Mercedes AMG F1 W05

[Per]

I think it is a too simple assumption. For example, what if the tyres are good but the track is made of ice? The friction coefficient between the track and the contact patch of the tyre is what limits the brake distance a priori. Then you have to consider that the friction coefficient may or may not change with the normal force the tyre is putting on the track and then there's the applied force to the brakes by the drivers: too much and the wheels will lock:

Seriously, all the things you are saying is what an engineer in racing calls being tyre limited. The term means that the limit of what you can do is defined by the maximum lateral/longitudinal force between the tyres and the track. Whether you want to call it "tyre limited", "tarmac limited" or "friction coefficient limited", that's tomato/tomato.

Tim.Wright is right, braking is tyre limited. Owen.C93 is also right about saying "below a certain speed", because at some speed there is so much downforce that the driver can't apply enough pressure to lock the wheels (so in this case braking is driver-force-limited, if you will). But I do believe this "certain speed" is very high, I would guess above 250 km/h of course depending on downforce level, compound and track conditions.

So it's safe to say braking is mostly tyre limited. And the presence of ERS systems, trail braking etc. is irrelevant, because it changes nothing to the fact that the brake balance of an F1 car is around 65/35 (or 60/40, or in between). So front downforce is really important for braking.

Another problem I have is that high-speed corners, where downforce is most important, are by definition not sharp corners and hence the steering angle is not very high. I have included a screenshot of Alonso going through the first part of Pouhon in 2011 (click here for the video). The point in the screenshot is more or less the highest steering angle he gets through this corner and he is turning his wheel less than 60 degrees. Compare this to the picture posted by bhallg2k (this one) and you'll see Hamilton is turning his wheel by about 135 degrees. So it's nice to look at the steered front wheels but the wheels never take such "extreme" position in high speed corners.



So the theory that they use front wheel turbulence to reduce downforce and drag, but not when the driver steers (even if he doesn't steer much in a high-speed, tyre limited corner like Pouhon), is really hard for me to believe.

Again, bhallg2k, I don't want to criticize you because I really like the idea, I really like your explanations and to be honest I hope someone comes on here and explains why I am wrong. And I do agree that front wheel turbulence has a big influence on the front wing, that it changes when the wheel is steered and that teams might be working very hard to gain something from that phenomenon. Thanks for explaining that. I just disagree with the way you suggest they are using it - without being able to come up with a better alternative.

I hope the mods won't remove this for off-topic, I still consider this to be a discussion about the W05 front wing.

[ACJJ619]

Probably mind games, but could this be true? 560hp from the motor and aren't the electric systems meant to add about 130hp? In Top Gear maths that's seven 'undred horsepower total.

Link: http://www.gptoday.com/full_story/view/ ... als_Lauda/

Also, my knowledge of brake-by-wire is very limited but this braking chat has made me think. Braking is tyre-limited - there's only so much braking force you can use before the wheels lock. At high speed though the drivers can't apply enough force to lock the brakes - could this be overcome by the brake-by-wire system? As in, could the system increase the braking pressure at certain speeds so they have maximum braking force at all speeds?

Or would this make it A: Dangerous from the risk of locking up at 200mph and B: Inconsistent braking throughout the whole range?

[PlatinumZealot]

Probably mind games, but could this be true? 560hp from the motor and aren't the electric systems meant to add about 130hp? In Top Gear maths that's seven 'undred horsepower total.

Link: http://www.gptoday.com/full_story/view/ ... als_Lauda/

LIES!! lol jk

anyway Renault touted 600 horsepower. So maybe the merc quoted "race" horsepower???

[smlbstcbr]

One learns a new thing everyday!

So... back on the turbulence hypothesis, didn't the engineers want a car to be insensitive (mostly) to changes in the airflow? Because having a car that suddenly looses a significant amount of downforce when hit by turbulence cannot be a good thing. I imagine (can be wrong) that they look for stability in the downforce levels when the airflow changes, something like Electronics Engineers (like me ) do when designing amplifiers: one designs an amplifier to be stable for a broad range of frequency and variations in the bias voltages. Nobody wants an amplifier that changes its gain if the biasing voltage changes by a small quantity. I think the same could be applied to downforce: to have the most downforce available in all flow conditions.

[bhall]

[...]

So the theory that they use front wheel turbulence to reduce downforce and drag, but not when the driver steers (even if he doesn't steer much in a high-speed, tyre limited corner like Pouhon), is really hard for me to believe.

Again, bhallg2k, I don't want to criticize you because I really like the idea, I really like your explanations and to be honest I hope someone comes on here and explains why I am wrong. And I do agree that front wheel turbulence has a big influence on the front wing, that it changes when the wheel is steered and that teams might be working very hard to gain something from that phenomenon. Thanks for explaining that. I just disagree with the way you suggest they are using it - without being able to come up with a better alternative.

No worries. I think the effectiveness of the concept with the new wings remains to be seen. This was undoubtedly a whole lot easier to do last year with wings that spanned the entire width of the car.



It may very well not work anymore.

What sounds like quite a small change, a 75mm reduction in the width of the front wing on each side, has had a big aerodynamic effect.

Previously, the front wing end plate allowed us to put the flow off the tip of the wing outside of the front wheel, but now the front wing end is right in front of the wheel – about the worst possible place. It's not inside or outside, so that means the majority of the flow now stagnates in front of the front wheel. A little bit finds its way outside and the rest comes inside, and in doing so makes quite a mess. The front wheel wake becomes much bigger and that causes all sorts of problems downstream as you approach the side pod and diffuser.

One thing to keep here in mind here, though, is that attempts to increase downforce in yaw are nothing new to F1. The use of outwash front wings is simply the latest iteration.

McLaren used "Viking horns" to redirect air flow to the rear wing when cornering.



BMW tried to use whatever these things were called for the same purpose...



...and they eventually landed on this device.



Red Bull copied that...



...and they used a "shark fin" engine cover.



Williams toyed with these cockpit fins.



The purpose of each one of those devices was to increase downforce in yaw and remain neutral the rest of the time so as to not inflict a drag penalty.

[Per]

Also, my knowledge of brake-by-wire is very limited but this braking chat has made me think. Braking is tyre-limited - there's only so much braking force you can use before the wheels lock. At high speed though the drivers can't apply enough force to lock the brakes - could this be overcome by the brake-by-wire system? As in, could the system increase the braking pressure at certain speeds so they have maximum braking force at all speeds?

At ALL speeds, no. Up to a certain speed, yes. The rules limit harvesting by the MGU-K to 120 kW. But apart from this little limitation you make a very good point.

[smlbstcbr]

Also, my knowledge of brake-by-wire is very limited but this braking chat has made me think. Braking is tyre-limited - there's only so much braking force you can use before the wheels lock. At high speed though the drivers can't apply enough force to lock the brakes - could this be overcome by the brake-by-wire system? As in, could the system increase the braking pressure at certain speeds so they have maximum braking force at all speeds?

At ALL speeds, no. Up to a certain speed, yes. The rules limit harvesting by the MGU-K to 120 kW. But apart from this little limitation you make a very good point.

But isn't the pressure on the braking pads limited by the Rules?

[SectorOne]

So it's safe to say braking is mostly tyre limited. And the presence of ERS systems, trail braking etc. is irrelevant, because it changes nothing to the fact that the brake balance of an F1 car is around 65/35 (or 60/40, or in between). So front downforce is really important for braking.

The brake balance of an F1 car is about 50/50 at high speed but then you have another setting for low speed brake distribution that you can set so the front has more bite.

Even 60/40 sounds too high.

[astracrazy]

The purpose of each one of those devices was to increase downforce in yaw and remain neutral the rest of the time so as to not inflict a drag penalty.

With the nose mounted wings/horns etc. i think you may be wrong there.

I understood the reason for them was to turn the air towards the sidepod intakes so they could reduce the size of the intake and so reduce some drag? I may be wrong or perhaps some teams were using them for different things. But i certainly read that was the reason for mclarens.

Edit: i've read around and some teams used them for different things. Honda for example just for pure downforce.

[timbo]

The brake balance of an F1 car is about 50/50 at high speed but then you have another setting for low speed brake distribution that you can set so the front has more bite.

During the 2007 Spygate hearings it was revealed that Ferrari had braking system that delayed rear braking, so the braking bias was almost 100:0. Anyway, usually the braking bias is more rearward in medium-low speeds, not the other way around.

[Just_a_fan]

The tyres does not limit braking power, it limits braking distance!

Power is the rate of doing work. If you can't brake as quickly then you can not generate the same braking power. Thus the tyres limit the braking power. Simple.

I think it is a too simple assumption. For example, what if the tyres are good but the track is made of ice?

Then you have the wrong tyres - studded tyres on ice would regain grip and thus allow for higher braking power. So the tyre is limiting the braking power.

The friction coefficient between the track and the contact patch of the tyre is what limits the brake distance a priori.

Friction between track and tyre is determined by the choice of tyre - the track can not be changed by the team. Thus the tyres limit the braking power.

In any situation where the brakes are able to lock the wheels, the tyres are the power limiting factor. If F1 had tyres so grippy that you couldn't lock them in any situation then the brake pads/discs would be the power limited factor.

[bhall]

The purpose of each one of those devices was to increase downforce in yaw and remain neutral the rest of the time so as to not inflict a drag penalty.

With the nose mounted wings/horns etc. i think you may be wrong there.

I understood the reason for them was to turn the air towards the sidepod intakes so they could reduce the size of the intake and so reduce some drag? I may be wrong or perhaps some teams were using them for different things. But i certainly read that was the reason for mclarens.

Edit: i've read around and some teams used them for different things. Honda for example just for pure downforce.

To my knowledge, you can't make downforce with a vertical element by itself. So, what you do is use that vertical element to redirect air flow to devices downstream that can make downforce.

Broadly speaking, air flow is reoriented over a car during the initial stages of a turn (from blue to orange in the picture below), when the car is said to be in yaw. Devices such as the rear wing then suffer a loss of efficiency due to sub-optimal air flow over them, which I guess is a good way to put it.



Solutions like McLaren's "Viking horns" redirected that sub-optimal air flow to a more optimal path, which then increased the efficiency of the rear wing. This is true of each of the components I listed earlier. (The BMW/Red Bull "nose antlers," or whatever the hell they were called, also redirected upwash from the front wing to the rear wing, but that's neither here nor there.)



Front wings these days perform much the same function, but in reverse. When the car is driven straight ahead, the front wheels cause a downstream blockage that decreases the efficiency of the wing. When the wheels are steered, the blockage is removed, and the wing becomes more efficient. This is the result of designers taking an entirely unavoidable situation - the interaction between the front wheels and the front wing - and using it to their advantage.

[astracrazy]

thanks for the explanation

[Per]

So it's safe to say braking is mostly tyre limited. And the presence of ERS systems, trail braking etc. is irrelevant, because it changes nothing to the fact that the brake balance of an F1 car is around 65/35 (or 60/40, or in between). So front downforce is really important for braking.

The brake balance of an F1 car is about 50/50 at high speed but then you have another setting for low speed brake distribution that you can set so the front has more bite.

Even 60/40 sounds too high.

This makes no sense. They easily make 4g deceleration (with peaks of more than 5g) so even with an F1 car's low CG and long wheelbase, the load transfer during braking will be quite significant, creating the need for more front bias. At low speed they have less downforce, so lower deceleration, so less load transfer, so less front bias. Which is exactly the opposite of what you are saying... (the reducing aero drag of the rear wing has the opposite effect on load transfer, but the effect is way smaller)

Also I very much doubt the existence of different settings (at least until 2013; brake by wire will probably change things a lot), since the whole braking system was completely mechanic/hydraulic and it cannot sense the car's speed. This is the reason why some drivers are adjusting their brake balance during a flying lap in qualifying (shifting it more to the rear for corners where the approaching speed is lower).

Edit: sorry mods for OT. This was my last post about braking here, unless directly related to the W05.

[bhall]

thanks for the explanation

No problem.

[...]

So it's safe to say braking is mostly tyre limited. And the presence of ERS systems, trail braking etc. is irrelevant, because it changes nothing to the fact that the brake balance of an F1 car is around 65/35 (or 60/40, or in between). So front downforce is really important for braking.

[...]

I seem to recall Hamilton having a great deal of trouble with the W04's braking characteristics last year.

The car is different to the McLaren, it behaves differently and it pitches differently.

It's just the way the technology is now, there are some things that help us benefit elsewhere but it hampers the car a little bit for me under braking. It's something we are working on and we can improve on over the course of time.

I wonder what caused that.

Perhaps assumptions that his braking difficulties were FRIC-based missed the mark?

At any rate, I've said my piece here. Sorry I hijacked the thread.

I now return you to your regularly scheduled programming.