Williams FW31

Kazuki Nakajima driving the FW31 at the 2009 Spanish Grand Prix
Category	Formula One
Constructor	Williams
Designer(s)	Sam Michael (Technical Director) Ed Wood (Chief Designer) Jon Tomlinson (Chief Aerodynamicist)
Predecessor	Williams FW30
Successor	Williams FW32
Technical specifications[1]
Chassis	Carbon-aramid and honeycomb composite monocoque.
Suspension (front)	Carbon fibre double wishbone, with pushrod activated springs. Zero keel geometry.
Suspension (rear)	Double wishbone, with pushrod activated springs.
Wheelbase	3,100 mm (122.0 in)
Engine	Toyota RVX-09 2.4 L (146 cu in) 90° V8. Limited to 18,000 rpm. naturally-aspirated, longitudinally mid-mounted.
Transmission	Williams 7-speed electro-hydraulically actuated, semi-automatic, seamless shift.
Power	740 hp @ 18,000 rpm[2]
Weight	605 kg (1,334 lb) (including driver)
Fuel	Esso
Lubricants	Mobil 1
Tyres	Bridgestone Potenza
Competition history
Notable entrants	AT&T Williams
Notable drivers	16. Nico Rosberg 17. Kazuki Nakajima
Debut	2009 Australian Grand Prix
Last event	2009 Abu Dhabi Grand Prix
Races Wins Podiums Poles F/Laps 17 0 0 0 1

The Williams FW31 was a Formula One motor racing car, designed and built by Williams F1. The AT&T Williams team used the FW31 to compete in the 2009 Formula One season. The car was unveiled on 19 January 2009 at the Autódromo Internacional do Algarve circuit in southern Portugal, and was first driven by the team's test driver Nico Hülkenberg. It was a mid-field runner, in contention for points on many occasions when driven by Rosberg, but rarely contending for podiums. Rosberg could have finished in third position at Marina Bay during the 2009 Singapore Grand Prix if he had not run wide on the exit of the pit lane and received a penalty.

Rosberg was criticised for failing to achieve a pole position while topping the times in practices on numerous occasions, notably at the 2009 Brazilian Grand Prix - the Williams cars had excelled during practice sessions in wet conditions, but did not produce the same level of performance in qualifying. While Rosberg often scored points, and elevated the car to a finishing position that it was considered incapable of, Nakajima failed to score a point all season and possibly cost the team a higher position in the championship standings than the seventh place they eventually achieved.

The Williams FW31 was the first British F1 car to use Esso-branded fuel since 1973, as well as the first Williams F1 car to use Mobil 1 lubricants since 1988 season, as they had been using ExxonMobil brands since 1999.

Diffuser controversy

At the first race of the season, an official complaint was launched by other teams against the rear diffusers of the Williams FW31, Toyota TF109 and the Brawn BGP 001 saying that they were illegal,^[3] but after analysing the cars, the FIA reported that the cars were not illegal.^[4] The teams appealed and after much deliberating the car were deemed legal by the FIA.^[5]

Season review

The Williams FW31 was a slight improvement compared to previous FW28-30 cars as the team tried to get used to the major new rules in 2009. Rosberg proved to be a consistent challenger for points, though he could not clinch a podium finish. It could have been a 2nd consecutive podium finish in Singapore for Rosberg, who was running 3rd before a pit-stop. After the pit-stop, his car ran wide, causing a drive through penalty. The safety car was sent out on track, and he could not serve his penalty until the safety car was called in, ending his chances of a podium finish.

Gallery

• 
  Nico Rosberg at the 2009 German Grand Prix, July 2009
• 
  Kazuki Nakajima during Spanish Grand Prix Qualifying, 9 May 2009
• 
  Nico Rosberg at the 2009 Turkish Grand Prix, June 2009
• 
  Kazuki Nakajima in the wet at the 2009 Chinese Grand Prix, 19 April 2009
• 
  Nico Rosberg and Kazuki Nakajima at 2009 Japanese Grand Prix, 4 October 2009
• 
  Mechanic working on Nico Rosberg's Williams FW31 during practices on Friday of 2009 Turkish Grand Prix
• 
  Front wings outside Williams garage between two 2009 Turkish Grand Prix Friday practice sessions
• 
  The Williams team practice pit stops during Australian Grand Prix Friday Practice, 27 March 2009
• 
  Nico Rosberg and Jenson Button at the 2009 British Grand Prix, Silverstone, 21 June 2009

Formula One World Championship results

(key) (results in bold indicate pole position; results in italics indicate fastest lap)

^† Driver failed to finish, but was classified as they had completed >90% of the race distance.
^‡ Half points awarded as less than 75% of race distance completed.

Other

The Williams FW31 was featured in the racing simulations F1 2009 and iRacing.