% Front weight

[Roger the knife]

One of the main quotes currently doing the rounds is the ability to increase the % front weight to work with the new Bridgestone slicks. My impression is that some cars last year were already running around the 50% front weight mark, so are we looking at a rear wheel drive car with a purposely designed distribution of obver 50% on the front? Expert analysis and comments would be most enlightening.

[sdimm]

One of the main quotes currently doing the rounds is the ability to increase the % front weight to work with the new Bridgestone slicks. My impression is that some cars last year were already running around the 50% front weight mark, so are we looking at a rear wheel drive car with a purposely designed distribution of obver 50% on the front? Expert analysis and comments would be most enlightening.

It´s quite intresting because you would think that as much weight as possible should be at the rearwheels since they have to put down all that power.

This is more of a guess from my side since I don´t have any real data to go on.


I believe there are two reasons that they would want to have more of the weight at the front.
First, with these extremly large front wing that will be used in combination with the smaler rear ones there will be a tendensy to get more grip in the front than previously on the f1 cars. Therefor the center of pressure will be moved forward in the car. Now to get a car that isnt oversteering the center of pressure must be behind the center of gravity to get stability. In other words if the car has a 45/55 weightdistrobution the balance and downforce pressure must be at <45 for the front and >55 at the back so that the car doesn´t turn by it self in the fast corners.
Since the new regulations are as they are with the downforcelevels maybe beeing 50/50 the weight disturbution must follow.

The second reason I belive is tyrewear and temperature. Having these new sticky tyres will give alot of grip in the slower corners both in entry and exit of the corners. Getting the rear tyres to heat up is not a big problem on the f1 cars, just be a little more aggresive on the throttle. On the front however you can´t go faster that the total amount of grip that can carry you through a corner and maybe it becomes quite hard to push the front tyres enough to keep the right heat in them. So what can you do?
Well, when you scrubb your hand to each other they become warm, and if you push them harder to each other it becomes warmer.
So by adding more weight to the front tyres (this is in slow speed corners where not alot of downforce plays in) they add more stress on the front and therefore more grip and tyre wear that would otherwise have eathen more of the reartyres.
Maybe something like that?
And by adding more weight on the front tyres the car naturally becomes more oversteer and it might suite them since they then can then also have a bit softer rearsprings or harder front ones.


Mattias

[Roger the knife]

Thanks for the informative comments Matthias.

I went back and re-read the previous post "Ferrari weight distribution", which is where my interest in this topic started, and seeing that the discussion at the time was whether Ferrari had already exceeded the 50% margin. The discussion was based on a "quoted 55/45 balance" and although this was doubted at the time, figures of 48/52 were thought to be believeable, I'm curious to see if the there is any firm evidence for a 50%+ balance for 2009 cars.

[sdimm]

Thanks for the informative comments Matthias.

I went back and re-read the previous post "Ferrari weight distribution", which is where my interest in this topic started, and seeing that the discussion at the time was whether Ferrari had already exceeded the 50% margin. The discussion was based on a "quoted 55/45 balance" and although this was doubted at the time, figures of 48/52 were thought to be believeable, I'm curious to see if the there is any firm evidence for a 50%+ balance for 2009 cars.

Well it could maybe be seen when they lift the cars up after they crash, Somehow measure how much of center the top is that they lift in and then figure it out.

I know from sources that the car were between 44-47% in front in 2007-2008 on the f1 cars.

[NDR008]

if you get a side shot of the new renault being pulled up we could guess the weight ratio. But don't forget, an F1 pilot/driver is a main heavy component of the vehicle. Meaning the weight ratio will always be with the driver in it. And though the driver is more or less at the CG longitudinally, I am sure it differs from driver to driver.

[Belatti]

I think sdimm assumptions are in the right path. I think also that a front bias weight would make the car have a serious understeer tendency every time it looses front or mechanical aero grip. I guess they would tend to use a stiffer rear that can also cause traction problems... but these are only guesses!

[connollyg]

Most of the new cars seem to have wide but slim noses, but the Renault, looks like its nose was done by bob-the-builder

Maybe because its carrying lots of weight (batteries and stuff?)?

[sdimm]

Most of the new cars seem to have wide but slim noses, but the Renault, looks like its nose was done by bob-the-builder

Maybe because its carrying lots of weight (batteries and stuff?)?

Possibly, but at the same time you don´t want alot of weight on away from the center of a car since that greatly reduces the rotationmovement that happens when you turn intro a corner. At least that´s what I´ve heard

[Jersey Tom]

It's generally good design practice to lower the moment of yaw inertia, but IMO it's not that huge a deal relative to most other things.

Regarding mass distribution, it's all about trade-offs. You want the car the car to develop the most grip in the most balanced trim at all important speeds or points on the track. It could be that the fronts are more load sensitive than the rears, and moving that static mass distribution forward gives you better overall grip.

Does it mean less grip at the rears? Sure. But you're not traction limited ALL the time. Each tire has a sweet spot with each car. If that means 50/50, so be it. If that means a little forward or a little aft depending on the track.. so be it.

[ced ampo]

Well, it still depends on what is the driver's style of driving. It also depends on the car's characteristics. Also some driver's will prefer oversteer, some understeer so they can vary the weight distribution to get the characteristics they like. It can also be used to counter the unliked characteristics of the car.

[ackzsel]

Well, it still depends on what is the driver's style of driving. It also depends on the car's characteristics. Also some driver's will prefer oversteer, some understeer so they can vary the weight distribution to get the characteristics they like.

Sounds true to me. But does anyone know how much this parameter can be changed in favour of the driver? I can imagine that a car just doesn't "work" anymore if you change the weight distribution alot while it's designed for a, let's say, 45-55 distribution.

[Roger the knife]

Something else I have just seen is the new Acura LMP1 car running rear tyres on the front. Another example of a car with an excess of front downforce, needing larger front tyres, and also large front wright percentage to maintain the staic margin. I find it fascinating to see how aero characteristics are determining weight distribution more than mechanical requirements

[Scotracer]

Current F1 cars are about 42:58 to 46:54 bias to the rear. Whilst 50:50 is generally accepted as the "best" balance state, this does not effect cornering force, it upsets balance (with the current balance F1 cars will oversteer). They counteracted the tendency by having a downforce bias towards the rear (about 60% of downforce last year was at the rear).