Center of Gravity COG 1990's F1

[Testdrive]

Does anyone if there was standard COG for F1 1990's car's?

I've experimented with 37% and 40% in the simulator, they seem to work well. 37% seems work best for getting rear traction, 40% more frontal grip. I was making some calculations last night, some engines weighted 125KG some 150KG.
Just 20KG is enough to change COG by 3% - 4%.

I'm assuming, they used ballset to tune COG, and I'm assuming their set Aero Dynamic Balance to match COG.

I've watched some qualifying laps, noticed their frontal grip was not high, some I'm assuming they used 37% COG and 37% Aero Balance.

[jjn9128]

No spec COG until 2010(11?). Aero load is balanced against COG location. It's why those 90s cars had so much rear wing vs front wing.

[Tim.Wright]

Does anyone if there was standard COG for F1 1990's car's?

I've experimented with 37% and 40% in the simulator, they seem to work well. 37% seems work best for getting rear traction, 40% more frontal grip. I was making some calculations last night, some engines weighted 125KG some 150KG.
Just 20KG is enough to change COG by 3% - 4%.

I'm assuming, they used ballset to tune COG, and I'm assuming their set Aero Dynamic Balance to match COG.

I've watched some qualifying laps, noticed their frontal grip was not high, some I'm assuming they used 37% COG and 37% Aero Balance.

Aero balance is normally more rearward than the CG to induce understeer (stability) at higher speed.

Balance comes principally from the interation between tyre sizing, CG location, aero balance and mechanical balance. You can't assume that a lack of frontal grip is due to the mass distribution if you can't rule out the tyres, aero or mechanical balance.

What kind of simulator are you using? Seems strange that adding more front weight is giving you more front grip. Should do the opposite albeit with somewhat faster response times.

[Testdrive]

Does anyone if there was standard COG for F1 1990's car's?

I've experimented with 37% and 40% in the simulator, they seem to work well. 37% seems work best for getting rear traction, 40% more frontal grip. I was making some calculations last night, some engines weighted 125KG some 150KG.
Just 20KG is enough to change COG by 3% - 4%.

I'm assuming, they used ballset to tune COG, and I'm assuming their set Aero Dynamic Balance to match COG.

I've watched some qualifying laps, noticed their frontal grip was not high, some I'm assuming they used 37% COG and 37% Aero Balance.

Aero balance is normally more rearward than the CG to induce understeer (stability) at higher speed.

Balance comes principally from the interation between tyre sizing, CG location, aero balance and mechanical balance. You can't assume that a lack of frontal grip is due to the mass distribution if you can't rule out the tyres, aero or mechanical balance.

What kind of simulator are you using? Seems strange that adding more front weight is giving you more front grip. Should do the opposite albeit with somewhat faster response times.

Assetto Corsa

I set the COG to 0.370, so that's 63% of weight on rear tyres. Tyres are 25cm fronts and 37cm rear's 1990's specs
I then set the aero balance to match 37% frontal
Frontal Diffuser 37%
Rear Diffuser 63%
I set front and rear wings with the same downforce.
This seems to work well, car seems stable. I can get qualifying lap times.

I've experimented with COG of 0.400, it shifts more on the front, gives you better turn in, but you lose rear grip. If you had Traction Control 0.400 COG might be beneficial.

Then again my diffuser is cheating as it's getting the optimal downforce at all times, I suspect maybe they shifted the aero balanced to the rear, as maybe a way to tune a more realistic diffuser.

[Tim.Wright]

My point was, knowing the real CG location isn't going to help you. The tyres and aero are not going to be modelled correctly anyway so you just need to find a balanced CG location that in the end gives a behaviour similar to the real car.

Btw, moving the CG without correcting the roll stiffness distribution means you are not evaluating a pure CG movement but you are also changing the suspension behaviour.

[Testdrive]

My point was, knowing the real CG location isn't going to help you. The tyres and aero are not going to be modelled correctly anyway so you just need to find a balanced CG location that in the end gives a behaviour similar to the real car.

Btw, moving the CG without correcting the roll stiffness distribution means you are not evaluating a pure CG movement but you are also changing the suspension behaviour.

Your Tim Wright (Principal Engineer) of MP4/3 and more?

There are lots of settings in car which I don't fully understand. I usually use 90nm springs on rear and front, tends to be better with grip on the front and rear. But I guess it's a simulation, Tyre model is probably toughest thing to get right. But it gives you lots of stuff to tinker with, Aero, Tyres, COG, has it's wing app telling you the drag, down-force etc. I always try to get the qualifying lap times of 1990, 1980's. I just wonder what their setups were back then, their lift and drag, engine power. But with COG and Aero Balance, from looking at the real thing, watching their cornering speeds, It's seems like it was about 35% to 40%. I suspect the Benetton was using 40%, majority of the rest 35 to 37% I think for 1994. With in the simulation, I'm tending to prefer 37%, I liked 40% before, but since I shifted 3% more downforce to the rear diffuser, and 3% of the entire aero balance to the rear, taking off and rear grip is so much more beneficial.

But then again, It's a simulation, real tyres, compared to digital tyres might have entirely different grip levels, giving one a totally different perspective

[Tim.Wright]

Your Tim Wright (Principal Engineer) of MP4/3 and more?

No unfortnately not - it's a common name in the Automotive field. Here is the complete list of Tim Wright's of which I am not:

• Tim Wright - the McLaren member from the 80-90s
• Tim Wright is Sergio Perez' race engineer
• Tim Wright - the Chief Engineer at Fisker
• Tim Wright - the motorsport consultant in the UK
• Tim Wright - the engineer at Jaguar Land Rover
• Tim Wright - the design engineer at GM.

I'd suggest shifting the aero balance a few percent more rearwards than the CG - this is a typical target for race cars because it increases your stability with speed. If your CG and aero balance equal to each other, you will never capture the way the balance changes with speed correctly. Then you can fill in the gaps with the tyres, setup and mass distribution. It's never going to be right - but you should be able to get something representative.

[Testdrive]

Must be a common name.

I will try a 37% COG and 34% Aero Balance. That should give me more rear traction, but the front is going to be more unstable, I guess.

[Testdrive]

Your Tim Wright (Principal Engineer) of MP4/3 and more?

No unfortnately not - it's a common name in the Automotive field. Here is the complete list of Tim Wright's of which I am not:

• Tim Wright - the McLaren member from the 80-90s
• Tim Wright is Sergio Perez' race engineer
• Tim Wright - the Chief Engineer at Fisker
• Tim Wright - the motorsport consultant in the UK
• Tim Wright - the engineer at Jaguar Land Rover
• Tim Wright - the design engineer at GM.

I'd suggest shifting the aero balance a few percent more rearwards than the CG - this is a typical target for race cars because it increases your stability with speed. If your CG and aero balance equal to each other, you will never capture the way the balance changes with speed correctly. Then you can fill in the gaps with the tyres, setup and mass distribution. It's never going to be right - but you should be able to get something representative.

Well, I think I finally solved my diffuser issue(was using an unrealistic setting, where it was optimal at all times.
EG I told the car it was at 2cm ride height for the front and rear, giving it the optimal diffuser downforce, it ran 37% Aero/COG stable for the entire lap also). This time I enabled the diffuser to be realistic, I set the front diffuser ride height to 35mm and rear diffuser ride height at 50mm, I shifted the aero balance back as you stated.
I went with 40% COG, I added more lift to the rear diffuser, about 65% from 63%, 35% from 37% on the front diffuser, reduced front wing by about 0.10 CL. The Aero Balance now might be 35%, since it was about 37, 38%

On the straight, the frontal drops down to 37%, at low speed corners and starts it becomes 40%, same as COG.
Front Diffuser drops to 20mm and Rear to 20mm at high speed, goes up a lower speed corners and loss's some diffuser downforce.

There is no unsteer or oversteer at high speed. So there you go, I think the riddle has been solved.
There seems to be a 3 to 4% shift for center of gravity through a lap. I guess I could experiment with 37% COG and 34% Aero Balance, see how it goes. I though front and rear wing down-force were equal, but it doesn't seem to be the case, the more you move the aero balance, more downforce on the rear is needed.

Thanks for your advice of shifting the aero balance to the rear, The F1 car with the realistic diffuser is now finally drivable.

[Andi76]

Does anyone if there was standard COG for F1 1990's car's?

I've experimented with 37% and 40% in the simulator, they seem to work well. 37% seems work best for getting rear traction, 40% more frontal grip. I was making some calculations last night, some engines weighted 125KG some 150KG.
Just 20KG is enough to change COG by 3% - 4%.

I'm assuming, they used ballset to tune COG, and I'm assuming their set Aero Dynamic Balance to match COG.

I've watched some qualifying laps, noticed their frontal grip was not high, some I'm assuming they used 37% COG and 37% Aero Balance.

If you are still interested, i got some data from a 1990s car.


Weight Distribution 40%front 60% rear
Centre of Gravity Height 0.3m
Centre of Gravity position 58%rear
Centre of pressure position 61% rear
Downforce at 240 km/h 8.5kn
Drag at 240 km/h 4.0kn
Roll stiffness 60% rear

[Tim.Wright]

If you are still interested, i got some data from a 1990s car.


Weight Distribution 40%front 60% rear
Centre of Gravity Height 0.3m
Centre of Gravity position 58%rear
Centre of pressure position 61% rear
Downforce at 240 km/h 8.5kn
Drag at 240 km/h 4.0kn
Roll stiffness 60% rear

How is the weight distribution different to the CG position?

Those number look a little too round to be realistic too. Probably reasonable estimates though.

[Andi76]

If you are still interested, i got some data from a 1990s car.


Weight Distribution 40%front 60% rear
Centre of Gravity Height 0.3m
Centre of Gravity position 58%rear
Centre of pressure position 61% rear
Downforce at 240 km/h 8.5kn
Drag at 240 km/h 4.0kn
Roll stiffness 60% rear

How is the weight distribution different to the CG position?

Those number look a little too round to be realistic too. Probably reasonable estimates though.

Sorry, i didn't read it properly in the hurry. This weight distribution was the most rearward weight distribution possible.

The numbers are from an article published in the Journal of Automobile Engineering from 1992. Probably estimates. It is not mentioned if its real or estimates.

[Testdrive]

The Downforce seems wrong. I calculated.

407KG of drag
877KG of downforce? Maybe they left out the weight of the car? That's 1382KG if you do.
Thats 3.4 Lift to Drag Ratio. This must be the Williams with active suspension, explains why COG is 40% and COF is at 61%. Keeps balance through out the lap.

The 3.4 Lift to Drag, seems like Williams Superior Aero Dynamics, or maybe active suspenstion?

Thanks for this, very interesting information, the weight distribution, I've always suspected was 40%.

[Tim.Wright]

weight of the car is not included in lift to drag ratio calculations.

[Testdrive]

Silly me, I made an error.