Brake Ducts, Tire Cooling, and beyond

[Farnborough]

I can understand the reticence of any team to fully describe a failure, that just giving a common advantage to competitor if they can interpret it in some way.

That's regardless of anything unusual it would appear.

They did describe to Lando during race though, with estimate of how far the pedal would increase in millimetre for each lap of use to reassure him and reduce his alarm. Just looks like classic and simple leak of one hydraulic part in reality.

Probably didn't want a penalty for unsafe operation either, should it come to protest by another.

[AR3-GP]

I can understand the reticence of any team to fully describe a failure, that just giving a common advantage to competitor if they can interpret it in some way.

That's regardless of anything unusual it would appear.

They did describe to Lando during race though, with estimate of how far the pedal would increase in millimetre for each lap of use to reassure him and reduce his alarm. Just looks like classic and simple leak of one hydraulic part in reality.

Probably didn't want a penalty for unsafe operation either, should it come to protest by another.

You are right. It may be completely unrelated to cooling. Nevertheless, the idea is interesting on its own. I didn't want to exclude ideas that are not "precisely" what Mclaren have done (we don't know anyway).

[krisfx]

Newey invented the blown diffusor. As this was forbidden, the coanda was used...and so on...

Blown diffusers were around in the 80s...

I have a running joke with friends that Newey gets credit for inventing everything

He really does!

[_cerber1]

[.poz]

this is from youtube comments and in my opinion he is right

What I'm a bit confused about is - for a continuous system across a stint duration during a race, in order for Mclaren to have lower tyre temperatures, the total cooling capacity across the stint duration needs to increase versus its competitors - which seems to be the basis for Red Bulls protestations.

A phase change material can consume a larger amount of energy/heat for a short duration of time as outlined within the video, but as soon as the material has changed state, it is no longer going to do so.

Therefore, the best case that I can see is that the total cooling capacity of the McLaren brake ducting is not larger than that of its rivals - the phase change material could absorb a sizeable amount of thermal energy during a braking event (of which is not transferred to the tyres), and then while the car has exited a corner/corner complex, the ducting then cools the phase change material and resets it for the next braking event.

Therefore the 'peaks' of thermal energy are lower, and this thermal energy is dissipated over a longer period of time whilst the phase change material changes back to its original state.

As covered in the video, if this were located internally to the drum this would be an ideal location, and if carefully tuned (perhaps different configurations circuit to circuit), it certainly sounds plausible!

From an electrical circuit perspective, it kind of seems like a capacitor that is smoothing out 'ripple', but within the thermal domain in this case.

[AR3-GP]

It would make sense for McLaren to use a phase changing material like the one currently circulating. Remember the brakes finding fire in testing last year. I thought that was very unusual at the time because for an F1 team that would be amateurish work. But they were certainly in the early stages of developing a phase changing material and a system with it, hence the burning of the brakes. Likewise, the fluid residues that were mentioned last year could have been the residues of a system that was not yet 100% perfect and not completely sealed or sufficiently developed in terms of phase changing.

I'm struggling to believe in the theory of "phase changing material" that absorbs heat because although every material has a "heat capacity", and some may also have a latent heat associated with a phase change, it's not enough to sustain heat absorption over a whole race distance (90 minutes). At some point the phase change material becomes "saturated" (imagine filling a carton with eggs, eventually run out of room) and then it's simply a heat conductor.

[AR3-GP]

this is from youtube comments and in my opinion he is right

What I'm a bit confused about is - for a continuous system across a stint duration during a race, in order for Mclaren to have lower tyre temperatures, the total cooling capacity across the stint duration needs to increase versus its competitors - which seems to be the basis for Red Bulls protestations.

A phase change material can consume a larger amount of energy/heat for a short duration of time as outlined within the video, but as soon as the material has changed state, it is no longer going to do so.

Therefore, the best case that I can see is that the total cooling capacity of the McLaren brake ducting is not larger than that of its rivals - the phase change material could absorb a sizeable amount of thermal energy during a braking event (of which is not transferred to the tyres), and then while the car has exited a corner/corner complex, the ducting then cools the phase change material and resets it for the next braking event.

Therefore the 'peaks' of thermal energy are lower, and this thermal energy is dissipated over a longer period of time whilst the phase change material changes back to its original state.

As covered in the video, if this were located internally to the drum this would be an ideal location, and if carefully tuned (perhaps different configurations circuit to circuit), it certainly sounds plausible!

From an electrical circuit perspective, it kind of seems like a capacitor that is smoothing out 'ripple', but within the thermal domain in this case.

How does the latter theory account for fast tire warmup? Otherwise, it seems like a reasonable suspicion...Like surge suppression in a fluid transport system, or an inductor in an electrical circuit. It could damp spikes in the transport medium. I think something is still missing for me (it sounds more like an advanced "heat shield"), but it could be close.

[Andi76]

Blown diffusers were around in the 80s...

I have a running joke with friends that Newey gets credit for inventing everything

He really does!

Actually Newey did not even invent the Red Bulls Blown-Diffuser. It was basically a copy of Ferraris intended diffuser for 1998. Unfortunately Carbon and heat-protecting was not at the level at that time to make it work, so Rory Byrne came up with the Periscope-Exhaust, but the famous first Blown-Diffuser Newey used at Red Bull was actually an almost 1-1 copy of this system.

[Hoffman900]

It would make sense for McLaren to use a phase changing material like the one currently circulating. Remember the brakes finding fire in testing last year. I thought that was very unusual at the time because for an F1 team that would be amateurish work. But they were certainly in the early stages of developing a phase changing material and a system with it, hence the burning of the brakes. Likewise, the fluid residues that were mentioned last year could have been the residues of a system that was not yet 100% perfect and not completely sealed or sufficiently developed in terms of phase changing.

I'm struggling to believe in the theory of "phase changing material" that absorbs heat because although every material has a "heat capacity", and some may also have a latent heat associated with a phase change, it's not enough to sustain heat absorption over a whole race distance (90 minutes). At some point the phase change material becomes "saturated" (imagine filling a carton with eggs, eventually run out of room) and then it's simply a heat conductor.

For it to absorb heat and then dissapate, it’s essentially dynamic braking that’s been around on railroad locomotives for 80 years.

What a thermal imaging camera would also show, is where that is being dissapated and would be east for RB to call out. They haven’t done so. Last I recall, any form of dynamic braking on the front axle is illegal anyway.

Everyone can claim to “design a fluid” or “use a material”. But what are these materials? Call some specific ones out. F1 very rarely if ever has “invented” their own materials, usually stealing commercially available materials from aerospace (it’s only exotic in the sense joe public has never heard of it). Would be even less likely in the cost cap era.

[langedweil]

this is from youtube comments and in my opinion he is right

What I'm a bit confused about is - for a continuous system across a stint duration during a race, in order for Mclaren to have lower tyre temperatures, the total cooling capacity across the stint duration needs to increase versus its competitors - which seems to be the basis for Red Bulls protestations.

A phase change material can consume a larger amount of energy/heat for a short duration of time as outlined within the video, but as soon as the material has changed state, it is no longer going to do so.

Therefore, the best case that I can see is that the total cooling capacity of the McLaren brake ducting is not larger than that of its rivals - the phase change material could absorb a sizeable amount of thermal energy during a braking event (of which is not transferred to the tyres), and then while the car has exited a corner/corner complex, the ducting then cools the phase change material and resets it for the next braking event.

Therefore the 'peaks' of thermal energy are lower, and this thermal energy is dissipated over a longer period of time whilst the phase change material changes back to its original state.

As covered in the video, if this were located internally to the drum this would be an ideal location, and if carefully tuned (perhaps different configurations circuit to circuit), it certainly sounds plausible!

From an electrical circuit perspective, it kind of seems like a capacitor that is smoothing out 'ripple', but within the thermal domain in this case.

How does the latter theory account for fast tire warmup? Otherwise, it seems like a reasonable suspicion...Like surge suppression in a fluid transport system, or an inductor in an electrical circuit. It could damp spikes in the transport medium. I think something is still missing for me (it sounds more like an advanced "heat shield"), but it could be close.

I saw that same comment .. and that's the way I'd use it; just on the cusp of what's needed, so you can keep re-using it instead of once.
On the other hand, conducting the heat outwards through the brakefluid is a working theory as well.
Anyway, I think a lot of teams will get to the principle soon, especially the larger teams. Develop and test could very well be done outside the BC and on non-F1 cars (or even 3yr old cars). So the principle could be simply tried over and over again by chucking brains/time/money towards it. As soon as it gets really viable, one could enter it into the team's BC. I'd say it's tackled by one or more teams by round 10-12, latest after Summer break.

[dialtone]

How does the latter theory account for fast tire warmup? Otherwise, it seems like a reasonable suspicion...Like surge suppression in a fluid transport system, or an inductor in an electrical circuit. It could damp spikes in the transport medium. I think something is still missing for me (it sounds more like an advanced "heat shield"), but it could be close.

Not taking any part in this yet but...

You can design a material to have any particular threshold temperature and thermal capacity, but it fundamentally depends on what it does. If the material is operating as a controller of sorts you just need to tune the PC Temp range such that it "switches" on and off in the range of braking and cooling.

Other way of explaining it: if you have ever seen a bidet, or some sinks, or a dam, they usually have a spillway that allows the dam to regulate the max amount of water in it, the speed with which it's filled is independent.

The material in case doesn't need to change the speed with which temperature is gained, it's just acting as a thermostat or PID controller, for example the open/close of brake ducts would be a natural way to use this although maybe not practical in this case.

I'm a bit skeptical of the brake fluid used for cooling, fluids move heat via convection, if you don't have molecules that move like that, the temperature gradient has to be massive. I don't have time to research a paper that backs this up but: https://citeseerx.ist.psu.edu/document? ... be70e9e879 this paper experimented with 1%<x<3% aluminum nanoparticles suspended in water to observe how brownian motion transfers heat within natural convection and the conclusion was that not only it doesn't, but it actually conducts worse. Only way that this could work is if they have something that re-circulates the brake fluid.

Another example here: there would be no need of a water pump for CPU water cooling if brownian motion was enough.

And this is setting aside the difficulty in managing constant pressure in the break circuit upon the fluid changing volume while heated and cooled.

Anyway... I'm not a physicist.

[AR3-GP]

What are we seeing here? This is the Mclaren rear brake. The 3 photos are the 3 compartments. The cover over the rear brake disk in the first photo looks like it is of a mixed composition.

[ringo]

The answer to this riddle is not as complicated as purported here.
A lot of details and explanations, but what has yet to be mentioned is the temperature range that the tyres needs to be in.
Let us start there.
C0 (Hardest): ~100°C to 120°C
C1: ~95°C to 115°C
C2: ~90°C to 110°C
C3: ~85°C to 105°C
C4: ~80°C to 100°C
C5: ~80°C to 95°C
C6 (Softest): ~75°C to 90°C

The widest range of control is 20 degrees C.

Cooling is only achieved by air flow over the tyre outer surface and through brake duct to rim.
Warming occurs under braking, slip, friction from vertical load, and heat from brakes to rim.

No moving parts are permitted.

Whatever is being done is allowing heat transfer to the tyres up to a certain temperature before heat transfer coefficient is reduced so as to halt temperature rise enough for the cooling effect to balance the heating effect.

When the temperature drops at the lower limit, the heat transfer coefficient increases to permit heating again.

The most active control over the race distance would be to cool the tyres on the straights, or reduce the thing that causes heating. Realistically it's not vertical load that is being reduced, unless this is done on the straight.

It could be KERS regeneration under braking with an oversized brake caliper to reduce heating. It can be differential control to reduce sliding in the corners.

There can be a combination of all of these things. The varying heat transfer coefficient material would be helpful in qualifying where heating is important. During the race cooling effect is most desirable.

The oversized caliper and rotor with KERS regen is the easiest to do.

[AR3-GP]

I can understand the reticence of any team to fully describe a failure, that just giving a common advantage to competitor if they can interpret it in some way.

That's regardless of anything unusual it would appear.

They did describe to Lando during race though, with estimate of how far the pedal would increase in millimetre for each lap of use to reassure him and reduce his alarm. Just looks like classic and simple leak of one hydraulic part in reality.

Probably didn't want a penalty for unsafe operation either, should it come to protest by another.

There's "intermediate" device in the rear brake line to proportion the rear retardation between the regenerative part, then moving toward pure friction of disc usage and all without driver input to be ultimately invisible to him.

Look up BBW if you're unaware of the system used.

I want to revisit this as I have discovered some new information. There is a category of parts on the F1 cars known as Open source components (OSC) in the regulations.




Here is the list of open-source components relating to the braking system for which competitors must share the designs for other teams.

OSC list

Pedals
Front axles (outboard of the contact surface with the wheel spacer), nuts & retention system
Rear axles (outboard of the contact surface with the wheel spacer), nuts and retention system
Brake disc, disc bell, and pad assembly
Brake calipers
Rear brake control system (brake by wire)
Brake master cylinder

There's also another note about being required to disclose faults encountered in the usage of any OSC design.

Competitors are responsible for the installation and operation of any OSC parts (including from a liability perspective) but there is also a requirement to share information on any problems that arise.

So again, why does he answer like this? What is he hiding?

“Lando and the team did a great job in managing the situation and adapting the driving style to the problem, which then got worse to the point where it put the result at risk, which is unacceptable from a reliability point of view, we need to do better.”

Stella gave a limited explanation behind the issue, but sought privacy rather than disclosing the whole picture.

“We understand what the problem is, which I can’t disclose for IP reasons,” he said.

“But fundamentally, it had to do with a leak in one of the components, not in the brake line, but somewhere else, and the main action required was to limit the peak brake pressure.”

The BBW module, master cylinder, pedals, and caliper are open source components. So not only must Mclaren share the designs of these parts of the brake system, but they must also disclose any faults during their operation to competitors. So what is there to hide? What component in the braking circuit is not open source?

[AR3-GP]

And this is setting aside the difficulty in managing constant pressure in the break circuit upon the fluid changing volume while heated and cooled.

Well, the Mclaren drivers struggle a lot with braking...