Michael Schumacher will take the famous "Raidillon" at the Francorchamps circuit flat out at the wheel of his Petronas Mercedes F1 car.

In the run-up to the Belgian Grand Prix this year I stumbled on some very interesting information from the Mercedes-Bens press people. They gave some comments about the magnificent Raidillon on the Spa circuit, which is a delight to watch in itself, let alone with racing cars on it… Indeed, the pace at which this stretch of the circuit is taken behind the wheel of a Formula One car, is nothing short of utterly astonishing…

Hans Knol ten Bensel

Born 72 years ago…

Seventy-two years ago, it was no more than a fairly innocent change to speed up the circuit layout: when the teams arrived for the 1939 Belgian Grand Prix at the end of the June, the fiddly Virage de l’Ancienne Douane (Customs House Hairpin) early in the lap had been bypassed with a new, steep uphill section linking to the long straight towards Les Combes. But actually, a legend was born. That piece of tarmac, Le Raidillon de l’Eau Rouge, the steep uphill right hander, the “Raidillon”,  is now engraved in the minds of all sporting drivers and spectators alike.

Nico Rosberg will also be driving up the "Raidillon" at more than 300 kph...  

But watch here the speed at which Formula One Cars are taking this curve…they take it flat out!

Le Raidillon de l’Eau Rouge is reduced to three simple corner numbers on the official map of the Spa-Francorchamps circuit: Turns Two, Three and Four. Turn Two, the left-hand kink which crosses the bridge over the creek named Eau Rouge, is taken at …306 kph, with a lateral G-force of 2.4G; Turn Three, the right-handed uphill sweep, at 303 kph with a lateral G-force of 4G; and Turn Five, the left-hander over the crest, at 296 kph with a lateral G-force of 2G.

Shumacher will have to withstand considerable G-forces on his drive in Spa...  

The cars also undergo significant vertical loadings through this section: a vertical force of -1.7G in the compression at the bottom of the hill and +1G over the crest. Although the section is taken flat-out, the cars lose approximately 10 kph through the sequence. The series of corners is 535 m long (7.6% of the lap distance) and is negotiated in 6.4 s (6.1% of the 2010 pole time). The sequence from La Source to Les Combes, including the Raidillon, lasts for 23.5 s and is the longest full throttle sequence of the entire season! 

Vertical accelerations present particular challenges…

This upward vertical acceleration of 1G effectively means the car is weightless as it goes over the crest; contact with the road is therefore assured by downforce alone, and not the weight of the car. However, at such speeds, the downforce generated is approximately 2.5 times car weight. The high levels of vertical acceleration could also compromise engine and gearbox reliability if not accounted for in system designs and installations.

Due to the high speeds and very high G-forces, F1 engines take a serious beating in Spa. Here a photo of the Mercedes F1 engine.

The pick-up points in the oil tank must be accurately placed to ensure the pumps are continuously primed during these phases.

Other significant high-speed corners…

The other major high-speed challenges are Blanchimont (Turn 17), which is taken flat-out at over 300 kph; and the double left-hander at Pouhon (Turns 10 and 11), which are taken in fifth gear at 240 kph, with a lateral G-force of 3.75G. Pouhon is the longest corner on the circuit, lasting for a total of 7.8 seconds.

Michael Schumacher commented…

Of course, the German champion already gave some comments on the circuit ahead of the Belgian Grand Prix this weekend: “The race in Spa will certainly have a special touch to it this time, as this is where I drove my first ever Formula 1 race 20 years ago. It is hard to believe that this is back such a long time.

Shumacher will be very much in action in Spa...

"A lot has changed in those 20 years, but one thing has not: the track still is sensational. I just love this great nature and the resulting layout with all the ups and downs. To me, Spa remains my ‘living room’, because it has been the stage for so many things which have been remarkable for my sporting career.”

Needless to say, your servant will be watching the Belgian Grand Prix this weekend on this magnificent and one of the last remaining classic road circuits in the sport: Spa-Francorchamps 

Hans Knol ten Bensel