Why don't all F1 cars have S-ducts?

[AlainProst]

It's probably a silly question but I'm not an expert so I will ask you why all teams don't have a S-duct. It seems that it is proven to be beneficial in any car ?

[Silent Storm]

It's probably a silly question but I'm not an expert so I will ask you why all teams don't have a S-duct. It seems that it is proven to be beneficial in any car ?

Different aero philosophy. It's not that you can just bolt on a S-duct and it will give you downforce. Mclaren, Redbull and Toro Rosso have their front designed with the S-duct in mind.

[AlainProst]

Yeah, I understand what you say but I don't see what problems can cause a S-Duct...
Have you an idea of that ?

The first S-duct is created there over 3 years I think. I feel that only some teams working on it (Red Bull, Sauber, McLaren and Force India now) while other teams are never interested them (I am thinking especially of Ferrari). Do you have an aerodynamic explanation for this?

[chuckdanny]

I think it's the same reason as for the gt cars and others like the pikes peak 208 where the radiator outlet is exiting in front of the windscreen, it alter the way that the air accelerate while taking the curve at the edge between windcsreen and roof hence producing lift. So it reduces lift.
The reason why we see it more on the medium (large) to long nose is that the undernose behaves a bit like a diffuser but without a proper extractor like a short nose in ground effect is. Air speed is less.
So the longer nose create a bigger turbulent boundary layer growth which is detrimental to the proper functionning of the sidepod flow so it is extracted by the s-duct. THe 2 functions i can see.

To sum up, long nose => greater length and slower speed(under), 2 reasons why turbulent boundary layer growth is bigger.
Almost short(medium) but wide and too big inlet => less speed so greater turbulent boundary layer growth (potential dirty air)
I would had, may be its one the functions of the angry bird of the W06 to catch that dirty air and bring it to a more controllable structure that is a vortex : vorticity concentration.

There is maybe another possible explanation (pick the good one ). THe way the nose is shaped (tight tip, more or less incline) work the air differently (wether short or long or medium nose) that is despite the low nose you still get the same amount of air going toward the sidepod because the air does not go along the top profil of the nose but it goes around. In doing so part of it is swirling back from the side to the inlet in a vortex that prevent dirty air from arising, do you get the picture? I don't need my cfd tool anymore, good
So, in the ferrari case, only a fraction near the top of air goes over the top and from near the top, little acceleration plus a streamwise swirl control the turbulent boundary layer, no need of a hard to fit s-duct whose gains would be marginals in this case.

For ferrari : they are working on a short nose, there pull suspension maybe is less compact especially as they increased the stiffness of it because the kinematic was all over the place, non linear effects.

[AlainProst]

Thanks for your answer chuckdanny ! I'm impressed by the quality of the explainations I can find on this forum It's the best forum that I never saw.