The man with the toughest job in F1 Tyres are the key to performance in Formula 1, and as Caterham s Head of Tyres, Peter Hewson s job is to know as much about them as possible. There s only one problem: he s not allowed to know what they re made of
S ometimes it s easy to forget that for all the complicated aerodynamics, intricately designed parts and powerful computing resources that go into making a Formula 1 car, the only thing connecting it to the race track are four round bits of rubber. Make no mistake: understanding tyres is the key to a winning car in this sport. What makes this slightly tricky is that F1 teams are not allowed to know what the Pirelli tyres are made of and that s where people like Peter Hewson come in. As Caterham F1 s Head of Tyres, it s his responsibility to find out as much as he can about the tyres and give the team as much information about them as possible in order to maximise the car s performance. It s important to remember that while we do a vast amount of work in Formula 1 on aerodynamics, all aero does is squash the tyre into the track, says Peter. If the tyre doesn t work, it doesn t matter how good your aero is. If a Formula 1 team simply put four cold tyres onto a car and sent it out onto the track, it wouldn t make it round the first corner. Therefore trying to understand how and when to get heat into the tyres is a massive part of what preoccupies Peter Hewson. He spends a lot of his time analysing track data and making computer models of tyres in an attempt to optimise tyre performance, but his job is one of the most complex in Formula 1 Peter, you re Head of Tyres for Caterham F1. How difficult is it to be the head of something that you don t make and you don t know the internal make-up of? Ha ha! You re right the most immediate challenge is that I have to work with something that I don t fully understand, which is a bit bizarre. My job is about trying to gain a better comprehension of something we don t make ourselves. It s about analysing as much data as we can to understand as much as we can about tyres. We look at data from lots of different sources, like track data, rig test data, the data supplied by Pirelli themselves and any other data we can get all with the intention of building up the best possible knowledge of the tyres. What are you trying to find out about the tyres specifically? We try to calculate tyre energies, and work The challenge of my job is having to work with something that I don t fully understand
The compounds change every season. We try to do as much science as we can, but tyres really are a black art out how fast it s going to heat up and how fast it s going to wear. By putting all these methodologies in place we can build up a picture of the tyre and in turn try to work out why it degrades. Is it because it s wearing too quickly? Is it overheating? If so, is it overheating inside the tyre or on the tread? Is the tyre becoming too compliant and in danger of losing cornering stiffness, which could cause it to become too hot? We re watching out for all these things. What does a typical day involve for Caterham F1 s Head of Tyres? My job is 90 per cent about analysing data and calculating these parameters, looking for trends and relationships. For example, we can calculate wear energy and also look at the actual wear of the tyre, and then try to work out the relationship between the two. This becomes a study that lasts the entire season. The thing that makes it difficult is that the compounds change every season. They re quite a bit different this year, which means that when you look at last year s data it s not for the right compound. We try to do as much science as we can, but at the end of the day tyres really are a black art. I just use my trusty 8GB Dell Latitude laptop, which has all of the telemetry software on it, as well as all of the modelling software to help analyse burnouts. If we ask a driver to do three burnouts lasting a second each, for example, this software enables us to know exactly how much the tyre temperature will rise by, and how much it will then drop after a certain number of seconds. Plus I ll even use spreadsheets you can t beat good old Excel! Do you ever wish that you were allowed to get a tyre, cut it open and have a look inside it? Ha ha! There s no doubt that all teams would have a better understanding of the tyres if we knew what the exact details of the construction and compounds were. For example, we use tyre models in our simulator which are pretty sophisticated what we call thermo physical tyre models. They re a set of alger rhythms that represent the tyre in a mathematical format, and it requires in-depth knowledge of the physical and thermo-dynamic properties of the tyre in order to make them. We can have educated guesses about what a lot of those parameters are, but without actually doing detailed scientific measurements on the compounds, we ll never know exactly what those properties are.
Do you ever get data back about the tyres and find yourself completely flummoxed? Oh, all the time. Tyres can be incredibly frustrating. Even tyre manufacturers can t guarantee how a particular tyre is going to behave in various different circumstances. Look at the Chinese Grand Prix this year: in 2012 the Soft tyre was a really good tyre there this year it lasted about six laps! It was astonishing. Ultimately our job is to work as hard as we can to get the best understanding that we can as quickly as we can, but sometimes a situation like China can be helpful, because it tells you something extreme about the tyre that you didn t know before. You can then look at it and find out why it happened. During a formation lap at a race, drivers tend to do lots of weaving and burnouts. Is that random or calculated beforehand? Well, most people watching a race might think it s random, but it s not. The aim of what the drivers are doing with all the weaving and burnouts is to get the tyre in the best possible condition for the start of the race. There are two aspects to consider for the start of a race: the first is that you want the best possible launch that you can get, the second is that you want the best first-lap performance that you can get. Now, getting the best first-lap performance is about getting the pressures at the right level, and having the core, structural temperature of the tyre in the right place and it takes a long time to get that structural temperature into a tyre and keep it stable. Tyres have a great deal of thermal mass, so it takes a lot of time to get the energy into the tyre and generate heat via that energy, and once it s there it s very difficult to get rid of again. So how do you go about getting the right amount of heat into the tyres? Well, that first-lap performance is a multistaged process. The first part is that we have to get the tyre blankets correct, because the amount of time tyres spend being heated in the blankets and at what temperature is very carefully calculated beforehand. We ll do a lot of work back at the factory on this, mixed with guidelines we get from Pirelli. The thing is, if you put too much heat into the tyre then the tread doesn t behave correctly it starts to age very quickly. So we have to monitor the temperature progression very closely, because if we set the blankets at 80 C then it s going to take time for the inside of the tyres to get to that temperature. Once the blankets are correct and the car has left the garage, then to some extent it s out of our hands, but we give the driver
an awful lot of guidance on what we want them to do. We ll advise them on what to do before they get in the car, and also speak to them over the radio while we re looking at the telemetry that tells us about the internal and external temperatures of the tyres, because we have about 20 external tyre temperature sensors and quite a few internal ones as well. If we want to get more structural temperature into the tyres by that we mean the temperature in the whole tyre we ll ask the driver on the radio to weave from side to side. This deforms the tyre, and when rubber deforms it gets hotter. Weaving at higher speeds is particularly helpful, because if the car is going faster that generates downforce which squashes the tyre vertically, and the weaving triggers the lateral forces. This all needs to happen without the tyre sliding and getting its surface damaged, which is where you rely on the skill of the driver. The drivers who are good at doing that are the ones who will get the benefit on the first lap. What about when the car gets into its grid slot and stops just before the start of the actual race? Once you ve got about 90 per cent of the formation lap out of the way and the cars are approaching the grid, what we need to do then is get the rear tyres conditioned so that the surface of the rubber is exactly as If we want to get more temperature into the tyres, we ll ask the driver on the radio to weave from side to side we want it, and that s where things really start getting into the fine details. We re targeting a very small temperature range of less than 5 C on the surface of the tyre and it s only within that range that we ll get the perfect launch off the grid at the start of the grand prix. What adds another layer of complication to all this is the fact that getting the perfect start is also a function of the clutch tuning, so we work with the control engineers too. If we think we ve got lots of tyre grip then they ll give us lots of clutch bite; if we don t think we ve got a lot of grip on the rubber they ll give us less bite so that we don t spin the tyres. We re searching for that perfect situation where we ve got just the right amount of tyre grip and just the right amount of clutch slip so that we get the best possible traction off the line. Peter Hewson s incredibly detailed role highlights the extreme lengths that F1 teams have to go to in order to get a competitive edge on the rest of the grid. It s also no exaggeration to say that his job, in one respect, is vastly more complex than any other role within Caterham s technical team. Those who work in aerodynamics or design have highly complicated jobs, but at least they know the specific parameters they re working under, because F1 s very detailed sporting regulations are written down for all to see. Peter is working with the objects that are the most vital to understand, but which he knows nothing about. Would he not secretly love to know the precise ingredients of Pirelli s tyre compounds to make his life easier? You re right, it would make things easier, he laughs, but it s all part of the challenge. If everyone had access to every piece of information it wouldn t be as fun. When you re working with a limited amount of information, it all comes down to the skill of people like me who can make the difference. It s about how you develop a thermo physical tyre model when you don t have all the information you d like to have to do it. That s the challenge and I love it.