One month after the Hungarian round, Formula 1 is back on track for the first round of the second half of the season valid for the assignment of both world titles. The historic, evocative and challenging stage of Spa-Francorchamps inaugurates a hat-trick of races on some of the most beautiful tracks on the calendar, which will continue on the renewed Zandvoort and will end with the eagerly awaited Monza event.
In Belgium, the championship continues from where it left off in July, namely from the dualism between Max Verstappen and Lewis Hamilton and between Red Bull and Mercedes. The world championship competition is renewed on one of the most popular circuits in the world, as well as the longest on the calendar, with its 7004 meters in length that connect 19 curves, evenly distributed between right and left. Of these, curves 1, 18 and 19 are the only ones to be characterized by a minimum radius of curvature equal to or less than 16 meters with a low travel speed, where the mechanical grip guaranteed by the suspension unit and traction qualities are rewarded. Excluding these curves and the points addressed without partializing on the accelerator, such as Eau Rouge, Radillion and Blanchimont (2-3-4-16-17), all the other folds of the track are joined by radii of curvature between 40 and 60 meters and bending step which, based on the data provided by Federico Albano, they stand on values of 5 and 6.
The track therefore sees a preponderance of medium-high speed curves with several elements in common, a discrete homogeneity which therefore facilitates the search for aerodynamic balance, as there is a reduced need to compensate for the different behavior of the car when cornering at high and low distances. In addition to the aforementioned curves 1.18 and 19, the only other exception that stands out clearly from the rest of the track is in fact the double fold of Pouhon (10-11), which in 2020 was addressed in full by Mercedes alone, thus placing a challenge and at the same time a clear element of comparison for the 2021 single-seaters.
Spa-Francorchamps stands out for the long-distance corners in which the driver is called upon to design and interpret the trajectory, but the competitiveness on the lap is also the result of the speed on the numerous extensions of the track. The cars travel with the engine at full speed for 79% of the lap time, making the power of the power unit an even more important factor. The hourly average on the qualifying lap is close to 250 km / h, among the highest values of the entire calendar, an element that pushes the teams to adopt low-medium downforce set-ups. It is no coincidence that the Belgian track is often used by the teams to test the aerodynamic package dedicated to Monza on Friday.
The most important extension of the track is that of 1800 meters which leads from La Source (turn 1) to Les Combes, passing through Eau Rouge, Radillion and the Kemmel straight, which the single-seaters face in full for 24 seconds. The length of the straight is such as to significantly cool the tires and brakes, an aspect that the drivers must be able to foresee when approaching the braking of Les Combes and in the following corners. In the current season, the Mercedes have highlighted problems with the temperature of the tires, which is why it will be essential for the Silver Arrows to contain the cooling on the extension of the Kemmel and to be able to quickly bring the tires back to temperature in the following sector.
The seven kilometers in length of the track, mostly tackled with the accelerator pedal, require a important energy expenditure for the hybrid part. However, the usable energy is limited by the battery capacity and even more by the regulatory limit of 2 MJ per lap that can be delivered by the MGU-K, the electric motor generator coupled directly to the transmission. In Spa we are witnessing a wide use of clipping in qualifying, with the control unit that cuts the electric power at the end of the straights to ration the energy available for each lap. In addition to the absolute power of the power unit, in Belgium the management of hybrid power over the course of the single lap becomes crucial, an aspect in which Honda showed a slight margin over Mercedes in the first half of the season. However, between Silverstone and Budapest the Anglo-German engines appeared invigorated by the work on the hybrid exploitation strategies carried out at Brixworth, improvements that can be evaluated with greater care on a probative track such as Spa.
The weight of the power unit factor on the long straights of the Ardennes makes Spa a plausible theater for the debut of the third engine of the season for some engineers. Despite the prohibition imposed by the regulation on making changes to the power unit during the season, there are still margins of intervention to improve reliability, indirectly leading to a slight increase in usable power. In fact, improved reliability makes it possible to use a single mapping for qualifying and race on average more aggressive, guaranteeing a modest increase in performance. In Belgium it will therefore be advisable to evaluate any narrowing or opening of the gaps between individual engineers.
Despite the low-medium aerodynamic load level chosen by the teams, the high travel speeds of the corners of the Ardennes subject the tires to high lateral stresses, to which are added the high longitudinal traction stresses and a fair abrasiveness of the asphalt. Pirelli confirmed the 2020 choice, opting for the intermediate compounds of the range, namely the C2, C3 and C4. The minimum inflation pressures recommended by the Italian tire dealer are respectively about 24.0 and 22.0 psi front and rear, significantly higher than the 19.0 and 18.0 psi of Budapest and more in line with the parameters of Silverstone.
In terms of brakes, the track has only seven braking sections, a relatively low number when compared to the track’s record length. According to the data provided by Brembo, the cumulative load on the brake pedal during the race is just 36 tons, with the rider using the system for about 13% of the time. Of the seven braking sections at Spa, however, six have a deceleration greater than 4 g, two of which are characterized by peaks of over 5.3 g, an aspect that prompted Brembo to classify the track with a severity of 4 out of 5 for the braking system. The most demanding braking is the one that precedes the Bus Stop (turn 18), characterized by a slowdown of over 200 km / h with a peak deceleration of 5.9 g.
McLaren aims for the stretches
At the center of the group the McLaren they aim to perform well on the stretches of the Ardennes forest, thanks to the great competitiveness expressed in straight lines throughout the season. The Scuderia di Maranello on the other hand does not enjoy the favors of the prediction, considering the lesser competitiveness of the SF21 both on the straight and in the medium-high speed corners. However, it should not be overlooked as the same Ferrari has progressed in the work of preparation and definition of the set-up, managing in some circumstances to stem the limits of the car and to subvert the initial prediction, as happened for example with the excellent performance at Silverstone.
Finally, in Belgium the challenge for the fifth constructors place between Alpine, Aston Martin and AlphaTauri. The Faenza team has what appeared to be the most complete and balanced car of the trio, but is called upon to fill the gap of nine points in the standings.
In Spa the second act of a particularly hard-fought world championship will open at different levels of the classification, from the run-up to the title to the challenges for the first, third and fifth place among the constructors. With the development of the cars almost completed and the resources diverted to 2022, the preparation work in the factory and the refinement of the track set-up on Friday will be the real discriminators of the world competitions. The big variable for the Belgian weekend, however, could be the rain, currently expected on all days of the Grand Prix, which could affect the choices of the teams’ set-up regardless of whether the forecasts actually materialize.