Ferrari SF-25

[FDD]

One thing I haven't seen talked about is that for all the reduction in sidepod size, the lower part that meets the floor has become noticeably bulkier this year. So I think we can see where some of the internal repackaging efforts have gone.

Ton of empty volume underneath the sidepod. They can always pull the v-wall back if need be. What's interesting is how far outboard the floor stays are mounted.

https://ibb.co/5X291cJQ

Exactly what I wanted to say.
I noticed 2 different trends, some cars try to create a high pressure point there, some try to avoid it.
At least we know Ferrari is not unable to create a larger cutout, but they choose not to!

This means either different floor philosophies, or different aero tunnel correlation perhaps?
I think that area is the most deciding factor of current cars, determining if the car is stable in the corners or less so. Other aerodynamic parts seems to be a lot more straightforward and understood I think.

Maybe they'll create a larger cut out in later stages of development, playing now on the save side and getting data from this aero model.
I do not know, not an aero expert, just thinking about the next development steps.

[maxxer]

They have a new shorter gearbox, am I correct?
I was curious if they used the gained space for the diffuser, and it seems like that to me.

Looks that way. Central and side vertical kicks on the boat section seem to be adding efficient downforce, being in high ground effect zone, which is why teams try using them as much as possible most likely. They are probably susceptible to ride height changes and this is why Ferrari and Red Bull had to remove them after the summer break last year

Do you work in f1 ? your posts are so detailed

[Vanja #66]

Do you work in f1 ? your posts are so detailed

No, people working for F1 teams aren't allowed to go into some of these details privately, let alone publicly

[Vanja #66]

Low-speed Analysis

On many occasions in Bahrain test, we could see SF-25 having a small, but clear rake angle, indicating significantly higher rear end in static conditions. This allows the team to employ softer suspension in the first phase of spring compression, ensuring optimal traction levels getting out of low speed corners

This also means the diffuser kick on the floor will be quite high on SF-25, which means lower Ground Effect benefits and thus stronger front end. In low-speed, this may not be a huge aerodynamic loss as the softer rear end will make up aero-load grip with better mechanical grip - when everything is working perfectly.

Ferrari ran a relatively high F1-75 in 2022, while RB18 also had a small rake angle - most likely for these same benefits



Medium-speed Analysis

In these corners, the rear should start going down quicker than the front and this should start to balance out the floor performance overall. The trick in this corner speed range is finding optimal balance between mechanical traction (softer suspension) and stable rear aero load (stiffer suspension) to provide peak performance on corner exits



High-speed Analysis

With these cars, high-speed sections require extreme low ride heights and very stiff suspension in this final compression phase. This means all the rear traction on corner exits comes from aero load and in these speeds (say 220-230+ kmh) these loads are extremely high, so the floor balance needs to be shifted to the rear

In my view, Ferrari is achieving this despite relatively high diffuser kick with the help from central keel-kick (analysed in the original quoted post) now being very low to the ground and reaching peak efficiency. Additionally, diffuser vortices are getting stronger due to bigger pressure difference under the floor and this also boosts rear end performance

Ferrari tried using this combination of diffuser and keel kick on SF-24 and it worked until it didn't - with Barcelona upgrade package. These things are now getting very tricky to iron out and find the optimal balance, simply because these cars are reaching their performance ceiling and small gains seen in CFD and Wind Tunnels may not be seen on track and/or may be having a slightly different operating window due to unintended floor material flexure

[FDD]

https://i.ibb.co/bg0xztMR/ezgif-com-ani ... -maker.gif

Low-speed Analysis

On many occasions in Bahrain test, we could see SF-25 having a small, but clear rake angle, indicating significantly higher rear end in static conditions. This allows the team to employ softer suspension in the first phase of spring compression, ensuring optimal traction levels getting out of low speed corners

This also means the diffuser kick on the floor will be quite high on SF-25, which means lower Ground Effect benefits and thus stronger front end. In low-speed, this may not be a huge aerodynamic loss as the softer rear end will make up aero-load grip with better mechanical grip - when everything is working perfectly.

Ferrari ran a relatively high F1-75 in 2022, while RB18 also had a small rake angle - most likely for these same benefits

https://pbs.twimg.com/media/GlWVaHsWMAA ... name=large

Medium-speed Analysis

In these corners, the rear should start going down quicker than the front and this should start to balance out the floor performance overall. The trick in this corner speed range is finding optimal balance between mechanical traction (softer suspension) and stable rear aero load (stiffer suspension) to provide peak performance on corner exits

https://pbs.twimg.com/media/GlWWsIfWQAA ... name=large

High-speed Analysis

With these cars, high-speed sections require extreme low ride heights and very stiff suspension in this final compression phase. This means all the rear traction on corner exits comes from aero load and in these speeds (say 220-230+ kmh) these loads are extremely high, so the floor balance needs to be shifted to the rear

In my view, Ferrari is achieving this despite relatively high diffuser kick with the help from central keel-kick (analysed in the original quoted post) now being very low to the ground and reaching peak efficiency. Additionally, diffuser vortices are getting stronger due to bigger pressure difference under the floor and this also boosts rear end performance

Ferrari tried using this combination of diffuser and keel kick on SF-24 and it worked until it didn't - with Barcelona upgrade package. These things are now getting very tricky to iron out and find the optimal balance, simply because these cars are reaching their performance ceiling and small gains seen in CFD and Wind Tunnels may not be seen on track and/or may be having a slightly different operating window due to unintended floor material flexure

https://pbs.twimg.com/media/GlWXPidWQAA ... name=large

Awesome as always, great insight, easy to understand, you have to work as a profesor.
Question, every aero expert is saying that pull rod is generating outwash, do you have any visualisation for this or if you don't can you make/explain?
Thank you

[Vanja #66]

Awesome as always, great insight, easy to understand, you have to work as a profesor.
Question, every aero expert is saying that pull rod is generating outwash, do you have any visualisation for this or if you don't can you make/explain?
Thank you

Basically, Newton's 3rd law applies on aerodynamics as well - obviously. Airplane wing produces upward force and so the airflow as the medium doing the work will proceed to go down - so we have downwash. It's the opposite on race car wings, they generate upwash.

The pull rod is placed at an angle in front view, so when the front wing upwash hits it it will generate a lifting force, so the airflow passing it will continue with reduced upwash and some outwash component

However, I think the big part of going with pull rod on these cars might be cleaning up the geometry on top of the chassis to provide cleaner path locally

[venkyhere]

Awesome as always, great insight, easy to understand, you have to work as a profesor.
Question, every aero expert is saying that pull rod is generating outwash, do you have any visualisation for this or if you don't can you make/explain?
Thank you

Basically, Newton's 3rd law applies on aerodynamics as well - obviously. Airplane wing produces upward force and so the airflow as the medium doing the work will proceed to go down - so we have downwash. It's the opposite on race car wings, they generate upwash.

The pull rod is placed at an angle in front view, so when the front wing upwash hits it it will generate a lifting force, so the airflow passing it will continue with reduced upwash and some outwash component

However, I think the big part of going with pull rod on these cars might be cleaning up the geometry on top of the chassis to provide cleaner path locally

https://i.ibb.co/tpn4yxQL/Untitled.png

Continuing in the same vein, Q :

1) the pullrod's carbon fibre "wrapper" , does it have an aerofoil cross section, and if it does, is it like an airplane 'wing' , ie to 'grab' as much pressure 'underneath' the rod (sacrificing a small amount of downforce on the tyres) so as to 'straighten' the flow as much as possible before it enters the mid section (cooling intake, sidepod underside pressurisation) of the car ?

2) what about the 'wrappers' around other 'elements' of the suspension - wishbones and track/tie rod ; do them as well have an aerofoil profile, and are they all 'lift' generation type ?

[sucof]

Awesome as always, great insight, easy to understand, you have to work as a profesor.
Question, every aero expert is saying that pull rod is generating outwash, do you have any visualisation for this or if you don't can you make/explain?
Thank you

Basically, Newton's 3rd law applies on aerodynamics as well - obviously. Airplane wing produces upward force and so the airflow as the medium doing the work will proceed to go down - so we have downwash. It's the opposite on race car wings, they generate upwash.

The pull rod is placed at an angle in front view, so when the front wing upwash hits it it will generate a lifting force, so the airflow passing it will continue with reduced upwash and some outwash component

However, I think the big part of going with pull rod on these cars might be cleaning up the geometry on top of the chassis to provide cleaner path locally

https://i.ibb.co/tpn4yxQL/Untitled.png

Continuing in the same vein, Q :

1) the pullrod's carbon fibre "wrapper" , does it have an aerofoil cross section, and if it does, is it like an airplane 'wing' , ie to 'grab' as much pressure 'underneath' the rod (sacrificing a small amount of downforce on the tyres) so as to 'straighten' the flow as much as possible before it enters the mid section (cooling intake, sidepod underside pressurisation) of the car ?

2) what about the 'wrappers' around other 'elements' of the suspension - wishbones and track/tie rod ; do them as well have an aerofoil profile, and are they all 'lift' generation type ?

As for everything there is a rule for this. Based on the frontal "thickness" some length is allowed for the covers of the rods. Or for the shape of them. Meaning, all teams use this to make all of the parts of the suspension system aerodynamically positive for the car.
They even design the suspension in order to put certain elements to certain places where they can have the most positive effect.
These covers as I know, might have a few degrees of rotation difference as well compared to neutral. So they can guide air up, down, produce downforce or lift.
This is especially interesting at the rear suspension where they usually put the driveshaft in line with one suspension element, using the rule to create a large common cover for them, guiding air just before the diffuser, where it is so important. Check out images over the net.

[Vanja #66]

Continuing in the same vein, Q :

1) the pullrod's carbon fibre "wrapper" , does it have an aerofoil cross section, and if it does, is it like an airplane 'wing' , ie to 'grab' as much pressure 'underneath' the rod (sacrificing a small amount of downforce on the tyres) so as to 'straighten' the flow as much as possible before it enters the mid section (cooling intake, sidepod underside pressurisation) of the car ?

2) what about the 'wrappers' around other 'elements' of the suspension - wishbones and track/tie rod ; do them as well have an aerofoil profile, and are they all 'lift' generation type ?

Suspension fairings need to have symmetrical aero foils, there are tight limits on angle in relation to reference plane and they have to have decent relative thickness of 1/3.5 which is 2-3 times as thick as typical general aviation wing today. Maximum chord is 100mm or 150mm for drive shaft plus another suspension member

[Brahmal]

However, I think the big part of going with pull rod on these cars might be cleaning up the geometry on top of the chassis to provide cleaner path locally

https://i.ibb.co/tpn4yxQL/Untitled.png

I recall one of the team staff talking about how the pull-rod aero interaction with the front brake duct as an additional advantage over push-rod, but cannot find the quote.