After Williams launched their 2013 car at Barcelona, it wasn’t long before talk soon turned to their somewhat different exhaust design. This was also a similar situation Caterham found themselves in with the CT03 at the Jerez test a few weeks ago.
Extracting downforce from the exhaust gases is a big topic in F1 as so much performance can be found when combined with the rear floor of the car, and to stop the teams going all 2011 on us when this idea was at its peak, the FIA’s technical regulations are worded extremely carefully on this subject to try and halt those clever engineers.
On what seems to be the standard exhaust exits for 2012 and now 2013, there’s a ‘tunnel’ which forms around the exit of the exhaust in order to guide the exhaust gases to where it would most improve downforce. Sauber, for example, has this on their 2013 car in much the same way as Ferrari.
In Caterham’s interpretation they’ve added a small winglet which sits inside the u-shaped tunnel. Like turning vanes that are used under the car to guide airflow, this will be used to better direct the exhaust gases to the rear of the car.
In Williams’ interpretation, rather than a turning vane-esque piece, they have added two sections which nearly form a loop, making it look like there are two exits to the exhaust tunnel.
These have both allegedly been declared illegal after a conversation with the FIA on morning of the first day at Barcelona, and most of this would seemingly fall under section 5.8.4 of the technical manual which deals with what immediately follows once the exhaust tailpipe has been defined:
There must be no bodywork lying within a right circular truncated cone which :
a) Shares a common axis with that of the last 100mm of the tailpipe.
b) Has a forward diameter equal to that of each exhaust exit.
c) Starts at the exit of the tailpipe and extends rearwards as far as the rear wheel centre line.
d) Has a half‐cone angle of 3° such that the cone has its larger diameter at the rear wheel centre line.
Furthermore, there must be a view from above, the side, or any intermediate angle perpendicular to the car centre line, from which the truncated cone is not obscured by any bodywork lying more than 50mm forward of the rear wheel centre line.
Essentially, an imaginary circular cone is projected behind the tailpipe and no bodywork is allowed to fall within that cone which match the scenarios above, as well as no bodywork must be used to block the the view of the “cone” from certain angles.
For Caterham, they may argue point a) as the exhaust tailpipe actually exits at a significantly different angle to the winglet in the u-shaped tunnel. For Williams, their additional piece doesn’t seem to fit into the cone area specified as far as I can tell and they have also left a gap (albeit very small!) – which in their view may mean the “cone” isn’t obscured from view.
Unlike a race weekend however, the teams are free to try what they want – so Caterham and Williams may continue with these interpretations while they discuss this further with the FIA, with a final say coming before the cars are sent off for the first round in Australia.