ENDURANCE | PERFORMANCE ANALYSIS
Happy hour Analysing the potential gains to be had during the performance ‘sweet spot’ of the Le Mans 24-hour race By Andrea Quintarelli
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he 24 Hours of Le Mans is one of the most exciting and demanding races in motorsport history. It catches the attention of millions of fans around the world, and fascinates experienced professionals due to the very special challenges it poses. From an engineering perspective, beside the complex task of building a car reliable and safe enough to be driven at the limit for 24 consecutive hours, yet still capable of competitive performance at the more conventional tracks and events that are part of endurance championships around the world, there are a number of human and physical challenges the teams working on track need to overcome. For starters, driver crews normally include three or more drivers, with different driving styles and preferences in terms of set-up. In some classes, at least one of them is normally not a professional driver either, so the teams must find the best compromises to enable the best possible average performance across the whole race. Then there’s the track itself, which has a layout unique in today’s motorsport scene. The combination of a permanent circuit and open street sections include very long straights, separated by a mix of slow corners and extremely fast sections, such as Indianapolis or the Porsche Curves. At 13.6kms, the circuit is also very long, nearly
24 Le Mans 2022 • Racecar Engineering
twice the distance of Spa Francorchamps, the longest track on the Formula 1 calendar. Top class cars operate at full throttle for more than 80 per cent of each lap, with top speeds in excess of 330km/h (205mph) and lateral acceleration peaks over 3.5g. To complicate things further still, both track and weather conditions can change dramatically over a 24-hour period. Even in the lucky event of not having any rain during the race – an unusual situation at Le Mans – ambient conditions vary enormously between day and night, which have a significant impact on tyre, car and driver performance. This means variables like tyre choice, driver rotation, stint length and set-up decisions can make a huge difference to how a team performs over the duration of the race. Even without considering technical troubles, a car with a slightly lower potential than another over a single lap can easily be lapped more than once at Le Mans.
Special moments During the 24 Hours of Le Mans there are many special moments, but the start and finish of the race are two inevitable highlights, while some very emotive impressions can be experienced when night falls on the Saturday evening. Similarly, at sunrise on Sunday. These two latter moments are also particularly interesting from an engineering
perspective, because they represent the two zeniths of transition regarding track and ambient conditions. As night comes, temperature drops, visibility reduces and both drivers and engineers have to adapt their targets accordingly. At sunrise, on the other hand, besides offering improved visibility for the drivers and wonderful picture opportunities for photographers, performance picks up again. This is the time many call ‘happy hour’, because it is the phase of the race when the cars perform best and, coupled with less traffic on circuit due to the inevitable retirements overnight, has historically often produced the quickest lap times of the race. Traditionally, happy hour occurs roughly between 5 and 7am on Sunday morning, with sunrise occurring around 6am at Le Mans in June. Last year, however, was an
The cooler ambient conditions lead to a higher air density that influences two crucial parameters linked to car performance
