A double decker diffuser has become a vital accessory for 2009. Ross Brawn pointed out last year that the rules were ambiguous last year before teams started designing their cars, but other teams indicated that they were happy with the rules and did not want them to be “clarified”.
At the start of the season just Brawn, Toyota and Williams had included them in the aero package for their cars. Once it was clear that the Brawn and Toyota had a significant advantage the other teams initially objected about the system, but as soon as it was declared legal they all scrambled to adapt and convert their cars.
Williams have continued using their Double Decker Diffuser since the first race. Here in Turkey the front wing has been revamped with the three elements having the top two split into two each. The front wing now has five separate wing elements one on top of the other. They have also modified the outside vertical ends of the wing to guide the air flow around the tyre better.
McLaren do not have much new here and are hoping to rush through a major upgrade in Silverstone.
Red Bull introduced the first version of their Double Decker Diffuser in Monaco after struggling to overcome the difficulties of fitting it around the pullrod rear suspension. Despite the new package the Red Bulls struggled in Monaco due to their car having less dynamic grip on the slow Monaco corners.
It was a good move to introduce the package in Monaco (because despite the in season testing ban) they were able to test it at the track and get to understand it.
Once they arrived in Turkey they were immediately quick on the first two fast sectors, but consistently (along with other teams) lost 0.4 seconds to the Brawns on the final sector.
Over the course of the practice sessions they whittled this down and following a broken engine on Friday ended up with Vettel being the fastest in all three qualifying sessions, ending up using the soft tyres to take pole position. Webber managed fourth behind the two Brawns.
Red Bull are working at a feverish pace to develop and improve the car. While most teams simply moved on from Monaco to Turkey as if it was a “fly away” race Red Bull were still fitting new parts on Saturday morning.
BMW Sauber finally got their Double Decker Diffuser package ready for Turkey, following a totally disastrous outing in Monaco where the BMW just did not work well with the Soft and Super Soft tyres.
Their F1.09 was not initially designed with the Double Decker Diffuser in mind so they have had to do quite a lot of aerodynamic changes to introduce it. In addition to the Double Decker Diffuser in Turkey they have aero updates to the front wings, side bargeboards, rim shields and the rear of the engine cover.
Initially at the start of the year it seemed that bargeboards were outlawed, but it seems that they are progressively creeping back onto the cars as aerodynamicists tune the new body shapes.