McLaren MP4-28 Mercedes

[turbof1]

Extra downforce can cause the tyres to degrade faster. There is a relationship with the mechanical properties of the tyre, the rotational speed and time. Degradation is inevitable but a car that is putting more load through the tyres over a period of time will cause them to degrade faster, ie the mechanical properties will degrade.

Perhaps at long straights this might be true, but the downforce is essentially only very harmful in the corners if you push the car to use the extra DF. You don't need to, you can deliberate take the corner a bit slower. You can argue "why the extra DF then when you are not using it", but remember that teams still need to do a qualifying.

If there was no qualy, teams would remove the downforce they don't need to use, to get rid of the drag that comes along.

Mind you that while extra DF itself shouldn't be harmful, running bad airflow onto the tyres to get more DF (or better L/D) will make the tyres go away faster.

[Jackles-UK]

When they say they are down "25-35 points of downforce" if they run legally - is that not true of all teams? I'm sure if RBR decided to slam the car into the tarmac running negligible ride-heights they could generate even more downforce (creating a perfect ground effect scenario for example). McLaren has a problem with what it can't do ordinarily rather than what it can do theoretically.

That being said I get the feeling it will be one turning point upgrade that will remedy their shortfall rather than an entire front-to-back package as has been mooted for Catalunya. The understanding of what you have is often more effective than adding more of what you don't (see Silverstone 2010).

[R_Redding]

Extra downforce can cause the tyres to degrade faster. There is a relationship with the mechanical properties of the tyre, the rotational speed and time.

I can see that been correct.

Willem Toet (in his Lanchester lecture at 11 mins) explained how the friction coefficient (force v load) of the tyres gets worse with too much added DF , and you dont get the gains you may think....and that you need an optimum slip angle to get the optimum grip.

Rob

[Crucial_Xtreme]

Not true, at least most of the time. In general, more load onto the tyre means more grip on the road, means less sliding, means less degradation. I can see only very limited scope for this causation not to occur.

Ff = Friction Force
Cf = Coefficient of Friction
Fv = Vertical force

Ff = Cf x Fv. More vertical load(downforce) is going to increase the contact patch = increase friction(heat) = increase tyre wear, namely thermal degradation. Sounds like you're speaking of graining, blistering, etc. I'm not saying RB is stripping of DF, although their use of the most shallow RW on the grid points to it, what I'm saying is everything you stated above; more load, & grip seems to me would help contribute to quicker thermal degradation of the '13 tyres, something Pirelli worked hard at increasing with this years new tyres.

From Pirelli:

Design and Construction
All the compounds are generally softer, which leads to enhanced performance and a deliberately higher degree of degradation, with increased thermal degradation in particular.

Edit:

A tyre has only so much energy contained within it and, other things being equal, the more downforce you apply through it, the faster you use up that energy.

The harder the tyre is being squashed into the ground, the more you take out of it and that downforce squares with speed

if the tyre slides too much - because there is not enough downforce acting upon it - it overheats its surface and degrades that way.

http://www.bbc.co.uk/sport/0/formula1/13514134

** Should be noted this years tyres have higher thermal tyre deg than article cited**

[Just_a_fan]

Extra downforce can cause the tyres to degrade faster. There is a relationship with the mechanical properties of the tyre, the rotational speed and time. Degradation is inevitable but a car that is putting more load through the tyres over a period of time will cause them to degrade faster, ie the mechanical properties will degrade.

Perhaps at long straights this might be true, but the downforce is essentially only very harmful in the corners if you push the car to use the extra DF. You don't need to, you can deliberate take the corner a bit slower. You can argue "why the extra DF then when you are not using it", but remember that teams still need to do a qualifying.

If there was no qualy, teams would remove the downforce they don't need to use, to get rid of the drag that comes along.

Mind you that while extra DF itself shouldn't be harmful, running bad airflow onto the tyres to get more DF (or better L/D) will make the tyres go away faster.

Downforce is only necessary in the corners and it's what makes the car fast over a lap. If you take off downforce then you make the car slower over a lap (excepting odd tracks like Monza). The cars run downforce because it is essential to fast lap times. The one time they don't want it is on the straights.

The aim of the designers is to maximise L/D i.e. the downforce to drag ratio. If downforce could be added without adding drag the teams would run as much downforce as they could put on the car. At no point would a team choose to run less downforce in the race (other than on straights) as downforce is king.

Not sure what you mean by "running bad airflow onto the tyres to get more DF will make the tyres go away faster". Sounds like double talk.

[turbof1]

Downforce is only necessary in the corners and it's what makes the car fast over a lap. If you take off downforce then you make the car slower over a lap (excepting odd tracks like Monza). The cars run downforce because it is essential to fast lap times. The one time they don't want it is on the straights.

Yes, I know, but DF you have for the corners is also DF you have on the straights. Except for DRS, you can't take it away.

The aim of the designers is to maximise L/D i.e. the downforce to drag ratio. If downforce could be added without adding drag the teams would run as much downforce as they could put on the car. At no point would a team choose to run less downforce in the race (other than on straights) as downforce is king.

Which I didn't contest?

Not sure what you mean by "running bad airflow onto the tyres to get more DF will make the tyres go away faster". Sounds like double talk.

Teams have flow conditioners etc all over the car. I am not aware of the flow patterns, but if they have to divert air to the tyres (I am aware teams generally try to avoid that) in order perhaps for creating more DF somewhere else, then that does influence tyre wear. Generally, tyres don't like to run in disturbed/dirty air, being from a car in front, or air coming off from vortex creators, exhaust gasses, etc, but these elements are there in place for creating DF.

[timbo]

http://img809.imageshack.us/img809/388/vertload.gif
Ff = Friction Force
Cf = Coefficient of Friction
Fv = Vertical force

Ff = Cf x Fv. More vertical load(downforce) is going to increase the contact patch = increase friction(heat) = increase tyre wear, namely thermal degradation. Sounds like you're speaking of graining, blistering, etc.

You should remember that there are different modes of friction. When there's no sliding, there's only a static friction. In this mode there's very little heat generated (as relative velocity between tyre and surface is zero in the absense of sliding). Of course wheels always slide (due to longitudinal and lateral slippage) to some extent and that's where kinetic friction comes into play and that's what generates heat.
The more DF you have the less the extent of kinetic friction would be, so less heat generated. However I guess there might be more abrasion wear.
I imagine that with imbalanced chassis or with a lack of DF there is more of a risk of overheating the tyres, while when there's plenty of DF there could be more abrasion wear. I guess it would come down to tyre compound and construction what is worse.

[Lazy]

I seem to remember red Bulls complaint being that their extra df was causing the tyre to deform more thereby generating extra heat in the tyre and therefore causing more thermal degradation, this would happen on the straights as well as the corners. They were complaining about this last year as well .

[timbo]

I seem to remember red Bulls complaint being that their extra df was causing the tyre to deform more thereby generating extra heat in the tyre and therefore causing more thermal degradation, this would happen on the straights as well as the corners. They were complaining about this last year as well .

Yes more deformation may lead to more heat generation as tyre would be constantly contracting/expanding along the radius. I think that the heating would moslty occur at tyre shoulders though, how much that affects degradation once again should depend on compound/construction.

[turbof1]

A moderator should come here and move the tyre conversation to the appropriate topic.

Any news about the updates? Button suddenly claims they are just routine improvements, contrary to early reports that they are to fix the problems.

[PlatinumZealot]

Not true, at least most of the time. In general, more load onto the tyre means more grip on the road, means less sliding, means less degradation. I can see only very limited scope for this causation not to occur.

http://img809.imageshack.us/img809/388/vertload.gif
Ff = Friction Force
Cf = Coefficient of Friction
Fv = Vertical force

Ff = Cf x Fv. More vertical load(downforce) is going to increase the contact patch = increase friction(heat) = increase tyre wear, namely thermal degradation. Sounds like you're speaking of graining, blistering, etc. I'm not saying RB is stripping of DF, although their use of the most shallow RW on the grid points to it, what I'm saying is everything you stated above; more load, & grip seems to me would help contribute to quicker thermal degradation of the '13 tyres, something Pirelli worked hard at increasing with this years new tyres.

From Pirelli:

Design and Construction
All the compounds are generally softer, which leads to enhanced performance and a deliberately higher degree of degradation, with increased thermal degradation in particular.

Edit:

A tyre has only so much energy contained within it and, other things being equal, the more downforce you apply through it, the faster you use up that energy.

The harder the tyre is being squashed into the ground, the more you take out of it and that downforce squares with speed

if the tyre slides too much - because there is not enough downforce acting upon it - it overheats its surface and degrades that way.

http://www.bbc.co.uk/sport/0/formula1/13514134

** Should be noted this years tyres have higher thermal tyre deg than article cited**

This is true for Non-slip conditions.
In conditions with slip, more down-force can improve tyre life.

It is all track dependent.

[Pup]

Interesting tangent.

On the post that started it...

And what about the rumour RedBull is sacrificing available DF these days as it would only destroy the tyres in no time? That 30counts for one second in laptime is a phantom an oversimplification of reality.

total numbers ´/maximums just don´t matter

"Maximum downforce" is a lot different from getting the most out of a diffuser/floor. There isn't a team on the grid that wouldn't want to get more downforce from their diffuser. So when Whitmarsh laments losing 30 points of df from their diffuser, I think it's a real problem, not an oversimplification. I also think he's talking about how much it drops when the aero quits on them, relative to before it goes south rather than to some maximum, though he could be.

Even at Monaco, I don't think the teams run the most downforce they can design. It's always a tradeoff among downforce, drag, tire wear, fuel consumption, etc., so it really isn't a question of whether or not teams are running "maximum downforce". They run whatever gets them around the track the quickest for however many laps they've got to run.

But that doesn't mean anything when talking about the diffuser, because within reason, more is always better and it's the wing where those tradeoffs play out.

What I think they're meaning is "we know a way of generating more downforce using our exhaust solution, but we're designing it in a non-optimal way because the optimal design would overheat the tyres".

Possibly - but from exhaust heat I'd guess, not from tire wear. My guess would be that the design tradeoff is between maximum and consistent, where consistent wins.

[turbof1]

Even at Monaco, I don't think the teams run the most downforce they can design. It's always a tradeoff among downforce, drag, tire wear, fuel consumption, etc., so it really isn't a question of whether or not teams are running "maximum downforce". They run whatever gets them around the track the quickest for however many laps they've got to run.

Especially not at Monaco. The surface is so bumpy they have to drive way above average ride heights. Mclaren especially will have to do that.
I can understand the desire to extract the most DF out of the diffuser though. It is essentially almost drag free. The more you can get out of it, the more DF you can remove out of the rear wing, removing drag and lowering fuel consumption (due less drag). Essentially coming from this point McLaren isn't wrong trying so.

[trinidefender]

Even at Monaco, I don't think the teams run the most downforce they can design. It's always a tradeoff among downforce, drag, tire wear, fuel consumption, etc., so it really isn't a question of whether or not teams are running "maximum downforce". They run whatever gets them around the track the quickest for however many laps they've got to run.

Especially not at Monaco. The surface is so bumpy they have to drive way above average ride heights. Mclaren especially will have to do that.
I can understand the desire to extract the most DF out of the diffuser though. It is essentially almost drag free. The more you can get out of it, the more DF you can remove out of the rear wing, removing drag and lowering fuel consumption (due less drag). Essentially coming from this point McLaren isn't wrong trying so.

Ok saying it is almost drag free is a drastic overstatement. Just because the L/D ratio of a diffusor is much greater than a normal curved wing like the rear wing, for example, does not mean it is "almost drag free"

[Pup]

Kinda-sorta.

The thing is that if you look at the car as a whole, any increased drag produced by a better diffuser can be countered by reducing the wing - net result being either more downforce or less drag or both, you pick. Of course, the two are somewhat dependent on one another. The diffuser works in large part because it exits into a low pressure area created by the car and wing, so you might say that it is dependent on drag.

Having said that, here is an interesting post from a few years back that shows how introducing a diffuser actually decreases the overall drag on the car. It wasn't discussed further, but its interesting, despite being somewhat beyond my understanding...

http://www.f1technical.net/forum/viewto ... 39#p164039

So, one might argue that the diffuser is not only drag free - it's drag negative.