Amount and distribution of downforce in a 2003 F1 car

[GGSF1]

Hello,

I am trying to do a simulation of 2 cars of the F1 2003 season (Ferrari and Renault) using the game rFactor.

Currently I am trying to simulate the aerodynamics, and I have found the following information:

About drag, the drag coefficient is between 0.7 (Monza) and 1.1 (Monaco). That seems to be quite clear. The problem comes with the distribution of the drag in the different parts of the car:

I have found this distribution:

Front wing: 10%
Rear wing: 35%
Underside of the car: 15%
Rest of the car: 40%

Then I looked at values of the F2002 car from the game F1 Challenge, which is the car that I am using as reference (I just thought that if the game was licensed, the physical values shouldbe realistic), and the distribution is the following:

Front wing: 20 - 25%
Rear wing: 10 - 40%
Bodywork: 40 - 65%

So I am confused and I don't know what values I should use.

The same problem comes with the downforce, because I have found very different information.

I have found this distribution:

35 - 40%: rear wing
25 - 30%: front wing
20 - 25%: diffuser
5 - 10%: body work

But I've also found that one:

Front wing: 30%
Rear wing: 30%
Underside of the car: 55%

Then I looked at values of the F2002 car from the game F1 Challenge, and the distribution is the following:
Front wing: 17 - 28%
Rear wing: 14 - 32%
Diffuser: 40 - 68%

And also there's different values of the amount of downforce.

I have found that at 240 km/h, the car has got 1200 kg of downforce at Monaco and 1000 kg of downforce at Monza. In another website I have found that at the same speed, the car has got around 1900 kg of downforce. And the values of the amount of downforce from the F2002 from F1 Challenge are 770 kg at Monza and 1300 kg at Monaco (at 240 km/h).


So I decided to ask here to find the correct values. What I need is the distribution of drag and downforce in the different parts of the car (it would be great to know if the distribution changes depending of the track) and the amount of drag and downforce that the car generates (and at which speed) at Monza and at Monaco. Everything should be from the year 2003, and it doesn't need to be exact, an approximation can be useful too.


Thanks in advance,

GGSF1

[Scotracer]

From the work the OWG did when working towards the 2009 aero regs, they put a F2004 in the wind tunnel and this is the distribution they found (and it will be almost identical in 2003):

Diffuser/Underfloor: 37%
Rear wing: 29%
Front wing: 34%

This is verified wind tunnel data - you wont get more accurate

[xpensive]

Right Scot, it would be interesting to learn how much the total aerodynamic downforce is at 240 km/h however?

[timbo]

Here are some numbers for Ferrari F1-2000 from Peter Wright's book which I desperately craving to get...

Components DRAG | DOWNFORCE | L/D RATIO
CD %TOTAL | CL %TOTAL |
FRONT WING 0.123 13.2% | 0.966 36.9% | 7.859
REAR WING 0.297 31.8% | 0.899 34.4% | 3.029
UNDERFLOOR 0.099 10.6% | 1.080 41.3% | 10.911
FRONT WHEELS 0.150 16.0% | -0.038 -1.4% | -0.251
REAR WHEELS 0.187 20.1% | -0.061 -2.3% | -0.326
TURNING VANE 0.023 2.4% | -0.020 -0.8% | -0.889
OTHER 0.055 5.9% | -0.210 -8.0 | -3.793
TOTAL 0.935 100% | 2.617 100% | 2.802

front rh=16mm, rear rh=46mm, medium downforce

[xpensive]

Most interestin timbo, but would you care to xplain the individual numbers?

FRONT WING 0.123 13.2% | 0.966 36.9% | 7.859

In particular 0.123 and 0.966, is there a unit there somewhere?

[timbo]

Most interestin timbo, but would you care to xplain the individual numbers?

FRONT WING 0.123 13.2% | 0.966 36.9% | 7.859

In particular 0.123 and 0.966, is there a unit there somewhere?

They are drag/load (actually may be lift, but the sign would be opposite) coefficients I believe, dimensionless.
My pity, I can't remember which forum member posted this, but it is definitely on this site . Should watch my previous posts...

[xpensive]

The percentage is obvious, get that, but the table has total downforce as "2.617"-something, absolute numbers at what speed would be priceless.

[timbo]

I think you can use that
http://www.grc.nasa.gov/WWW/K-12/airplane/liftco.html
but the problem is we can only guess what is the total area estimation.
Besides I can be completely wrong with my guess about lift coefficient

PS my guess can probably be verified by using some reasonable total area (wings + bodywork) estimation and calculating lift. It should be around 2-3 weights of the car at around 300kph... Hmm... too many guesses.

[Scotracer]

It is said that a 2004 F1 car had 3000kg @ 300km/h in medium/high downforce state. You can scale that back with aero load exponential with speed - wing area, and air density can be assumed to be constant so you can easily do it.

[xpensive]

If we can assume 30 kN ("3000 kg") downforce at 300 km/h, it's easy to downscale it, when it's a squared relation. This gives us a total 1920 N at 240 km/h, afterwhich timbo's percentages can be used for wings, underbody and so on?

Come to think of it, the total of "2.617" in the table above, is perhaps 2617 N?

Areas matters little, when the issue was Force and not Pressure to begin with.

[timbo]

If we can assume 30 kN ("3000 kg") downforce at 300 km/h, it's easy to downscale it, when it's a squared relation. This gives us a total 1920 N at 240 km/h, afterwhich timbo's percentages can be used for wings, underbody and so on?

Come to think of it, the total of "2.617" in the table above, is perhaps 2617 N?

Areas matters little, when the issue was Force and not Pressure to begin with.

Have you read that NASA link?))

The more I think of it, the more I'm sure it's C of lift.
However, my estimation (based on Scotracer's 30kN number at 300kph) yield only 2.6 square meters reference area... Too little I suppose?

[Scotracer]

Just to clear things up, it is the Coefficient of Lift.

If we can assume 30 kN ("3000 kg") downforce at 300 km/h, it's easy to downscale it, when it's a squared relation. This gives us a total 1920 N at 240 km/h, afterwhich timbo's percentages can be used for wings, underbody and so on?

Come to think of it, the total of "2.617" in the table above, is perhaps 2617 N?

Areas matters little, when the issue was Force and not Pressure to begin with.

I was just stating that if it's constant, it's an easy interpolation - none of the variables in F = rho*A*U^2*Cl change, apart from the velocity.

[PNSD]

3000Kg?!!!!

I expected it to be nearer 2500Kg! Wow, for an open-wheeler that is just amazing!

[timbo]

I was just stating that if it's constant, it's an easy interpolation - none of the variables in F = rho*A*U^2*Cl change, apart from the velocity.

So, what's the units used to calculate Cl? Any guesses?
I used rho=1.21 kg/m^3, U=83.3m/sec, F=30kN and got A=2.75, probably square meters=)))
I guess it's too small for F1 car?

[Scotracer]

I was just stating that if it's constant, it's an easy interpolation - none of the variables in F = rho*A*U^2*Cl change, apart from the velocity.

So, what's the units used to calculate Cl? Any guesses?
I used rho=1.21 kg/m^3, U=83.3m/sec, F=30kN and got A=2.75, probably square meters=)))
I guess it's too small for F1 car?

The coefficient of lift wont be calculated for an F1 car, it will be found in the wind-tunnel or CFD because it runs directly from chord length and plan area etc - something that isn't directly applicable.

Oh and I've been an eejit, it's F = 1/2*rho*A*U^2*Cl - woops

The area is the plan area - the surface area that the air is subject to. 2.75 (or whatever it is after you redo it without my idiocy included) on a car that is 4.5x1.8 metres does seem a bit low but when you consider the size of the floor and the wings, it might not be too far off.