31 replies to this topic

[bugeye]

So there I am watching the old SV broadcast of Malaysia, and they show the new Ferrari brakes which looked just like drums with no obvious venting. Does anybody know they story behind this? I don't remember it being discussed before, according to Matchett Byrn was working on these things at Benneton finally perfecting them now.

What are they?


Thanks

Dave

[perfectelise]

I noticed the drum shape during a pit stop wheel change.
At the time I thought it might be a structure (like a centrifugal impeller) to draw cooling air through the wheel without having something out in the air flow - like Maclaren most notibly.

perfectelise

[palmas]

If I knew the story, I would give up the day job!

Even centrifugal pumps have intake and output, and I cannot see either one.

They seem drum brakes. We need better photos or inside info!

Any way, they work quite well.

[DangerMouse]

“At the time I thought it might be a structure (like a centrifugal impeller) to draw cooling air through the wheel without having something out in the air flow”

Perfectelise, your assumption is correct that’s exactly what the Ferrari brakes are. Looking at the Macs though they seem to be running a conventional system with normal ducting for cooling.

[bugeye]

But DM, Wouldn't that require relatively large cross drilled holes in the brakes to let the air through? Also they looked small to me, but maybe that's just the increased cross section contributing to the illusion. Could they be running more than one set of disks in the brakes? Also they seemed perfectly round (Though the view wasn't the best) where have they hidden the calipers? I think there may be more to it than simply using fans, how would does a fan perform when the airflow is parallel to the fan? I am not an expert aero so I have no Idea, but it would seem counterintuitive...

Dave

[AndyM]

Hi,
here is a picture of the brakes from Friday Practice at Sepang. Normal Disc brakes but with a more bulky front hub, reckon there must be some kind of centrifugal cooling fan situated in there as there are no conventional brake ducts to be seen on the F1-2001.




The mechanics are just about to cover the one nearest up with a towel or cloth, so they are hiding something!!

Andy

[perfectelise]

The drum shape looks like its carbon fibre (same colour as front suspension).
It's definitely not a drum brake.

perfectelise

[bugeye]

Ahhh,

There would be the Caliper...I didn't think they would be using a drum, but doesn't the caliper look rather large? and I believe last years was on the bottom..I suppose the fan could direct the air through the inside of the disk(by that I mean the inner diameter) up through the vents in the middle of the disk...If their not solid (hard to tell from the photo)

The metal part sandwiched in the middle is curious as well, The Brakes being CF and the fan or whatever is is being CF you wouldn't think you'd need a heat shield...

The thought occured to me that the fan may be in fact be acting like a vacuum and creating a low pressure area near the disk to draw in air from the wheel area, this would explain why the brake dust ends up on the car rather than blown out towards the wheel.
I wonder if the wheels are any different or not..

Dave

[Engineguy]

Originally posted by bugeye
The metal part sandwiched in the middle is curious as well, The Brakes being CF and the fan or whatever is is being CF you wouldn't think you'd need a heat shield...

I'd remind you that CF brake discs have a carbon matrix (i.e. the material is totally carbon) while virtually all other CF parts (tubs, wings, brake ducts, etc. have an epoxy matrix... even the most heat resistant epoxies don't come close to Carbon/Carbon in ability to survive heat.

[random]

Any bets as to when and who will be the first team to sucessfully copy Ferrari's ductless impeller brakes?

Steve Matchette said during the US broadcast that the brake ducts have more effect on the aero than even the front nose.

I'd say McLaren has the best chance, I think we'll see them by Monaco.

[bugeye]

Originally posted by engineguy

"I'd remind you that CF brake discs have a carbon matrix (i.e. the material is totally carbon) while virtually all other CF parts (tubs, wings, brake ducts, etc. have an epoxy matrix... even the most heat resistant epoxies don't come close to Carbon/Carbon in ability to survive heat. "


You sir are SO right.

that would 'splain it.


Dave

[Ross Stonefeld]

There is a duct inlet, its within the canister. The chassis side is open and the duct sits in the hollow

[palmas]

Come again?!?

[Ross Stonefeld]

The new widget. Its not got a 'face' on it. Its open air and there's a duct sitting in it

[random]

Do you have any photos of the face of the system? I've only seen photos from the rotor side.

[Dents]

Palmas is right, I recall seeing a very slender rectangular duct..

It does stick out from the hub though (very little)... it looked to be about half an inch wide & 4 inches tall (rectangular)

here's some pics

[Ross Stonefeld]

During Speedvision's Malaysia Pre-Race they grabbed a live-shot from the cars going to the grid and showed the brake thing, and it was from the suspension side, you could see the duct quite clearly

[Russ Brooks]

I thought I might clarify some points to Palmas, Perfectelise and everyone else that is mystified by Ferrari's braking system. It was nice to get a good look at the brakes close up on TV during QF for the Malaysian GP, but thanks also to AndyM and Dents for providing some nice shots too!!

DM and Ross are both perfectly correct. Ferrari are using (and have been developing for over 3 years now) the centrifugal inpellor induction system for cooling the brakes. The reason for this new development actually stems for the regulatory downforce reductions, which have reduced drag to the point where the brakes are being pushed to their limit under heavy deceleration.

It is important to remember that the disks themselves are DESIGNED to heat up to around 800deg/c. at which point they are at their most efficient.

The point of cooling is NOT to stop the disks from overheating - they will never overheat. The pads that GRIP the disks however, don't have the surface area (for efficient cooling) or 'longevity' of the disks themselves and over the course of a gruelling 70 odd laps they start to perish. In doing so they also "scrape" the carbon disks causing "grooving" - hence lack of contact area, brake fade, and the black dust you see at the pit-stops.

To try and solve the problem the ingenious use of the impellor has been adopted. Firstly to stabilise disk temperatures to an optimum level (so that they don't transfer so much heat into the pads and calipers). But more importantly to utilise the rotational energy of the wheel to feed cool air to the calipers - without sacrificing aerodynamic stability or drag coefficiency.

Kinetic impellors would have been adopted if it were legal years ago, but today their weight would be prohibitive anyway. Kinetic impellors use centrifugal force to "hold the fan" geostationary with the wheel whilst the car is accelerating and then release the fan under braking, the momentum of the fan (including flywheel) sucking cool air onto the pads simultaneously.

I always wished that I'd invented the system - but seeing as it's banned in virtually all motorsport, the patent would be worthless anyway!!!

Don't mean to sound harsh (please forgive, I'm not arrogant) but did I see someone mention drums????!!!! Not used F1 for years and years and years....!!

Sorry Palmas.;) Just kiddin' !!!

[palmas]

Thank you for the explanation, Russ, it has been quite usefull for me. It all makes more sence now. In drums I was refering to the shape, not that they were drum brakes.

There is also something you could try to explain me: normaly brakes use the air cooling to remove the energy from disks, during braking. If you do not cool the disks, how do you remove the energy?

[bugeye]

Ross, when you say it's "Open air" do you mean you can clearly see the impeller?I am very curious about the ducting of the thing internally, I wonder if they vent it to the rear of the disk or out the wheel? Out the wheel would seem the most sensible, but I am bugged by the presence of all that brake dust on the sidepods, which is why I thought thwey might be drawing air in from the outside of the wheel, but clearly that's not the case given the intake duct on the front/inside of the wheel. In any case it's nice to see something different in the f1 world, though I have to admit I was hoping for something a little more exotic..


Dave

[Ross Stonefeld]

eh? impeller?

I meant it has a brake duct. Like most cars have one sitting in the air stream, the big scoopy looking things. It has one of those sitting inside the canister. The inside-side isnt covered. If you were sitting on the nose cone and looked at the wheel's it'd be a brake duct sitting in a cake pan

[Russ Brooks]

Leave it Ross...flogging a dead horse I'm afraid.....LOL!

In answer to your question Palmas. Energy (in the form of heat) dissipation from brake disks is normally required to stop the disks from overheating, and as I said in my post - this can't happen with CCFR disks. The natural ducted airflow in "normal" F1 braking systems is not quite enough to protect the whole system - hence the use of the impellor.

[palmas]

The cooling is not only for safety reasons. Energy have to be exchanged, it cannot disapear.

The kinetic energy of a 300km/h F1 is about 2MJ

If it were to stop, and if the four disks would have a total mass of 1kg, if the cp of carbon fiber is less than 0,5 kJ/kgºC (I don't have the correct number, but this is good enough for the purpose), then, without cooling, the disks would increase they temperature 4000 ºC every time they brake from 300km/h to 0.
Of course you need to dissipate the heat. The good point with carbon brakes is that with high temperatures (over 800ºC) the energy exchange can hapen with less contact surface (disk/air), and allowing reduced air flow
This is comun Thermodinamics and is all about exchanging energy.

So, Russ, one of us is not quite following the other.

[bugeye]

Er...Sorry Ross, Meant Russ...


Anyway...nevermind

[Engineguy]

Has anybody actually seen an impeller, or is this just one of those deals where someone mentioned an impeller and everybody else ran with that assumption until it became gospel? An impeller would be hard to package inside there with the upright. I'd be more inclined, given the shape and size, to think the inside of the wheel might have helical ribs that, right up close to the "drum" surface pumps air to (following the internal contour of the wheel) wash over the outside face of the disc, with the smallish conventional duct cools the inside face. Or maybe the "wheel pumps" pull the air the other way... between the "drum" and rim, toward the center of the car, exiting at the inner sidewall (explaining the dirty sidepods). Or not.

[Russ Brooks]

Point duly noted Palmas. The heat dissipation from the disks is not a problem. The disks cool down very rapidly after the pads release contact, with most of the energy being transferred into the air through convection. The remaining energy, although a lot less - but still enough to cause problems - is transferred to all the other components (brake hubs, calipers, pads, hydraulics etc.) via all three thermodynamic laws, i.e. convection, conduction, and radiation.

And that is the point. Your maths and physics - although approximate - are well grounded, which is why the impellor works.

The ratio of energy transferral between the two is altered in the system components favour. For example,

If the heat dissipation between the system and air = [A] and,

the heat dissipation collected BY the system = [B], and

the total energy loss = [C], then,

we could summise the following :-

[A] + [B] = [C]. Thermodynamic law, as you rightly pointed out.


System 1) No Impellor.

Let's say [A] = 80% [B] = 20% (so obviously [C] = 100%)


System 2) With Impellor.

[B] is REDUCED. [C] has to remain 100% therefore [A] is increased.

I don't need specific energy figures because the laws of physics are unchangeable. So the equations deciding relative energy dissipation (so as to keep nature's status quo) can remain purely algebraic, or logical.

As for the total distribution of the car's 2 MegaJoules (if indeed that's what it is, I shall take your word for it) you have to remember that,

1) The car is not always travelling at 300km/h, and so the equation gets very complicated throughout a complete lap or race. You would have to build in a time factor in relation to "brakes on - brakes off" - for every zonal acceleration and deceleration. Plus the air temperature, pressure, and humidity would change the transfer rates across the board.

and,

2) A lot of the cars kinetic energy is swallowed up by all the other macro-systems contained within the car. For example you could include the friction between everything and everything (LOL!) i.e. tyre and track, air and car surfaces, running gear e.g. gearbox, clutch, etc. As well as all the other energy transferrals like thermal, chemical, and quantum etc.

So I do concur wholeheartedly with your post - apart from the last two points, that is. Why does that sound smug??? I didn't want it to sound like I was an arrogant know it all in anyway. But if I was to read my own postings then that is what 'I' would be thinking!!!! See, I can show some humility!

PS. Engineguy - IT IS AN IMPELLOR. FACT. MARTIN BRUNDLE AND EVERYONE ELSE IN THE KNOW HAS CONFIRMED THIS. Q.E.D.

[palmas]

These discutions are not to decide who's right, but to reflect learn something from them.
Any way, thanks again.

[perfectelise]

Originally posted by Engineguy
An impeller would be hard to package inside there with the upright. I'd be more inclined, given the shape and size, to think the inside of the wheel might have helical ribs that, right up close to the "drum" surface pumps air to (following the internal contour of the wheel) wash over the outside face of the disc, with the smallish conventional duct cools the inside face

My thoughts too.
I was trying to thing of possible modifications to the inside of the wheel and the spokes of the wheel.
Is there a heat reflective surface on the inside of the wheel to save the tyre (and tyre pressure) from brake heat?
Could the shape of the spokes be modified to give the effect of an impeller?

perfectelise

[imaginesix]

Originally posted by Engineguy
Or maybe the "wheel pumps" pull the air the other way... between the "drum" and rim, toward the center of the car, exiting at the inner sidewall (explaining the dirty sidepods). Or not.

I'd just like to try and dispell what seems to me to be a risky assumption we are all making, that the dust on the tops of the sidepods of the Ferraris must come from brake dust expelled from the inside of the front wheels.
In truth it is arrogant to assume that we can tell a car's aerodynamic principles just by looking at it.
It is conceivable that the brake dust is coming from the outside of the wheels, that's all.

[Engineguy]

Originally posted by imaginesix
...a risky assumption we are all making...

...it is arrogant to assume that we can tell...

Speak for yourself; I know everything!

Seriously, note the "Or not "

90% of everything we write here, while we may applying our sound engineering knowledge to it, is based on speculation, educated guesses, and just plain old thinking out loud. I try to throw in an adequate number of "maybes", "probably" and such to try to avoid angry debates and keep it fun as technical banter. Nobody is going to die, or even lose a race if I'm wrong about something, so I can't afford the time to do research before making comments (I'm on the internet WAY too much as it is).

[bugeye]

Originally posted by imaginesix


I'd just like to try and dispell what seems to me to be a risky assumption we are all making, that the dust on the tops of the sidepods of the Ferraris must come from brake dust expelled from the inside of the front wheels.
In truth it is arrogant to assume that we can tell a car's aerodynamic principles just by looking at it.
It is conceivable that the brake dust is coming from the outside of the wheels, that's all.

That's true, it could be tire particles, second hand smoke, pixie dust, BAR oil or any number of things.

What makes this particular question of the brakes so interesting to me is that it is great fun to try figure out what's inside a black box. Here we have a device we all understand fairly well (Brakes) presented in a new way. I think it's nice way to pass the time trying to figure out what's in there, why they did it etc. etc.

Dave

[random]

During the US broadcast of the Malaysian GP, Steve Matchette said he'd asked Nigel Stepney of Ferrari about the dirt on the top of the sidepods.

Nigel admitted it was brake dust but wouldn't say anything more.