Upcoming Events

Rookie friendly WTCR sereis Weekly BMW races on Simracing.GP Weekly BMW races on Simracing.GP Other regular AC events on Simracing.GP Weekly GT3 Sprint Races on Simracing.GP Weekly GT4 Sprint Races on Simracing.GP

Any Aero.ini, lut experts? building wings from scratch

Messages
50
Points
0
Hello

I've tinkered with aero, CL and CD files, but I want to create more realistic wings for the F1 cars.
Also another question which I'm not sure? The Lift and Drag Values in in Lut Files? At those Values based on 100KM or like 300KM? Because at different speed's those values would be different.

What I'm trying to do is get a calculator that takes the size and angle, returns the drag and lift, so I can create my own lut files.

Thanks
 
Messages
50
Points
0
The values are coefficients, meaning they are the standard dimensionless constant that works at any speed.

We chatted before, I'm having a second attempt. I was never any good at math's. Aero just doesn't compute in my brain logically. The size of wings like 1 x 1.5 meters, yet they have different values for drag and lift. I mean If I was doing it , I would have wing size, an angle, and speed, then caculate the lift and drag and apply it to that point. That would make sense. I just don't understand how assetto corsa has huge visiable wings, then apply's different drag and lift.
 

Stereo

Premium
Messages
4,155
Points
2,212
Same thing as how you have to input mass in kg, it uses the most common format for measurements (in Italy anyway) and if you have data in something else it's easy to convert cause it's so common. You might see "20lb at 100mph" in a magazine but any detailed wing analysis uses Cd.
 
Last edited:
Messages
50
Points
0
Same thing as how you have to input mass in kg, it uses the most common format for measurements (in Italy anyway) and if you have data in something else it's easy to convert cause it's so common. You might see "20lb at 100mph" in a magazine but any detailed wing analysis uses Cd.

I guess what I know, is that 1.0 x 1.5 meter square called rear or back wing is given certain about lift and drag which is distributed through out that square. Lets say, If change the wing size to like to like 90 x 30 cm, then all drag and lift will be on that wing which should cause hand differely to if it was distrubuted by larger wing, but drag and lift should be the same. It seems like aero is generic, rough front and back downforce and drag which distributed front and rear. I'm just trying find any easy way to create more wings, with their perfect drag and lift for their specif sizes and angle, so that I get more of a realistic aero. I can just edit aero.ini and use 3D model of the F1 car place the wings in right spot, that will sort out the correct distribution, but then I need to make sure that the wing gets correct drag and lift from the angle and size of the wing. Information on 1990's early 1990 F1 cars seems limited, I don't even know how rear drag and lift a F1 car would have at like Monaco. I'm for realism, even the tires are also getting at me, that's another issue.
 

mclarenf1papa

Premium
Messages
1,815
Points
2,012
I guess what I know, is that 1.0 x 1.5 meter square called rear or back wing is given certain about lift and drag which is distributed through out that square. Lets say, If change the wing size to like to like 90 x 30 cm, then all drag and lift will be on that wing which should cause hand differely to if it was distrubuted by larger wing, but drag and lift should be the same. It seems like aero is generic, rough front and back downforce and drag which distributed front and rear. I'm just trying find any easy way to create more wings, with their perfect drag and lift for their specif sizes and angle, so that I get more of a realistic aero. I can just edit aero.ini and use 3D model of the F1 car place the wings in right spot, that will sort out the correct distribution, but then I need to make sure that the wing gets correct drag and lift from the angle and size of the wing. Information on 1990's early 1990 F1 cars seems limited, I don't even know how rear drag and lift a F1 car would have at like Monaco. I'm for realism, even the tires are also getting at me, that's another issue.
TL;DR is: Drag Force = Cd * Area * 0.5 * air_density * Velocity^2

Cd*A (Coefficient of drag * area) in AC is: CHORD*SPAN*CD_GAIN*LUT_AOA_CD(AOA)*LUT_GH_CD(GH)

Parenthesis indicating inputs into a lookup table. CD and CL interchangeable and correspond with drag and downforce coefficients respectively. Standard air density is 1.225 (kg/m^3), velocity in m/s will give you force in newtons.

So drag force at a given velocity is: F = 0.5*CHORD*SPAN*CD_GAIN*LUT_AOA_CD(AOA)*LUT_GH_CD(GH)*air_density*V^2


Other notes that might help you: Wings in AC aren't actual airfoils, they're just points where aero forces can be applied, so anything about size/shape/angle must be baked into the coefficients you enter into the lookup tables. There's nothing physical about them nor do they represent anything physical. Their names (body, rear, etc) also mean nothing.

If the above doesn't help then unless you find someone with extraordinary patience, I'm not sure you'll achieve the results you're looking for.
 
Last edited:
Messages
50
Points
0
TL;DR is: Drag Force = Cd * Area * 0.5 * air_density * Velocity^2

Cd*A (Coefficient of drag * area) in AC is: CHORD*SPAN*CD_GAIN*LUT_AOA_CD(AOA)*LUT_GH_CD(GH)

Parenthesis indicating inputs into a lookup table. CD and CL interchangeable and correspond with drag and downforce coefficients respectively. Standard air density is 1.225 (kg/m^3), velocity in m/s will give you force in newtons.

So drag force at a given velocity is: F = 0.5*CHORD*SPAN*CD_GAIN*LUT_AOA_CD(AOA)*LUT_GH_CD(GH)*air_density*V^2


Other notes that might help you: Wings in AC aren't actual airfoils, they're just points where aero forces can be applied, so anything about size/shape/angle must be baked into the coefficients you enter into the lookup tables. There's nothing physical about them nor do they represent anything physical. Their names (body, rear, etc) also mean nothing.

If the above doesn't help then unless you find someone with extraordinary patience, I'm not sure you'll achieve the results you're looking for.

Well thanks very much for putting the time to explain this, It's certainly helped lots of understanding Aero. Yesterday I did reduce the wing sizes, and lost lots of drag. The size of the wings is in that equation that you stated. I'm simple minded, there isn't many tutorials on the internet on this art. I'm more of getting the equation, step 1, step 2, simplified and applied. This reminds me of high school, when you don't want ask more questions because the teacher will get angry for not understanding it :p. But many thanks, I'm sure many will learn from this post. When I finally get it down to a simplied method I'll create a youtube video to help others.
 
Messages
7
Points
0
TL;DR is: Drag Force = Cd * Area * 0.5 * air_density * Velocity^2

Cd*A (Coefficient of drag * area) in AC is: CHORD*SPAN*CD_GAIN*LUT_AOA_CD(AOA)*LUT_GH_CD(GH)

Parenthesis indicating inputs into a lookup table. CD and CL interchangeable and correspond with drag and downforce coefficients respectively. Standard air density is 1.225 (kg/m^3), velocity in m/s will give you force in newtons.

So drag force at a given velocity is: F = 0.5*CHORD*SPAN*CD_GAIN*LUT_AOA_CD(AOA)*LUT_GH_CD(GH)*air_density*V^2

I have a few questions regarding this.
If a wing, such as the body or rear wing doesn't have a GH LUT, would the LUT value just be 1 in the equation for finding the wing's CL or CD?
Also i'm not getting the correct results with this equation, I'm using CL_GAIN * AOA * GH for some of my wings and with quick hand calculations I'm getting CL and CD values half of the ones that the wings dev app shows me in AC.

I know this is an old subject so any input would be appreciated
 
Last edited:
Messages
50
Points
0
I have a few questions regarding this.
If a wing, such as the body or rear wing doesn't have a GH LUT, would the LUT value just be 1 in the equation for finding the wing's CL or CD?
Also i'm not getting the correct results with this equation, I'm using CL_GAIN * AOA * GH for some of my wings and with quick hand calculations I'm getting CL and CD values half of the ones that the wings dev app shows me in AC.

I know this is an old subject so any input would be appreciated

It's the wing size, try
CHORD=1.0
SPAN=1.0

It should match the CD and CL from the lut files.

You can make it more of a rectangle, but it needs to be kinda be equal to 1meter square.

EG
CHORD=0.65
SPAN=1.54

0.65 x 1.54 = 1.00
1.0 x 1.0 = 1.00
 
Last edited:
Messages
7
Points
0
It's the wing size, try
CHORD=1.0
SPAN=1.0

It should match the CD and CL from the lut files.

You can make it more of a rectangle, but it needs to be kinda be equal to 1meter square.

EG
CHORD=0.65
SPAN=1.54

0.65 x 1.54 = 1.00
1.0 x 1.0 = 1.00

I see how that would affect the forces generated but the CL and CD are unitless and multiplied against those dimensions for the forces. My issues is that the CLs and CDs themselves are off by just over a factor of 2.
 
Messages
50
Points
0
I see how that would affect the forces generated but the CL and CD are unitless and multiplied against those dimensions for the forces. My issues is that the CLs and CDs themselves are off by just over a factor of 2.

Not having GH, should result in 100%. GH just tells % of drag or lift at a certain height.
Well in my experience, changing the wings size's changes what's written in lut. I always try to match whats written in the lut to what's written in the wings apps, it's all about making sure its wing size equals 1.0. Also make the sure wing's are pointing to the correct lut files. In setup.ini sometimes body, is a rear wing.

Hope this helps.
 
Last edited:
Messages
7
Points
0
Not having GH, should result in 100%. GH just tells % of drag or lift at a certain height.
Well in my experience, changing the wings size's changes what's written in lut. I always try to match whats written in the lut to what's written in the wings apps, it's all about making sure its wing size equals 1.0. Also make the sure wing's are pointing to the correct lut files. In setup.ini sometimes body, is a rear wing.

Hope this helps.

I didn't fully understand what you meant at first but I see now. That seems odd to me that the value presented in AC as CL is actually CL*A, but glad it all makes sense now. Thanks for the help
 
Top