33 replies to this topic

[Taxman]

Hey guys, this is my first post on the forums here. I wanted to discuss inboard brakes in F1. Most people here seem to think it would be advantageous to decrease the reliance on aerodynamic grip and increase mechanical grip. In my opinion it would seem logical to mount the brakes inboard and use liquid cooling with a separate radiator (I know liquid cooling is banned). A small vent in the nose like the 2008 Mclaren could also be used to further assist cooling.

Mechanically it would be more complex, but steel brakes could also be utilised to reduce cost. Fitting the front brakes in the nose may also pose some difficulty.

As I see it the benefits outweigh any negatives. It would significantly reduce unsprung weight and therefore increase mechanical grip. Aerodynamically it could be more efficient.

Are inboard brakes banned in the rules or do the teams just prefer outboard brakes?

What do you guys think?

[Ben]

Why would it significantly increase mechanical grip?

Ben

[MatsNorway]

Why would it significantly increase mechanical grip?

Ben

It would make the dampers job easier. tires would bounce less etc. but yea it would not be significantly.



Taxman:

It has been done in F1 before but i think its banned. prob to do with the fact that if the drive shaft/transfer shaft breaks your going to have a mega crash.

but today i think it should be possible to make such a shaft basically bullet prof. Or have both one tinny brake at the wheel and a beefy at the gearbox, as a failsafe.

pic of cars with inboard brakes: http://www.facebook....mp;id=836285018
http://www.facebook....mp;id=836285018

Edited by MatsNorway, 15 January 2010 - 15:20.

[Taxman]

'Significantly' was probably the wrong word. I'm no technical expert and thought it would increase mechanical grip to some degree. I guess the technology is not used for the same reasons as active suspension, even though it may be beneficial, it would be too dangerous.

Thanks for the pictures.

[DaveW]

I suspect that inboard brakes in a modern F1 vehicle would require solutions to be found for several potential issues. A braking event is quite violent, so a structural engineer would like the torque tube to be stiff (hence large diameter) to avoid dynamic problems caused by the torque tube "winding up". On the other hand, an aerodynamicist would like the torque tube not to interfere with airflow, so he would like a small diameter tube (hence flexible). The unsprung weight reduction would be offset, to some extent, by the need to add a strong CVJ at either end of the torque tube. Cooling would be an issue that might be solved by water-cooling, but that solution would carry with it a weight overhead. Finally, there is not too much room at either axle to package inboard brakes in a modern F1 chassis. My guess would be that one design iteration might convince you that outboard brakes are not such a bad idea after all, whatever the regulations stipulate....

[MatsNorway]

I suspect that inboard brakes in a modern F1 vehicle would require solutions to be found for several potential issues. A braking event is quite violent, so a structural engineer would like the torque tube to be stiff (hence large diameter) to avoid dynamic problems caused by the torque tube "winding up". On the other hand, an aerodynamicist would like the torque tube not to interfere with airflow, so he would like a small diameter tube (hence flexible). The unsprung weight reduction would be offset, to some extent, by the need to add a strong CVJ at either end of the torque tube. Cooling would be an issue that might be solved by water-cooling, but that solution would carry with it a weight overhead. Finally, there is not too much room at either axle to package inboard brakes in a modern F1 chassis. My guess would be that one design iteration might convince you that outboard brakes are not such a bad idea after all, whatever the regulations stipulate....

1+

I have believe in a combination with a minor brake at the gearbox. the rear shaft needs to take quite some torque from the engine anyway, mounting a brake that goes close to engine max torque out on drive shaft would be a good thing.

Ill check the rules later for clues about its legality.

the 2010 rules had a 4wd proposal btw. but they got ditched.

[MatsNorway]

11.1.1 With the exception of a KERS, all cars must be equipped with only one brake system. This system must comprise solely of two separate hydraulic circuits operated by one pedal, one circuit operating on the two front wheels and the other on the two rear wheels. This system must be designed so that if a failure occurs in one circuit the pedal will still operate the brakes in the other.

11.2 Brake calipers:
11.2.2 No more than two attachments may be used to secure each brake caliper to the car.
11.2.3 No more than one caliper, with a maximum of six pistons, is permitted on each wheel.
11.3 Brake discs:
11.3.1 No more than one brake disc is permitted on each wheel.
11.3.2 All discs must have a maximum thickness of 28mm and a maximum outside diameter of 278mm.
11.3.3 No more than two brake pads are permitted on each wheel.

Its doesn't say brake must be mounted directly on the wheel does it?

11.3.1 No more than one brake disc is permitted on each wheel. if they mean connected TO the wheel they can not have it.

So that`s a big NO tho inboard brakes then.


source: http://www.formula1....s/8696/fia.html

[J. Edlund]

Hey guys, this is my first post on the forums here. I wanted to discuss inboard brakes in F1. Most people here seem to think it would be advantageous to decrease the reliance on aerodynamic grip and increase mechanical grip. In my opinion it would seem logical to mount the brakes inboard and use liquid cooling with a separate radiator (I know liquid cooling is banned). A small vent in the nose like the 2008 Mclaren could also be used to further assist cooling.

Mechanically it would be more complex, but steel brakes could also be utilised to reduce cost. Fitting the front brakes in the nose may also pose some difficulty.

As I see it the benefits outweigh any negatives. It would significantly reduce unsprung weight and therefore increase mechanical grip. Aerodynamically it could be more efficient.

Are inboard brakes banned in the rules or do the teams just prefer outboard brakes?

What do you guys think?

I can't find any reason behind the advantages you claim, I can however see several problems and reasons why such a system would have a negative impact on the car.

The brakes operate at high temperatures (about 500-1000 degC) and handle very high power rates (peaks around 2000 kW). To cool the hot brake discs directly with air will require a much lower airflow (equals less aerodynamic drag) than to cool a say 130 degC coolant. Heat radiation from the discs are also an issue, so I would prefer to have the brakes in the wheels rather than within the body of the car where the heat can affect several components.

For F1 cars, the airflow from the front wing (between the wheels and the tub) and the flow to the lower rear wing are important and with inboard brakes this airflow will be more restricted compared with brakes in the wheels since the space inside the wheels are 'free'. Especially if we consider the driveshafts required with inboard. The front would also require some sort of bearing for the disc.

The current carbon/carbon brakes are very light, just a few kg per brake, this is no significant issue in terms of unsprung weight. Add the weight of driveshafts, radiators and such and the current system is lighter.

It's also questionable if iron (not steel) brakes would offer any significant cost reduction.

[MatsNorway]

11.1.1 With the exception of a KERS, all cars must be equipped with only one brake system. This system must comprise solely of two separate hydraulic circuits operated by one pedal, one circuit operating on the two front wheels and the other on the two rear wheels. This system must be designed so that if a failure occurs in one circuit the pedal will still operate the brakes in the other.

11.2 Brake calipers:
11.2.2 No more than two attachments may be used to secure each brake caliper to the car.
11.2.3 No more than one caliper, with a maximum of six pistons, is permitted on each wheel.
11.3 Brake discs:
11.3.1 No more than one brake disc is permitted on each wheel.
11.3.2 All discs must have a maximum thickness of 28mm and a maximum outside diameter of 278mm.
11.3.3 No more than two brake pads are permitted on each wheel.

Its doesn't say brake must be mounted directly on the wheel does it?

11.3.1 No more than one brake disc is permitted on each wheel. if they mean connected TO the wheel they can not have it.

source: http://www.formula1....s/8696/fia.html

Actually, it doesnt say the brake must be on the wheel (hub) right?

Just that its not allowed with more than one per wheel.

[saudoso]

BAR at some point tried some front semi-axle system, didn't them? If they really did it would link the two front's with a differential but I'm not sure about inboard brakes.

Google didn't help me here, does someone remember that?

[Tony Matthews]

BAR at some point tried some front semi-axle system, didn't them? If they really did it would link the two front's with a differential but I'm not sure about inboard brakes.

Google didn't help me here, does someone remember that?

I remember someone - BAR possibly - connecting both front wheels via a 'differential', to balance left and right front brakes. Or do I...?

[saudoso]

I remember someone - BAR possibly - connecting both front wheels via a 'differential', to balance left and right front brakes. Or do I...?

And it was banned, never made to track...

[McGuire]

Benneton in '99. The front brake rotors (outboard) were coupled via half-shafts and a viscous diff, the idea being to avoid locking the inside front. Wasn't worth the weight and packaging issues, apparently. The later systems (BAR and others) were banned -- by mutual agreement if I recall.

[Ross Stonefeld]

BAR ran a similar in 2004

Ban/appeal http://www.autosport...rt.php/id/39026

Second attempt http://www.autosport...rt.php/id/39621

More http://www.autosport...rt.php/id/39691

Total ban http://www.autosport...rt.php/id/40415

Explanation and picture, mid-page http://atlasf1.autos...carborough.html

[MatsNorway]

I guess one brake disk per wheel means that it MUST be directly attached to the wheel then.



anyway seems like it would have a positive effect. worth the extra weight.

Hopes lotus starts to make all kinds of strange rulebook interpretations.

[dexter311]

I suspect that inboard brakes in a modern F1 vehicle would require solutions to be found for several potential issues. A braking event is quite violent, so a structural engineer would like the torque tube to be stiff (hence large diameter) to avoid dynamic problems caused by the torque tube "winding up".

We had that exact problem at the rear of our FSAE car in 2006. We used dual inboard disc brakes and the halfshafts would react like a torsional spring, which contributed to some dynamic windup issues at the rear of the car under heavy braking. Packaging them was more difficult too, so the year after they were relocated outboard.

At the front of the car, a halfshaft for inboard brakes would be required to sustain much larger torques than halfshafts that only transmit engine torque, since an F1 car can brake at up to 5G but only accelerate at (as a guess) 2G maximum. Braking torques are probably the largest loads in the entire suspension system. And relocating them inboard would require the front of the monocoque to be much different since these braking loads would now be concentrated into a single load point (at the caliper) instead of being distributed nicely at the four suspension pickup points like the are with outboard brakes - the monocoque would probably turn out heavier.

[MatsNorway]

I don't believe in inboard brakes at the front.

just at the rear.


if 4wd gets legal in the future however it would be a benefit i think.


Ohh.. If brakes gets relocated to the chassis the rims could be in carbon.Just like on some motorbikes, that would improve things even more.

[Bloggsworth]

Mercedes and the Lotus 72 used them successfully, but with CF brake discs, the driver would probably be choked by dust before the race was half finished.....

[desmo]

Rindt's survivors may quibble with the term "successfully" in the 72's case although it would probably be unfair to blame the inboard brake concept as opposed to its execution.

[Ray Bell]

Originally posted by MatsNorway
I don't believe in inboard brakes at the front.

just at the rear.....

It's evident that this is the case...

Your posts earlier in the thread didn't follow the train of thought of the OP and you talked about things nobody else was mentioning.

I'm a big believer in getting rid of CF brakes, and this could be a way around it. But it's unlikely it would work out because of the immense braking torque that can be used today. If the 72 broke shafts with the almost subtle braking (by comparison) of 1970, just imagine what size shafts would be required. I think they might outweigh the brakes at the wheels!

[MatsNorway]

It's evident that this is the case...

Your posts earlier in the thread didn't follow the train of thought of the OP and you talked about things nobody else was mentioning.

were are you going? im not following. english is somewhat hard to understand at this forum.

I'm a big believer in getting rid of CF brakes, and this could be a way around it. But it's unlikely it would work out because of the immense braking torque that can be used today. If the 72 broke shafts with the almost subtle braking (by comparison) of 1970, just imagine what size shafts would be required. I think they might outweigh the brakes at the wheels!

what means OP?


The forces involved should be possible to figure out. 5G`s, car weights in at 610? lets say total of 700kg X 5 = 3500kg / 4 wheels = 875 * 10 = 8750N.

yeye rotational momentum, yeye airresistance brakes alot.

radius is lets say 45cm 8750 * 450 = Mv (moment twisting) = 3937500Nmm

Re = lets say some high quality steel. 1400Nmm2

Tau (Tv) = Re / root of 3 = 866nmm2

Mv/Tv = Wp = for a solid axl = 3937500Nmm/ 866nmm2 = 4548mm3


Wp= (pi*D^3)/16

blabla twist and turn

D = 29mm without safety factor the airbraking forces and rotational forces to stop ++, that's the slimmest possible. if im right.

edit: front brake is 60-80%? hehe i forgot that.

anyway hopes it gives some clarification.

Edited by MatsNorway, 19 January 2010 - 18:02.

[J. Edlund]

I don't believe in inboard brakes at the front.

just at the rear.


if 4wd gets legal in the future however it would be a benefit i think.


Ohh.. If brakes gets relocated to the chassis the rims could be in carbon.Just like on some motorbikes, that would improve things even more.

Carbon fiber rims are not allowed, that's why nobody is using them right now. It has nothing to do with the brakes. Infact, today the brakes are more or less shrouded from the rim by carbon fibre covers.

[Ray Bell]

Originally posted by MatsNorway
.....what means OP?

Original Poster...

Thanks for the thought you've put into that... a 29mm shaft is quite a hefty thing, weight (if solid) would contribute handsomely to unsprung weight, I'd think. And if there's an allowance for error or shock loads or whatever... hmmm.

[dexter311]

radius is lets say 45cm 8750 * 450 = Mv (moment twisting) = 3937500Nmm

Current F1 tyres are 660mm diameter -> 330mm radius so the shafts could be a bit slimmer, but you'd need a safety factor to account for dynamic loading.

There's also the tripod joints and their associated housings which would need to be added, not to mention beefing up whatever the brake calipers are attached to since the load is more concentrated. With the lightweight carbon brakes they use I doubt relocating them inboard would be an advantage.

[MatsNorway]

Original Poster...

Thanks for the thought you've put into that... a 29mm shaft is quite a hefty thing, weight (if solid) would contribute handsomely to unsprung weight, I'd think. And if there's an allowance for error or shock loads or whatever... hmmm.

Yea its beefy but not scary big.

possible to get it working just fine at the rear i think, since you probably get way better steel than that.

Brake bias as i mentioned would possibly make it easier to slim some more but then again we have not looked at the dynamic part.

maintaining its outer dimension and making it a pipe would help lightness.


Edlund: thats a silly rule, carbon today is prob cheaper than magnesium wheels. the heat protection of the carbon inside the wheels is prob not cheap either if i know F1 traditions correct.

Edited by MatsNorway, 20 January 2010 - 16:36.

[Tenmantaylor]

Aerodynamics: Surely having the discs and pads tucked inside the rim rather than massively bulking up the nose is an advantage? Not to mention the extra "brake shaft" in the airflow which would probably be as substantial, probably more so, than the actual drive shafts.

[Tony Matthews]

thats a silly rule, carbon today is prob cheaper than magnesium wheels.

Lots of rules are 'silly', but they are still rules.

[MatsNorway]

Lots of rules are 'silly', but they are still rules.

wow i did not know that.

[J. Edlund]

Yea its beefy but not scary big.

possible to get it working just fine at the rear i think, since you probably get way better steel than that.

Brake bias as i mentioned would possibly make it easier to slim some more but then again we have not looked at the dynamic part.

maintaining its outer dimension and making it a pipe would help lightness.


Edlund: thats a silly rule, carbon today is prob cheaper than magnesium wheels. the heat protection of the carbon inside the wheels is prob not cheap either if i know F1 traditions correct.

Forged magnesium rims are light (a F1 rim is around 3 kg), durable and quite cheap to produce. Carbon fibre rims are light, but also less durable and more expensive.

The carbon fibre shields within the wheels are not heat protected by any special means.

[MatsNorway]

Forged magnesium rims are light (a F1 rim is around 3 kg), durable and quite cheap to produce. Carbon fibre rims are light, but also less durable and more expensive.

The carbon fibre shields within the wheels are not heat protected by any special means.

thanks man. How come the carbon don't burn up? Covered in more carbon? (graphite?)

[Ray Bell]

Originally posted by MatsNorway
wow i did not know that.

Another thing you seem to not know...

Everyone else here is talking about front brakes, you seem to still dismiss them and only talk about rear. Please discuss the front.

[MatsNorway]

Please discuss the front.

ok doorbell, your the boss.

lets say it has 80% of the braking is done at the front, weighting in at 750 with fuel. 750 * 0,8 * 5gs = 3000Kg pr wheel.

3000kg * 10 * wheel radius (500mm?) = 15 000 000Nmm



This time lets use some god steel

Re = 2000Nmm2

Greek T (tau)

Wp= Mt/Tt ( tiny t for twist) 15 000 000/ (2000/ rot of 3) = 12 990mm^3

for a massive axl

D^3 = (Wp*16)/pi = 66 159mm

third rot of 66 159= D = 41mm


and again this is without the dynamic parts like bumps and oscillation due to flex in the axles++


Pi*R^2 = 1320mm^2

Area divided with length = A* 800mm? = 10 560 203mm^3 -> 1056cm^3

volume divided with density

lets say they have steel in the lighter end of the scale.

= 1056 * 7.75 = 8186grams -> thats 8.186Kg each axl.

say they get the weight reduced on the rims by 1kg they still have added 14.4kg in pure axle weight.

And you must expect some further add on when the gigantic transfer joints gets mounted at the wheel and in the nose.



As i said before unless 4WD gets legal i don't see it likely to happen.

how heavy are those brake disks anyway?

Give me a source for some propper steel/aluminum and ill re do it.

Edited by MatsNorway, 23 January 2010 - 11:05.

[J. Edlund]

thanks man. How come the carbon don't burn up? Covered in more carbon? (graphite?)

Cooling air flow around the uprights and through the brakedisc keeping it and all the shrouding cool. It is possible that the inside surface of the shroud has some form of heat reflecting properties, a thin layer of metal foil or a paint with metal pigment is probably enough to reduce heating due to radiation. The small air gap between the disc and the shroud means that it can only be heated by convection and radiation, not conduction. Given the airflow, heat radiation is probably the only heat transfer method that has a significant impact.

Temperature resistant matrix can be required for the carbon fibre instead for the conventional epoxy.

Carbon fibre is also used as heat shields for exhaust manifolds.

[McGuire]

Lots of rules are 'silly', but they are still rules.

Exactly. In the immortal words of Walter Sobchak, this is not Vietnam. There are rules.