Technical analysis: Brazilian GP

The 2009 world championships were surprisingly decided with a race to spare, but the teams fighting for the lower positions still have plenty to fight for.

However this race for the lesser placings has not brought a great rush of late season development parts. It seems the two Asian races saw the major updates and the teams have switched their attention firmly to 2010.

Only the Brawn team brought new parts to last weekend's Brazilian Grand Prix, while the other teams ran a mix of the Singapore and Japan updates and older parts to suit the unique nature of the Sao Paulo track.

Interlagos is one of the few tracks to run anticlockwise, and its three sectors are split into two separate demands. Sectors one and three are made up of long straights and curves, while the middle sector is a long sequence of slower turns.

The long uphill run to the start finish straight demands engine power, which is diminished by the thin air due to the altitude. This long straight would normally require a low drag set-up, but such is the importance of the middle sector, the cars run a high downforce level.

But it is a tight balancing act - too much downforce will impede straight line speed. The wet weather also tipped the emphasis onto more grip and less top speed. Many teams were torn in deciding the set-up to enter qualifying with, hoping that loss in lap time from a dry set-up would be rewarded with a dry race.

Developments

Brawn further revised its front wing endplates with a 'C' shaped undercut to the footplate © AUTOSPORT

Brawn was the only team to bring major parts to the Brazilian race, with new bargeboards and front wing endplates. Possibly matched to other new parts, these were the largest visible changes to the car for several races.

Taking a leaf from the 2008 Honda design book, the small bargeboards were given a stepped upper edge. With the loss of the previous fenced upper edge, this change would break up the single large vortex off the top of the board. This part probably complements the fin added for the Japanese race.

The endplates on the front wing were also subtly revised. Since Silverstone the team has tried a more square shape to the footplate, over the conventional wavy version used since the car was first raced. Now the footplate meets the wing with a rounded shape, which curls under to create a 'C' shape. The rounded shape should keep airflow moving, which should encourage the airflow around the front tyre.

Red Bull continued to try similar understated changes to its endplates. The wider footplate and revised cascade tried by Mark Webber in the Japanese race was run again in Brazil.

Force India ran both the extended shark fin and the finned wheel covers in Brazil © AUTOSPORT

Force India refitted the extended shark fin tested previously on the VJM02. This is a slimmer version of the Red Bull version. A convenient split near the rear wing allows the top body to be removed. Additionally the finned rear brake ducts were raced - these sport eight fins to aid airflow extraction from the rear wheels.

Lastly BMW Sauber shunned its Brawn style brake ducts and went back to the boxy old design. Not withstanding this retrograde step the car was competitive in both qualifying and the race, finishing second in the hands of Robert Kubica.