F1 Braking at high speeds.

[timbo]

So a brick of an aero design would be better under braking?

IMO Cd of an F1 car is already approaching "brick"

[Caito]

Very good ideas guys, thanks.

To sum up a little bit.

We could say that at high speeds there's lots of downforce, there's little heat in the brakes so a low CoF.

In this condition to lock the wheels one would need an amazing force, since we have all this downforce and this little mu. If we tried to generate this force, as the calipers are limited in there modulus of elasticity, instead of braking we would be tearing the caliper apart.


So I can conclude that when they start braking they're actually not treshold braking(in the limit tire) because there's a mechanical limit.

Up to this point(all caliper, etc being equal) all drivers brake in the same distance, and a better driver would only start to take advantage when the tires reach their limit. The driver who is more capable of being at the limit will brake "better".

How can we know at which (maximum)speed is the driver capable of blocking the wheels? With this we could know how much of an influence does a better or worse driver can make in braking.


Bye!


Caito.-

[riff_raff]

"If we tried to generate this force, as the calipers are limited in there modulus of elasticity, instead of braking we would be tearing the caliper apart."

Caito,

Even a caliper made of aluminum is in no danger of coming apart under heavy braking. Calipers are designed for maximum stiffness, and not for stress limits. A stiff caliper is important for giving precise pedal feedback to the driver.

An aluminum caliper, with its lower MoE, can be made almost as stiff as a titanium or steel caliper for the same weight. This is due to the similar specific stiffness (MoE/density) values of these materials. The only issue with aluminum is the loss of strength at elevated temperatures. In close proximity to carbon brake discs/pads, the aluminum caliper will likely need some cooling.

riff_raff

[autogyro]

I think it also important to realise that the driver is not just brakeing to slow the car without wheel lock.
The driver is also using steering and throttle as well as the brakes to unsettle the car, position it relative to the corner entry with all forces in a chosen balance, so as to achieve the shortest time through the corner and the fastest exit speed.

[alexbarwell]

And other effects like mr webber using a lotus and working against gravity (briefly) for some of the braking effort - that seems to get rid of a fair bit of KE...

[mep]

I think it also important to realise that the driver is not just brakeing to slow the car without wheel lock.
The driver is also using steering and throttle as well as the brakes to unsettle the car, position it relative to the corner entry with all forces in a chosen balance, so as to achieve the shortest time through the corner and the fastest exit speed.

I wonder why you did not mention downshifting. Using the engine braking is something we should also take into account.

[autogyro]

Manual upshifts but automatic downshifts.
Downshifts are not realy in control of the driver, other than reacting to the handling upset at each shift.
With the main force acting on the car being downforce, driver feel of the mechanical set up is much more limited to how it was years ago.
It is another aspect of the difficulty in overtaking as well as just the aero turbulance.
IMO any braking other than in a strait line becomes much more of a lottery.

[Tec5nical]

Up to this point(all caliper, etc being equal) all drivers brake in the same distance, and a better driver would only start to take advantage when the tires reach their limit. The driver who is more capable of being at the limit will brake "better".

How can we know at which (maximum)speed is the driver capable of blocking the wheels? With this we could know how much of an influence does a better or worse driver can make in braking.

Well cars are different from each other in terms of 'downforce' and the place of 'center of pressure' they produce at each speed. So the more downforce amount you have, and the further this downforce is towards the front wheels relative to other cars at a given speed, the more you can keep your brake pressure as you slow your car down.
CoP could be accounted important, as you hit the brakes, weight transfers towards front wheels so you will have more grip on fronts and less on rears. This is why there is interest to bias the brakes to the front wheels (as high as 60/40), cuz as the result tendency to block the rear wheels reduces, and on the other side, you can benefit more from your left foot's input force to slow the front wheels down more.
In the end, the drivers who consider CoP balance, reduction of DF, the change in weight transfer (as the car will face different deceleration values during the brake line) and the brake bias he has chosen, will brake better in the straights, no chamber, no slop, no winds.

[Tec5nical]

I wonder why you did not mention downshifting. Using the engine braking is something we should also take into account.

As far as I've understood, by removal of engine braking systems EBS systems from start of 2008 onwards, drivers have to be more cautious on braking to not to lock the rears up. Given the fact that, during a generic braking and downshifting period, EBS intelligently tried to use throttle to keep the engine alive enough and compensate and over-downshifts which normally ended up to rear wheel lock ups because of engine braking phenomena. Now, they should be more carefull to not to over-downshift. Thats why they have more tendency to put more loads on front wheels to reduce the punishment of an over-downshifting mistake. So if they don't, it ends up in engine braking added up to actual braking, tires just won't handle it and tear off in blocking.

[xpensive]

At 328 km/h, the air-resistance in itself is worth pretty much the same as your engine power deccelleration-wise,
lifting-off 550 kW gives you a braking force of 6 kN, 18 kNm if you wish to translate it to an equivalent "braking torque."

6000 N of force on a 700 kg object, means a deccelleration of 8.57 m/s^2 ( 0.87 g), this from air-resistance only!

Think about it.

So a brick of an aero design would be better under braking?

Indeed JET, remember that power is force times speed;
- A car with the same Hp, but higher Cv, have a terminal speed less than 328 km/h, but higher air-resistance to equal power.
- When decelleration is force over mass, the higher air-resistance would cause more deccelleration for the same mass.

[autogyro]

I wonder why you did not mention downshifting. Using the engine braking is something we should also take into account.

As far as I've understood, by removal of engine braking systems EBS systems from start of 2008 onwards, drivers have to be more cautious on braking to not to lock the rears up. Given the fact that, during a generic braking and downshifting period, EBS intelligently tried to use throttle to keep the engine alive enough and compensate and over-downshifts which normally ended up to rear wheel lock ups because of engine braking phenomena. Now, they should be more carefull to not to over-downshift. Thats why they have more tendency to put more loads on front wheels to reduce the punishment of an over-downshifting mistake. So if they don't, it ends up in engine braking added up to actual braking, tires just won't handle it and tear off in blocking.

This is not my quote!

[autogyro]

Any form pf braking other than aero drag, is limited by the tyres.
The regulations on downshifts and engine brakeing are solely to improve driver control over cars that are far to aero dominated.

[Tec5nical]

This is not my quote!

Yeah, sorry! I will resolve it now