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Carbon V Steel Brakes


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#1 Ali_G

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Posted 29 September 2001 - 17:19

Simple question. What sort of difference in braking are we talking about if both were used in F1.

I would guess that it would be bare meters but some people in RC try to drill it into our heads that the distances would be vast.

Niall

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#2 jetsetjim

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Posted 29 September 2001 - 17:43

In terms of braking performance, there is not a great deal to choose between CFRP and modern Steel brakes, contrary to popular opinion. Braking distances are more or less identical.

Williams have carried out numerous tests on the capability of steel brakes, and indeed ran them on Zanardi's car in 1999. Zanardi said that he preferred the "feel" from a steel brake.. Perhaps that is just because of what he was used to in CART.

Where steel brakes fall behind carbon brakes is in their efficiency. Carbon brakes do not suffer brake fade, whereas that is one of the biggest problems with steel brakes.

The other more obvious difference is in the weight.. Steel brakes on a car significantly increase the unsprung mass, which doesn't help with handling.

#3 rgagne

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Posted 30 September 2001 - 23:24

Originally posted by jetsetjim
In terms of braking performance, there is not a great deal to choose between CFRP and modern Steel brakes, contrary to popular opinion. Braking distances are more or less identical.


Are you sure of that?

I remember hearing some TV reporters say that Zanardi was braking something like 4 times the distance in advance when using steel brakes at Williams... They were using it as the explanation on why he was that much slower than his teammate.

RGagne

#4 desmo

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Posted 30 September 2001 - 23:55

First, Zanardi never ran the cast iron disc/Ferodo DS4000 brake combo in a race, although he did use them in practice and Q for the 1999 Hock race and practice only at Hungary, Austria and Belgium that year.

That package was in some respects superior to C/C brakes, notably higher initial mu values (to oversimplify, essentially braking torque) as well as higher peak mus on the brake dyno as well. As well because carbon can expand as it cools, ferrous brakes can be made to have less pad drag and less attention must be paid to pad retraction to avoid parasitic frictional losses. A good argument can be made that the only advantage C/C brakes have is unsprung weight, with ferrous disc packages adding ~11kg of unsprung weight v C/C brakes. That's enough however to make the use of C/C brakes virtually mandatory in F1.

#5 Ali_G

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Posted 02 October 2001 - 09:19

COuld someone explain to me why unsprung weight is such a problem in F1.

I thought placing ballast in the wheels rims would be an excelent place as it would not be affecting body roll or pitch.

Hence the handeling of the car would be better ?

Niall

#6 david_martin

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Posted 02 October 2001 - 09:24

Originally posted by Ali_G
COuld someone explain to me why unsprung weight is such a problem in F1.

I thought placing ballast in the wheels rims would be an excelent place as it would not be affecting body roll or pitch.

Hence the handeling of the car would be better ?

Niall


Ever considered what the inertial implications of increasing the mass of the brake rotors has on the frequency response of the suspension?

#7 PDA

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Posted 02 October 2001 - 12:28

Niall, the chassis and its contents movement is controlled by hte springs and dampers. The wheels and hubs move up and down without the benefit of control by springs and dampers. As the weight of the chassis and contents is so low, the impact of the weight of the uncontrolled wheel masses becomes more important. i.e. it is the ratio of sprung to unsprung weight that is really important. That is why the 5 kilo or so difference between a C:C disc vs. a steel disc is so important in a 600 kilo F1 car.

I would advise that you go to your local library and check out some books on basic race car design and operation, where you will find detailed explaination of these basics of chassis dynamics.

#8 Oho

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Posted 02 October 2001 - 13:23

Originally posted by PDA
Niall, the chassis and its contents movement is controlled by hte springs and dampers.


Ave !!!

Yes but the thing is that modern F1 caes have all but done away with front suspension, look http://www.atlasf1.c...&threadid=29246, they are so stiff. Rotational moments are an entirely different matter of which I undertand next to nothing.

- Oho -

#9 Rene

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Posted 02 October 2001 - 15:41

F1 should ban both Carbon and Steel brakes....this should allow us to see some passing as the teams try to find alloys which will make up the breaking distances they have lost....

#10 Pioneer

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Posted 02 October 2001 - 17:13

Then what would you suggest they use for brakes if not carbon or steel?

Rubber?

:)

#11 Ben

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Posted 02 October 2001 - 17:57

Originally posted by Oho


Ave !!!

Yes but the thing is that modern F1 caes have all but done away with front suspension

- Oho -


I seriously doubt that when they still use dampers that cost hundreds of pounds and all use torsion bars because they reduce friction in these dampers. A lot of effort if the thing doesn't move don't you think?

Ben

#12 PDA

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Posted 02 October 2001 - 23:29

Front wheel movement may only be 5 cm )(or even less), but the pivots allow greater length stroke for the dampers, and it is the damping of the movement which is of critical importance. The fact that unsprung mass movement is undamped is the big factor.

#13 Oho

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Posted 03 October 2001 - 09:14

Ave !!!

Actually the notion that the front suspension is turning into symbolic contraption wasn't mine at all.If I recall the idea was pushed forward by Yelnats who is either knowledeable or talented bull shitter and the idea was presented on this forum some time ago. Thinking about it made a lot of sense. The front suspension isn't really used to separate the bulk of the car from what happens between the tyre and the tarmac anymore, the suspension is used more to achieve desired handling characteristics with controll of roll and pitch angles of the chassis. I guess controlling the front ride height of the car is so critcal that the teams simply cannot allow it to change much hence the front of the car is stiff as a plank.

- Oho -

#14 Ben

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Posted 03 October 2001 - 19:24

Stiff as a plank maybe, but still compliant to some degree. Just because the movement's small it doesn't mean it isn't measurable and controllable.

I have a video review of the 1990 GP season and there is a qualifying lap at Monaco onboard with Senna and the vibration is astonishing compared to current GP cars. I think people underestimate how much more the suspensions move than in the recent past. A great deal was learnt during the active era and the engineers need advanced dampers and some useful suspension movement to replicate those effects.

Ben

#15 KenC

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Posted 10 October 2001 - 03:21

Originally posted by Ali_G
Simple question. What sort of difference in braking are we talking about if both were used in F1.

I would guess that it would be bare meters but some people in RC try to drill it into our heads that the distances would be vast.

Niall


You should look for Racecar Engineering or RaceTech on your newsstand. They often will have good tech articles including those on brakes.

As for carbon versus ferrous rotors, Desmo's post matches my recollection of Zanardi's experience in 99. I believe Ralf may also have tried ferrous rotors in practice.

Interestingly, Williams also had Damon Hill try ferrous rotors in 96. My vague recollection was that the performance difference was quite small, as the ferrous rotors generated 4.1Gs.

Fundamentally, I believe braking performance comes down to heat dissipation, because a brake converts rotational energy into heat energy, and the limiting factor is the dissipation of this heat generated before the brake fails.

#16 diosh

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Posted 10 October 2001 - 04:55

Originally posted by Ben
Stiff as a plank maybe, but still compliant to some degree. Just because the movement's small it doesn't mean it isn't measurable and controllable.

I have a video review of the 1990 GP season and there is a qualifying lap at Monaco onboard with Senna and the vibration is astonishing compared to current GP cars.


I've got a video of senna's qualifying lap at Suzuka in 1989 i think, and it's there huge vibrations in that too. However, i remember reading an interview with Alex Yoong after his first test with Minardi, the thing that stuck out for him, was how much the cars vibrated, and how we don't see it on the tele these days. He went on to say something about the camera's on the cars are suspended in liquids to stop the vibrations

#17 Ali_G

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Posted 10 October 2001 - 14:35

COuld I jut suggest something.

To slow the cars down why don't the FIA mandate a minimum weight for each wheel.

This could slow the cars down substantially from what you guys have been saying.

Niall

#18 Ben

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Posted 10 October 2001 - 17:23

With the greatest respect Niall, you often seem to jump on any performance related discussion we have and say, "oh, we could slow the cars down by adding that to the rules".

The point I feel you are missing in this case is that unsprung mass does influence performance (just looking at weight transfer equations will tell you that) but the effect is minimal compared to many other parameters.

A minimum wheel weight wouldn't slow the cars as much as many other factors. You have to look at the system as a whole. Was it desmo the other month who said "It's all about synergies".

Also a minimum wheel weight (I assume you meant heavier than they are now?) would be bloody dangerous in an accident.

diosh: Good point about the cameras.

Ben

#19 jpf

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Posted 10 October 2001 - 19:45

Also about cameras, now even handheld cameras have fuzzy logic image stabilization designed to reduce the appearance of vibrations. I imagine the F1 cameras have similar software in addition to liquid or other physical vibration dampers in the mountings.

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#20 KinetiK

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Posted 11 October 2001 - 04:52

Originally posted by Pioneer
Then what would you suggest they use for brakes if not carbon or steel?

Rubber?

:)


!boing!

#21 RJL

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Posted 12 October 2001 - 16:50

Originally posted by Ali_G
COuld someone explain to me why unsprung weight is such a problem in F1.

I thought placing ballast in the wheels rims would be an excelent place as it would not be affecting body roll or pitch.

Hence the handeling of the car would be better ?

Niall


Niall,

Please try not to be offended, but I gotta tell you that this is one of the funniest things I've read here in a long time. I actually burst out in laughter. Thanx, I needed that.  ;) :D :) :stoned:

#22 Croaky

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Posted 13 October 2001 - 14:48

Unsprung weight is the only reason why F1 cars aren't allowed to use monster truck wheels, which would look much cooler.

#23 Pioneer

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Posted 13 October 2001 - 15:23

Nah... monster truck wheels would have a huge drag penalty. Plus in addition to the whole unsprung weight thing... lets not forget that the wheels themselves are rotating driveline components. They are rotational inertia to be overcome. Making them heavier robs power directly.

I imagine that if you took the wheel size restrictions off that the designers would design the wheels to be about the same size as they are now. Maybe a little bit larger but not very much all other things being equal.


#24 MRC

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Posted 14 October 2001 - 00:14

The monster truck tires would make some things nice; traffic would not be a problem.