2011 rule changes - ban on double diffusers 03 February 2011
Brawn GP pioneered the concept to championship-winning effect in 2009, everyone had them in 2010, and now they are outlawed. The 2011 rules make it clear that there must be no gap between reference plane, step plane and diffuser, so no more big holes in the underbody like those seen in this Ferrari image from last season. Single, blown diffusers are still allowed, but regardless, the proportion of downforce generated by the diffuser will be far lower.
FIA Technical Regulation
3.12.9 - In an area lying 450mm or less from the car centre line, and from 450mm forward of the rear face of the cockpit entry template to 350mm rearward of the rear wheel centre line, any intersection of any bodywork visible from beneath the car with a lateral or longitudinal vertical plane should form one continuous line which is visible from beneath the car. When assessing the compliance of bodywork surfaces in this area the aperture referred to in Article 3.12.7 need not be considered.
3.12.10 In an area lying 650mm or less from the car centre line, and from 450mm forward of the rear face of the cockpit entry template to 350mm forward of the rear wheel centre line, any intersection of any bodywork visible from beneath the car with a lateral or longitudinal vertical plane should form one continuous line which is visible from beneath the car.
3.12.11 Compliance with Article 3.12 must be demonstrated with the panels referred to in Articles 15.4.7 and 15.4.8 and all unsprung parts of the car removed.
