New tyres, safety cars and rain set scene for Brazil GP finale
With a fairly high likelihood of a safety car and a new tyre choice from Pirelli which brings the two compounds closer together on performance, thi...
With a fairly high likelihood of a safety car and a new tyre choice from Pirelli which brings the two compounds closer together on performance, this should be one of the most interesting races of the season from a strategy point of view. The weather forecast also adds spice to the event with a strong likelihood of showers on Saturday and Sunday.
The Brazilian Grand Prix is special for a number of reasons; set in a natural bowl around a lake in a suburb of Sao Paulo, the passionate and noisy crowd can see most of the circuit from their seat. The venue is also at one of the highest altitudes of any F1 circuit at just over 800 metres. This means that the atmospheric pressure is almost 10% less than at sea level and this cuts engine power, downforce and drag by a similar amount.
It is also the shortest lap of the season in terms of lap time, a quick lap there being under 1m 12 seconds, so the qualifying and racing have an intense quality about them. The circuit has a fast opening downhill sector and final uphill sector, with a tight infield sector in the middle.
It is one of five anti-clockwise circuits on the calendar.
Contents – the Key Strategy considerations
• Track characteristics
• Form guide
• Weather forecast
• Likely tyre performance
• Number and likely timing of pit stops
• Chance of a safety car
• Recent start performance & Pit Stop League Table
Interlagos – 4.309 kilometres. Race distance - 71 laps = 305.909 kilometres. 15 corners in total. Average speed 210km/h. A classic circuit set in a natural bowl, in a suburb of Sao Paulo.
Aerodynamic setup – Med/High downforce. Top speed 323km/h (with DRS open) 311km/h without.
Full throttle – 60% of the lap time (ave/high). Total fuel needed for race distance – 144 kilos (ave/low). Fuel consumption – 2.00 kg per lap (low)
Brake wear- light. Number of braking events – 6, Time spent braking – 16% of the lap.
Loss time for a Pit stop = 15 seconds
Total time needed for a pit stop: 20 seconds
Fuel effect (cost in lap time per 10kg of fuel carried): 0.33 seconds (ave)
The Brazilian Grand Prix is the final round of 19 in the 2011 FIA F1 World Championship. The championship was decided three races ago in favour of Red Bull’s Sebastian Vettel, who was also the winner of the Brazilian GP last season. In 2009 Mark Webber won the race for Red Bull.
Interlagos is a real Red Bull circuit, the car does well on the second gear corners in the second sector and on the higher speed turns as well, such as the crucial final left hander onto the pit straight.
Felipe Massa won the race for Ferrari in 2006 and 2008, while Michael Schumacher has won it four times. McLaren hasn’t won there since 2005 and neither Lewis Hamilton nor Jenson Button has ever won there, despite both clinching their world titles at this event by finishing in fifth place in 2008 and 2009 respectively.
Only 7 drivers have finished on the podium so far in 2011 - a very low number - and if that remains the case after Sunday’s race it will tie the record low in one year, set in 1992, 2000 and 2002.
Rain showers are a common occurrence in Sao Paolo at this time of year and many Brazilian Grands Prix have experienced sudden showers over the years. The forecast for the weekend is for temperatures around 25 degrees centigrade but with storms on Friday and showers on Saturday and Sunday.
Likely tyre performance and other considerations
Pirelli tyre choice for Brazil: Soft (yellow markings) and Medium (white markings). This combination has been seen several times, but the soft tyre this weekend is a different model from the one used all year.
Pirelli has been working on a new soft compound, testing it in Germany and again the recent Young Drivers’ test at Abu Dhabi. It is slightly harder than the soft tyre that has been in use for most of this season and is closer in performance to the medium tyre, the difference being around a half a second to seven tenths.
The tyre also has better thermal durability. It should be possible to use this tyre for longer than the old soft, opening up strategic options.
The track does not have a particularly abrasive surface and the energy going into the tyres is not particularly high, apart from the series of left hand corners before the final straight. On top of that, the tyres get plenty of rest on the two long straights.
The limiting factor on this track is the rear tyre, with the stop-start traction events in the series of corners in the middle part of the lap and the last corner onto the uphill final straight.
In the event of a wet race, drivers are not obliged to use both compounds of dry Pirelli tyres. Pirelli will have full wet and intermediate tyres on hand.
During Friday practice drivers will have two sets of Pirelli's new experimental hard tyre to try out with a view to 2012.
Number and likely timing of pit stops
The pit lane at Interlagos is quite short and the time needed for a stop is only 15 seconds plus the stationary time. The indications, with this in mind and with the likely behaviour of the tyres, are that two stops will be the way to go.
However the new soft tyre will be capable of longer runs than its predecessor and with the high likelihood of a safety car, we may see teams try some one stop strategies as this can be greatly helped by a safety car deployment. Some teams will probably split the strategies (see notes under Safety Car below)
Overtaking at Interlagos isn’t too much of a problem, thanks to the long uphill straight leading to the Senna S. And with the DRS wing it should be even more possible this year.
Chance of a Safety Car
The chances of a Safety Car are high at 71%. The Safety Car has been used in seven of the last ten races. It is often called into action on the first lap, as it’s a short lap with 24 cars charging into tight corners.
This makes the Safety Car an important element to factor into Race Strategy planning. It encourages teams to hedge their bets and split strategies with one car doing a conventional two stop plan and the other on a one stop, which would benefit from a safety car. This is because a safety car would close up the field reducing any time loss and if timed well, would allow a one stopping car to effectively get a free pit stop.
Recent start performance
Starts are a critical part of the race and strategy can be badly compromised by a poor start, while good starts can make strategists change their plans in the hope of a good result.
In Abu Dhabi, the winners off the line were Liuzzi, Barrichello and Kobayashi (gained 5 places) and Alonso (gained 3 places). The losers were Senna (lost four places), and Vettel who retired after a tyre deflated suddenly after the first corner.
Below is a chart showing aggregate 2011 start performances. Places lost due to contact with other cars or incidents at the start are counted, those where a car has retired without contact are not. Drivers have gained (+) or lost (-) places off the start line this season on aggregate as follows:
+29 Schumacher *
+15, Buemi #
+8 Di Resta, Massa
+4 D’Ambrosio, Heidfeld ******
-3 Vettel ######
-8 Hamilton, Maldonado
- 9 Sutil ##,
-11 Button, Alguersuari####
-12 Perez ###
-20 Senna, Barrichello #####
- 23 Webber
* Schumacher had one bad start in Australia, losing 8 places but since then has been the season’s outstanding starter. He gained 9 places in Spa and four in Monza.
** Kobayashi lost 10 places in Spain, prior to that he had gained 8 in 4 starts. He lost 7 places in an incident at the start in India.
*** After losing places in the first three races, Alonso has reversed that trend. His starts in Barcelona and Monza were outstanding.
**** Petrov had a good record until he lost 4 places at the start in Valencia. He was on a +2 balance before Monza where he was taken out at the start.
***** Rosberg lost four places at the start in Silverstone and was on a +6 balance before Monza where he was taken out in the first corner
****** Heidfeld had gained 20 places but lost 12 at the start in Germany
******* Di Resta had consistent start form and gained 7 places in the first nine races, but lost 12 at the start in Germany.
# Buemi made up nine places at the start in Hungary having started 23rd on the grid
## Sutil had a positive start balance until Hungary where he lost 12 places at the start
### Perez lost nine places off the start in Hungary.
#### Alguersuari was doing well with a +6 record prior to Spa, where he was hit by another car and lost 18 places. In Monza he gained 7 places at the start.
##### Barrichello lost 7 places at the start in India
###### Vettel had a non-contact puncture and retired on lap 1 in Abu Dhabi
Pit Stop League Table
Of course good strategy planning also requires good pit stop execution by the mechanics and there have been some amazing performances; we have seen tyre stops carried out in less than two and a half seconds this year.
The league table below shows the order of the pit crews based on their average time for a stop in this year’s world championship, taking out anomalies.
1= Red Bull Best
1= Mercedes Best
3 McLaren + 0.3s
4 Force India + 0.4s
5 Ferrari + 0.5s
6 Renault + 0.9s
7 Williams + 1.1s
8= Lotus + 1.3s
8= Sauber + 1.3s
8= Toro Rosso + 1.3s
11 Virgin + 1.6s
12 HRT + 3.2s
The UBS Strategy Briefing is prepared by JA on F1, with input and data from engineers and strategists of F1 teams.
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