The Story of the FW31

“This could be our most important season for a decade,” says Frank Williams. “The rule changes give Williams F1 a chance to re-establish itself.” Whether the team returns to its former championship glories, only time will tell, but such is the extent of the regulation changes for 2009 that the team has an opportunity to move up the order.

There are very few carry-over parts from last year’s car – only the fuel-flap activators, some hydraulic manifolds and the gearbox internals – and the FW31 is conceptually very different to any Williams of the last 30 years.

The new rules were ratified in October 2007, since when the design of the FW31 has been paramount in the minds of the team’s design, aero and engineering departments, led by Williams F1’s Director of Engineering, Patrick Head and Technical Director, Sam Michael. Work on the car started in November ’07 and the first wind tunnel test took place between Christmas and New Year the following month. Thereafter, the amount of resource placed on the FW31 increased progressively and by mid-’08 this car was the sole focus of the R&D department at Grove. The three main points of focus were aerodynamics, the Kinetic Energy Recovery System (KERS) and the return of slick tyres.

Compared to last year, the front wings are lower (75mm) and wider (1800mm), with driver-adjustable flaps; the rear wing is taller (level with the top of the airbox) and narrower (750mm); the diffuser has been moved back by 350mm so that it’s level with the rear wing and all extraneous winglets, chimneys and bargeboards have been outlawed.

“Once we’d read the rulebook,” says Sam Michael, “the first thing we did was look at the geometric differences between last year and this year. We legalised a car, put it in the wind tunnel and looked at the numbers. The loss in downforce was enormous – about 50 percent – and we immediately saw these rule changes as a great opportunity to gain an advantage.”

One of the team’s two wind tunnels was immediately dedicated to the development of the ’09 car and Head of Aerodynamics Jon Tomlinson and Chief Designer Ed Wood turned their teams’ attention to the layout of the FW31. The positions of the gearbox, engine, wheels and fuel tank had to be signed off by mid-May, which meant all the fundamentals of the car’s design had to be decided during the busiest part of the ’08 racing season. Consequently, the development of last year’s car, the FW30, quickly took a back seat.

“The last upgrade on the FW30 was for the German Grand Prix,” says Nico Rosberg. “It made it tough at the latter races of the season, knowing that we were going to find it hard to be competitive, but we had to do what was right for the long-term interests of the team.”

Key bits of information about tyre performance were needed in order to decide the fundamental layout of the car, which made the first on-track test of Bridgestone’s 2009-spec slicks in April a crucial fact finding mission. The slicks generate eight percent more grip than last year’s grooved rubber and this four-day test at Barcelona gave Williams F1’s design team all the ammunition they needed to work out the weight distribution and suspension geometry on the new car.

“There were so many factors to consider with the new car,” says Sam Michael, “but the tyres – being the contact patch to the asphalt – were the most fundamental. How they interact with everything else on the car is fundamental to performance and those early tests gave us important information about the slick tyres. We’ve had to do things like significantly stiffen the suspension to cope with the increased forces and change the kinematics, all due to the extra mechanical grip available.”

Throughout all this, another aerodynamic factor needed to be taken into account: heat rejection. The lack of chimneys in the sidepods, thanks to the new ‘R75 rule’, means that all heat has to exit via the rear of the car. That’s why the FW31 has sprung cooling exit louvers for the oil and water on the sides of the cockpit and for the gearbox on the sides of the airbox.

The last of the FW31’s major performance differentiators is KERS. The system recovers the normally wasted kinetic energy generated by the car under braking and stores it using a mechanical flywheel that spins at over 40,000rpm. That power is made available to the driver via a boost button, which, under the current regulations, equates to a power gain of 80bhp for 6.6s per lap.

“KERS is a fantastic thing for Formula One,” says Sam Michael. “Although we may not use ours at the first race, it will be effective and it’s the kind of technology that Formula One should be embracing. The current KERS system is worth about 0.3s per lap, but the lap time benefit will increase as the FIA increases the power and energy available in the coming seasons. Although it’s a tremendous challenge right now, we’ll all look back in years to come and say it was the right thing to do.”

The FW31 is using a flywheel system, which has been designed (and for the most part patented) by Williams Hybrid Power. Each flywheel has the durability to last the entire season and should give the FW31 an advantage in terms of weight distribution.

By mid-September ’08, all the different design projects contributing to the FW31 were progressing well and the team decided to complete the picture by testing ’09-compliant front and rear wings on one of last year’s cars. An interim FW30, known as FW30B, ran at Jerez for the first time and allowed the team to establish the aero balance for the wings, while also finding out how the narrow rear wing interacted with the rear tyres. Testing of this hybrid continued after the end of the season, by which time the focus of the entire team was on the build of the FW31.

“We wanted to run the new car as soon as we could after Christmas,” says Kazuki Nakajima, “because we wanted to get as many miles on it as we could before the introduction of the in-season testing ban. We’ve been able to do that and I must say that I enjoy driving the new car.”

“It’s impossible to say where we’ll be in Melbourne,” says Frank Williams, “but I’m cautiously optimistic that we’ll make a step-up in performance this year. To be close to the top three would be a big step forward in year one.”