Holidays are over. The circus restarts on Spa circuit, the longest track
After the long summer break, the F1, championship where many teams involved are equipped by BMC, is starting back up and as per tradition, the engines will fire up at Circuit de Spa-Francorchamps, home of the Belgium GP, from August 25 to 27 in the 12th race of the 2017 World Championship.
Nestled in the Ardenne hills, it is unanimously considered the most complete track in the World Championship for its combination of fast turns, blind corners, elevation changes and infinite straightaways.
This is the 50th time Formula 1 has returned to the track, but the circuit has changed dramatically over the course of the years: since 2007 is has measured 7 km, making this the longest track in the World Championship. It stands out for having 19 turns, yet it only has four braking sections characterized by extreme outputs of energy.
The cooling off of the braking systems is guaranteed by the presence of big, fast corners like Eau Rouge and Blanchimont, where the brakes aren't touched at all. The unknown variable is the weather: Last year, the air temperature reached 29°C but in 2014 it didn't go over 15.5°.
According to Brembo technicians, who have classified the 20 tracks in the World Championship on a scale of 1 to 10, the Circuit de Spa-Francorchamps is one of theleast demanding on the brakes. The Belgium racetrack earned a difficulty index of 5, which surpasses only Silverstone, Suzuka and Interlagos.
The demand on the brakes during the GP
Even though it is a really long track, the brakes are used barely eight times per lap, just like in Barcelona except that track is 2.25 km shorter. Additionally, two of the eight braking sections on the Belgian circuit last less than one second. Which explains why the brakes are used for less than 13 seconds per lap, like in Monza where the brakes see action for only 12% of the race.
The mean deceleration per lap is 4 G, the same registered on the tracks in Baku and Budapest. The average is lowered by the braking in sectors 2 and 3, with the exception of the chicane at the top that was once called the Bus Stop (turn 18).
Obviously then, the energy each car dissipates in braking during the entire GP race is lower than at other tracks: The total of 102 kWh here is less than half of the energy dissipated on Hungaroring. Still, this amount is equivalent to what seven medium-sized spa tubs consume on daily basis.
From the starting line to the checkered flag, each driver will exert a total load of 46 metric tons on the brake pedal. Although lower than other GP races, it is still a sizable force that is equivalent to half a ton for every minute racing.
The most demanding braking sections
Of the 8 braking sections at the Circuit de Spa-Francorchamps, only one is classified as demanding on the brakes, five are of medium difficulty and the other two are light.
The toughest on the braking system is at the second to the last corner before the finish line. The single-seaters arrive going 308 km/h and decelerate to 77 km/h in just 65 meters, which is less than half the space needed to stop a station wagon going 200 km/h. The Formula 1 drivers only need to brake for 2.45 seconds, but they have to apply a force of 157 kg on the brake pedal and they experience a deceleration of 4.6 G.
Another noteworthy braking section is La Source at turn 1 because in just 60 meters, the single-seaters have to decelerate by more than 212 km/h to go from 289 km/h to 77 km/h. The force on the drivers is slightly more contained. They apply a load of 152 kg on the brake pedal and experience 4.5 G in deceleration.
Compared to the previous years, braking at Les Combes (turn 5) has been reduced due to the larger size tires that enable the drivers to enter the corner at a faster speed. The cars start to turn going 161 km/h after having cut their speed almost in half in 1.58 seconds and 44 meters.
The tyres situation
Pirelli will bring the P Zero Purple ultrasoft tyres for the first time to Spa-Francorchamps, together with the P Zero Red supersoft and P Zero Yellow soft. These are the three softest tyres in the range, selected together for the sixth time so far this year. But one famous variable in Spa is the weather, so there’s also a strong chance of seeing the Cinturato Green intermediate or Cinturato Blue full wet at some point during the weekend. Spa is a favourite of nearly all the drivers, incorporating classic corners such as Eau Rouge and Pouhon that make it a real rollercoaster ride, as well as a true test of bravery.
The circuit from a tyre point of view
Longest circuit of the year at 7.004 kilometres.
Geographical layout means it can be raining on one part of the track but dry on another.
Elevation changes and compressions generate forces on tyres from all directions.
Compromise set-up needed to provide downforce in corners but not too much drag.
High speeds and big corners place significant energy loads through the tyres.
Overtaking is very possible at Spa, opening the door to a variety of different strategies.
The teams have nominated all three available compounds in their choices rather than concentrating on the softer tyres.
The analysis of…
Mario Isola – Pirelli Motorsport – Head of Car Racing
“Pirelli was racing at Spa for the 24 Hours last month, which showcased everything this circuit is famous for: changeable weather, unpredictable competition, and heavy demands on the tyres. Now that we are bringing the ultrasoft tyre there for Formula 1, we would expect those demands to increase further with the latest generation of cars: two stops would appear to be a likely strategy but we will know more after the first free practice sessions. Working out the optimal race strategy is especially tricky at Spa as it has to be flexible: the possibility of rain, safety cars, or even a red flag – as we saw last year – means that teams often have to react to changing circumstances rather than follow a fixed plan”.
Curiosities & numbers
23.5 psi(1.516 bar) minimum starting pressures (front slick)
21.5 psi(1.447 bar) minimum starting pressures (rear slicks)
–2.75° camber limit (front)
–1.50° camber limit (rear)