Win number three for Brawn GP in Paris?

The hearing follows protests made in Melbourne by Ferrari, Red Bull and Renault, claiming the 'double decker' diffusers on the Brawn, Toyota and Williams cars are against the regulations. BMW Sauber also made a protest, but this was rejected as it was made too late. These seven teams, along with McLaren, will all be present at the FIA headquarters today.

The regulations on diffusers no limit the main part of the diffuser to a width of 1000mm, a length of 350mm and a height of 175mm. Most teams have taken a very literal interpretation of this, and produced remarkably simple diffuser designs. However, the 'diffuser three' have exploited a loophole in the diffuser rules, themselves simply part of a wider range of bodywork regulations.

One key part is that all three cars have a 'hole' to feed air to the diffuser, where the flat floor meets the diffuser. On the Brawn car, this is, importantly, a vertical hole.

Rory Byrne, Ferrari's Design and Development Consultant, gave his view. "It's a rule set at least 14-15 years ago, and that for many years everyone interpreted in the same way," Byrne told Gazetta dello Sport. "If you look at the Brawn car from underneath, you can see the suspension."

Article 3.12.5 of the Formula One technical regulations states that "Fully enclosed holes are permitted in the surfaces lying on the reference and step planes provided no part of the car is visible through them when viewed from directly below." As the hole is vertical, by very definition you would not be able to see through it from below.

Additionally, article 3.12.1 defines clearly that the regulations only extend to sprung parts of the car. "All sprung parts of the car situated from 330mm behind the front wheel centre line to the rear wheel centre line, and which are visible from underneath, must form surfaces which lie on one of two parallel planes, the reference plane or the step plane." The suspension is, clearly, an unsprung part of the car.

Further back, the central crash structure is being used to create a third channel in the diffuser. Again, the seven other team shave taken a very simple interpretation of the regulations, and come up with a boxy structure. Brawn have a heavily contoured crash structure that conditions the airflow, making the diffuser work harder and, therefore, adding to the downforce available.

Finally, there is an ambiguous rule which appears to allow more than one surface to exist in this area, where the bodywork is defined separately from the diffuser. This has allowed the 'diffuser three' to create multiple levels. The main diffuser is as long, wide and tall as the rules allow, but the floors appear to extend into the upper area of the diffuser, creating an opening that allows airflow above the main diffuser element and, in doing so, creates a larger exit area. This creates a lower pressure area that literally pulls the car to the ground.

The case in Paris will no doubt revolve around whether these extra channels are to be considered part of the diffuser, or part of the bodywork. A case could be made either way, with careful interpretation. However, some of the complainants appear to be basing their cases on the three cars being against the spirit of the rules.

Our expectation is that the diffusers for Australia and Malaysia will be declared legal, and the race wins for Jenson Button and Brawn GP will stand. The legality going forward is unclear, and the FIA could find either way.

However, there's always been designers in F1 coming up with something seemingly innocuous that gives a car huge chunks of time, and then putting something very visible on the car to deflect attention. Could that be the case at Brawn GP? We believe so.

Trick diffuser or not, let the wins continue.