## C.O.G and weight distribution

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It would appear so. I have used a much less elegant solution before in small open wheeled cars, so I am assuming it works the same way.

The pads under each wheel are scales that tell them the static weight distribution of the car. The hydraulic rams on each side (I used wood blocks) are used to lift one side of the car higher than the other. By seeing how much weight shifts between the two wheels, you can calculate the CG of the car (don't have the equation on me).
Chris
UB Motorsports: Formula SAE '08-'10
Captain '09-'10
engineguru00
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Joined: 18 Mar 2010
Location: Buffalo,NY

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raymondu999 wrote:I don't know about you, but if I was a team owner/boss I wouldn't want to hang my multimillion pound supercar on a rope/cable

First off, if this was ever proposed, it would be done in a professional and safe manner. Obviously, the rope method may not be appropriate, but more than anything, I wanted to point out that sometimes results can be obtained by the simplest of methods, and sometimes we don't need to over-complicate things. Think about it, with just a block and tackle, some rope, a few polariods, ten minutes, and I can determine the specific and exact center of gravity.

But the science of accurate weight estimates is an old one, shipbuilders have been doing this for many years, and with accurate and consistent results. Same with the aviation industry.
A proud Canadian, and yes, HOCKEY is our game.
DaveKillens
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Joined: 20 Jan 2005

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engineguru00 wrote:It would appear so....

Agreed, but I'm not sure it would be the best way to estimate c.g. height of an F1 vehicle, where the dimension would be expected to be very small so large pitch angles would be required to identify the parameter reliably. The set-up seems to be hugely complicated, & (curiously) a fair few vehicle parts are missing (nose box, front & rear wings, rear bodywork &, possibly, the undertray). It would also seem that test structures have been attached to the vehicle. All very strange....
DaveW
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Joined: 14 Apr 2009

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raymondu999 wrote:actually saw this photo in the RB6 thread. Credits go to imightbewrong for the photo's original poster. Could this be a measuring of COG?!

Looks to me like they could pre-load the suspension in some way judging by the thinkness of those beams and the way they are mounted.

Maybe something to do with making a suspension adjustment under a certain amount of vertical load to represent downforce?
RH1300S
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Joined: 6 Jun 2005

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marcush. wrote:
mep wrote:You can put a scale under each of your tire.

Aaaaaah you see there you have your RB6 standing on for scales:

So no need for rolleyes.
mep
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Joined: 11 Oct 2003
Location: Germany

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The photo's been posted twice already, no need to post it again

raymondu999
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Joined: 4 Feb 2010

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marcush.
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Joined: 9 Mar 2004

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RH1300S wrote:
n smikle wrote:I don't even think they design for centre of gravity.

I can't speak for the f1 teams but If I were designing an F1 car, think I would just make everything as low and as light as possible. When the design is done THEN I would just check what the Cog is, and if I can improve it later on, I just make the offending parts lower and lighter. That's how I would do it.

Why would they do that? If they designed everything to be as low as possible then everyone would be driving a pan-cake and lying flat in the car. It's CofG would be low, but compromised in other areas such as aero, geometry and packaging.

Of course they design with CofG in mind. To say they don't is like saying they build a car with no particular objective, when it's finished they check the CofG - then modify all the geometry to suit the CofG they seem to have discovered by accident.

The CofG location has a fundamental importance in the way a car uses it's tyres. Like everything else in the car the CofG height & location is about making choices and having design obejctives then setting out to achieve them.

I don't know about you.. but I have done some machine designs already. And I know you can't predict where the Cog will be before you model the machine (not talking about simple boxy symmetrical stuff here). You have to model the car first, find where the CG lands then you adjust the model to get it where you want. Obviously you design it to get the Cog in a certain ballpark, like putting the heaviest obejects near the centre etc. but you can't predict it. You have to model the car then get where it is.

You may know where you want the CoG to be. But can't just predict where it's going to be bore you start modeling the car, there are so many parts! You guys make it sound so easy. It's not easy..Almost impossible to know the exact location without making(on the computer) the whole car first. Even when people build the car it might not even match exactly what is on the computer.
"I was blessed with the ability to understand how cars move," he explains. "You know how in 'The Matrix,' he can see the matrix? When I'm driving, I see the lines."
n smikle
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Joined: 12 Jun 2008

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Established teams have the data on previous cars though.
A simple matter to work out a simple computer model for a new one with that and the component details that change.
autogyro
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Joined: 4 Oct 2009

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My guess is that the cars are designed in a similar manner to an aeroplane. The cg is locked in a position by design. This will be dependant mainly on the tyres. Then during the design process the weight of every subsystem is tracked to ensure the cg ends up at the right spot.

From my short experience in looking at design/manufacturing packages for commercial jets, there are stringent controls on the mass properties of the produced parts. Designs must be signed off by the weights department before they are released. So I guess it is done the same in F1.

Tim
Tim.Wright
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Joined: 13 Feb 2009

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Tim.Wright wrote:My guess is that the cars are designed in a similar manner to an aeroplane. The cg is locked in a position by design. This will be dependant mainly on the tyres. Then during the design process the weight of every subsystem is tracked to ensure the cg ends up at the right spot.

From my short experience in looking at design/manufacturing packages for commercial jets, there are stringent controls on the mass properties of the produced parts. Designs must be signed off by the weights department before they are released. So I guess it is done the same in F1.

Tim

+1
It´s not rocket science ,it´s only addition of moment in all directions...so with most of the parts a re straightforward job really.
you cannot afford to accidentially arrive at a weight distribution,can you?
Again the aim has to be to go as much underweight as you can afford and therefore you will work harder on this on the end you think the weight needs to be removed.
In the end this is the ways to success ,to be able to move the CG where you actually need it.One variable is taken away by the ruling you are not allowed to alter things between Q3 and race....but for sure not every track favours the same weight distribution.
marcush.
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Joined: 9 Mar 2004

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hi everyone,
having read the whole thread i now understand how a basic C.O.G calculation can be done... what the general opinion is that we can use a tilt table to find out the C.O.G..
lets assume that i do not have complete car assembled right now.. but i do have the basic components like the engine, data of the driver and a theoretical weight estimation of the chassis... and also taking in to account the pedals, steering coloum and the brakes...radiator, intake manifold and the electronics... ( all theoretical values )...

i came up with this idea and it seems logical to me....
Why not create a solid model of all the components on a design software... and then using an analysis software put specific point loads on each solid component and then calculate the C.O.G of the car????.. this way it gives me a location of the c.o.g on the 3d component made....
"Be the change that you wish to see most in your world" -- Mahatma Gandhi
mach11
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Joined: 21 Aug 2009
Location: India

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if you know the specific cogs and masses of each you could just calculate the overall mass& cog.

raymondu999
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Joined: 4 Feb 2010

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having read the whole thread i now understand how a basic C.O.G calculation can be done... what the general opinion is that we can use a tilt table to find out the C.O.G..

I prefer the scale method it should give you a more accurate result for lateral position. Moreover it’s easier to do because you don't need a tilt table just a few scales.

i came up with this idea and it seems logical to me....
Why not create a solid model of all the components on a design software... and then using an analysis software put specific point loads on each solid component and then calculate the C.O.G of the car????.. this way it gives me a location of the c.o.g on the 3d component made....

Yep.
You don't even need additional analysis software. Every 3D design software immediately tells you the CG-location. Even a simple excel sheet would do it by the way.

The really interesting question is where do you want your CG to be?
mep
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Joined: 11 Oct 2003
Location: Germany

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mep wrote:
having read the whole thread i now understand how a basic C.O.G calculation can be done... what the general opinion is that we can use a tilt table to find out the C.O.G..

I prefer the scale method it should give you a more accurate result for lateral position. Moreover it’s easier to do because you don't need a tilt table just a few scales.

i came up with this idea and it seems logical to me....
Why not create a solid model of all the components on a design software... and then using an analysis software put specific point loads on each solid component and then calculate the C.O.G of the car????.. this way it gives me a location of the c.o.g on the 3d component made....

Yep.
You don't even need additional analysis software. Every 3D design software immediately tells you the CG-location. Even a simple excel sheet would do it by the way.

The really interesting question is where do you want your CG to be?

I think Mr.Newey is the correct person to ask? or would anyone prefer Ross Brawn?
marcush.
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Joined: 9 Mar 2004

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