Technical Regulations for 2009-2015

[xpensive]

I'm so glad that I missed the above deccelleration discussion between Ogami and WB, which I believe indicates that the latter is not xactly a mechanical engineer, not in the classic sense anyway.

First of all, to estimate deccelleration from air-resistance, there is a much more scientific way as Power is Force times Speed. If 550 kW results in a top-speed of 85 m/s (306 km/h), the resulting air-resistance will be 6470 N and nothing else, at that very speed.

As F equals mass times accelleration, a mass of 660 kg and an air resistance of 6470 N, would result in a deccelleration of 1 g, still at that very speed, but it will quickly drop off as air-resistance goes with the square of the speed.

If the engine has the power of 550 kW, that doesn't mean that it can help braking with the same, where did you get that idea?

And your 1800 kW figure of braking power seems to be taken straight out of the blue, that would depend on both speed and grip?

[WhiteBlue]

It would be helpful if you would put up your own set of figure, expensive. The typical breaking power you can get from Brembo for every Grand Prix. They publish these figures regularly.

1.8 MW is a figure that would probably coincide with a high power breaking for the 5.5 G that were used in my engineering example. The figures would apply to a medium downforce circuit. This weekend in Canada figures should be quite different. The downforce is low but the breaking power is very high with over 2 MW.

I would be interested how you evaluate the aero decelleration if you do not use the formula we used in our discussion.

[xpensive]

It is still most disappointing that you never seem to bother to properly read anyone elses posts, it is very simple indeed as
Power is always Force times speed, this applies both to air-resistance as well as braking force.

Knowing the ultimate grip, or Braking force, between the tyres and surface, you can calculate Braking power as Braking force times vehicle speed, but there will never be a constant Braking power, as it will come down with speed according to the Power formula above, but also as downforce decreases with the square of the speed and reduces available Braking force.

But with a "virtual" coefficent of friction of 0.8 and a total contactforce of 20 kN (two tons), Braking force would be 16000 N, resulting in a Braking power of 13600 kW at 85 m/s.

16 000 N + 6470 N (from air resistance), results in a deccelleration of 34 m/s^2, or 3.5 g for a 660 kg vehicle at 85 m/s (306 km/h).

You can play with the input numbers above if you wish, but the method of calculation will remain correct.

[WhiteBlue]

But with a "virtual" coefficent of friction of 0.8 and a total contactforce of 20 kN (two tons), Braking force would be 16000 N, resulting in a Braking power of 13600 kW at 85 m/s.

Proposing 13.4 MW of braking power is completely unreal. The figure is out of context by almost a magnitude. The figures you find quoted for max breaking power are between 1.4 and 2.1 MW.

[xpensive]

Interesting numbers that, a braking power of 2137 kW at 89 m/s (321 km/h) would mean a braking force of 24000 N at top speed, which in turn would suggest a total contactforce of 24000 N at a virtual friction coefficient of 1.0. In addition a speed of 89 m/s from 550 kW adds another 6200 N from air resistance, which gives a total stopping force of 30200 N, which in turn results in a deccelleration of 4.74 g, please note Brembo's 4.78, for a 650 kg vehicle!

But there's another way of going about it, losing the kinetic energy of a 650 kg object when going from 89 m/s (321 km/h) to 39 m/s (140 km/h) means 2080 kWs, while losing that in 1.78 seconds means an average Braking power of 1170 kW.

Thank you for helping me clearing this up WB, isn't math a beautiful thing at times?

[WhiteBlue]

Well, it appears that the peak of 2.1 MW applies sometime during that 106 m of breaking distance and that should obviously be at the start when the speed is greatest.

So the max braking power IMO is the correct figure to use when the breaking starts at the highest speed. The difference to the total needed to cause the decelleration of 4.74 G must be the drag braking.

So we have a total of 2.137 kW from the brakes and 550 kW from the drag for a total of 2.687 kW or call that 2.7 MW. Drag and break force should split 21%/79%.

The problem is that we do not know the downforce at this point. Two tons is an assumptions which may be much too high for such a circuit.

[xpensive]

That 550 kW from 6200 N of drag at 89 m/s is correct, you're catching up quickly WB, I'm glad. I think the "virtual" coefficient of friction is the key here, can it be more than 1.0?

But there is more, going from 89 to 39 m/ second in 1.78 seconds means an average deccelleration of 28.1 m/s^2, or 2.86 g.

[WhiteBlue]

I don't care much about the average decelleration. I want to know the downforce to drag relationship. That is best figured at max speed and at the initial breaking point when drag and engine power are in balance.

[xpensive]

Taking away the gravity of 6400 from the 24 000 N, it seems to me it should be roughly 3:1, depending on that "virtual" coefficient of friction?

[Pingguest]

Talking about future regulations, to fully justify it existence, Formula 1 should adopt rules making the sport more road relevant. This can be achieved in two particular areas: the tyres and the engines (including wasted energy recovery systems). As most road cars don't generate downforce, have closed wheels and bodywork covered suspensions, I can't see the relevance of Formula 1's aerodynamics. The current downforce levels caused the cornering speeds to be incredibly high and forced the FIA to restrict development in other, probably more relevant areas.

Therefore, shouldn't it be much better to reduce downforce to the absolute minimum (the amount necessary to keep the cars from coming off the ground) and allow road relevant development work to be done in other areas?

[WhiteBlue]

Turkey they do 5.1 G and 2.2 MW.(high)
Monaco they do 3.73 G and 1.372 MW (low)

A pity that we don't have access to the Monza figures yet. They brake from 337 km/h there but the downforce is low there and they may not get to the 5.1 G they do at Turkey.

[Ogami musashi]

Talking about future regulations, to fully justify it existence, Formula 1 should adopt rules making the sport more road relevant. This can be achieved in two particular areas: the tyres and the engines (including wasted energy recovery systems). As most road cars don't generate downforce, have closed wheels and bodywork covered suspensions, I can't see the relevance of Formula 1's aerodynamics. The current downforce levels caused the cornering speeds to be incredibly high and forced the FIA to restrict development in other, probably more relevant areas.

That's a SPORT! Would you restrict the training methods of althletes?? because one high or long jumper has nothing relevant in his traning down to his very motion to a causal men jumping..


People use the "road relevance" quite at their will... You wouldn't mind a big tyre that would never find its way to a road car (the day you'll see slicks on roads...call me) but aeros yes..

Funny, car people seem not to like what come from planes; But in fact it comes from nature.

[xpensive]

The numbers from Turkey suggests that at that particular braking point alone, there is 2220 kJ of energy wasted through the brakes and air-resistance.

Something for KERS enthusiasts to ponder.

[Pingguest]

Talking about future regulations, to fully justify it existence, Formula 1 should adopt rules making the sport more road relevant. This can be achieved in two particular areas: the tyres and the engines (including wasted energy recovery systems). As most road cars don't generate downforce, have closed wheels and bodywork covered suspensions, I can't see the relevance of Formula 1's aerodynamics. The current downforce levels caused the cornering speeds to be incredibly high and forced the FIA to restrict development in other, probably more relevant areas.

That's a SPORT! Would you restrict the training methods of althletes?? because one high or long jumper has nothing relevant in his traning down to his very motion to a causal men jumping..


People use the "road relevance" quite at their will... You wouldn't mind a big tyre that would never find its way to a road car (the day you'll see slicks on roads...call me) but aeros yes..

Funny, car people seem not to like what come from planes; But in fact it comes from nature.

I think every sport should take its social responsibility and motor sports has a great opportunity to contribute to the development of road car technologies. And talking about the tyres: I think we should go to 13-inch wide, non-spec, durable all-weather tyres. That would certainly add road relevance to Formula 1.

[Ogami musashi]

Then i disagree. A sport should stay what it is, an art of doing something unique; Not a laboratory for everyday life.

That's our opinions then, i respect yours.