How do you know how quick you can take a corner?

[BigDawg]

Now I know that on straights, you can theoretically go a limitless speed, and you won't spin out.

But when it comes to corners, with Newton's Laws of Motion & Centripetal Forces, etc... you can only go so quick, before your tyres will lose grip.

So I'm wondering: how do you know how quick your car can take a corner?
What do you use as a reference to work how fast you can go, and where the limit is? (or at least, when you're getting close to the limit!)

Thanks for any responses

[Racer65]

Practise.

Pick a braking point, turning point and exit point (circuit guides are great for starting points for those) and then just keep experimenting (usually braking point as turning points are generally the same for everyone) until you're spinning, scaring yourself too much or comprising the entry to the next corner!

There are only so many different types of corners so it usually only takes two or three laps of a new track to work out the basics and then it's fine tuning from there.

Data logging and video is great for working out what works best after the session. Doesn't need to be expensive or complex. I use an AIM Solo with a Hero 3 and that gives me all the data I need to work out where I made time and where I lost time.

[snailpace85]

I always reckon the simplest questions have the most complicated answers and vice versa! That's a monster of a question!

To take the theoretical first as that's implied in your question - it's complicated. You can get somewhere with the concept of a coefficient of friction combined with knowing the radius that you're trying to turn. Good tyres will give you over 1 g centripetal acceleration on a good flat surface in the dry. In reality, tyres don't have a simple constant coefficient of friction - nothing does really because it's a simplification used when teaching physics to GCSE students! In fact, setting up a car with different springs and anti-roll bars wouldn't work like it does if there was a simple coefficient of friction. To really understand it you could get Alan Staniforth's book on the subject as a starter but then there are proper university level text books on vehicle dynamics - I don't have the references to hand but I'm sure you could find better more modern ones than mine on Amazon. Suffice to say that, to get proper answer to your question requires a lot of data from the tyre manufacturer as well as car data. There are people doing that sort of thing but it gets very advanced and the vast majority of professional teams, never mind club level, would regard it all as way too theoretical.

So - to the practicalities then. As already said, practice is what gets people there. It's not just a case to going faster and faster until you spin. If you build up the speed progressively you start to feel the tyres get to their limit and you can get pretty good at feeling what's going on. Bear in mind that camber and changes of gradient have a significant effect as does the amount of braking or acceleration (longitudinal) you are applying - look up traction circle or ellipse on the internet - there are some good YouTube videos by Scott Mansell you could look at. Of course, wet track, high downforce, type of tyres etc. all have a huge influence.

The reason that you can feel the grip limit in the tyres is because the relationship between the centripetal force and the angle that the tyre makes to the direction of travel (the slip angle) is non-linear. Indeed, it reaches a maximum and then reduces as you try to corner harder and harder. In principle, you should be able to find that maximum without losing control. Ha, that's where all the fun is!

Basically, the answer to your question would fill a text book on the theory side or take a good many laps with a race instructor on the practical side.

Scott

[Lancsbreaker]

It came as something of a surprise to me after about 40 years of road driving to realise when I started track racing that I had no idea how to work out how fast I could take a corner, where to brake and how hard, etc, and of course 10 years on I'm still learning. Its often an amazement to look at my lap times and realise I've done one lap maybe 2 seconds quicker than any other....without the faintest idea why I suppose the aforementioned datalogging and video is the answer, but doubt I'll get round to it

[GregUK]

And then there's aero!

I'll never forget the sight of Rosberg ripping through Paddock in his Williams FW08C. The faster he drove, the more the car was sucked to the ground!

Different times.....

[BigDawg]

Thanks for the tip guys.

Are ordinary road cars likely to experience much extra downforce at higher speeds (e.g. - say >100 mph)?

Or is that something you only get with big wings, splitters, etc?

[Tourer]

Ordinary road cars experience lift, rather than downforce. Those fitted with wings etc can achieve reductions in lift or even neutral (no lift) results.

Some very high-end performance cars do develop actual downforce but they're a rarity and not cheap.

[GORDON STREETER]

There are a lot of "tricks" that you can do to on a saloon car to get rid of unnecessary high speed lift without resorting to air dams etc. I experimented with this a lot and found a fair bit of lap speed time at long fast circuits like Silverstone and Spa.
Outwardly there is no way that the car looked anything other than "normal" and would take a very good eligibility scrutineer to spot anything "untoward"

[ydd]

Originally Posted by BigDawg

Now I know that on straights, you can theoretically go a limitless speed, and you won't spin out.

But when it comes to corners, with Newton's Laws of Motion & Centripetal Forces, etc... you can only go so quick, before your tyres will lose grip.

So I'm wondering: how do you know how quick your car can take a corner?
What do you use as a reference to work how fast you can go, and where the limit is? (or at least, when you're getting close to the limit!)

Thanks for any responses

Are you familiar with the concept of the "traction circle" ?

You can express tyre "grip" in terms of lateral or longitudinal acceleration (commonly known as "g-force").

If you imagine your race car has a certain capacity to generate g-forces but only up to a limit.

To go as quickly as possible, your job as a racing driver is actually simply to keep your car at the limit of its acceleration potential - i.e. to keep your car at the cars maximum possible g-force limits.

To work out if you are doing this, you can measure the g-forces in the car, using a data logger, and see if you are maximising the cars potential.

There is a bit more to it, and it does take a bit of getting your head around but essentially that is how you can work out how quick your car can take a corner.

[terence]

Point to remember is that its the driver that makes the mistakes,not the car.
You need to develop a 'feel' for what the car is doing.Tryes starting to scrub is the first pointer that you are getting close to their limit of adhesion.On their limits the car becomes loaded,weight transfer to the outside of every corner,when you actually feel that you are being forced against one side of your seat.
That force should translate into feel,you start to learn the cars behavior.
Its a long learning curve,that can only be learnt by driving quickly,not only in a straight line.

[The Fat Clerk]

Spot on Terry.

[speedcraft]

I've used the concept of a 3D traction/friction circle to help drivers realize that 'the limit' is not a cliff that they will fall off of if they make a tiny error when exploring the limit; it's just an optimum point on a much larger continuum of tire performance ranging from almost no drift angle to scrubbing the tire sideways across the track.


The 3D traction circle (and it's relationship to the traditional 2D traction circle) are explained on pages 18-25 in this document.