Newly Revised/Release APR GTC 200 Wing
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Larger Chord, more aggressive camber, more downforce.
Link:
APR Performance - GTC-200 New Version
APR Performance - New GTC-200 - CFD Data
Link:
APR Performance - GTC-200 New Version
APR Performance - New GTC-200 - CFD Data
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572 Posts
Perhaps I'm not reading it correctly, but the downforce data looks rather weak. At 12 degrees AOA the downforce is only 184 lbf at 100 mph, and 264 lbf at 120 mph. Shouldn't a wing of this size make significantly more downforce?
As a comparisson here is Reverie's Exige wind tunnel test.
http://www.reverie.ltd.uk/Downloads/ReVerie_Wind_Tunnel_Test_Session.pdf
It's not exactly an apples to apples comparison, but they test a stock Exige and one with a larger wing at 100 mph. The Exige with the large wing at 12 degrees AOA makes 683 lbs more rear downforce than the stock Exige.
Also, the renderings look nice, but they need to run them with the uprights to show how they affect airflow and the wings performance. No one can run the wing without the uprights. I would be disappointed to go through all the effort and cost to install a wing like this for only 100 or 200 lbs of downforce at high speed.
As a comparisson here is Reverie's Exige wind tunnel test.
http://www.reverie.ltd.uk/Downloads/ReVerie_Wind_Tunnel_Test_Session.pdf
It's not exactly an apples to apples comparison, but they test a stock Exige and one with a larger wing at 100 mph. The Exige with the large wing at 12 degrees AOA makes 683 lbs more rear downforce than the stock Exige.
Also, the renderings look nice, but they need to run them with the uprights to show how they affect airflow and the wings performance. No one can run the wing without the uprights. I would be disappointed to go through all the effort and cost to install a wing like this for only 100 or 200 lbs of downforce at high speed.
I believe the forces are in Newtons. It is a poorly written report, with mph mixed with metric values and then unknown units. Definitely not done by engineers.
By having downforce values without uprights it shows the max potential of the wing in freestream air. This will never happen but every car is different so they can not show every possibility. A properly designed upright should have little effect on downforce. Mostly just a drag issue. The same amount of air will pass under and over the wing. Keep in mind that the AOA is not an angle relative to the ground but relative to the air vector. The higher the wing the more horizontal the air vector will be. If the wing is low then the air will be mostly following the contour of the back of the car, which will be turbulent for an elise and Exige and in a more downward direction. If you want to achieve results similar to what APR has posted then you will need to mount the wing high, farther aft and with thin uprights. The angle of the wing chord relative to the road surface is the incidence angle and this would have a lower value than the AOA due to the downward slope of the air flow hitting the wing. This is something the Reverie report fails to clarify and makes me question their entire setup. How are they measuring AOA? Do they even know what it means? And how does APR measure their AOA since the wing has variable twist? Average AOA, AOA at wing mount location or maybe AOA at tips? Also be aware that the twist in the incidence angle for the APR wing will give lower downforce results in a freestream air environment than the Reverie because the outboard sections and the inboard section will never both be at the optimum angle. This is done so the wing works better in the real world, where the center section is receiving air with a more downward direction (due to the car shape) and the outboard sections are closer to freestream. Thoeretically with the APR wing the AOA could be the same for the full span with the right car. This will never happen with the Reverie unless it is mounted very high.
By having downforce values without uprights it shows the max potential of the wing in freestream air. This will never happen but every car is different so they can not show every possibility. A properly designed upright should have little effect on downforce. Mostly just a drag issue. The same amount of air will pass under and over the wing. Keep in mind that the AOA is not an angle relative to the ground but relative to the air vector. The higher the wing the more horizontal the air vector will be. If the wing is low then the air will be mostly following the contour of the back of the car, which will be turbulent for an elise and Exige and in a more downward direction. If you want to achieve results similar to what APR has posted then you will need to mount the wing high, farther aft and with thin uprights. The angle of the wing chord relative to the road surface is the incidence angle and this would have a lower value than the AOA due to the downward slope of the air flow hitting the wing. This is something the Reverie report fails to clarify and makes me question their entire setup. How are they measuring AOA? Do they even know what it means? And how does APR measure their AOA since the wing has variable twist? Average AOA, AOA at wing mount location or maybe AOA at tips? Also be aware that the twist in the incidence angle for the APR wing will give lower downforce results in a freestream air environment than the Reverie because the outboard sections and the inboard section will never both be at the optimum angle. This is done so the wing works better in the real world, where the center section is receiving air with a more downward direction (due to the car shape) and the outboard sections are closer to freestream. Thoeretically with the APR wing the AOA could be the same for the full span with the right car. This will never happen with the Reverie unless it is mounted very high.
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I got received my new APR wing today, anything specific you'd like to see?
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Yeah, I just wanted more information on it. I know the price point is great but does it work and how well.
I decided to go a different direction...my car is so well balanced as is and taking it up in aero, power, etc. doesn't make sense on a few levels for me. I bought a DSR that is pure track focused so I most likely will be putting my lotus up for sale in the near future. If only I could keep it though as it's absolutely incredible. A V2 Motorsports built car is very special and if you were to drive different cars back to back the V2 car always makes the others feel clunky and sloppy. People always comment on how amazing it is when they drive it.
Anyway, I hope you guys enjoy your new wings
I decided to go a different direction...my car is so well balanced as is and taking it up in aero, power, etc. doesn't make sense on a few levels for me. I bought a DSR that is pure track focused so I most likely will be putting my lotus up for sale in the near future. If only I could keep it though as it's absolutely incredible. A V2 Motorsports built car is very special and if you were to drive different cars back to back the V2 car always makes the others feel clunky and sloppy. People always comment on how amazing it is when they drive it.
Anyway, I hope you guys enjoy your new wings
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I wonder how much the Gurney flap they sell helps.those APR wings do create DF, but they're very inefficient. Drag monsters. Lots of air separation, etc
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A Gurney flap, like vortex generators, are band-aid fixed for aerodynamics f*&k ups! The aerodynamicist f*&ked up and that's how they fix it cheaply. If I see a Gurney flap, that tells me one of two things...either the person installing it (the team) knows Jack $h!t about aerodynamics, or the aerodynamicist f*&ked up.
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I'm with LionZoo. Turbophil, <@¿@> ... what would you recommend as a more functional replacement?
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Depends on what your budget is.... A good wing is going to be 2-5 grand for the foil itself.
For whatever reason, there are still no well designed chinese knock-offs. I like APR as much as the next for certain things (not sure if they're chinese, but along those lines). They are certainly cheap (and HEAVY), but those APR 200 (new and old) wings are really tough to love and easy to loathe . Their bigger series wings are far --"less bad" IMO... choosing my words carefully there
So if a builder has a "reasonable" budget to dedicate to aero (few grand at least), then it's worth chatting about...
For the purposes of closed wheel GT cars like ours, I disagree about about the GF being a bandaid. Relatively dirty air (compared to a plane) with mess of turbulance from other cars and the body itself and at low speeds (car speeds), the GF has been proven to help prevent air separation and improve the efficiency on even the best designed profiles with minimal drag penalty. There are some nice NACA and Selig profiles with a high lift and low reynolds number that are very effective and still benefit from a GF at low speeds (car speeds). Many a "white paper" has been written by experts in the field on this...
My wing has a removable GF in a channel so the GF can be easily "tuned" or changed or deleted all together. The profile is a (Selig) S1223 which is proven to be VERY efficient in low speeds (car speeds)...
-Phil
For whatever reason, there are still no well designed chinese knock-offs. I like APR as much as the next for certain things (not sure if they're chinese, but along those lines). They are certainly cheap (and HEAVY), but those APR 200 (new and old) wings are really tough to love and easy to loathe . Their bigger series wings are far --"less bad" IMO... choosing my words carefully there
So if a builder has a "reasonable" budget to dedicate to aero (few grand at least), then it's worth chatting about...
For the purposes of closed wheel GT cars like ours, I disagree about about the GF being a bandaid. Relatively dirty air (compared to a plane) with mess of turbulance from other cars and the body itself and at low speeds (car speeds), the GF has been proven to help prevent air separation and improve the efficiency on even the best designed profiles with minimal drag penalty. There are some nice NACA and Selig profiles with a high lift and low reynolds number that are very effective and still benefit from a GF at low speeds (car speeds). Many a "white paper" has been written by experts in the field on this...
My wing has a removable GF in a channel so the GF can be easily "tuned" or changed or deleted all together. The profile is a (Selig) S1223 which is proven to be VERY efficient in low speeds (car speeds)...
-Phil
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3,229 Posts
All the GF does, is change the effective AOA of the foil...it is much more aerodynamically efficient to change the angle of the wing than it is to slap on (I mean tune as you say Phil) a GF.
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From my archives when we were playing with all this last year....
A decent write up touching base on several profiles, gurney flaps, etc.... There's a kuh-jillion studies on aero. Pick your poison
http://aerospace.illinois.edu/m-selig/uiuc_lsat/Low-Speed-Airfoil-Data-V1.pdf
There's a lot of subjectivity to go with the objectivity and that's why Adrian Newy gets paid more than whoever is doing the aero for Force India
One thing that is consistent is that good aero that doesn't act like an air brake relative to the DF is makes costs $$$$$$$.
-Phil
A decent write up touching base on several profiles, gurney flaps, etc.... There's a kuh-jillion studies on aero. Pick your poison
http://aerospace.illinois.edu/m-selig/uiuc_lsat/Low-Speed-Airfoil-Data-V1.pdf
There's a lot of subjectivity to go with the objectivity and that's why Adrian Newy gets paid more than whoever is doing the aero for Force India
One thing that is consistent is that good aero that doesn't act like an air brake relative to the DF is makes costs $$$$$$$.
-Phil
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6,306 Posts
That is contradictory to most of the research you'll find on this subject... Based on your comment, I think you're limiting your view on the GF to energy conservation, equal and opposite reaction from the GF "air kick", type of thought process. If that's the case, I think you're missing the point of the part... There's the underside (as it is on the car) of the wing's sensitivity to air separation and subsequent drag from such can be mitigated with proper use a GF--- particularly so with greater AoAs and at these lower speeds...
Don't have to take my word for it. Just read up on it
Phil
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