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      05-30-2020, 09:04 PM   #23
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>> A type of drag that is often ignored in these aero conversations is pressure drag. Pressure drag is caused by the airflow curling in on itself behind the vehicle, causing a low pressure area that 'pulls' the car backwards.

This would explain the down tilt in the test picture and means that the GTS wing (small, not in the air flow) acts more like a spoiler, rather than an actual wing to generate down force.
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      05-31-2020, 06:03 AM   #24
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i know you're not a fan of "set it and forget it" suggestions, lol, but hear me out-

the schrimer cars are tuned to be fast on the nurburgring. it higher speed than what you are doing, so just set it kinda high, but maybe a little less if you're concerned about drag, and forget about it.
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      05-31-2020, 06:18 AM   #25
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Quote:
Originally Posted by roastbeef View Post
i know you're not a fan of "set it and forget it" suggestions, lol, but hear me out-

the schrimer cars are tuned to be fast on the nurburgring. it higher speed than what you are doing, so just set it kinda high, but maybe a little less if you're concerned about drag, and forget about it.
I have two settings that I use albeit on a bigger wing. I try to run it flat but at some tracks I'll add a little more AOA if rear end feels light in high speed corners (downhill at LRP or turn 12 at Road Atlanta). If I was at a slow track like NYST I'd run max AOA. Probably just a placebo effect for an amateur driver like me.
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      05-31-2020, 06:25 AM   #26
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Quote:
Originally Posted by roastbeef View Post
i know you're not a fan of "set it and forget it" suggestions, lol, but hear me out-

the schrimer cars are tuned to be fast on the nurburgring. it higher speed than what you are doing, so just set it kinda high, but maybe a little less if you're concerned about drag, and forget about it.
I was driving the Schrimer cars angle all last year and the first two track days. I believe the Schrimer angle is also the angle of the aero test in the picture I uploaded.

But then I had some time waiting for a track day and I started to think. IF you look carefully at the GTS wing, it has a lot of wing. From a profile side.

If you look at the big wings, the one up at the air flow, they are much less wing, thiner profile.

So the if the GTS wing acts like a wing, AOA in relationship to the air flow coming off the roof was at a very steep angle and I suspect that angle was stalling the wing.

But... if the GTS "wing" is actually meant to be a spoiler, the the Schrimer angle make a lot of sense as the rear of the wing is at the roughly the same angle as the spoiler strip on the trunk, just bigger.

Probably I will return it to the angle shown in the picture I uploaded and forget it. As you said.

If you look carefully at the blow up, there is no way that angle is not stalling the wing.
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      05-31-2020, 07:04 AM   #27
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Quote:
Originally Posted by ThunderMoose View Post
Quote:
Originally Posted by roastbeef View Post
i know you're not a fan of "set it and forget it" suggestions, lol, but hear me out-

the schrimer cars are tuned to be fast on the nurburgring. it higher speed than what you are doing, so just set it kinda high, but maybe a little less if you're concerned about drag, and forget about it.
I have two settings that I use albeit on a bigger wing. I try to run it flat but at some tracks I'll add a little more AOA if rear end feels light in high speed corners (downhill at LRP or turn 12 at Road Atlanta). If I was at a slow track like NYST I'd run max AOA. Probably just a placebo effect for an amateur driver like me.
I love how you and admranger pretend to not know exactly what you're talking about.
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      05-31-2020, 07:07 AM   #28
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Quote:
Originally Posted by rhyary View Post
Quote:
Originally Posted by roastbeef View Post
i know you're not a fan of "set it and forget it" suggestions, lol, but hear me out-

the schrimer cars are tuned to be fast on the nurburgring. it higher speed than what you are doing, so just set it kinda high, but maybe a little less if you're concerned about drag, and forget about it.
I was driving the Schrimer cars angle all last year and the first two track days. I believe the Schrimer angle is also the angle of the aero test in the picture I uploaded.

But then I had some time waiting for a track day and I started to think. IF you look carefully at the GTS wing, it has a lot of wing. From a profile side.

If you look at the big wings, the one up at the air flow, they are much less wing, thiner profile.

So the if the GTS wing acts like a wing, AOA in relationship to the air flow coming off the roof was at a very steep angle and I suspect that angle was stalling the wing.

But... if the GTS "wing" is actually meant to be a spoiler, the the Schrimer angle make a lot of sense as the rear of the wing is at the roughly the same angle as the spoiler strip on the trunk, just bigger.

Probably I will return it to the angle shown in the picture I uploaded and forget it. As you said.

If you look carefully at the blow up, there is no way that angle is not stalling the wing.
I'd probably go along with this theory that it acts as an extended spoiler instead of acting as an airfoil. It isn't that much taller than the oem carbon spoiler that mounts to the end of the trunk, and it's a little more forward.
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      05-31-2020, 07:15 AM   #29
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Quote:
Originally Posted by roastbeef View Post
I love how you and admranger pretend to not know exactly what you're talking about.
The older I get the more I learn how little I actually know.

Sorry about the formatting. But relative speeds for tracks that I have driven in comparison to what I understand is a good time for NYST.

Track distance lap time avg mph
WGI 3.4 2.00 102
VIR 3.27 1:58 100
Road Atlanta 2.54 1:33 98
TWS 2.9 1:47 98
LRP 1.5 0:57 95
Mid Ohio - Club 2.4 1:34 92
NOLA 2.75 1:48 92
Mid Ohio - Pro 2.258 1:32 88
MSRH 2.4 1:38 88
COTA 3.4 2:26 84
Hallett 1.8 1:20 81
NYST 2.14 1:37 79
MSRC - 1.7CCW 1.7 1:20 77

Last edited by ThunderMoose; 05-31-2020 at 07:24 AM..
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      05-31-2020, 07:18 AM   #30
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Quote:
Originally Posted by roastbeef View Post
Quote:
Originally Posted by rhyary View Post
Quote:
Originally Posted by roastbeef View Post
i know you're not a fan of "set it and forget it" suggestions, lol, but hear me out-

the schrimer cars are tuned to be fast on the nurburgring. it higher speed than what you are doing, so just set it kinda high, but maybe a little less if you're concerned about drag, and forget about it.
I was driving the Schrimer cars angle all last year and the first two track days. I believe the Schrimer angle is also the angle of the aero test in the picture I uploaded.

But then I had some time waiting for a track day and I started to think. IF you look carefully at the GTS wing, it has a lot of wing. From a profile side.

If you look at the big wings, the one up at the air flow, they are much less wing, thiner profile.

So the if the GTS wing acts like a wing, AOA in relationship to the air flow coming off the roof was at a very steep angle and I suspect that angle was stalling the wing.

But... if the GTS "wing" is actually meant to be a spoiler, the the Schrimer angle make a lot of sense as the rear of the wing is at the roughly the same angle as the spoiler strip on the trunk, just bigger.

Probably I will return it to the angle shown in the picture I uploaded and forget it. As you said.

If you look carefully at the blow up, there is no way that angle is not stalling the wing.
I'd probably go along with this theory that it acts as an extended spoiler instead of acting as an airfoil. It isn't that much taller than the oem carbon spoiler that mounts to the end of the trunk, and it's a little more forward.
Exactly. I think this the conclusion we are collectively coming too.

But.... wait there is more....

I bought last evening Speed Secrets Lime Rock Virtual Track walk. And what do you think it says at hr:mn:sec 1:11:10?

They discuss exactly this topic. They said that the wings on the Prototype car produce 1000-3000Lbs downforce, but all the splitter/wings on TT and GT cars are mostly there to act as spoilers.

Direct quote:
"They call a GT car an aero car, but realistically its a reduction of lift car, rather than additional down force"

So there you have it... back to the picture angle or one steeper. But not and the angle I have it now set.
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      05-31-2020, 03:34 PM   #31
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Quote:
Originally Posted by roastbeef View Post
I love how you and admranger pretend to not know exactly what you're talking about.
Anymore I consider myself a great driver if I back both vehicles out of the garage and don't damage either one in the process.
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      06-07-2020, 04:49 PM   #32
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Got some data:
When the winglets are leveled I reached few times 132-133 end of straight at NYST before touching the brakes with rear pots registering -1.9mm (compressions)

When the Winglets pointing down (two holes) I reached few times 129 with rear pots registering -6.9mm.

So about 5mm on 900 rear springs.

Someone please calculate 5mm on 900 springs for downforce. My head hurts. .
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      06-07-2020, 05:14 PM   #33
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I thought there were downforce numbers on the GTS published by BMW somewhere on the interwebs.
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      06-07-2020, 09:05 PM   #34
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Quote:
Originally Posted by rhyary View Post
Got some data:
When the winglets are leveled I reached few times 132-133 end of straight at NYST before touching the brakes with rear pots registering -1.9mm (compressions)

When the Winglets pointing down (two holes) I reached few times 129 with rear pots registering -6.9mm.

So about 5mm on 900 rear springs.

Someone please calculate 5mm on 900 springs for downforce. My head hurts. .
Assuming stock .56 motion ratio, 5mm would be 55.5lbs at each rear wheel.
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      06-07-2020, 10:34 PM   #35
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Quote:
Originally Posted by Bartledoo View Post
Assuming stock .56 motion ratio, 5mm would be 55.5lbs at each rear wheel.
At 130mph, that's not much haha
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      06-07-2020, 11:13 PM   #36
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Quote:
Originally Posted by tsk94 View Post
At 130mph, that's not much haha
I think that is the delta he was getting between the two different AOA. Using the 6.9mm travel would give 76.6lb per rear wheel. Still not a lot though.

I'm calculating assuming he is measuring ride height change though. Could be measuring shock travel or spring travel. In that case my calculations would be wrong. If spring travel, then 136.8 lb per rear wheel.
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      06-08-2020, 04:40 AM   #37
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Quote:
Originally Posted by Bartledoo View Post
Quote:
Originally Posted by tsk94 View Post
At 130mph, that's not much haha
I think that is the delta he was getting between the two different AOA. Using the 6.9mm travel would give 76.6lb per rear wheel. Still not a lot though.

I'm calculating assuming he is measuring ride height change though. Could be measuring shock travel or spring travel. In that case my calculations would be wrong. If spring travel, then 136.8 lb per rear wheel.
The pots measures the shock travel.
I don't know how to convert shock travel to spring travel. I have divorced setup.

Yes, 5mm is the delta between the two positions.

I give about 2mph for that 5mm delta.

This is all estimates but generally points out to the fact that the GTS wing just cancels the lift rather than generate oodles of downforce.
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      06-08-2020, 10:56 AM   #38
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Quote:
Originally Posted by rhyary View Post
The pots measures the shock travel.
I don't know how to convert shock travel to spring travel. I have divorced setup.

Yes, 5mm is the delta between the two positions.

I give about 2mph for that 5mm delta.

This is all estimates but generally points out to the fact that the GTS wing just cancels the lift rather than generate oodles of downforce.
Okay, with shock travel you don't need to convert to spring travel if you know the shock motion ratio. I've read the stock motion ratio is .813, but I've never seen any confirmation. So, the downforce would be 94.2lb at each rear wheel (edit: read 188.4lb total rear DF) given a 282lb wheel rate provided by the 900lb spring.
((6.9/25.4)/.813)*(900*(0.56^2))
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      06-08-2020, 12:35 PM   #39
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Quote:
Originally Posted by Bartledoo View Post
Quote:
Originally Posted by rhyary View Post
The pots measures the shock travel.
I don't know how to convert shock travel to spring travel. I have divorced setup.

Yes, 5mm is the delta between the two positions.

I give about 2mph for that 5mm delta.

This is all estimates but generally points out to the fact that the GTS wing just cancels the lift rather than generate oodles of downforce.
Okay, with shock travel you don't need to convert to spring travel if you know the shock motion ratio. I've read the stock motion ratio is .813, but I've never seen any confirmation. So, the downforce would be 94.2lb at each rear wheel given a 282lb wheel rate provided by the 900lb spring.
((6.9/25.4)/.813)*(900*(0.56^2))
So round figure 100lbs
Is this any thing ?

According to some pages I have without the GTS front and rear the M3 actually generates lift at this speed. So better than lift I guess
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      06-08-2020, 02:33 PM   #40
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Same idea with the aero on the S2000 CR. It isn't so much that it provides real downforce as does a good job reducing some lift. Either way it's going to be good for the car.
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      06-08-2020, 03:19 PM   #41
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Quote:
Originally Posted by //steve\\ View Post
Same idea with the aero on the S2000 CR. It isn't so much that it provides real downforce as does a good job reducing some lift. Either way it's going to be good for the car.
I think this is the best way to describe the GTS wing.

If you want something that produces noticeable downforce you'll need a much larger wing. But the GTS wing eliminates the lift so it's a definite improvement over no wing.
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      06-08-2020, 03:35 PM   #42
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Some good info on the topic summarized here.
https://oppositelock.kinja.com/wings...ong-1665312667
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      06-08-2020, 08:31 PM   #43
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Quote:
Originally Posted by Ngilbe36 View Post
Some good info on the topic summarized here.
https://oppositelock.kinja.com/wings...ong-1665312667
Perhaps a dumb question, but when the GTS wing is at max AoA is it more of a wing/airfoil based on the shape? And where it is at the lowest AoA it acts as more of a spoiler?

Maybe even worse question... for those running a high kick spoiler with a GTS wing, are they negating the effect of the GTS wing because the high kick spoiler creates an air pocket and reduces the amount of air the GTS wing gets?
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      06-08-2020, 11:28 PM   #44
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High kick spoiler is downstream of GTS wing. So if anything, it's the spoiler that gets negated, not the wing.
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