In a recent interview, Rubens Barrichello described this year’s Williams-Cosworth FW33 as “aggressive”. It’s a sentiment shared by technical director Sam Michael, who talks today about the team’s 2011 FIA Formula One World Championship entry, the Williams Cosworth FW33, as it makes its track debut in Valencia this morning.

“Until you start testing,” says Sam, “you’re never sure how you’re going to stack up against the opposition, but we’re optimistic. We think this is a good car, but we’ll have a better overall picture in a few weeks time.”

New rules, which were only confirmed by the FIA’s World Motorsport Council in June 2010, compelled Williams F1’s technical team to take an innovative approach to its new car. The ban on double diffusers and the F-duct forced the aerodynamicists to seek new downforce solutions; KERS had to be incorporated into the layout and the team had to prepare for the arrival of a new tyre supplier, Pirelli, for the first time in five years.

“The design of this year’s car has been pretty smooth,” continues Sam. “We’ve improved our way of working by increasing the communication between the mechanical and aerodynamic departments, and that improved our decision making processes. It allowed us to increase the optimisation time spent on each part of the car.”

The car seen at today’s Valencia test is the first iteration of the FW33. This ‘launch spec’ will be replaced by an aero upgrade at the first race in Bahrain and there will be many others during the course of the year.

Sam Michael and his technical team expect aerodynamic performance to reach the same levels as 2010, despite there being less aero freedom in the rules.

What follows is a breakdown of the challenges that had to be overcome during the design of the FW33.

Chronology of the FW33’s design
Aerodynamic work started in December 2009, with the mechanical aspects of the FW33 beginning in March 2010. The major layout decisions were finalised in June, following the World Motorsport Council’s confirmation of the 2011 rule changes, and the new gearbox was on the dyno by September. The launch spec aerodynamic package was completed in November, since when the aero team has focused on the first-race upgrade.

Gearbox
The seven-speed ’box is the smallest ever produced by Williams F1 and works in conjunction with the new pull-rod rear suspension.

“With gearbox usage increasing from four to five races this year,” says Sam, “reliability is vital. But I’m not expecting it to be a problem because the new gearbox has the same stiffness characteristics as the old one and the rulebook forces us to be conservative with the internals. For the last few seasons the ratios have to be 12mm wide and 600g per pair, whereas in the past we were down to 8-9mm gears.”

Double diffuser ban
Williams F1 was one of only three teams to introduce a double diffuser at the beginning of 2009. The team optimised the design on last year’s FW32, but it has now been banned.

“The double diffuser ban is pretty significant,” says Sam. “Not only can you not open any holes between the reference and step planes, you must have continuous material through all lateral and longitudinal sections. The scope for developing anything on the diffuser is limited, so we’re looking at the centre, rear and front of the floor, as well as the sides of the floor and the little area around the tyre spat, all of which are still free.

“The ban on double diffusers should tighten up the field. It will probably happen straight away, but even if it doesn’t and someone comes to the first or second test with something you hadn’t thought of elsewhere on the car, it’ll be easy to replicate it and get it onto the car quickly because it shouldn’t affect the underlying car structure such as the gearbox.”

KERS
Kinetic Energy Recovery Systems (KERS) were permitted in 2009, before being outlawed in 2010. Now they’re back to stay. The system recovers the kinetic energy present in the waste heat created by the brakes and the exhausts. The energy is then stored in a battery, converted into power and a maximum of 60kw can be called upon by the driver to boost acceleration for up to 6.6s per lap.

Williams Hybrid Power (WHP) is developing a flywheel KERS for use in industry. The system was tested in an F1 car in ’09, but the current regulations favour the use of the battery system, which Williams F1 assembles and builds in-house.

“The rules have changed since KERS was last used in F1,” says Sam. “Re-fuelling is no longer permitted, so the packaging is different now. We have packaged our KERS system entirely inside the car’s survival cell, below the fuel tank, because we didn’t want to compromise any of the sidepod area for aerodynamics. The car is longer than last year as a result, but the advantages of doing that outweigh the negatives. Assuming you’re on the weight limit, there is no downside to KERS; it’s worth 0.3s and it gives you a better start.”

Moveable rear wing
One of the most controversial rule changes for 2011 is the introduction of a moveable rear wing. The top element of the wing has to be able to lift at the front until the slot gap is 50mm and it’s hoped that the resultant reduction in drag will increase speeds by up to 15kph. The wing’s sole purpose is to make overtaking easier, but not everyone is convinced.

“I don’t think the advantage gained by the rear wing is going to change overtaking dramatically,” says Sam, “because there isn’t going to be a big enough drag reduction. You only get help from the wing when you’re one second from the car in front, which might not be until halfway down a straight, depending on where the FIA places the timing loop that activates it. That will take a few races to fine tune.

“It’s another thing for the drivers to think about. Our system is powered by a hydraulic actuator, which is activated by a button on the steering wheel. By regulation there is no intermediate position control; it’s either on or off.”

Pirelli
After 14 years at the top echelon, Bridgestone pulled out of F1 at the end of 2010. Replacing the Japanese company as the sport’s sole tyre supplier for the next three years is Pirelli, who were last involved in F1 in 1991. The dimensions of the tyres will be the same as last year, but the performance characteristics are very different, as Williams F1 discovered during a two-day evaluation of the tyres in Abu Dhabi last November.

“The Abu Dhabi test was quite useful,” says Sam. “There is a change to the aerodynamics; lots of little details make a difference to the wake of the tyre and we learnt a lot about that in Abu Dhabi. The Pirelli rubber deflects and deforms in a different way to that of Bridgestone and it has different mould lines, all of which can affect the tyre wake.

“Overall, though, the arrival of Pirelli is not an intimidating change. We didn’t change a lot on the mechanical side of the new car after the Abu Dhabi test; the main changes we’ve made since then have been aero.”

Weight / weight distribution
The minimum weight of the cars has gone up from 620kg to 640kg this year. KERS has added mass to the car, as has the addition of more anti-penetration zylon panels to the sides of the chassis (they now go all the way to the drivers’ feet) and the need for double wheel tethers. The weight distribution is fixed at 46 percent on the front axle, plus or minus 0.5 percent. That’s more rigid than in the past, but Sam doesn’t believe it’s a game changer.

“The weight distribution is pretty close to where we were running on Bridgestones,” he says. “It wasn’t a big issue when it came to designing this car. However, the extra weight has forced us to increase our brake cooling. The cars will be doing higher top speeds due to KERS and the moveable rear wing, and in the slow corners the extra mass will have an influence, so the brakes will have to work harder.”

Conclusions
Unprecedented levels of R&D have gone into this year’s FW33 and a development programme is in place to ensure that upgrades are introduced at each grand prix of the 20-race campaign.

“Our ambition is get back to the front of the grid,” says Frank Williams. “We know that won’t be easy, but we hope this car will take us closer to the leaders than we were in 2010. As a team, we’re as ambitious now as we’ve ever been.”

The team now has 15 days of testing at four different racetracks ahead of the opening race of the season. Valencia, Jerez, Barcelona and Bahrain offer different challenges and varying climates, after which it’ll be time to go racing; time to stand up and be counted.