IndyCar’s race strategy is unlike any other motorsport series in the world. It is impossible to predict tyre wear due to the variety of tracks and the limited number of tyres. Teams also need to manage fuel consumption, pit windows and full course yellows – all with smaller teams and more competitive grids than the likes of Formula 1.
Track Types
The type of circuit that IndyCar races is what causes the most headaches for strategists. IndyCar races are held on three different types of tracks.
- Ovals – short ovals and superspeedways (which are more than two miles long)
- Road Courses – permanent tracks which feature both right and left turns
- Street Courses – made up of closed-off public roads or airport runways
The diverse circuits mean that lap times vary between 23 seconds in an oval to 1 minutes 45 seconds on a street course. The pit time relative to the average time of a lap varies greatly at each track. It is important to note that pitting during a full-course yellow can have a different effect. This means that the optimal race strategy depends on whether or not you are racing on an oval track, a road/street circuit, etc.
Types of tires
Firestone has had to come up with a wide range of tyre types and compounds to suit the requirements of each circuit. The engineers have a large number of tyres they need to figure out.
There are basically five different types of tires, depending on their construction.
- Street course tyres
- Road course tires
- Indy 500 tyres
- Superspeedway tires
- Short oval tyres
There are two compounds: the primary (black), harder compound, and the alternate (red), softer compound. Teams are only permitted to use the primary compound on ovals. However, because of the forces created by ovals, the tyres required for each corner differ slightly. On the street/road course, teams have a choice between primary and alternate compound as well as a wet tyre.
‘Firestone does tweak the tyres each year as well,’ highlights David Faustino, Lead Race Engineer at Team Penske. ‘Typically they are trying to tweak the balance between the primary and alternate tyre to get some crossover degradation. But it’s enough of a change which means going into a race weekend, it’s not always obvious how the tyres are going to behave relative to last year.’
Full course yellows
The biggest variable that is outside of the teams’ control is yellow flags and full course yellows. If a full-course yellow is displayed during a race unlike other series, the pit lane will close. The pace car then picks up and catches the leader of the race, while the rest of the cars gather behind. The pit lane is opened once the group has formed to allow cars to pit before the race starts.
If the car passes through the Pit Commitment Line following a yellow signal, the driver is not able to complete a pitstop in full (but he can fix damage or fuel for two seconds), so he must drive the pitlane and end up at the tail of the pack. When the pit lane is open again, they can do a complete pitstop.
The difference between ovals, road/street courses and their strategic differences
‘A lot of our strategy comes down to how IndyCar handles full course yellows,’ explains Eric Cowdin, Race Engineer at Chip Ganassi Racing. ‘On road and street courses you want to pit towards The the front of the pit window, because if a yellow comes out and you haven’t pitted, you have to wait until the pitlane opens again, by which time the pack has completely bunched up.’
‘Typically, cars that have completed a pit cycle before a full course yellow will have a track position advantage,’ highlights Faustino. ‘This is because the leaders will then pit under yellow and will cycle to the back of the cars that have stayed out, assuming they have enough fuel to complete the same number of stops overall. With the point structure in IndyCar you usually see the field split 50/50, so in a 26 car field, if you are the leader and haven’t pitted before a yellow, you could end up 13th, which is a substantial hit,’ Faustino continues. ‘So usually cars will stop early and take the risk of having to fuel save for the rest of the race, in the hope that they will get lucky with a yellow where they can then conserve fuel.’
However, on ovals it’s a different story. Fuel consumption is the first factor that determines pitstops. A normal pitstop could put a driver up to two or three laps behind the rest of his field. Therefore, by pitting under a full course yellow on an oval, once the pack has bunched up, a driver can complete a pitstop and re-join the track on the same lap – without going several laps down. So, if a yellow falls during a driver’s fuel window, then it is effectively a ‘free’ pitstop.
‘The strategy for ovals is the opposite to road courses. You want to run as long as you dare to try and catch that yellow,’ says Cowdin. ‘But then you also have to consider fuel and tyre degradation. There’s no point staying out 10 laps longer on older tyres if your rival is going considerably faster than you on a new set, because when you do pit, you will come out several places behind them.’
Race strategy software
With full course yellows capable of completely turning a team’s race strategy on its head, engineers need to be alert to this threat and have access to all the necessary information to respond quickly and accurately. IndyCar teams, unlike Formula 1 and WEC pitwalls that use live strategy software, rely on standard timing data along with their own strategy tools.
RaceWatch is a new race strategy program from SBG that has been adopted by teams like Arrow McLaren SP. This is a real-time prediction tool that synchronises data from the track, such as race control messages, weather updates, and live timing with data from cars, including GPS, telemetry and onboard video. The algorithms within RaceWatch then process and analyse this incoming data using statistical models which can predict the probability of an overtake, a driver’s pace during a session and the latest values of tyre degradation.
Our aim is to help engineers bring all the data they need into one place,’ highlights Mike Caulfield, Senior Motorsport Product Specialist at SBG and former Strategy Engineer at Mercedes and Haas F1 teams. ‘This avoids them having to manage several spreadsheets and manually move data to populate tools. Instead, RaceWatch automatically picks up all the necessary data streams and updates the models simultaneously,’ Caulfield continues.
‘Strategy software should never tell you what decision to make,’ says Caulfield. ‘In RaceWatch, we try to model the scenarios as best we can and provide all the relevant information in a clear and concise way so that teams can understand the options available to them and the level of risk associated with each. It is then up to the team to decide whether to take that risk or not.’
> To read the full article on IndyCar race strategy, check out the October 2022 issue
The article Mastering the art and strategy of IndyCar appeared first on Racecar Engineering.
