After a tense winter, with designers looking over their shoulders and comparing notes as they waited to find out whose creation would perform best, they finally got their answers in the two back-to-back races in Australia and Melbourne.
While the Melbourne and Sepang races take place on far from conventional circuits, and neither was run in ideal circumstances, some conclusions can be reached from the new formula. It's clear that the sweeping regulation changes for 2009, have shaken up the teams' order - and created a stir over the legality of some parts.
From the first day of winter testing in Portimao nearly ten weeks ago, some rival teams were claiming that the Williams and Toyota diffusers were not within the spirit of the rules. Then, in the run up to the first race Brawn GP arrived sporting a similarly controversial diffuser.
While Williams and Toyota's testing pace was not conspicuous, the surprising pace of the Brawn got everybody's attention and the wrangle over diffusers elevated rapidly.
The problem is down to differing interpretations of the new aerodynamic rules. These rules are aimed at reducing aerodynamic performance and improving overtaking, partly through the use of smaller diffusers. However the rules defining the area between the rear wheels are vaguely worded and in some places contradictory. By designing a double decker diffuser, the Williams, Toyota and Brawn teams have effectively added a false floor to the diffuser and have been able to create a taller and more effective device.
Non double-decker diffuser © AUTOSPORT
With a double decker design the teams treat the stepped underbody as three surfaces, each one feeding its own diffuser. The raised floor leads into the side channels (yellow), while the reference plane leads into the lower diffuser of the double decker (blue). Because both of these diffusers are no higher than 175mm, they meet the 'bodywork facing the ground' maximum height rules. The upper deck (red) is formed from the vertical surface, that forms the underbody step which converges around the gearbox and passes over the lower deck. This upper deck diffuser can go as high as 200mm (Art: 3.5.2 of the technical regulations) and 700mm wide.
Double-decker diffuser © AUTOSPORT
The basis of the protests made by the 'diffuser gang's' rivals has not been made public, but the Australian and Malaysian GP stewards felt the designs were legal and therefore the row must go to court for a formal hearing of the evidence. Depending on the resolution, the three teams might lose their points from the opening races, and\or be forced to change their cars. If the ruling goes in favour of these teams however, then all the others will be forced to create double decker designs of their own.
Although the leading teams in Melbourne were equipped with double decker floors, the pace of the Red Bull - which uses a far smaller diffuser volume - was impressive, and thus makes the argument that the taller diffuser is not the sole contributor to their pace.
Toyota had its qualifying times disallowed in Melbourne after it was found to have been using rear wings that were too flexible. The FIA did not state quite how they were flexing. This might be a design aim or a design fault.
The flap on the Toyota rear wing is held in place by slot gap separators as demanded by the rules. These separators wrap around the wing to ensure the flap and main plane remain in the same position relative to each other. Toyota's take on these separators aligns the device to the oncoming airflow, such that the separator is at quite an angle to the flap, rather than at right angles to it.
This acute angle might prove less than stiff enough to fully support the flap under aerodynamic load. Toyota was able to make changes to the wings in parc ferme having been given the FIA's permission to resolve the issue.
Following the diffuser row, Williams counter-protested Ferrari and Red Bull, on the basis that their floors were not within the wording of the regulations. Although the exact details of the protest, which was subsequently dropped, have not been made public, it's understood to affect the front edge of the floor.
Both these teams have moved the front edge of their sidepods back to create more space to place bargeboards in the vacated area for aerodynamic benefit. After the protest was raised it transpired that other teams (including McLaren, Toro Rosso and Toyota) also had similar interpretations. Williams dropped the protest, but the issue will be taken up by the Technical Working Group (TWG) when it meets later this week.
McLaren's diffuser uses a large blanking panel, that might potentially lead to a double decker design. © AUTOSPORT
The team's new diffuser raised curiosity, as it appeared the design mimicked part of the Brawn double decker diffuser. Certainly the fit and finish of the bodywork suggested this was not a complete or definitive floor. There seems to be scope to add the upper deck to create a taller diffuser in the area taken up by the large blanking plate added over the top of the diffuser (Yellow).
More detail work was carried out in Malaysia with yet more flow viz tests on Friday. To tune the cars cooling, McLaren tried out several solutions, with greater cooling apparently available from the open exhaust fairing and flared sidepod panels.
A new rear wing uses an extra slot to create more downforce. © AUTOSPORT
Ferrari's car sported several major revisions since the final test, with an entirely new rear wing and revised bargeboards. The new wing has rounded rectangular endplates, an extra element ahead of the beam wing and an extra slot in the main wing profile.
The endplate itself sports a different gill arrangement near the wing, the usual stack of three curved vents, instead uses a simpler single vent. Then, just ahead of the beam wing, there is a second element spanning between the endplates and the crash structure. Lastly there is a 15cm slot in the middle of the rear wing, this prevents the airflow under the wing stalling and allows the wing to be steeper for more downforce.
Also the double turning vane solution fitted between the front wheels seen since the cars launch, has been changed for a simpler vane hanging from the front of the monocoque. The size and angle of this vane is much less aggressive than other teams have adopted. Allied to this change, Ferrari dropped the fences running along the edge of the front splitter. Most teams run these fences to prevent air flow spilling off it and passing under the floor.
Lastly, Ferrari also changed its front wheel fairing. It now extends forward to cover part of the rim and tyre for general aerodynamic improvement.
There's an unusual scallop on the BMW Sauber front wing endplate © XPB
At first it appears Toyota copied the Brawn front wing endplate solution. But on closer inspection it is closer to Ferrari's set up in that it has a vane added outboard of a conventional endplate. Toyota's vane is larger than Ferrari's however. Plus the cascade element has been merged into the main shape of the endplate.
A shapely vane on the Toyota endplate aids flow around the front tyre. © AUTOSPORT
Like Ferrari, Toyota's rear wing also sports an extra element in front of the beam wing. This is an unusual loophole in the bodywork rules, although the new element is quite thin, the effect it would have on conditioning the flow the beam wing would be useful given that the car has been shorn of other such devices as part of the new rules package.
Red Bull Racing
Having changed very little since its late launch, Red Bull's RB5 sported a slightly revised front wing.
The endplates gained small fins on the front upper edge, which most was likely to shed vortices to send the flow around the front wheels rather than for downforce production. As predicted at its launch, the Red bull engine cover had several cooling outlets which were opened up for the heat in Malaysia.
This tall vane on the Williams front wheel fairing aids flow to the rear of the car. © AUTOSPORT
Force India ran a new front wheel fairing allied to a vane on the front wing endplate © XPB
The Brawn team received a lot of attention at both races, thanks both to its pace and the legality of its diffuser.
Brawn's diffuser creates a more open double decker effect than that of the Williams or Toyota's. It's curved lower section (yellow) is there simply to meet the 'bodywork facing the ground' rules, and probably adds very little to the diffuser's efficiency. It is the taller section above it that aids the car's downforce.
Brawn has its own take on the double decker diffuser concept. © AUTOSPORT
Brawn suffered gearbox problems at both races and also a number of problems with their starts. It is reported that this was related to the SECU not being perfectly tuned to the Mercedes engine just yet. Also smoke was seen coming from the cars on Friday practice in Malaysia, but this was just an over-filled oil tank and not a technical problem.