK TO VIEW)" section.

Hopefully that helps someone. It's not the most straightforward concept, so let me know if there are any questions!

TL; DR: Most S2000s I see on the track could go faster, getting more dowforce for less drag, if they just dialed in less angle into the rear wings.