Visualising the aerodynamic rules of 2009
Formula One will never be the same again. It has been given a completely different look and a much reduced development cost by the introduction of the most radical (aerodynamic) changes since banning the ground effect cars.
While it was previously explained why there was a need for new regulations, here follows a deeper look into the aerodynamic rule changes. Under the motto "an image says a thousand words", we - F1technical and mariof1 - have created a model that reflects the new outset of bodywork limitations.
One of the crucial changes introduced by the overtaking working group is a major shift in front wing filosophy. Because if was found that the smaller and higher wing were counter-productive for overtaking, the design jumped 10 years backward. The new wing is now allowed to be wider and low to the ground.
The above image marks the most important areas that specify where bodywork is allowed. Any area outside of the drawn zones is forbidden - leaving aside the nose cone which was left out for simplicity.
Marked in yellow is the most crucial part to improve overtaking. In this area, the FIA set very stringent regulations by specifying exactly the aerofoil dimensions that go here. The aim was to neutralise the middle part of the front wing as it is the most susceptible to a leading car's wake.
The green area then denotes a zone where all sorts of bodywork is allowed, as long as its surface is no more than 20,000mm².
Article 3.7.5 is marked in the image with red, which 3.7.6-7 relate to the blue, outer parts of the front wing.
3.7.6 : Ahead of the front wheel centre line and between 840mm and 900mm from the car centre line there must be bodywork with a projected area of no less than 28,000mm2 in plan view. Furthermore, when viewed from underneath, the bodywork in this area must form one continuous surface which may not be more than 100mm above the reference plane.
3.7.7 : Any longitudinal vertical cross section taken through bodywork ahead of the front wheel centre line and between 840mm and 900mm from the car centre line must contain an area no greater than 15,000mm2.
Article 3.18 of the technical regulations specify a novelty in Formula One. It defines the area where driver-adjustable bodywork is allowed. As such, the area marked yellow defines the bounds where bodywork is allowed to "change incidence while the vehicle is in motion within a maximum range of 6°, provided any such change maintains compliance with all of the bodywork dimensional regulations."
At the same time, the rules also stipulate that the movement is strictly limited to be controlled by the driver by means of the standard ECU. Except when the car is in the pit lane, a maximum of two adjustments may be made within any single lap of a circuit.
Bodywork around the front wheels
The dimensions of allowed bodywork around the front wheels have also been altered to remove all types of appendages on the car. It was found that the teams spent lots of time developing turning vanes in this area. Since the FIA considers this 'invisible' to the fans, they have moved to simplify this area too, immediately helping to reduce the aerodynamic development costs.
Note the area under the nose, in between the front wheels where no bodywork is allowed. It is actually this rule, specified in 3.11.2 that is the subject deciding whether the nose cone of the Renault R29 is allowed.
Getting rid of winglets
For several years it was found that the unlimited addition of flipups, winglets and gills had to be limited somehow. Powered by the need to reduce costs, several areas of the bodywork ahead of the rear wheels are now bound to be continuous sections without apertures - apart for the exhausts and suspension beams.
In the above images, all green areas mark the total surface that prohibits aerodynamic bodywork extensions, as specified in article 3.8.4.
- the volume between 50mm forward of the rear wheel centre line and 300mm rearward of the rear face of the cockpit entry template, which is more than 25mm from the car centre line and more than 100mm above the reference plane ;
- the volume between 300mm rearward of the rear face of the cockpit entry template and the rear face of the cockpit entry template, which is more than 125mm from the car centre line and more than 100mm above the reference plane
- the volume between the rear face of the cockpit entry template and 450mm forward of the rear face of the cockpit entry template, which is more than 350mm from the car centre line and more than 100mm above the reference plane.
The surfaces lying within these volumes, which are situated more than 55mm forward of the rear wheel centre line, must not contain any apertures (other than those permitted by Article 3.8.5) or contain any vertical surfaces which lie normal to the centre line of the car.
3.8.5 : Once the relevant bodywork surfaces are defined in accordance with Article 3.8.4, apertures may be added for the following purposes only :
- single apertures either side of the car centre line for the purpose of exhaust exits. These apertures may have a combined area of no more than 50,000mm² when projected onto the surface itself.
- apertures either side of the car centre line for the purpose of allowing suspension members and driveshafts to protrude through the bodywork. No such aperture may have an area greater than 12,000mm² when projected onto the surface itself.
The regulations therefore ban CART-alike flipups, winglets, midwings, shark gills chimneys and McLaren's bull horns in the specified areas. Given the limited areas where bodywork is allowed, it has also become nearly impossible to add airbox wings like Williams and Toyota have often used in the recent past.
Further limitations on allowed bodywork just ahead of the rear wheels have also made sure that most of the rear wheels is free into the airstream - mark how the maximum height of bodywork ahead of the rear wheels decreases in two steps. This alone would have banned flipups as we used to know them.
A rear end with less downforce and reduced efficiency
The rear end changes are all designed by the overtaking working group as they aim to reduce downforce while also creating a wake that is more useful for a trailing car.
First of all, the rear wing height has been increased to match the car's maximum height, while its width is reduced. These changes make the rear wing less efficient while also simplifying its design. Previously, due to the proximity of the rear wing and the diffuser, the rear wing's design itself greatly influenced the diffuser because of its powerful upwash. By its increased height, the rear wing's own upwash is more independent from the rear of the rear, making it easier to design and test.
Additionally, any bodywork in this area must produce uniform, solid, hard, continuous, rigid (no degree of freedom in relation to the body/chassis unit), impervious surfaces under all circumstances.
Apart from these changes however, other specifications for the rear wing have remained the same. There is still a maximum of 2 horizontal panels allowed in the upper area of the rear wing. This limitation is only valid in the areas that are more than 75mm away from the centreline of the car and hence does not outlaw Toyota's 2008 rear wing. Just like last year these elements must be supported with a spacer to ensure its rigidity.
The rear wing endplates meanwhile still are similar in width but can now extend from the level of the car's stepped plane to the car's maximum height. The Red Bull RB5 for instance greatly puts this to use by extending the end plates to the floor, making these also effective for the diffuser - and again adding to the coupling between rear wing and diffuser. Only the area marked as yellow does require a minimal surface to ensure advertising space.
The diffuser itself has been moved backward compared to 2008. While its maximum height was increased to 175mm, the tall central channel is now missing, resulting in a net downforce decrease. The central part of the car still allows the diffuser to be a little longer, and when designed wisely can be helped by the rear impact shock absorber (between 200mm and 400mm above the reference plane.
For a broader view on all the rules changes, make sure to check out Red Bull's animation that overviews the key areas.