GTS Wing's Aerodynamics

[roastbeef]

And if anyone is interested, my mk2 wing with extended risers is for sale.

[rhyary]

@roastbeef what about the holes in the trunk deck? this is why after initially thinking about selling ny GTS wing, I went looking for a used trunk.

[roastbeef]

Originally Posted by rhyary

@roastbeef what about the holes in the trunk deck? this is why after initially thinking about selling ny GTS wing, I went looking for a used trunk.

I still have my oem trunk. Hoping to upgrade to carbon soon, and I want an aeromotions active wing to go with it.

[rhyary]

Schedule to pickup the car today
.

[rhyary]

APR set to 5 deg AOA
Gurney flap not installed yet.

.

[tsk94]

You're not measuring AOA based off the element, right?

Edit: My bad, didn't read that correctly. W/o a gurney flap and w/ the adjustable endplates that should be correct. I'd suggest installing the gurney though. Makes the wing a lot more effective and not a huge loss in efficiency

[rhyary]

Originally Posted by tsk94

You're not measuring AOA based off the element, right?

Edit: My bad, didn't read that correctly. W/o a gurney flap and w/ the adjustable endplates that should be correct. I'd suggest installing the gurney though. Makes the wing a lot more effective and not a huge loss in efficiency

I have the Gurney.
The Gurney will be installed on June 7th.
According to APR with the Gurney Installed, you subtract 4 deg from the angle meter.

So 9 with Gurney is 5 AOA

[tsk94]

Originally Posted by rhyary

I have the Gurney.
The Gurney will be installed on June 7th.
According to APR with the Gurney Installed, you subtract 4 deg from the angle meter.

So 9 with Gurney is 5 AOA

Sounds good.

Just make sure the floor you're measuring on is level then. Otherwise it won't be accurate.

[rhyary]

Originally Posted by tsk94

Sounds good.

Just make sure the floor you're measuring on is level then. Otherwise it won't be accurate.

Yes. My garage is leveled (1 deg slope for drainage)

[rhyary]

Update:
based on rear pots analysis, having the GT250 at 5deg AOA relative to ground provided no effect.

Between 80-132mph the top speed at NYST was the same and no measurable downforce was recorded.

I adjusted the wing to 10 AOA relative to ground will see if I can see in the data that it makes a difference.

Since I don't have a wind tunnel, yet, I can only record AOA relative to the ground, since I don't have a way to see the angle of the air.

This will need to be a trail and error exercise, unless someone has a better idea

BTW, the front did actually recorded down force

[Bartledoo]

Lol

[tsk94]

There's absolutely no way that wing produces 'no measurable downforce between 80-132mph' at 5*. Either the wing is setup wrong (the AOA is not at what you think it is, ie. it's much less), your pots are incorrect or you're interrupting the data from the pots incorrectly.

Something's up, that's all I can say. Especially when the front is 'recording downforce' when all you have is a GT4 style lip, which doesn't do very much.

[rhyary]

Originally Posted by tsk94

There's absolutely no way that wing produces 'no measurable downforce between 80-132mph' at 5*. Either the wing is setup wrong (the AOA is not at what you think it is, ie. it's much less), your pots are incorrect or you're interrupting the data from the pots incorrectly.

Something's up, that's all I can say. Especially when the front is 'recording downforce' when all you have is a GT4 style lip, which doesn't do very much.

As I tried to explain, I don't have a way to measure the AOA in relation to the air. So AOA relative to ground is a reference point but not a "true" aerodynamic AOA.

The true AOA, I will have to find by trail and error.

Yes, the front was recording very little downforce. This is adjusted to 10 AOA in reference to ground.
.

[tsk94]

Originally Posted by rhyary

As I tried to explain, I don't have a way to measure the AOA in relation to the air. So AOA relative to ground is a reference point but not a "true" aerodynamic AOA.

The true AOA, I will have to find by trail and error.

Yes, the front was recording very little downforce.

How is APR measuring AOA to get the lift/drag values published on their site? Surely there is a way for you to replicate the AOA they claim is 5*. Have you contacted them?

From the figure you posted, that wing at 5* at 120mph produces 166lbs of downforce - without a gurney. With a gurney it would be significantly more. If the wing is setup properly to achieve this level of downforce you'd definitely notice the added rear grip, regardless of what the data is showing you (which again could be wrong..).

[rhyary]

Originally Posted by tsk94

How is APR measuring AOA to get the lift/drag values published on their site? Surely there is a way for you to replicate the AOA they claim is 5*. Have you contacted them?

From the figure you posted, that wing at 5* at 120mph produces 166lbs of downforce - without a gurney. With a gurney it would be significantly more. If the wing is setup properly to achieve this level of downforce you'd definitely notice the added rear grip, regardless of what the data is showing you.

APR only publish AOA in relation to the air.

Any yes, I contacted them, but as you know, aero is way more complicated than AOA.

The main challenge is to find the true AOA since every installation will be different.

Again, the issue is not what the wing is doing at 5 AOA, but finding where is 5 AOA.

[rhyary]

Car feels great.
But unless I can back up my "feelings" with data, I can't sleep at night.

[tsk94]

Originally Posted by rhyary

APR only publish AOA in relation to the air.

Any yes, I contacted them, but as you know, aero is way more complicated than AOA.

The main challenge is to find the true AOA since every installation will be different.

Again, the issue is not what the wing is doing at 5 AOA, but finding where is 5 AOA.

That's what I thought. My point was, hopefully they can give you at least a rough estimation of how you can calculate 5* on the car to what they call 5* to the air.

Originally Posted by rhyary

Car feels great.
But unless I can back up my "feelings" with data, I can't sleep at night.

Feels like you're overcomplicating things. Just crank the wing up till you feel a difference.

I didn't need to look at the data to confirm adding a wing allowed me to carry 6mph through a turn at my track and added more stability under braking, on an otherwise unchanged car. Use the data to confirm what you're feeling, but not the other way around.

You said the data showed no measurable amount of downforce being produced at 5*, but what did you feel? Did you notice any difference compared to before?

[sc_tr0jan_m3]

This thread keeps delivering… I applaud your determination. But boy, this seems like a bit of overkill.

[rhyary]

Originally Posted by sc_tr0jan_m3

This thread keeps delivering… I applaud your determination. But boy, this seems like a bit of overkill.

Doing HPDE days for 4 years @ 25-30 per year solidified my opinion that people that like cars, and like driving, enjoy HPDE in different ways.

A time attack or W2W race has a deterministic outcome, you either went one lap very fast, or you won your race. Everything else is chit chat.

HPDE is different in away that there is no outcome but the individual pure enjoyment from the activity.

So the concept of "over complicated" does not exist. I enjoy knowing and I strive to understand.

If I just cranked the wing and the car went faster, I would not enjoy that with out seeing in the data why. If the data does not show why, the I continue to find math channels, user profiles and tune my potentiometers to see why

If I know why then that gives me satisfaction.

My way is not for everyone, nor should it be. Regardless, I enjoy sharing what I am doing and usually the Forum give me something to think about that I missed.

This may sound funny to you guys, but I have started to take everything I have learned and have began to data coach people that know me. So far I got two people to do PB after my instructions.

Also, I got accepted to Certified BMW CCA coaching program at Watkins Glen. So I plan to take everything I have learned data wise, tire wise, traction management wise and hopefully help some people enjoy the sport.

I am learning a lot from both a suspension engineer I am working with that is a wizard AIM math channel guy and virtual coach. I am working with them regularly after almost every track day.

I wish my driving would progress as quickly as my understanding. However, this is a sport that executing what you know seems to be difficult and elusive.

[leftfootbr8king]

There's about to be a run on ebay tires under your tutelage. Get them while you still can!

In all seriousness, congrats on being accepted into the coaching program.

this thread is a good reminder of different strokes for different folks. There's a reason why race teams have race engineers who get their kicks knowing why the car went fast, and the person behind the wheel who got theirs by simply going fast.

[rhyary]

Quick update.
Over time I have been adding AOA to the APR wing. I started at 5* moved it about and went back to 5*.

After the initial playing with the holes, because they are there, I started to systematically hole by hole from 5*.

At 7.5* at LRP i really liked it. But with 7.5* I also got to 130mph coming into T1 @ NYST.

If the wing was truly 7.5* AOA in relation to the air stream, I don't think I could have gotten to 130mph.

So I adjusted the wing one more hole.
Now at 9.60* with ground reference.

Will see how that works.