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PostPosted: Thu May 30, 2013 11:20 am 
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If we assume there's enough grip between the tyres and the road, how much power (preferrably in hp to easily compare to the engine!) are the brakes able to produce? I guess it's a little bit difficult to divide the stopping power into work done by the brakes and the air resistance. At low speeds the air resistance is far lesser, but OTOH the full braking power can't be utilized without breaking traction.
On an average track with average grip, with average aero on the car, up to which speed is it possible to lock the brakes? I.e. how low does the speed have to be for the downforce to be low enough for the braking force to overcome the friction between the tyres and the road?

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PostPosted: Thu May 30, 2013 8:56 pm 
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This will run :D

All the break can do is lock the wheel. (not the most efficient. as a locked wheel slides)
It is relatively easy to lock the wheel, the control comes from almost locking the wheel and keeping the biggest rubber patck in contact with the road and the weight in the right place.

The retarding force is the friction between the rubber footprint and the road surface. This has to be constant and balanced.
It is not about 'power' of the brake, this only has to be enough to clamp the disk.

Compounded of course by harvesting from the KERS

I get the feeling I am mis understanding you though?


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PostPosted: Fri May 31, 2013 5:15 am 
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moby wrote:
This will run :D

All the break can do is lock the wheel. (not the most efficient. as a locked wheel slides)
It is relatively easy to lock the wheel, the control comes from almost locking the wheel and keeping the biggest rubber patck in contact with the road and the weight in the right place.

The retarding force is the friction between the rubber footprint and the road surface. This has to be constant and balanced.
It is not about 'power' of the brake, this only has to be enough to clamp the disk.

Compounded of course by harvesting from the KERS

I get the feeling I am mis understanding you though?

Not necessarily misunderstaning but we might have differing background info on this. I'm under the impression that because of the huge downforce at speeds, the friction between the tyres and road becomes far greater than what the brakes can overcome, thus locking the wheels is not possible over certain speeds? And if the wheels are not locked, the negative acceleration of the car during braking is caused by air resistance and braking power.

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Thank you Nico - You´re the champ!

PF1 Pick 10 Competition 2016: CHAMPION (2 wins, 8 podiums)


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PostPosted: Fri May 31, 2013 9:04 am 
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Covalent wrote:
moby wrote:
This will run :D

All the break can do is lock the wheel. (not the most efficient. as a locked wheel slides)
It is relatively easy to lock the wheel, the control comes from almost locking the wheel and keeping the biggest rubber patck in contact with the road and the weight in the right place.

The retarding force is the friction between the rubber footprint and the road surface. This has to be constant and balanced.
It is not about 'power' of the brake, this only has to be enough to clamp the disk.

Compounded of course by harvesting from the KERS

I get the feeling I am mis understanding you though?

Not necessarily misunderstaning but we might have differing background info on this. I'm under the impression that because of the huge downforce at speeds, the friction between the tyres and road becomes far greater than what the brakes can overcome, thus locking the wheels is not possible over certain speeds? And if the wheels are not locked, the negative acceleration of the car during braking is caused by air resistance and braking power.



I see what you are saying, but would it not still depend on the contact patch? The strength of the tyre, and indeed the tarmac? I don't know what the forces are, but the footprint is still the same so it would just 'grind the rubber away' from that patch wouldn't it?

Assuming of course the wheel can be locked, which can be done with much less technical kit on 40 ton trucks, which is the equivalent of downforce I suppose?


As usual I stand (expect :D ) to be corrected.


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PostPosted: Fri May 31, 2013 10:35 am 
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moby wrote:
Covalent wrote:
moby wrote:
This will run :D

All the break can do is lock the wheel. (not the most efficient. as a locked wheel slides)
It is relatively easy to lock the wheel, the control comes from almost locking the wheel and keeping the biggest rubber patck in contact with the road and the weight in the right place.

The retarding force is the friction between the rubber footprint and the road surface. This has to be constant and balanced.
It is not about 'power' of the brake, this only has to be enough to clamp the disk.

Compounded of course by harvesting from the KERS

I get the feeling I am mis understanding you though?

Not necessarily misunderstaning but we might have differing background info on this. I'm under the impression that because of the huge downforce at speeds, the friction between the tyres and road becomes far greater than what the brakes can overcome, thus locking the wheels is not possible over certain speeds? And if the wheels are not locked, the negative acceleration of the car during braking is caused by air resistance and braking power.



I see what you are saying, but would it not still depend on the contact patch? The strength of the tyre, and indeed the tarmac? I don't know what the forces are, but the footprint is still the same so it would just 'grind the rubber away' from that patch wouldn't it?

Assuming of course the wheel can be locked, which can be done with much less technical kit on 40 ton trucks, which is the equivalent of downforce I suppose?


As usual I stand (expect :D ) to be corrected.


We need someone with more expertise to help us out :lol:
I'm not sure what you mean by your first paragraph? The contact patch is basically the same yes, but since friction is proportional to the normal force you could assume more weight/downforce --> more friction --> more force needed to overcome the frction in order to start the wheel sliding over the tarmac instead of rolling on it.

I think that the brakes on a 40 ton truck are more powerful than on an F1 car (because of them being pneumatic and larger in size?), and the fact that they have at least 8 braking wheels negates a little bit of the weight difference.

I can't remember seeing a single incident when an F1 car cas locked its brakes at very high speeds - usually the lock ups happen close to the apexes - so does that offer some kind of "proof" that the wheels can't be locked at high enough speeds?

But all this aside, with infinite friction you couldn't lock up the wheels and the brakes and air resistance would do all of the deceleration and you would be able to calculate roughly the power of the brakes?

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Räikkönen - Vettel - Bottas
Thank you Nico - You´re the champ!

PF1 Pick 10 Competition 2016: CHAMPION (2 wins, 8 podiums)


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PostPosted: Fri May 31, 2013 9:36 pm 
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Covalent wrote:
moby wrote:
Covalent wrote:
moby wrote:
This will run :D

All the break can do is lock the wheel. (not the most efficient. as a locked wheel slides)
It is relatively easy to lock the wheel, the control comes from almost locking the wheel and keeping the biggest rubber patck in contact with the road and the weight in the right place.

The retarding force is the friction between the rubber footprint and the road surface. This has to be constant and balanced.
It is not about 'power' of the brake, this only has to be enough to clamp the disk.

Compounded of course by harvesting from the KERS

I get the feeling I am mis understanding you though?

Not necessarily misunderstaning but we might have differing background info on this. I'm under the impression that because of the huge downforce at speeds, the friction between the tyres and road becomes far greater than what the brakes can overcome, thus locking the wheels is not possible over certain speeds? And if the wheels are not locked, the negative acceleration of the car during braking is caused by air resistance and braking power.



I see what you are saying, but would it not still depend on the contact patch? The strength of the tyre, and indeed the tarmac? I don't know what the forces are, but the footprint is still the same so it would just 'grind the rubber away' from that patch wouldn't it?

Assuming of course the wheel can be locked, which can be done with much less technical kit on 40 ton trucks, which is the equivalent of downforce I suppose?


As usual I stand (expect :D ) to be corrected.


We need someone with more expertise to help us out :lol:
I'm not sure what you mean by your first paragraph? The contact patch is basically the same yes, but since friction is proportional to the normal force you could assume more weight/downforce --> more friction --> more force needed to overcome the frction in order to start the wheel sliding over the tarmac instead of rolling on it.

I think that the brakes on a 40 ton truck are more powerful than on an F1 car (because of them being pneumatic and larger in size?), and the fact that they have at least 8 braking wheels negates a little bit of the weight difference.

I can't remember seeing a single incident when an F1 car cas locked its brakes at very high speeds - usually the lock ups happen close to the apexes - so does that offer some kind of "proof" that the wheels can't be locked at high enough speeds?

But all this aside, with infinite friction you couldn't lock up the wheels and the brakes and air resistance would do all of the deceleration and you would be able to calculate roughly the power of the brakes?


I mean the tyre structure breaking up or peeling or the tarmac the same. I would assume that the driver would not lock up at high speed as he would lose control.
Yes, I'm guessing :D so any knowledge would help.


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PostPosted: Thu Jun 06, 2013 4:07 am 
How much power would it take to accelerate a Formula One car at 5 G's? That is how much "power" brakes have, easily two to three times the power of the engine.

If that was not impressive in itself, making them last an entire race is amazing. As well what really impresses me is designing a system that allows precise control and feedback while having pedal throw and pressure levels low enough so a driver can do it all race.


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PostPosted: Thu Jun 06, 2013 12:47 pm 
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Yeah, that's what I'm getting at! Exact figures please:)

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Thank you Nico - You´re the champ!

PF1 Pick 10 Competition 2016: CHAMPION (2 wins, 8 podiums)


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PostPosted: Thu Jun 06, 2013 8:21 pm 
With a weight of 642 Kg, and stopping in 2.1 seconds from 200 kph at a distance of 65 meters requires 2,291 HP.


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PostPosted: Thu Jun 06, 2013 9:16 pm 
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Blinky McSquinty wrote:
With a weight of 642 Kg, and stopping in 2.1 seconds from 200 kph at a distance of 65 meters requires 2,291 HP.


Not sure that is a usable measure though. It would stop shorter if it ht a brick wall, but can not say a wall has 'power' can you?


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PostPosted: Fri Jun 07, 2013 2:10 am 
Power is defined as the rate at whiich energy is transferred, used, or transformed. So much of the brakin action is converting forward kinetic momentum into heat.

I based my calculation on the minimum weight for a Formula One car quickly decelerating from 200 kph to zero, which by Formula One standards is rather modest. At the end of a long straight they haul down from around 300 kph, so the brakes must be able to convert well over 3000 HP worth of kinetic energy into heat.


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