This system was called « S-duct » because of the shape of the duct housed in the space of 150 mm which it was authorized to occupy in front of the axis of the front wheels. And while the design still bears the same name almost a decade later, the complexity has increased somewhat over the years.
S-duct of the Sauber C31
The turning point came in 2016 when Toro Rosso and Mercedes came up with solutions that allowed them to place the air intake much further forward, as had been the case with the interpretation of the nose duct of the Ferrari in 2008.
This was made possible by an interpretation of the rules regarding the single section, implying that the entrance is not really a hole but rather a shell-shaped opening. A cut was made in the device, which made it possible to comply with the single section required by the regulations.
Therefore, when you look in the entry of many solutions, you will see separators that help teams maintain this legality.
Only one team on the grid does not currently have an S-duct on their car (McLaren), with the other teams having spent the last few years tweaking theirs.
At the front of the grid, Mercedes and Red Bull Racing show similarities at the nose with a « cape » attached to the main part.
However, the internal and external configuration of the S-ducts is very different, as can be seen below in the illustrations by Giorgio Piola.
Both have air inlets on either side of the nose in the forward position, to suck in air earlier. But while Mercedes maintains separate channels on the right and left to feed the airflow to the outlet housed on the chassis-mounted cosmetic panel, Red Bull has merged its channels into one that feeds a much narrower outlet.
There are several reasons why a team may choose one design format over another for S-duct internal piping. However, the most obvious is the make-up of the internal structure of the nose, which must be able to pass the strict requirements of the FIA crash tests.
Speaking of Red Bull’s nose, it’s also worth noting the changes the team have made to their device to improve flow under the chassis. You’ll notice that while most teams, like Mercedes, create a narrow « boat tail » under the nose towards the middle section of the cape, Red Bull has opted for a wider opening.
This opening is now under the chassis, in the section where the team used to house their guide vanes, and it provides a controlled passage for the airflow collected under the nose.
Red Bull Racing RB16B and RB16 noses comparison