After nine months, 18 races in 17 countries across five continents, the 2011 FIA Formula One World Championship finally reaches its conclusion with the last race on the calendar; the Brazilian Grand Prix.
The race is held at the Autodromo Jose Carlos Pace in the megalopolis of Sao Paulo. It is however more commonly known as Interlagos due to its location between two lakes, the Guarapiranga and Billings, which were constructed in the early part of the 20th century as reservoirs for city's enormous water needs. It was renamed in 1985 after the Brazilian Formula 1 driver who died in a plane crash in 1977.
The track is a 4.309km rollercoaster ride of a track set in a natural amphitheatre. It features a twisty back section with off camber corners, radial turns and tightening bends, all of which feature several large bumps. The final section is an uphill straight, which requires good acceleration, meaning the Renault RS27 engine must offer driveability, responsiveness and strong top end power to the driver.
Renault engines have won 25% of the 28 Brazilian Grands Prix to be held at Interlagos, with René Arnoux taking the first win in 1980. Nigel Mansell won in 1992, with Schumacher, Hill and Villeneuve taking victory from 1995 - 1997. Red Bull Racing Renault has won the past two editions of the race, with Webber victorious in 2009 and Vettel taking the spoils in 2010.
Brazilian Grand Prix facts and figures
The Interlagos track is located in the Sao Paulo metropolitan area in Brazil. The city itself is located on a plateau in the vast region known as the Brazilian Highlands, with an average altitude of 800m above sea level. As altitude increases, air pressure drops and the air is thinner with a lower oxygen content. With less oxygen available for the fuel to burn, power output drops. For every 100m the engine loses around 1% of its potential power output, meaning the RS27 could be capable of producing around 8% less power than at a sea-level race such as Korea.
To combat the potential loss of power, the engine settings will be carefully monitored. However, the lower air density does have one benefit, a lower fuel level may also be used to achieve the optimum air-to-fuel ratio. Having engines with fewer miles on the clock is also an advantage: an engine near the end of its life will have approx 3 - 4 less horsepower than a brand new one.
The first corner of the Interlagos track, the Senna S, is an off camber left hand turn that also drops sharply downhill. Cars will take the corner at an angle of approx 30° - the only time in the season when they will be at such a sharp incline. The change in gradient will cause the lubricants in the engine internals to move suddenly to the left, which can move the fuel or oil away from the pick ups of the pumps, which can be momentarily starved. To avoid any engine 'starvation' - particularly in the later stages of the race when levels are low - the fuel and oil systems, and particularly the fuel collector, need to be designed with a good pick up ability. Higher fuel and lubricant levels in the race may also be used to safeguard against any momentary stall.
The curved straight running from turn 12, Juncao, past the pits and to the first corner sees the track go sharply uphill, with an elevation change just shy of 40m. Gear ratios will be carefully calibrated to give a good acceleration up the hill, whilst also bearing in mind the reduction in power caused by the altitude. It's likely that DRS will not give as much of a boost as usual on the end of straight since the engines will be straining right at the limit of their power.
There are however some benefits to being at such high altitude; drag reduces since the air the cars are 'carving' through is thinner. Yet there is still a need to generate downforce through the twisty back section; ultimately wing levels will look like a high setting (somewhere like Valencia) but the amount of downforce generated will be the equivalent of a medium setting (for instance Nürburgring).
Although the lower ambient pressure is at a detriment to engine power, it does give the pistons an easier life. This intrinsic reliability bonus gives Renault Sport F1 engineers greater freedom to run more aggressive engine strategies to compensate for the potential power reduction.
THE DRIVERS' VIEW
Bruno Senna, Lotus Renault GP
I am very excited about racing in Brazil, close to my home and my family. It's a very special feeling to do what you love in the country you grew up. It's a classic track, with some quick, tricky off camber corners in the first section, long slow turns in the mid section and then finally that long straight back up past the pits and the main grandstand, which means you need your engine to respond across all levels.
The high altitude does mean that you're slightly down on power so I'll be working closely with my engine engineer - Ricardo Penteado, a Brazilian like me - to optimise the options available. It's a big challenge and the pressure I put on myself to get a good result is high, but the motivation to do well outstrips any stress.
THE ENGINEERS' VIEW
Head of Renault Sport F1 track operations Rémi Taffin gives his thoughts on Brazil:
After a long season we're pleased to be at the final race, and Brazil is always a fantastic place to end the year. The atmosphere is always electric, the racing close and unpredictable and the track is challenging enough to make it an interesting event for engine engineers.
The circuit itself is very bumpy and run in an anti-clockwise direction. Like Spa and the Nurbürgring, the land undulates so the circuit changes elevation a lot over the relatively short lap. It requires every engine characteristic to be on form; strong top end power down the long, curved - but also uphill - straight, good driveability through the back section. But the main story about Interlagos is the overall altitude of the circuit; around 800m above sea level.
The atmosphere is always electric, the racing close and unpredictable
When humans go to altitude, we can struggle to breathe and feel lethargic - it's exactly the same story for the RS27, which will produce around 8% less power than at sea level races such as Valencia, Korea and Abu Dhabi. There are a number of things we can do to combat this, such as tuning the engine mapping settings for these ambient conditions and also keeping fresher units with a lower mileage.
On this point, we're actually looking pretty good. We introduced new units across all of our clients in Abu Dhabi so we're confident that at least some of this power loss will be offset compared to other engine manufacturers. Nevertheless, it's still a challenge to keep us alert after a very long season!
Did you know?
Interlagos is the bumpiest permanent track of the year. Monaco and the other street circuits feature 'natural' bumps over manhole covers and drains, but the high ambient humidity, geographic position and relative lack of use of Interlagos means the track develops large contusions. Due to the low ride height of the cars and the hard suspension, running directly over the middle of a bump makes the car temporarily 'take off'. Even if it's just for a nano second, with no load running through the wheels the engine suddenly hits the rev limiter, which puts the internal parts under huge stress.