GTS Wing's Aerodynamics

[rhyary]

Originally Posted by Bartledoo

Lol I thought you wanted less understeer. So you're gonna throw a big wing on with no front splitter?? This is all very confusing, especially when you add in wider, stickier tires in the rear vs the front.

Also, if you are doing a GT-250 wing you can just mount it directly to the trunk, unless you have a carbon trunk without reinforcements. Mounting further back like that hard setup in the photo will give you even more understeer.

I do have a splitter. It is just not as big as Dogbone's.

why do you think I don't have a splitter?

[Bartledoo]

Originally Posted by rhyary

I do have a splitter. It is just not as big as Dogbone's.

why do you think I don't have a splitter?

Are you referring to the gts splitter? I don’t consider that a real splitter.

[rhyary]

Originally Posted by Bartledoo

Are you referring to the gts splitter? I don’t consider that a real splitter.

Got it.
Thanks for the clarification.

[rhyary]

This idea perhaps is completely wrong, but let me explain anyway.

I am focused mainly on three tracks that are close to me. LRP, NYST and PMP.

This means I need aero for 70-100 mph turns and 130-140 straight line braking.

According to the scale at ACM my car weigh 2001Lbs front and 1707Lbs rear. I believe this is with the driver in. Let's round it up to 300Lbs front bias.

This bias is for two reasons supercharger (80Lbs on the nose) and normal lightness in the rear (Akra, Cs ds, Voltfreek).

So to go back to closer to 50/50 the rear aero needs to produce 300Lbs before I have to worry about effective splitter.

The APR GT-250 @ 10 degrees produce 131Lbs at 80mph - so no need for a splitter here. Still rear is light. So most of my "high speed" turns should not be an issue of understeering


The APR GT-250 @ 10 degrees produce 300Lbs at 120mph - so for a straight line braking (end of LRP, NYST and PMP) I will be at 50/50 weight distribution and I don't see a need for a better splitter here also

The GTS produces 66Lbs downforce at 120mph and does not contribute much for braking in a straight line. It designed to counter lift of the regular M3 body.

At WGI I plan to run the GT-250 at 5 degrees.
@5 deg AOA it produce 300Lbs at 160mph.

At 10deg it produces 500Lbs and I don't think I am ready for that. In addition, I am not sure the M3 can go 150mph with a 10deg angle.

My thinking could be completely wrong, but this how I came up with what I want to do next.

Also, I am doing Hard mounts for two reasons:
1. I like the way it looks
2. I like the 2D wing which needs to be higher than a 3D wing

[Bartledoo]

That's quite an analysis.

[sc_tr0jan_m3]

Originally Posted by Bartledoo

That's quite an analysis.

😂

[Epoustouflant]

You may also be interested in this: GT4R (160cm) on extended mounts

[rhyary]

What are the specs on GT4R?

[Epoustouflant]

Originally Posted by rhyary

What are the specs on GT4R?

160cm width - pre preg, mounts on extended or standard mounts.

[rhyary]

Originally Posted by Epoustouflant

160cm width - pre preg, mounts on extended or standard mounts.

What are the are the specs?
L/D
Downforce at 80, 120, 150
drag
AOA

These specs

[Epoustouflant]

Originally Posted by rhyary

What are the are the specs?
L/D
Downforce at 80, 120, 150
drag
AOA

These specs

It's sold as a universal wing for usage across all M cars. That data is unavailable.

[jid2]

Sorry, but it's not as simple as just applying the force from the wings in free air. A few points.

You need to understand the aero balance of the car itself at speed. Most cars create lift as speed increases, and the balance of front lift vs rear lift is import.

The car is a balance beam, you don't get to just add force (with a single change) to either the front or the rear without removing it from the other. If you create 50 lbs of force on the rear of the car, expect to see maybe 20 lbs of force removed from the front.

Remember that 10 degree angle of attack while mounted on the car is likely achieved with the wing mounted around 0 degrees angle to the world.

[rhyary]

Originally Posted by jid2

Sorry, but it's not as simple as just applying the force from the wings in free air. A few points.

You need to understand the aero balance of the car itself at speed. Most cars create lift as speed increases, and the balance of front lift vs rear lift is import.

The car is a balance beam, you don't get to just add force (with a single change) to either the front or the rear without removing it from the other. If you create 50 lbs of force on the rear of the car, expect to see maybe 20 lbs of force removed from the front.

Remember that 10 degree angle of attack while mounted on the car is likely achieved with the wing mounted around 0 degrees angle to the world.

Good point. Very good point.
To oversimplify, if I am looking to balance 300Lbs, than adding 150 on the rear will take off 150 from the front. Assuming not change on the front

Will start with 0 AOA and collect data.

[Bartledoo]

Originally Posted by rhyary

Good point. Very good point.
To oversimplify, if I am looking to balance 300Lbs, than adding 150 on the rear will take off 150 from the front. Assuming not change on the front

Will start with 0 AOA and collect data.

I don't know where you are coming up with this - balancing weight distribution with a wing. Maybe the VW/Audi guys just need a huge wing to fix their problems.

[tsk94]

Originally Posted by rhyary

This idea perhaps is completely wrong, but let me explain anyway.

I am focused mainly on three tracks that are close to me. LRP, NYST and PMP.

This means I need aero for 70-100 mph turns and 130-140 straight line braking.

According to the scale at ACM my car weigh 2001Lbs front and 1707Lbs rear. I believe this is with the driver in. Let's round it up to 300Lbs front bias.

This bias is for two reasons supercharger (80Lbs on the nose) and normal lightness in the rear (Akra, Cs ds, Voltfreek).

So to go back to closer to 50/50 the rear aero needs to produce 300Lbs before I have to worry about effective splitter.

The APR GT-250 @ 10 degrees produce 131Lbs at 80mph - so no need for a splitter here. Still rear is light. So most of my "high speed" turns should not be an issue of understeering


The APR GT-250 @ 10 degrees produce 300Lbs at 120mph - so for a straight line braking (end of LRP, NYST and PMP) I will be at 50/50 weight distribution and I don't see a need for a better splitter here also

The GTS produces 66Lbs downforce at 120mph and does not contribute much for braking in a straight line. It designed to counter lift of the regular M3 body.

At WGI I plan to run the GT-250 at 5 degrees.
@5 deg AOA it produce 300Lbs at 160mph.

At 10deg it produces 500Lbs and I don't think I am ready for that. In addition, I am not sure the M3 can go 150mph with a 10deg angle.

My thinking could be completely wrong, but this how I came up with what I want to do next.

Also, I am doing Hard mounts for two reasons:
1. I like the way it looks
2. I like the 2D wing which needs to be higher than a 3D wing

Originally Posted by Bartledoo

I don't know where you are coming up with this - balancing weight distribution with a wing. Maybe the VW/Audi guys just need a huge wing to fix their problems.

Exactly. This approach, to me, makes no sense. Using a static weight distribution to try to determine how much AOA and what wing to choose isn't helpful. When you're braking hard into T1 you have NO WHERE near 50/50 weight distribution once the load transfers. Same for in the turns. The handling balance can be almost completely independent of the F/R static weight distribution, as so many other factors play a bigger role in contributing to that.

If you slap on a roof height wing onto the car with no other changes, put it at an AOA of 2-5*, the car will understeer more then 80mph turns. Because you've added grip to the rear, and as explained above, taken a bit away from the front. That doesn't mean the car will push like crazy now, but the balance will have shifted towards more understeer, whether you recognize it or not. So your analysis of not needing to upgrade your splitter to maintain the handling balance isn't very applicable.

You noted you were getting into ABS in the rear first, what phase of the braking zone is this in? A wing will help at the initial phase, but beyond that the benefits of the wing obviously decrease as the speed goes down. Also, getting into ABS isn't a bad thing.. If you're not getting into at least a bit of ABS at the hardest braking zones on your track, you're leaving time on the table. My point being, I'm not sure why you're concerned with that. A more applicable concern that would call for the wing upgrade is you want more high speed braking stability. If the rear is moving around under hard braking then that's something where the wing will really help.

A counter to your initial thoughts would be; Why does a GT3 Cup car use such a large rear wing and relative lack of front aero given it's weight distribution? If you apply your thinking to this, it makes no sense for the Cup car to run such a large rear wing as it already has a 35/65 weight distribution. The same can be applied for how the static weight distribution doesn't influence cornering balance. If you say you can add X amount of downforce as 'weight' to the rear of your car before the front starts to understeer, why don't FWD cars oversteer? Stock FWD cars are a good example. But it can go both ways; why doesn't a FWD understeer with all that weight up front AND why doesn't it oversteer with such little weight in the rear and the reverse to something like a rear engine 911. Because, as a whole, static weight distribution plays a very small role in overall corner handling balance.

I still think the rear wing is a good upgrade, as it will have benefits. But I'd suggest to not get too caught up in the numbers until you actually test the wing at different AOA's on track and can feel the difference yourself. At the end of the day that's what matters, the feel or at least how it feels for you. The numbers on paper are irrelevant to a large extent. Also don't run it at 10* like you've mentioned, you'll create so much drag you'll be way slower then at an appropriate angle and likely slower then with your current wing. My current home track is fricking slow, top speed of 110mph, and I'm running like ~6*. For the tracks you visit you should be in the ~1-3* range, 5* at the absolute most if you're prioritizing increased confidence from the car.

[rhyary]

@tsk94

>> . If the rear is moving around under hard braking then that's something where the wing will really help.

yes, the rear is moving around under hard braking.

I am working with Ray Phillips and the data shows a wing will be beneficial. I may not be able to explain too well why.

I agree with your suggestion about beginning running the wing at 0 AOA rather then 10*.

I plan to experiment with all AOAs.

[DRLane]

Originally Posted by rhyary

@tsk94

>> . If the rear is moving around under hard braking then that's something where the wing will really help.

yes, the rear is moving around under hard braking.

I am working with Ray Phillips and the data shows a wing will be beneficial. I may not be able to explain too well why.

I agree with your suggestion about beginning running the wing at 0 AOA rather then 10*.

I plan to experiment with all AOAs.

The rear movement is also attributable to your zero toe alignment.

I think what's weird or at least strikes me as odd. Is you're so analytically aware in your approach, but then sloppy in modeling, and conclusions. And then when knowledgeable folks ask questions there's a defensiveness that's odd given you're participating on a track focused public forum with the intent of "sharing".

I totally understand ignoring snide or a'hole remarks (I've definitely been a culprit), but I guess I don't understand what is the goal with these posts?

Are you looking for blind agreement?

[rhyary]

Originally Posted by DRLane

The rear movement is also attributable to your zero toe alignment.

I think what's weird or at least strikes me as odd. Is you're so analytically aware in your approach, but then sloppy in modeling, and conclusions. And then when knowledgeable folks ask questions there's a defensiveness that's odd given you're participating on a track focused public forum with the intent of "sharing".

I totally understand ignoring snide or a'hole remarks (I've definitely been a culprit), but I guess I don't understand what is the goal with these posts?

Are you looking for blind agreement?

Not at all. I am simply sharing my thoughts and what I am doing. I enjoy comments, suggestions and advise. But, I am definitely not looking for people to agree with me.

I do try to explain why I do certain things. This can misinterpreted as defensiveness. Which is understandable.

While I am not shy of trying things, I report back what my findings are. In this instance, if the wing will make slower, I will report on that. It it makes me faster, I will report on that as well.

[rhyary]

[QUOTE=DRLane;27263252]

Originally Posted by rhyary

@tsk94

>> The rear movement is also attributable to your zero toe alignment.

No it does not. , but I don't want to derail the GTS / Wing discussion

The rear is moving under 1100psi braking, not when I go 135mph in a straight line. car is perfect on any long run into turn 1 in NYST, LRP and PMP.

Potentiometers suggested too much rebound and I dialed rebound back

[DRLane]

[QUOTE=rhyary;27263370]

Originally Posted by DRLane

No it does not. , but I don't want to derail the GTS / Wing discussion

The rear is moving under 1100psi braking, not when I go 135mph in a straight line. car is perfect on any long run into turn 1 in NYST, LRP and PMP.

Potentiometers suggested too much rebound and I dialed rebound back

I meant, when threshold braking at the conclusion of a long straight. That wiggle or movement in the rear can also be attributable to your rear toe alignment. You're saying it does not?

[rhyary]

[QUOTE=DRLane;27263436]

Originally Posted by rhyary

I meant, when threshold braking at the conclusion of a long straight. That wiggle or movement in the rear can also be attributable to your rear toe alignment. You're saying it does not?

It is not. I have been on 0 toe for awhile and it is more due to my experimenting with the JRZ rebounds.

I dialed the rebound back from 15-16 to 8 and at least on road tests it worked as expected.

And since someone is going to comment, I went up the rebound tree to see the effect on roll.

[rhyary]

I just saw on IND web site that my RKP GTS wing goes for $2500.00. Someone is going to enjoy that wing for a lot less soon.