Eau Rouge elicits a range of emotions

SPA-FRANCORCHAMPS, Belgium -- If you want to see a racing driver's eyes sparkle with delight and awe and a touch of apprehension, just mention one of the most challenging, fast, difficult, intimidating and satisfying corners of any racetrack anywhere in the world.

Eau Rouge!

Belgium's daunting Spa-Francorchamps track, set in the hills of the
Ardennes forests, is one of the world's great tracks. Many Formula One
drivers rate it as their favorite. Spa has a wide variety of corners from
hairpins to fast sweepers, but Eau Rouge is the most famous and infamous complex of turns of all.

You come out of La Source Hairpin in second gear at about 36 mph and then plunge down a steep hill with the accelerator flat to the floor as you go up through the gears hitting about 197 mph in seventh gear.

The drop is about 140 feet. At the bottom of the hill the track slants up
so steeply that it looks like you are facing a wall. The car bottoms out,
with the floor scraping the ground as the road flicks left and then sweeps
right as it shoots you up toward the sky in a steep 190-foot climb. At
the end you are topping 200 mph. Mark Webber says it's like getting shot out of a cannon.

According to figures published by F1 Racing magazine, the driver undergoes a 3.1 G lateral force to the right quickly followed by a 4.6 G lateral force to the left.

"It has been likened to threading a needle and that's not a bad analogy,"
Ralf Schumacher says of getting through Eau Rouge at high speed.

The big challenge is to take Eau Rouge "flat," which means having the
accelerator flat to the floor and not lifting off.

"Eau Rouge is definitely the most exciting corner," says six-time Belgian
Grand Prix winner Michael Schumacher. "You get the impression that you are flying all the way down from La Source, then suddenly you have this huge mountain in front of you. It's almost as though you have just touched down again. And then you begin to climb and you feel the sensation that must be the best, the most satisfying that any racing driver could experience."

In recent years the profile of Eau Rouge has been softened. Run-off areas
have been increased. Add in the fact that F1 cars have better grip and
downforce than they used to, and taking Eau Rouge flat is easier than it
used to be.

"Even if today's cars make the circuit a little easier," Schumacher says,
"it is still a major challenge. It is tremendously exciting trying to pick
out the ideal line, especially at certain points. It is no coincidence
that drivers from several generations have enthused about Eau Rouge."

Jacques Villeneuve had two enormous accidents trying to take Eau Rouge flat in 1998 and 1999. Even though the corner is easier these days, Villeneuve says that there still is a conversation between his brain and his right foot every time he heads down the hill, and he feels a clenching feeling of apprehension and excitement.

The late Ayrton Senna once reflected on Eau Rouge.

"One year I didn't take Eau Rouge flat during practice until I knew I could
do it," Senna said. "I was following my instincts of self-preservation.
The corner arrived just so quickly! It's between the entry and the apex
that everything unravels. And before you reach the entry, the decision
whether to take the corner flat or not hinges on your anticipation. That
can make the difference between winning and losing.

"You have to evaluate the consequences of risk and the time you might gain if you succeed, a factor that might make a winning difference. This is what you are compelled to weigh up from the previous lap, from the morning, from the evening before and even as you approach the corner afresh every lap."

It's not only the lateral G forces that push the driver around. They feel
1.4 vertical G as well.

"There are some amazing sensations," Giancarlo Fisichella says of Spa,
"especially through Eau Rouge where you have the compression and then the steep uphill section. In the last couple of years it was taken flat, and
it is a fantastic sensation but hard to explain. It is totally different
to how we normally feel in the car."

The river owes its name to the ferruginous, carbon dioxide-bearing springs that are scattered along its route. The minerals make the water look red.

In the days of the Roman Empire, Eau Rouge was clearly defined as a state border. The Eau Rouge steam marked the frontier between the Netherlands -- or, subsequently, Belgium -- and Prussia from 1815 to 1920.

Of course, there is more to the Spa circuit than Eau Rouge. Drivers and
engineers cannot just set the car up to be fast through Eau Rouge as it
would compromise the setup for the rest of the lap. Pouhon, a sweeping
downhill double left-hander, is another daunting corner that the drivers
arrive at about 192 mph, brake and then go through at 155 mph.

But Eau Rouge remains the granddaddy of all corners.

"Eau Rouge is probably the most exciting corner in modern F1," Villeneuve said. "Going flat-out there doesn't actually make your overall lap faster, but it does make you feel proud. Pride is stupid, but it is important!"

Dan Knutson covers Formula One for National Speed Sport News and ESPN.com.