58 replies to this topic

[angst]

This is a simple question - I think. With all the bodywork restrictions in F1, the CDG wing, the proposed 2500 N downforce limit etc. etc. I wondered whether or not a reduction (quite a substantial reduction) in the tyre contact area might be the simplest way to resolve all the issues that said regulations are attempting to address - especially with the limit of seven sets per weekend.

I know that the grooved tyre, as implemented by Max, was an attempt to do just that but perhaps the nature of the construction of 'grooved' tyres is a problem, and the level of contact area wasn't reduced enough.

The tyres are the ultimate limiter on grip levels. Given that, with a greatly reduced contact area then chasing downforce becomes redundant, because no matter how much downforce one generates it has to be transferred into grip through the tyres. At what point would it become advantageous to allow a much greater degree of lateral 'scrub' on the tyres, as the fastest way round a circuit ( a return to easily visible drifts?). Because of the seven tyre set rules, there would be little option for super-sticky tyres, and harder compounds would be the way forward. There would be an increase on braking 'zones', because you can have all the brake in the world, but if the grip from the tyre isn't there, then you're not going to stop any quicker - so more opportunities for out-braking manouvres. There would be less grip coming out of corners, so acceleration would be later.

Could this approach actually swing the balance of mechanical:aerodynamic grip back toward mechanical?

[Ross Stonefeld]

How does reducing mechanical grip, increase the ratio of mechanical grip over aero grip? That doesnt seem mathematically sound.

[angst]

Originally posted by Ross Stonefeld
How does reducing mechanical grip, increase the ratio of mechanical grip over aero grip? That doesnt seem mathematically sound.

But are you reducing mechanical grip? Surely what you are doing is reducing grip. Full stop. The tyres are the medium for that grip. Atm, bigger tyre contact patch just means that more downforce can produce more grip through the tyres. If the tyre contact patch is reduced then you can create all the downforce in the world, but the limiting factor is the tyres. In other words you don't increase the dependency upon aero downforce, you minimise the amount of grip overall of the vehicle. The slower the vehicle becomes, the more important mechanical grip is in ratio to aerodynamic grip.

[Ross Stonefeld]

Sure doesnt look that way when I watch F3 and Gp2 races.

[angst]

Originally posted by Ross Stonefeld
Sure doesnt look that way when I watch F3 and Gp2 races.

How much difference is there between GP2 and F1 tyre contact patch/power ratios? F3 is so underpowered as to be useless as a comparison. F1 with F3 size wheels? That would be interesting.

[angst]

I've posted this on the Technical Forum precisely because I want to be put right if I've got the wrong end of the stick.

Ross made the link between reducing tyre contact area and reducing mechanical grip but, as far as I can see, that's a misapprehension. Mechanical grip is the product of such as CoG, weight distribution, weight transfer and suspension geometries, the tyres are merely the conduit of grip, whether that be aerodynamically or mechanically generated - surely?

My thinking is that by reducing the amount of grip available through the medium of the tyres, chasing aerodynamic downforce would be limited. Especially so when the ratio of power to available grip is high.

F3 is limited by the amount of available power to grip, so scrubbing speed through drifting is too 'expensive' to overall lap time as scrubbed speed cannot be regained very easily. With a surfeit of power any speed lost can be more easily regained - the limiting factor is the available grip through the tyres, and so overcoming that limit by means of drifting ought to be the natural progression.

[-RM-]

Angst:
Are you discussing this from a lap time equivalence perspective?

[GregorV]

The grooved tyres showed that reducing the overall grip of the tyres meant that the teams then focused on creating more downforce to compensate for this, as very likely in such a situation even with increased drag a high downforce configuration would create better laptimes. It is probably sensible what you suggest, though, if downforce is indeed limited via other means. Then indeed reducing the grip of the tyres will make the cars directly slower overall as there would be no mechanism to compensate for the lack of grip.

[angst]

Originally posted by GregorV
The grooved tyres showed that reducing the overall grip of the tyres meant that the teams then focused on creating more downforce to compensate for this, as very likely in such a situation even with increased drag a high downforce configuration would create better laptimes. It is probably sensible what you suggest, though, if downforce is indeed limited via other means. Then indeed reducing the grip of the tyres will make the cars directly slower overall as there would be no mechanism to compensate for the lack of grip.

Did they really focus on creating more downforce? Any more than the year on year search for extra downforce that takes place anyway? I think the idea was to reduce the contact area, but it failed in being badly implemented (grooves instead of a simple size reduction?), and - as so often with F1 rules, half-assed - so that the reduction in contact area was too minimal to make any appreciable difference except to make the compounds a little harder.

I say again, a reduction in the contact area of the tyres is NOT a reduction in mechanical grip, it is a reduction in overall grip. The limiting factor is the contact area, the potential grip of the tyres. If the teams are limited to seven sets of (dry weather) tyres over a race weekend, and if the tyres are reduced insize, appreciably, then chasing aerodynamic downforce would be redundant. The tyres will only offer up so much grip.

[GeorgeTheCar]

As I understand it, tires don't respond linearly to downforce, but more downforce always gets an advantage

The other side of the equarion is that pure mechanical grip is more linear so you can cut the mechanical grip more easily than downforce grip.

It seems to me that will give you the exact inverse of what you are seeking, less mechanical grip and a much greater inperative to generate downforce, and if the imperative is there, people will chase it

[angst]

Originally posted by GeorgeTheCar
As I understand it, tires don't respond linearly to downforce, but more downforce always gets an advantage

The other side of the equarion is that pure mechanical grip is more linear so you can cut the mechanical grip more easily than downforce grip.

It seems to me that will give you the exact inverse of what you are seeking, less mechanical grip and a much greater inperative to generate downforce, and if the imperative is there, people will chase it

The very fact that tyres don't respond linearly to downforce suggests that there will be a point at which the available grip through the medium of the tyres will tilt the balance toward mechanical grip. It's a matter of where that point lies. If mechanical grip is linear, and aerodynamic grip is exponential, then at some point there is a convergance and it follows that the less grip the closer the exponential curve (aero grip) gets to the linear curve (mechanical). So if what you say is correct, then reducing the available grip through the tyres will tip the scales more favourably in favour of mechanical grip.

Bear in mind, also, that tyre wear will also be a factor. Creating tonnes of downforce might well enable you to create masses of grip from the skinniest of tyres - but at what cost to the durability of those tyres?

[-RM-]

I know that this is inaccurate information but I fired up lapsim using the example F1 car as a template. I set one car at aproximatly 2500 N of downforce at 300 km/h, one car with high dowforce but a tire friction coefficient which made it have practically the same lap time and the example car as a reference.
Running the car at Zandvoort once notices a few things. Into turn one, the low dowforce car brakes 25 meters earlier than the low friction car which in turn brakes 25 meters earlier than the F1 example car. One can also see on the curvy straight after turn 3 the F1 car does not lift, the low friction car does a slight lift but the low downforce car has to do a full lift. In turn 5 which is a 205 km/h turn with the F1 car, the speed is 169 for the low friction car and 161 for the low downforce car. If one looks at a slow corner like turn 7, the F1 car does 95 km/h, the low downforce car 89 km/h and the low friction car 84 km/h.

[GregorV]

Very interesting, RM, thank you! I was just about to answer to angst that without laptime simulations it's of course hard to speak in definites but you beat me to it .

What would be interesting to see is, assume you have a car in its optimal aero configuration for the track. This means you cannot alter drag and downforce independently but simultaneously. If you now put tyres with less grip on, how should you modify the drag and downforce to achieve the best laptime with the new tyres? I would imagine you would indeed end up with a higher downforce configuration as that not only keeps up the speed in the corners but also helps speed on the exit for the straights. Can one do a similar sort of thing with those laptime simulations?

[Greg Locock]

I built a spreadsheet that spat out an estimated CdA for a given aero config for Laptime, I'll try and find it tonight.

That is, split the ClA contribution up into front and rear wing, and the body, give each a nominal A and Cd/Cl ratio, and ignore all interactions.

[Dmitriy_Guller]

Originally posted by Ross Stonefeld
How does reducing mechanical grip, increase the ratio of mechanical grip over aero grip?

By decreasing cornering speeds.

[Paolo]

Angst is spot on.
AND by use of thinner tyres we would see an increase in critical slip angles, which would allow much more spectacular driving.

The whole "mechanical grip vs aero grip" thing is nonsense.There are no separate contributions. Zero mechanical grip = zero grip. Whatever the aero.

[Gustave]

Here’s my take on it:

Mechanical grip is simply the grip the car would have (or does have) when there is no aerodynamic downforce. Mechanical grip is dependent on suspension setup and geometry.

Aero grip is that additional grip caused by an increase in the normal load on the tires due to aerodynamic downforce. A car could have horrible mechanical grip, but if it has 3000 lbs of downforce at 150 mph, then it might still go pretty well in terms of lap times.

Tire Load Sensitivity = as you increase the normal load on a tire, the coefficient of friction between the tire and the road surface decreases. Usually, the increase in normal load overcomes this effect, so that even though the mu value is lower, there is still more grip produced by the tire(s) overall.

Tire Load Sensitivity is the reason that race cars like a low CG. If tires did not behave this way, then they would corner just as fast with 100% weight transfer as they would with no weight transfer, and we’d be less concerned with lowering the CG all the time.

Gustave

[GeorgeTheCar]

I have a hard time understanding the last post.

How does the coefficient of friction change for the worse?

If we think of mechanical grip as the rubber being forced into the voids in the track surface, more downforce on hard tire gives more advantage than a soft tire as at sime point all the voids are filled and this happens sooner with a hard tire than soft.

Ever since I have been following the sport we have been adding wider and wider tires as the tracks get smoother and grip has gone up.

Perhaps tha challenge should be to create random roughness (undulation) into the corners to change the equation and require more compensation movement in the suspension rather than obsess on the tires.

[Gustave]

Originally posted by GeorgeTheCar
I have a hard time understanding the last post.

How does the coefficient of friction change for the worse?

It is not an easy subject to understand, that's for sure.

In fact, the simple question "Why are Wider Tires Better?" is not easy to answer.

I've yet to see a book answer it properly. I once posed the question to Mark Ortiz, and he mostly answered it in his column in Racecar Engineering.

You will have to trust me on the "reduced coeficient of friction with increasing normal load". That is not my opinion, but is actually fairly well proven. There are plenty of data plots in the literature demonstrating this behaviour. Just research under the heading "Tire Load Sensitivity".

Gustave

[angst]

Originally posted by GeorgeTheCar
I have a hard time understanding the last post.

How does the coefficient of friction change for the worse?

If we think of mechanical grip as the rubber being forced into the voids in the track surface, more downforce on hard tire gives more advantage than a soft tire as at sime point all the voids are filled and this happens sooner with a hard tire than soft.

Ever since I have been following the sport we have been adding wider and wider tires as the tracks get smoother and grip has gone up.

Perhaps tha challenge should be to create random roughness (undulation) into the corners to change the equation and require more compensation movement in the suspension rather than obsess on the tires.

The reason I 'obsessed' on the tyres was because I was looking for the simple solution to a problem that has, repeatedly, tried to be solved through various other methods - which has resulted in incredibly over-prescriptive regulation (set to become even more so), and through which the debate seems to have altered to become an attempt to force 'closeness' of competition between the various entrants.

The grooved tyre thing was a complete mess - half conceived and implememnted without any real thought into the possible side effects. The reduction in contact area was nowhere near enough to have any meaningful effect for any reasonable length of time. The construction of the tyres altered because of the need for the 'grooves' - just, generally, a mess.

So, in order to slow the cars year on year more and more restrictive bodywork regulations have been put into place. Among the many changes implememnted by the FIA was the raising of the front wing........ straight into the full glare of the 'upwash' of any preceding car. Result? Even less likelihood of being able to follow another car through anything approaching a fast turn. And because of the increasing restrictions, the teams chased the downforce through ever more conoluted means - winglets, flip-ups etc. etc. So the cars become even more sensitive to aero disturbance, and cause even more aero disturbance themselves. This has also led to a huge increase in the costs required to remain even half competitive, wind-tunnels being built left, right and centre.

Who knows what pleasures we have in store when the CDG split wing comes into play. Never tested, no real investigation into it's effects in tandem with other cars.

So, what I was looking for was the simple solution. Tyres. Skinny tyres that limit the amount of available grip. What could be simpler? Trying to create a 'roughness' or undulations on the circuits? Haven't the circuits been given enough of the burden of safety, of cost, over the last 30 years or so? Not to mention just how much over-regulation one could foresee with the measurement of 'roughness'.

To my mind. Skinny tyres, a limited fuel load, all to be held within the car from the start of the race - that would a) keep speeds down and b)create a more spectacular event. The current bodywork restrictions could be loosened greatly - we might even get cars that look appreciably different from one another.

[Gustave]

Originally posted by angst
To my mind. Skinny tyres, a limited fuel load, all to be held within the car from the start of the race - that would a) keep speeds down and b)create a more spectacular event. The current bodywork restrictions could be loosened greatly - we might even get cars that look appreciably different from one another.

I see what you're saying, and don't disagree with the way the FIA just seems to pile "regulation on top of regulation" in a never ending attempt to achieve "something".

I'm not sure about the narrow tire being necessary though.

I seem to remember seeing cars in the 70's with very wide tires pulling glorious power slides through the turns. I think it is aero that has eliminated that more than anything. Though admittedly the compounds in the 70's were nothing like what is available today.

Gustave

[Greg Locock]

Here's some numbers on tire load sensitivity. i expect the author of the article pulled them out of his ahem hat

http://en.wikipedia....oad_sensitivity

[zac510]

Originally posted by Gustave

I seem to remember seeing cars in the 70's with very wide tires pulling glorious power slides through the turns. I think it is aero that has eliminated that more than anything.

I think it is attention to detail, development, evolution of the car, methodically refined driving, fitness and attention to detail by the driver that has removed the aspect you remember fondly.

[angst]

Originally posted by zac510


I think it is attention to detail, development, evolution of the car, methodically refined driving, fitness and attention to detail by the driver that has removed the aspect you remember fondly.

I don't think it has anything to do with "methodically refined driving" or "attention to detail by the driver", it has everything to do with how the cars and tyres have developed. Do you think the drivers were powersliding because they didn't really know what they were doing? That, if only they could have figured it out they could have driven the cars as if on rails? If you stuck today's drivers in ye cars of old they would drive them the same way as their original pilots did, because that would be the quickest way round.

I think that the primary driver in ever increasing speeds has been the development of tyres, and the chase for aerodynamic downforce has been led by that extra potential grip year on year, and by the various layers of regulation that have been introduced to try and control that development. If you look at how much time was gained between, as an example, 1979 and 1980 it's clear that there was little aerodynamic development ( a bit of tidying up of air flows and such) with the Williams and Ligiers, yet the increase in speed was phenominal. Where was that coming from?

[zac510]

Yes certainly the mechanical aspect too, which I partially mentioned.

But can you imagine James Hunt doing 3 hours of physical training every day for months before a race?

The whole driving technique has been refined by engineering principles. You could probably say that it has been subdued to the loss of the fans, but from an engineering principle a sliding car is a slow car and that's the overriding theory. (IMO!)

[Powersteer]

I would assume the narrower the tyre, the harder the pressure on its smaller contact patch given the same weight of a vehicle. Wide tyres relieve it like having bigger shoes walking through mud evens out the load. This has an effect on downforce as it loads up the small contact patch. The same downforce would only be an addition to both narrow and wide tyres grip and might not benefit both in terms of pure grip. So when aero is not there, the narrower tyre will lose all its glory. 2 cents only.

[benrapp]

Originally posted by zac510
But can you imagine James Hunt doing 3 hours of physical training every day for months before a race?

Not the best example; despite his hedonist lifestyle, Hunt was supremely fit -- his other sporting interest was squash, at which he was (from memory) a county-level champion.

Keke Rosberg sucking down a Rothmans before setting a 160mph qually lap at Silverstone is more like it.

[zac510]

hehe, yeah not the best example, but you got what I meant.

I now recall hunt didn't drink or smoke after Wednesday before a race weekend either.

[Deepak]

IMO aero is not simply increasing normal load on the tire but also how the forces are distributed among the 4 wheels especially during medium-high speed cornering. Specifically pitch & yaw stability during the transient phase.

Aero development will always continue in order to achieve the optimum weight distribution while minimizing tire wear.

I guess in a way aero & mechanical grips are a parallel development activity & not always one binding over the other.

My 2 cents.

[angst]

So here's the point. The FIA are trying to apply more and more restrictive regulation in order to try and cut the influence of aerodynamic downforce, all riddled through with loopholes and just generally making a rod for it's own back, as well as both over-complicating said regulations and homogenising (?) F1 cars more and more.

They have already commited to a single tyre supplier from 2008 (and indeed will be operating on that basis from 2007). Well, why not put that supply up for tender on the basis that they want a low grip tyre with high slip angles. That would benefit everyone. It would keep speeds down, which would avoid constant fiddling with the regulations. It would allow some of the bodywork restrictions to be relaxed (raised front wing etc) which, combined with an overall reduction in the need for aerodynamic appendages) make the cars more capable of following and racing each other. It would make the cars more spectacular to watch, giving a much better visual show to sell the viewing public. Combined with some simple changes as to how the electronic aids on the cars are fed information (no transmitters around the circuit) it would put the emphasis back onto the driver to control the car, without the need for standard ECUs, and without any attempt to ban TC - just make it much less efficient. If the grip levels were set low enough, then the tyre company involved would have the great advertising of their wet weather tyres being almost on a par with their dry slicks - for a company with no opposition to beat, that is surely advantageous publicity. Everyone, in other words, is a winner.

[Calorus]

The point is the all you can do is reduce the base mu. You cannot cap the the the total mu*R. and even though R may reduce slightly with load, Formula One cars are with an absolute maximum load of 11kN are in no way getting towards a point of mu reducing inversly proportionally with mu which is what would need to happen to cancel out the increase of R (or Fz as Wiki pedia refers to it). The point raised on Wiki is that the variation was x^0.7 to x^0.9 - so you're heading on a very long, asymptotic form curve to infinty; it never stops inceasing it merely increases more slowly all of the time. The net result is that whilst increasing the load always yields more grip, the amount of extra grip decreases slowly.

And so having a lower initial mu, simply means that the unloaded car will have even less grip, and that subsequently the increase of Aerodynamic grip will have to be even more aggressive, meaning that teams will be forced to accept yet lower l/d efficiencies causing eeven more dependence on Aero, and even dirtier wakes.

[angst]

Originally posted by Calorus
The point is the all you can do is reduce the base mu. You cannot cap the the the total mu*R. and even though R may reduce slightly with load, Formula One cars are with an absolute maximum load of 11kN are in no way getting towards a point of mu reducing inversly proportionally with mu which is what would need to happen to cancel out the increase of R (or Fz as Wiki pedia refers to it). The point raised on Wiki is that the variation was x^0.7 to x^0.9 - so you're heading on a very long, asymptotic form curve to infinty; it never stops inceasing it merely increases more slowly all of the time. The net result is that whilst increasing the load always yields more grip, the amount of extra grip decreases slowly.

And so having a lower initial mu, simply means that the unloaded car will have even less grip, and that subsequently the increase of Aerodynamic grip will have to be even more aggressive, meaning that teams will be forced to accept yet lower l/d efficiencies causing eeven more dependence on Aero, and even dirtier wakes.

Given that, explain the differential in speed between wet and dry laps. Surely the downforce is similar, but speeds are nowhere near. The reason? Could it be that the tyre is the deciding factor on grip. And, those cars with greater mechanical grip gain on their rivals under those conditions. Again, why would that be?

[Calorus]

Originally posted by angst


Given that, explain the differential in speed between wet and dry laps. Surely the downforce is similar, but speeds are nowhere near. The reason? Could it be that the tyre is the deciding factor on grip. And, those cars with greater mechanical grip gain on their rivals under those conditions. Again, why would that be?

>>> RC Forums

[Ben]

Originally posted by angst


Given that, explain the differential in speed between wet and dry laps. Surely the downforce is similar, but speeds are nowhere near. The reason? Could it be that the tyre is the deciding factor on grip. And, those cars with greater mechanical grip gain on their rivals under those conditions. Again, why would that be?

Downforce is a function of velocity squared. So if the speed is less the downforce will be less...

Rubber to road friction is less in lubricated conditions but a car with downforce will still have more grip in the wet than one with no downforce.

A tyre generates grip as a function of a vertical force. It doesn't care whether the force originates from mass (of the car) or a transfer of momentum from a lot of air (downforce)

I think the problem in these debates is a fairly small but important piece of semantics. When an engineers talks about mechanical grip or aero grip they actually mean mechanical and aerodynamic contributions to the tyre's normal load. The actually grip (i.e. forces between tyre and road) are generated by the tyre alone.

Ben

[angst]

Originally posted by Ben


Downforce is a function of velocity squared. So if the speed is less the downforce will be less...

Rubber to road friction is less in lubricated conditions but a car with downforce will still have more grip in the wet than one with no downforce.

A tyre generates grip as a function of a vertical force. It doesn't care whether the force originates from mass (of the car) or a transfer of momentum from a lot of air (downforce)

I think the problem in these debates is a fairly small but important piece of semantics. When an engineers talks about mechanical grip or aero grip they actually mean mechanical and aerodynamic contributions to the tyre's normal load. The actually grip (i.e. forces between tyre and road) are generated by the tyre alone.

Ben

I think you've pretty much said what I was trying to say. The tyre is is the medium of any grip. The limit of grip is the tyre. Grip is grip, whether that grip is mechanical or aero generated. As speeds decrease, so aero efficiency decreases.

With the amount of data that a company like Bridgestone has built up, it should be possible for them to design a tyre that meets the criteria as devised. Low grip, low operating temperatures, high slip angles. Grip (and therefore speed) is limited, downforce (tyre temperatures) limited - both of these allowing greater freedoms in how that downforce is generated, clearing up some of the mess caused by the bodywork regulations (which were initially to resolve exactly those issues - speeds and downforce).

[Greg Locock]

OK, we can design a tire like that, polyurethane would probably do, or even steel.

[zac510]

Maximum tyre pressure?

[Ben]

Originally posted by angst


I think you've pretty much said what I was trying to say. The tyre is is the medium of any grip. The limit of grip is the tyre. Grip is grip, whether that grip is mechanical or aero generated. As speeds decrease, so aero efficiency decreases.

With the amount of data that a company like Bridgestone has built up, it should be possible for them to design a tyre that meets the criteria as devised. Low grip, low operating temperatures, high slip angles. Grip (and therefore speed) is limited, downforce (tyre temperatures) limited - both of these allowing greater freedoms in how that downforce is generated, clearing up some of the mess caused by the bodywork regulations (which were initially to resolve exactly those issues - speeds and downforce).

I do agree on some level. In that sense a control tyre would be a good thing. The ban on tyre changes last year is the only way to get rid of really soft tyres without forcing a single tyre suplier.

Because F1 is about technical competition I would prefer last year's regs to a single supplier.

Ben

[angst]

Originally posted by Greg Locock
OK, we can design a tire like that, polyurethane would probably do, or even steel.

Nothing like a good bit of exaggeration, eh?

Is it soooo diificult to imagine cutting downforce by, I dunno, 50%, and to allow some lateral movement on the tyres?

Thing is, the FIA already have a limit of 12500N set for F1. They don't say how they are going to implement it. The FIA are proposing to introduce a split rear wing - completely untested, with far more questions surrounding it than answers, based upon the results of one brief computer simulation. In order to make that work the FIA are proposing incredibly restrictive bodywork regulations. So, the cars will have spec tyres, spec bodywork (all but), spec engines (all but).

Given that, and given the FIA's decision to pursue a single tyre supplier I thought..... Bridgestone (the most likely supplier) must have a heap of data. They'll have worked with teams on producing the best tyres for their cars, they will know what sort of compounds will work best with varying degrees of downforce and heat generation. Why not use that one spec item to enable the other restrictions to be lifted somewhat? Why not use that one spec item to resolve the increasingly burdensome and complex regulations and the increasingly complex methods of measurement in order to uphold those regs? Why not use that one spec item in order to free up other technical regulations and how allow some innovation in F1?

[Deepak]

Originally posted by angst


...Why not use that one spec item in order to free up other technical regulations and how allow some innovation in F1?

But doesnt this stiffle innovation in tyres? I mean what incentive would that leave the tyre manufacturer to remain in F1?

[angst]

Originally posted by Deepak


But doesnt this stiffle innovation in tyres? I mean what incentive would that leave the tyre manufacturer to remain in F1?

Without competition, what exactly would they be innovating for? The only incentive for a single, contracted tyre supplier to be involved in any series is simply that of advertising and promotion. I argued against the single tyre supplier on the basis that it is against the spirit (imo) of Grand Prix racing but, as the FIA have decided (in their infinite wisdom) to go ahead with a 'spec' tyre, then why not use that?

As advertising and promotion is the only real objective of supplying the F1 grid, then the publicity of that company's wet weather tyres being almost on a par with their dry tyres would be a positive selling point. AND, it could be publicised that all the great racing that F1 now has is due to Bridgestone's (or whoever, as if there's really a question mark ) skill in the design of their compounds/construction - the reason you're seeing the cars slide so much is thanks to Bridgestone's expertise in designing the sort of tyre that F1 wants.

As the FIUA have made this decision then lets use it to everyones advantage, this works for everyone. The FIA get complete control over speeds (and therefore safety) as well as less administrative costs on enforcing/implementing regulations. The teams get simplified regulations, the engineers a little more freedom. The drivers get to have normal neck muscles, without the pain and strain of excessive lateral forces. The fans get to see the drivers styles and nuances far more readily with cars that move about on track visibly.

[hyperbolica]

Originally posted by Paolo
The whole "mechanical grip vs aero grip" thing is nonsense.There are no separate contributions. Zero mechanical grip = zero grip. Whatever the aero.

Are you stating the trivial fact that lateral force equals mu times normal force, and therefore it is immaterial if normal force is generated by gravity or downforce?

My opinion is that this perspective is entirely wrong. Assuming that downforce is proportional to v^2, normal force is

mg + c*v^2

implying that max lateral force is

mu*(mg+c*v^2).

Here you clearly see two separate contributions, one from gravity ("mechanical grip") and one from downforce ("aero grip").

Typical values today are mu=1.7 and c=3 kg/m. So already at a speed below 50 m/s downforce "generates more grip" than friction from gravity alone. Considering that most of today's Grands Prix are run at average speeds exceeding 50 m/s, most of the corner grip is due to aero.

Compute the radius of a flat-out bend! Assume that F1 cars don't go faster than 100 m/s. Start with no aero (c=0). Then max lateral force is

mu*m*g = m*v^2/r

implying that the radius of a flat-out bend is

r = v^2/mu/g.

Using mu=1.7, g=10, and v=100 gives r=600 m or so.

Now introduce aero at c=3 kg/m. Then you have a max lateral force of

mu*(m*g+c*v^2) = m*v^2/r.

Solve for r, using m=600 kg. Then you get r=100 m, approximately. That's quite different from the previous result of r=600 m! So today's aero implies that you can go flat through any turn that isn't fairly tight. To reduce speeds so that not every corner is flat out, you therefore need either chicanes or Mickey Mouse tracks. That's the price of modern aero. :

[Stian1979]

Originally posted by angst
This is a simple question - I think. With all the bodywork restrictions in F1, the CDG wing, the proposed 2500 N downforce limit etc. etc.

2500N sound unfair. The car weighs may be diferent and a more heavy car will nead more downforce to do the same turn at the same speed and if not the aceleration off mass sideways will just pull it out into the grawel trap.

It should be in % off the cars weight including driver, race ready without fuel.

Originally posted by angst


Without competition, what exactly would they be innovating for? The only incentive for a single, contracted tyre supplier to be involved in any series is simply that of advertising and promotion. I argued against the single tyre supplier on the basis that it is against the spirit (imo) of Grand Prix racing but, as the FIA have decided (in their infinite wisdom) to go ahead with a 'spec' tyre, then why not use that?

2007 one tyre manufacturer . 2008 engine development stop . 2012 one engine suplier . 2014 everybody race lola chasi . 2016 drivers play musical chairs for who is geting witch car so we can see all the drivers in diferent teams over 1 season . 2018 a FIA testdriver is setting up all the cars so all of them will be equal during race regardles to driving style . 2020 The TV companys are charging money to send f1 . 2022 the tv companys will no longer send it even for money because it's destroying there reputation.

Max is seriously hurt in a road acident aparently runn over by a weel chair, people say they have seen Frank Wiliams drive away from the scene off the crime.

[Ben]

Originally posted by hyperbolica




implying that max lateral force is

mu*(mg+c*v^2).

Here you clearly see two separate contributions, one from gravity ("mechanical grip") and one from downforce ("aero grip").

Or you see one type of grip (mu) between the tyre and the road) and two contributions to the normal load on the tyre (mg and CV^2)

I think the point that Paolo was making was the same as me. The downforce doesn't generate the grip but it allows the tyre to generate more.

"Aero grip" is a misnomer, but one that makes having a conversation with a driver much easier...

Saying you have two different types of grip makes understanding the tyre a lot harder if that's the way you look at it.

Ben

[hyperbolica]

Originally posted by Ben
The downforce doesn't generate the grip but it allows the tyre to generate more.

"Aero grip" is a misnomer, but one that makes having a conversation with a driver much easier...

Saying you have two different types of grip makes understanding the tyre a lot harder if that's the way you look at it.

Ben

Clearly, but the important point is that the "added grip" from aero downforce depends on velocity (kinematics) while standard friction grip from gravity only depends on weight (statics). This is certainly a valid distinction, and it has changed racing completely, including track design criteria.

In slow corners, where speed is negligible, you only have "mechanical grip" but on fast corners the situation is entirely different; the car behaves in a way governed mostly by kinematics, and not by static loads.

Misnomer or not, we are dealing with two very distinct phenomena, and I think it's important to recognize that.

[angst]

Out of interest, would a low operating temperature ensure low downforce? My understanding is that the more downforce, the greater the temperature generated. Rather, should the question be, with all the data that a company like Bridgstone have, would it be possible to create a tyre who's optimal operating temperature would require a reduction in the downforce created by the cars? A tyre that degraded exponentially above this optimal operating temperature.

[Lephturn]

I think you folks have gone off on a tangent here that doesn't address the problem.

The real problem is this IMO:

Downforce is reduced when you run close behind another car. That means the more downforce these cars generate, the farther they must run from each other to maintain speed in fast corners. The result is, more downforce = crappy racing and you end up with a track like Spain where it's a parade. So to get decent racing you need to either limit the downforce on the cars, or rebuild all the tracks so there are not so many fast corners, and no fast corners that lead on to straights. With high downforce cars you need low speed corners leading into the straights so that the cars can stay close enough to each other to pass on the straight or in the braking zone at the end.

Second issue is cost. How much do teams spend developing aero and running wind tunnels. Yep, a ton. I'd rather see them doing technical developents on suspension, brakes, and even engine. All must be cheaper than developing aero. Now a 2500 nm limit on downforce only partially fixes things, as then the game shifts to finding the most efficient way to hit that limit, ie: that downforce with the lowest drag.

Smaller tire contact means slower laps sure. Allow more downforce for an equivalent laptime and what you end up with is cars that can't run within 2 carlenghts of each other in a corner over 100 Kms. Kind of like now... the higher the downforce in comparison to the pure mechanical grip, the worse this problem gets. The reason you want to reduce aero and put slicks on is so that the cars can race closer together, actually pass each other, and still keep the speeds down.

Lephturn

[hyperbolica]

Here's an additional remark -- albeit purely academic -- on the formula

mu*(m*g+c*v^2) = m*v^2/r

above. Note that if mu*c > m/r, then there is no upper limit on corner speed at all. This corresponds to

r > m/mu/c,

which, with today's technical data m=600kg, mu=1.7, c=3kg/m, gives r=120m. Suprisingly tight, isn't it.

This means that if it were technically and biologically feasible (relativistic effects have been neglected ;) ), you could drive through a corner of radius 120m at infinite speed: a curve of this radius will never require any slowing down, either from braking or from lifting off.

By contrast, if you have a no downforce car (c=0 above), you get

mu*g = v^2/r,

implying that there is always an upper limit on the cornering speed, v=sqrt(mu*g*r).

In my previous post we saw that if the car's max speed is 100 m/s the "flat-out-corner" has a radius of 100m. In practice, you don't often reach the car's max speed, so in practice the flat-out-corner has a smaller radius still, which I think every kart driver has experienced.

The way I interpreted angst's post was whether one could shift today's emphasis on high downforce to one of mechanical grip by reducing tyre contact patch area, effectively reducing mu in the equation above. But as mu multiplies the entire quantity on the left-hand side of the first equation, you would still chase maximum normal force (by using aero, of course) as that would be the only way to increase lateral force and acceleration.

Instead, if one wants an emphasis on "mechanical grip," there's just one thing to do: reduce c.

This could be done in several ways. One would be to drastically reduce wing area, possibly banning wings altogether, and relying for downforce on say venturi tunnels of limited cross section. Such a solution might have the added benefit that "dirty air" would be less of a problem, so that overtaking is easier.

Of course, which much less downforce, tracks may have to be redesigned -- again.

[Ben]

Two reasons this doesn't occur.

1. You become power limited (think superspeedway Champ and IRL cars) because you need a slip angle to generate the force and a component of this will then oppose forward motion.

2. Mu tends to saturate with load. This is mentioned by Milliken

Ben

[hyperbolica]

Originally posted by Ben
Two reasons this doesn't occur.

1. You become power limited (think superspeedway Champ and IRL cars) because you need a slip angle to generate the force and a component of this will then oppose forward motion.

2. Mu tends to saturate with load. This is mentioned by Milliken

Ben

1. Obviously -- this is one of the technical limitations I mentioned; another is that eventually both stucture and tyres will break under the increasing loads.

2. The (theoretical) argument holds for any positive mu (if it saturates is immaterial). If downforce is proportional to v^2 both normal force and lateral force increase in proportion to v^2 (at the same rate) there is a (theoretical) finite curve radius such that you won't have to slow down, no matter how fast your car can go. If your car were capable of 200, 300, 400 or 500 mph is immaterial. The point is that this unlimited speed radius isn't very large. Therefore corners have to be quite tight today to require significant slowing down, which is one of the preferred situations for overtaking (out-braking).

This role of aero is -- as you point out -- clearly demonstrated on superspeedways. 40 years ago a 150 mph lap on Indy was about what you could do. Since 15 years back, 250 mph is more or less technically feasible, and top times aren't far from such speeds.

The main factor behind the speed increase is downforce, and the main reason you can't go faster is that you run out of steam.