What is a racing line? The simplest is a constant radius curve that uses every inch of the road.

I wanted to explain a bit about this to follow on from the posts about Michael Schumacher as I discussed his approach to learning more about his trade. Imagine a 90-degree corner has a 7 unit radius (middle of corner) and is 2 units wide. A car that uses 20% of track width can take an 11.5 unit constant cornering radius. Clearly, that is going to be much faster than operating in the middle of the road. Just to put numbers on it, and ignoring downforce, if you could go around the centreline of the road at 95, using all the road allows you to go at 122 (at the same “g-force”). The thing with constant cornering radius is that, if it is at the limit, it will be at virtually constant speed too. There is additional resistance to motion when cornering so, if power is also on the limit, then the car will slow slightly.

Therefore, in this diagram, the braking is short and there is no increase in velocity until the cornering has finished at where the (green) acceleration zone starts. Of course, there is a transition phase between states but, in F1, that is very quick. If you are able to go around a corner flat out, you might want to take a line a bit like this so this line is best for the very highest speeds of corners for your vehicle.

A lot of what a driver has to do is to find the limit of the car all the way around the track and to maximise the average speed he can maintain. A big part of this is using all of the grip available from the vehicle. Braking uses all four wheels and has just the grip limit of the tyres as its limit (virtually). Cornering uses all four wheels as well. However, acceleration is limited both because it is rear wheels only (rules of F1) and because power is limited. Combined cornering with braking and accelerating uses the grip of all 4 wheels – and allows a driver to take advantage of that grip for more time / distance.

For these reasons, getting “on the power” earlier is a good thing to do. It isn’t enough just to be using the limit of one particular factor (grip or power for example) at any instant in time you need to maximise the sum of all the units of grip over time and that’s not always so intuitive (and certainly isn’t easy).

What would make you change a line for a particular corner? When racing you will need to adapt your style to try and overtake another driver of course, but that’s too obvious. Subtle differences in racing line – for example half way between the two diagrams above may be possible for a faster car that is trying to overtake a slower one. It may not be the best line for that corner but might allow a driver to be faster at a certain point in the corner to allow an overtake.

Mainly, let’s say when running alone, the ideal line for a particular corner will depend on the speed you’re able to go. If a corner is easy flat then the line becomes less important and, in fact, using a near constant radius may be the best way. How much power you have will also change the ideal racing line around a particular corner – the more power you have the more you will benefit from using the slow-in fast-out approach. A good friend (Ian Wright - see also an update from Ian below) described it as maximising acceleration time – I think that is an even simpler way of expressing it.

From those of you with experience of programming driver-in-the-loop simulators or software lap-time simulations, I’d be very interested to see if you have better ways of explaining these concepts. I stopped work on lap-time simulation in the mid 1990’s when I found someone that had written a better code than mine (at Ferrari). We sat and discussed the strengths of each code and I handed over my code for any benefits it may have had and focused on aerodynamics, which was after all my main job.

That man, by the way, is a very special human being. The first Ferrari “employee” that I knew personally who drove a Ferrari while working at Ferrari. How the hell could he afford to do that? He had earned his money early in life. He was “working” for free at the time because he wanted to prove that he could do a better job of writing lap-time simulation than had been done there up to that time. His fee? He got to keep the code for his own use afterwards – just as I did with my coding work. If you know the man concerned, you’ll know he’s a private person and wants to make it hard for people to find him so I won’t make his name public.

I used to scramble (before Motocross) and race motorbikes in Australia before I sat down and thought about racing lines. I won the odd event but fell off a lot. Those who have watched me compete even more recently will know that I haven’t changed personality. Enthusiasm and bravery were never a problem – apart from having an excess of both! However, I learned a lot from some old racing heads and applied that to my racing – doing better lap times despite being further from the accident limit. Racing lines make a difference and are worth learning about.

Racing lines I try to follow, but my love of driving sideways didn’t always help me to keep it “on the island”. That’s me in 1994 at a Prescott hillclimb. I’ve given up competition now and have time to write posts! :-)

Driver training via a simulator – not as good as the real thing but, despite expense, is cheaper than running a car and MUCH less dangerous. With driver “coaching” increasingly under the spotlight in F1 this becomes an ever more useful tool. A simulator is a good place to learn about racing lines if you can afford to go and take advantage of time in one.

To view my other posts, look here :- https://www.linkedin.com/today/posts/willemtoet1

Back to aerodynamics with the next post, what do you think?

UPDATE - text below from Ian Wright, (Chief Engineer - Driving Simulator Laboratory at Pratt & Miller Engineering). I worked with Ian at BAR/Honda. He stayed there leading the way on using simulations for the understanding of vehicle performance (including competitor comparison analysis) during the Brawn and recent Mercedes times.

"Drivers are experts at optimising the racing line for minimum laptime. To do this during a lap the drivers must to a greater or lesser extent be using the vestibular system to help them judge small differences in accelerations. The sensitivity of their vestibular system and how they can use it to sense small differences will therefore affect their ability to optimise laptime. An example of the small differences that drivers can detect fell out of an analysis project that we conducted at British American Racing in 2000 to help the drivers optimise their gear shift points (engine RPM).



At that time the Honda power curve had a shape that meant that the optimum shift RPM varied from gear to gear so we conducted some simulations with a view to putting lights / audio indications in the car to help the driver with gear shifts if there was laptime to be reduced. The analysis was conducted by putting a simple optimiser around the laptime simulation toolset to create the shift RPM for each gear to give the optimum acceleration on the longest straight at any given circuit. The predictions were then compared to on car logged data for Jacques Villeneuve and Ricardo Zonta. This analysis showed that Jacques Villeneuve consistently shifted gear at exactly the right point, even when the differences in acceleration were minuscule (5th to 6th or 6th to 7th) and would not gain any laptime from having any driver aids in this area. Whereas Ricardo Zonta was inconsistent in his gear shift points and would reduce his laptime with a gearshift aid.



Michael Schumacher's approach makes a lot of sense when you have someone capable of analysing the data and working with additional sensors to improve laptime. Whereas most drivers just do it from their internal vestibular sensor system."