Diffuser Lift data for F1 1990 cars?

[Testdrive]

Hello,

I'm a modder. I like drive and mod F1 car's in Assetto Corsa (car simulation application)
I'm trying to find actual data for F1 1990's car's. To me realistically, it seems like the average is 25% front, 35 rear % and 40% floor diffuser. Does anyone know the precise data? I've found some mods 1990's F1 cars with like 70% diffuser, and 30% for rear and fronts.

This 3D simulation seems to give the body, which should be the diffuser about 33%, similar for fronts and rear wings, but front seems rather big. So realistic it's probably 25% for the front wing.
https://www.simscale.com/forum/t/1990s- ... on/82704/2

[jjn9128]

Hello,

I'm a modder. I like drive and mod F1 car's in Assetto Corsa (car simulation application)
I'm trying to find actual data for F1 1990's car's. To me realistically, it seems like the average is 25% front, 35 rear % and 40% floor diffuser. Does anyone know the precise data? I've found some mods 1990's F1 cars with like 70% diffuser, and 30% for rear and fronts.

This 3D simulation seems to give the body, which should be the diffuser about 33%, similar for fronts and rear wings, but front seems rather big. So realistic it's probably 25% for the front wing.
https://www.simscale.com/forum/t/1990s- ... on/82704/2

Mike Gascoyne and Ben Agathangelou wrote a paper in SAE in 1998 with data for Tyrrells between '89 and '97.

Cz total was about 2.58 in '90 up to a peak of 3.04 in '92 down to a minimum of 2.3 in 1995 when the stepped floors came in - all with aerobalance of 36%. In absolute that's 18.35kN, 21.63kN, 16.36kN at 200mph based on a frontal area of 1.47m^2. Efficiency in the same years was 2.85:1, 3.3:1, and 2.5:1, so Cx was pretty consistent = 0.91/ 0.92/ 0.92.

Front wings were 25-30%, floor 40%, and rear wing 30-35%. Aero was more rear biased because weight was more rear biased with big heavy engines and gearboxes.

[Testdrive]

So cx was the diffuser?

I did wings tests with the Assetto Corsa MOD RSS F1 1990 and other's and it pushed diffuser to about 1.1

if you want to check it out

The test's are full wing rear and front at 241KM for a few Assetto Corsa F1 Mods. You can see how some use too much diffuser.

Thanks for the information.

[Testdrive]

Hello,

I'm a modder. I like drive and mod F1 car's in Assetto Corsa (car simulation application)
I'm trying to find actual data for F1 1990's car's. To me realistically, it seems like the average is 25% front, 35 rear % and 40% floor diffuser. Does anyone know the precise data? I've found some mods 1990's F1 cars with like 70% diffuser, and 30% for rear and fronts.

This 3D simulation seems to give the body, which should be the diffuser about 33%, similar for fronts and rear wings, but front seems rather big. So realistic it's probably 25% for the front wing.
https://www.simscale.com/forum/t/1990s- ... on/82704/2

Mike Gascoyne and Ben Agathangelou wrote a paper in SAE in 1998 with data for Tyrrells between '89 and '97.

Cz total was about 2.58 in '90 up to a peak of 3.04 in '92 down to a minimum of 2.3 in 1995 when the stepped floors came in - all with aerobalance of 36%. In absolute that's 18.35kN, 21.63kN, 16.36kN at 200mph based on a frontal area of 1.47m^2. Efficiency in the same years was 2.85:1, 3.3:1, and 2.5:1, so Cx was pretty consistent = 0.91/ 0.92/ 0.92.

Front wings were 25-30%, floor 40%, and rear wing 30-35%. Aero was more rear biased because weight was more rear biased with big heavy engines and gearboxes.

How were the tests done? 241KM with full front and rear wings? like a Monaco setup?

[jjn9128]

How were the tests done? 241KM with full front and rear wings? like a Monaco setup?

You're asking similar questions in two topics, so lets answer it all in here.

Those numbers from the Agathangelou/Gascoyne paper were from wind tunnel data, at the time probably 40% scale model at around 40-50m/s. But that doesn't really matter because aerodynamicists use coefficients, because they are insensitive to speed/atmospheric conditions, and F1 cars are fairly Reynolds number insensitive - i.e. there is no boundary layer state of flow change at race speeds assuming a constant car attitude - so forces scale quite satisfactorily from wind tunnel tests.

Downforce squares with speed and cooler/denser air means downforce increases, by the following equation:

where F is the lift force in Newtons, is air density, U is the velocity, is the force coefficient, and S is the frontal area. There is a legacy value for the frontal area of which has been used in F1 through the years and for ISA conditions is . So taking the peak coefficient (from 1992) from the table JJR supplied from that paper in the other topic of 3.04, I get a downforce of 12,165N at 240kph, with 3,698N of drag - up to 21,627N:6573N at 320kph. Power from the engines around that point would be 700-750bhp so from the drag and an assumed efficiency of 80% I get an back of envelope top speed between 285kph and 295kph.

The track they presented data for was probably Barcalona, because it's the main test venue. They also were for Tyrrell, which while a good team was not the team it once was through the 90s - so expect at least 20% more downforce for the top teams at that time (the gaps will be narrower now). There is also a tendency for F1 teams to obfuscate their data because they don't want to give anything away to an opponent so there really is very little real data out there to compare to.

You've also failed to satisfactorily answer the question of what the lookup tables contain, could it be you're just adjusting some baseline while the variable is the default?!

[Testdrive]

How were the tests done? 241KM with full front and rear wings? like a Monaco setup?

You're asking similar questions in two topics, so lets answer it all in here.

Those numbers from the Agathangelou/Gascoyne paper were from wind tunnel data, at the time probably 40% scale model at around 40-50m/s. But that doesn't really matter because aerodynamicists use coefficients, because they are insensitive to speed/atmospheric conditions, and F1 cars are fairly Reynolds number insensitive - i.e. there is no boundary layer state of flow change at race speeds assuming a constant car attitude - so forces scale quite satisfactorily from wind tunnel tests.

Downforce squares with speed and cooler/denser air means downforce increases, by the following equation:

where F is the lift force in Newtons, is air density, U is the velocity, is the force coefficient, and S is the frontal area. There is a legacy value for the frontal area of which has been used in F1 through the years and for ISA conditions is . So taking the peak coefficient (from 1992) from the table JJR supplied from that paper in the other topic of 3.04, I get a downforce of 12,165N at 240kph, with 3,698N of drag - up to 21,627N:6573N at 320kph. Power from the engines around that point would be 700-750bhp so from the drag and an assumed efficiency of 80% I get an back of envelope top speed between 285kph and 295kph.

The track they presented data for was probably Barcalona, because it's the main test venue. They also were for Tyrrell, which while a good team was not the team it once was through the 90s - so expect at least 20% more downforce for the top teams at that time (the gaps will be narrower now). There is also a tendency for F1 teams to obfuscate their data because they don't want to give anything away to an opponent so there really is very little real data out there to compare to.

You've also failed to satisfactorily answer the question of what the lookup tables contain, could it be you're just adjusting some baseline while the variable is the default?!

Thanks for your interesting reply, variables are probably default, seems like the application is going via 1.0, instead of the 1,47m as you stated and someone else. It explains why I only reach about 700KG of down-force for TOTAL of 2.9 CL. But if you times it by 1.4 it reaches 3.9 - 4 like in the application. I was tinkering yesterday I was trying 1993 setup, I tested about 1100KG of down-force with about 370KG of drag with 37% frontal. The car was stable, but had issues with slow speed frontal grip, but I think I need better balancing. Frontal Grip was getting about 37%, but slower speed's it was about 25%, so that seems to be the problem, more balancing required. Thanks for what you wrote, I now have a better understanding of aero dynamic's in 1990's and how it translates into Assetto Corsa.

[Dynamicflow]

How were the tests done? 241KM with full front and rear wings? like a Monaco setup?

You're asking similar questions in two topics, so lets answer it all in here.

Those numbers from the Agathangelou/Gascoyne paper were from wind tunnel data, at the time probably 40% scale model at around 40-50m/s. But that doesn't really matter because aerodynamicists use coefficients, because they are insensitive to speed/atmospheric conditions, and F1 cars are fairly Reynolds number insensitive - i.e. there is no boundary layer state of flow change at race speeds assuming a constant car attitude - so forces scale quite satisfactorily from wind tunnel tests.

Downforce squares with speed and cooler/denser air means downforce increases, by the following equation:

where F is the lift force in Newtons, is air density, U is the velocity, is the force coefficient, and S is the frontal area. There is a legacy value for the frontal area of which has been used in F1 through the years and for ISA conditions is . So taking the peak coefficient (from 1992) from the table JJR supplied from that paper in the other topic of 3.04, I get a downforce of 12,165N at 240kph, with 3,698N of drag - up to 21,627N:6573N at 320kph. Power from the engines around that point would be 700-750bhp so from the drag and an assumed efficiency of 80% I get an back of envelope top speed between 285kph and 295kph.

The track they presented data for was probably Barcalona, because it's the main test venue. They also were for Tyrrell, which while a good team was not the team it once was through the 90s - so expect at least 20% more downforce for the top teams at that time (the gaps will be narrower now). There is also a tendency for F1 teams to obfuscate their data because they don't want to give anything away to an opponent so there really is very little real data out there to compare to.

You've also failed to satisfactorily answer the question of what the lookup tables contain, could it be you're just adjusting some baseline while the variable is the default?!

Thanks for your interesting reply, variables are probably default, seems like the application is going via 1.0, instead of the 1,47m as you stated and someone else. It explains why I only reach about 700KG of down-force for TOTAL of 2.9 CL. But if you times it by 1.4 it reaches 3.9 - 4 like in the application. I was tinkering yesterday I was trying 1993 setup, I tested about 1100KG of down-force with about 370KG of drag with 37% frontal. The car was stable, but had issues with slow speed frontal grip, but I think I need better balancing. Frontal Grip was getting about 37%, but slower speed's it was about 25%, so that seems to be the problem, more balancing required. Thanks for what you wrote, I now have a better understanding of aero dynamic's in 1990's and how it translates into Assetto Corsa.

How is your ride height changing with speed? What are your front and rear spring rates?

[Testdrive]

You're asking similar questions in two topics, so lets answer it all in here.

Those numbers from the Agathangelou/Gascoyne paper were from wind tunnel data, at the time probably 40% scale model at around 40-50m/s. But that doesn't really matter because aerodynamicists use coefficients, because they are insensitive to speed/atmospheric conditions, and F1 cars are fairly Reynolds number insensitive - i.e. there is no boundary layer state of flow change at race speeds assuming a constant car attitude - so forces scale quite satisfactorily from wind tunnel tests.

Downforce squares with speed and cooler/denser air means downforce increases, by the following equation:

where F is the lift force in Newtons, is air density, U is the velocity, is the force coefficient, and S is the frontal area. There is a legacy value for the frontal area of which has been used in F1 through the years and for ISA conditions is . So taking the peak coefficient (from 1992) from the table JJR supplied from that paper in the other topic of 3.04, I get a downforce of 12,165N at 240kph, with 3,698N of drag - up to 21,627N:6573N at 320kph. Power from the engines around that point would be 700-750bhp so from the drag and an assumed efficiency of 80% I get an back of envelope top speed between 285kph and 295kph.

The track they presented data for was probably Barcalona, because it's the main test venue. They also were for Tyrrell, which while a good team was not the team it once was through the 90s - so expect at least 20% more downforce for the top teams at that time (the gaps will be narrower now). There is also a tendency for F1 teams to obfuscate their data because they don't want to give anything away to an opponent so there really is very little real data out there to compare to.

You've also failed to satisfactorily answer the question of what the lookup tables contain, could it be you're just adjusting some baseline while the variable is the default?!

Thanks for your interesting reply, variables are probably default, seems like the application is going via 1.0, instead of the 1,47m as you stated and someone else. It explains why I only reach about 700KG of down-force for TOTAL of 2.9 CL. But if you times it by 1.4 it reaches 3.9 - 4 like in the application. I was tinkering yesterday I was trying 1993 setup, I tested about 1100KG of down-force with about 370KG of drag with 37% frontal. The car was stable, but had issues with slow speed frontal grip, but I think I need better balancing. Frontal Grip was getting about 37%, but slower speed's it was about 25%, so that seems to be the problem, more balancing required. Thanks for what you wrote, I now have a better understanding of aero dynamic's in 1990's and how it translates into Assetto Corsa.

How is your ride height changing with speed? What are your front and rear spring rates?

I believe it was 90 for the suspension for all wheels, It might be I have placed too much drag on the rear. I have to do more testing. I suspect back is going down first then at higher speeds the front finally comes down all the way. It explains 37% front at 241KM, 25% at lower speeds. Either way I have redo the aero, since I changed things here and there, I moved frontal diffuser forward. So it's not an easy thing to do. Would be nice if some F1 Team from 1990's released their data, I would just input it. Either way, It would be close this 37% distribution. Drag/Lift Ratio's released by some authors. I guess when your trying to simulate an F1 car, you want it as close as the simulation can do it.

[Dynamicflow]

The front spring is usually harder than the rear - at higher speeds the rear should drop more than the front.

What are your static front and rear ride heights?

It appears your front ride height is too high - the contribution from the rear is obviously more as a result of this, however at higher speeds as the ride height drops, the diffuser usually stalls since it gets closer to the floor resulting in a slightly more contribution from the front. Ideally, you would need an aero map to understand the aerodynamics of your car better and set the car up accordingly.

[Testdrive]

The front spring is usually harder than the rear - at higher speeds the rear should drop more than the front.

What are your static front and rear ride heights?

It appears your front ride height is too high - the contribution from the rear is obviously more as a result of this, however at higher speeds as the ride height drops, the diffuser usually stalls since it gets closer to the floor resulting in a slightly more contribution from the front. Ideally, you would need an aero map to understand the aerodynamics of your car better and set the car up accordingly.

I put them as 2cm and 5cm rear, but all depends on tyre pressure, springs. It does have height values file, where you can edit it to have more downforce or less depending how close you get to the ground.. I might re-attempt it in future. These mod's for assetto corsa are little over the place with ride heights, people tend to do things differently. It comes to the point, you need a wind tunnel or an expert to get it as accurate as it can be in the game. I did come across data on internet, how ride height effects lift.

[Testdrive]

I guess the main difference between 1990's, 1989 with the lower L/D of 2.63, 2.85, compared 2.95 in 1991, 1993, and early 1994 was the less efficient floor diffuser.

How were the tests done? 241KM with full front and rear wings? like a Monaco setup?

You're asking similar questions in two topics, so lets answer it all in here.

Those numbers from the Agathangelou/Gascoyne paper were from wind tunnel data, at the time probably 40% scale model at around 40-50m/s. But that doesn't really matter because aerodynamicists use coefficients, because they are insensitive to speed/atmospheric conditions, and F1 cars are fairly Reynolds number insensitive - i.e. there is no boundary layer state of flow change at race speeds assuming a constant car attitude - so forces scale quite satisfactorily from wind tunnel tests.

Downforce squares with speed and cooler/denser air means downforce increases, by the following equation:

where F is the lift force in Newtons, is air density, U is the velocity, is the force coefficient, and S is the frontal area. There is a legacy value for the frontal area of which has been used in F1 through the years and for ISA conditions is . So taking the peak coefficient (from 1992) from the table JJR supplied from that paper in the other topic of 3.04, I get a downforce of 12,165N at 240kph, with 3,698N of drag - up to 21,627N:6573N at 320kph. Power from the engines around that point would be 700-750bhp so from the drag and an assumed efficiency of 80% I get an back of envelope top speed between 285kph and 295kph.

The track they presented data for was probably Barcalona, because it's the main test venue. They also were for Tyrrell, which while a good team was not the team it once was through the 90s - so expect at least 20% more downforce for the top teams at that time (the gaps will be narrower now). There is also a tendency for F1 teams to obfuscate their data because they don't want to give anything away to an opponent so there really is very little real data out there to compare to.

You've also failed to satisfactorily answer the question of what the lookup tables contain, could it be you're just adjusting some baseline while the variable is the default?!

[jjn9128]

I guess the main difference between 1990's, 1989 with the lower L/D of 2.63, 2.85, compared 2.95 in 1991, 1993, and early 1994 was the less efficient floor diffuser.

There were all sorts of changes through the early 90s, the rear wing was moved, the front wing and its endplates were moved, the tyres and track were made smaller in 1994. Mainly the arrival and banning of active suspension was a biggy. Cars got what would be very peaky aeromaps because the suspension controlled the attitude.

[Testdrive]

I guess the main difference between 1990's, 1989 with the lower L/D of 2.63, 2.85, compared 2.95 in 1991, 1993, and early 1994 was the less efficient floor diffuser.

There were all sorts of changes through the early 90s, the rear wing was moved, the front wing and its endplates were moved, the tyres and track were made smaller in 1994. Mainly the arrival and banning of active suspension was a biggy. Cars got what would be very peaky aeromaps because the suspension controlled the attitude.

Whats interesting, Tyrell came back with with 2.97 Lift to Drag for 1991. They had a wider track compare to 1994, 1993
plus bigger tyres. Yet managed pretty good ratio. Looking at the car, the body seemed light, low side pods probably contributed it.

[Stu]

I guess the main difference between 1990's, 1989 with the lower L/D of 2.63, 2.85, compared 2.95 in 1991, 1993, and early 1994 was the less efficient floor diffuser.

There were all sorts of changes through the early 90s, the rear wing was moved, the front wing and its endplates were moved, the tyres and track were made smaller in 1994. Mainly the arrival and banning of active suspension was a biggy. Cars got what would be very peaky aeromaps because the suspension controlled the attitude.

Whats interesting, Tyrell came back with with 2.97 Lift to Drag for 1991. They had a wider track compare to 1994, 1993
plus bigger tyres. Yet managed pretty good ratio. Looking at the car, the body seemed light, low side pods probably contributed it.

https://upload.wikimedia.org/wikipedia/ ... _Japan.jpg

I can’t help but love the look of that era of cars, there is no clutter....

[jjn9128]

I can’t help but love the look of that era of cars, there is no clutter....

Maybe its rose tinted specs but 90s F1 is superior to modern F1. Something is missing now in the over-managed professionalism (not that professionalism is bad but it's too sterile nowadays).