Mercedes W15

[matteosc]

The cylinder alone is not the mechanism my friend.

Huh? The basic prinpicle and motion are the same. Just the parts are looking a bit differently. So yes: basically the same as last year, but no: freshly made and redesigned parts.

Essentially all the brackets are redesigned and the actuation is along a pretty different angle. The angle at which it is attached to the wing is also significantly different, but that may be due to the different wing to start with.

[Emag]

What's peculiar about Mercedes is that they have undergone a rather significant philosophy shift from the W13 and W14, and yet the high speed weakness + bouncing is still haunting them.

This hints towards a deeper fundamental issue that somehow Mercedes is missing the third year in a row. It just seems to me, that from a conceptual point of view, their aerodynamics is not flawed in itself since we've seen RedBull incorporate design elements of the W14 into their own car and see benefits from it. But there must be something about the Mercedes' platform which is not allowing them to exploit the full potential they see from their design in CFD / wind tunnel.

We've had Ferrari sticking to their own suspension configuration, with the technical team there claiming suspension design is overrated, words which I must admit, I thought would come to bite them in the ass. However they have kind of proven their point with how that car is performing.

That's why I don't think the suspension configuration is to blame for whatever is troubling Mercedes at the moment. It's bizarre how this car was losing ~0.6s to McLaren in S1 at Jeddah. That's an enormous amount of laptime which you can't attribute to wing/downforce levels alone.

[matteosc]

What's peculiar about Mercedes is that they have undergone a rather significant philosophy shift from the W13 and W14, and yet the high speed weakness + bouncing is still haunting them.

This hints towards a deeper fundamental issue that somehow Mercedes is missing the third year in a row. It just seems to me, that from a conceptual point of view, their aerodynamics is not flawed in itself since we've seen RedBull incorporate design elements of the W14 into their own car and see benefits from it. But there must be something about the Mercedes' platform which is not allowing them to exploit the full potential they see from their design in CFD / wind tunnel.

We've had Ferrari sticking to their own suspension configuration, with the technical team there claiming suspension design is overrated, words which I must admit, I thought would come to bite them in the ass. However they have kind of proven their point with how that car is performing.

That's why I don't think the suspension configuration is to blame for whatever is troubling Mercedes at the moment. It's bizarre how this car was losing ~0.6s to McLaren in S1 at Jeddah. That's an enormous amount of laptime which you can't attribute to wing/downforce levels alone.

Agreed: suspension configuration is likely not the real issue, even though it could be related to the suspension's internal parts of to how it is operated.

[Vanja #66]

What's peculiar about Mercedes is that they have undergone a rather significant philosophy shift from the W13 and W14, and yet the high speed weakness + bouncing is still haunting them.

This hints towards a deeper fundamental issue that somehow Mercedes is missing the third year in a row

My strong suspicion is the lack of proper procedures in establishing floor performance targets. Ferrari had to reinvent their post-TD39 floor targets and design verification procedures last year - which different conditions for CFD/WT are to be used, how they are weighed to determine which design direction to follow etc. I'm sure Mercedes also did this, but somehow they seem to have missed something. Think they will need to "sacrifice" a weekend and practice sessions to perform new and expanded correlation runs, like Ferrari did in Zandvoort 2023.

[SiLo]

What's peculiar about Mercedes is that they have undergone a rather significant philosophy shift from the W13 and W14, and yet the high speed weakness + bouncing is still haunting them.

This hints towards a deeper fundamental issue that somehow Mercedes is missing the third year in a row

My strong suspicion is the lack of proper procedures in establishing floor performance targets. Ferrari had to reinvent their post-TD39 floor targets and design verification procedures last year - which different conditions for CFD/WT are to be used, how they are weighed to determine which design direction to follow etc. I'm sure Mercedes also did this, but somehow they seem to have missed something. Think they will need to "sacrifice" a weekend and practice sessions to perform new and expanded correlation runs, like Ferrari did in Zandvoort 2023.

Have we seen them run any pitot tubes underneath the floor like a lot of other teams have?

[Espresso]

What's peculiar about Mercedes is that they have undergone a rather significant philosophy shift from the W13 and W14, and yet the high speed weakness + bouncing is still haunting them.

This hints towards a deeper fundamental issue that somehow Mercedes is missing the third year in a row

My strong suspicion is the lack of proper procedures in establishing floor performance targets. Ferrari had to reinvent their post-TD39 floor targets and design verification procedures last year - which different conditions for CFD/WT are to be used, how they are weighed to determine which design direction to follow etc. I'm sure Mercedes also did this, but somehow they seem to have missed something. Think they will need to "sacrifice" a weekend and practice sessions to perform new and expanded correlation runs, like Ferrari did in Zandvoort 2023.

They are having problems in the high speed corners.
just my 2 cents…
Seems they have kinda controlled stability in the lateral axis better but not at all in the longitudinal axis. Stalling the outside in the high speed corners and porpoising as result.

Micro porpoising is sadly still visible at high speed straights. MB still got a lot of homework to do…

[ing.]

Porpoising is ultimately an aeroelastic phenomenon so interaction between aero, elastic (suspension) and inertia loads and where damping (structural, suspension, and aero) is critical.

Since this can’t be tested or simulated prior to the roll out of the actual car and a scale model with representative weight, stiffness, suspension, etc.—similar to what is done for airplanes, sans suspension obviously—is a practical impossibility, the car needs to be properly modeled to predict its dynamic behaviour. I suspect that this is what Merc don’t have a good handle on.

Underfloor aero and floor sealing edges will be huge contributors to its behaviour as contrary to airplane design where the lifting wings are designed to avoid twisting and creating more lift as they deflect, in F1 as the floor and edge translate down and deflect (the floor edge) the DF increases—this is an unstable situation prone to aeroelastic anomalies if the damping is inadequate. I believe some teams have a better handle on this modeling and the result is better control of the porpoising through appropriate floor design (and understanding of its performance mapping) and suspension behaviour and modeling.

And, who knows, perhaps Merc’s choice of having a quite horizontal rear push rod layout is not providing sufficient motion ratio so damping effectiveness is compromised.

[Vanja #66]

Have we seen them run any pitot tubes underneath the floor like a lot of other teams have?

As far as I saw, this year they didn't. But we saw them do it in 22 and 23.

They are having problems in the high speed corners.
just my 2 cents…
Seems they have kinda controlled stability in the lateral axis better but not at all in the longitudinal axis. Stalling the outside in the high speed corners and porpoising as result.

Micro porpoising is sadly still visible at high speed straights. MB still got a lot of homework to do…

Whatever is going on needs to be measured and correlated before it can be fixed. Last year in Monaco their floor was visibly lower (lower tunnels) than RB floor, this means raw performance which may not be as sustainable over wide range of conditions as Mercedes believes it is.

[Stu]

Porpoising is ultimately an aeroelastic phenomenon so interaction between aero, elastic (suspension) and inertia loads and where damping (structural, suspension, and aero) is critical.

Since this can’t be tested or simulated prior to the roll out of the actual car and a scale model with representative weight, stiffness, suspension, etc.—similar to what is done for airplanes, sans suspension obviously—is a practical impossibility, the car needs to be properly modeled to predict its dynamic behaviour. I suspect that this is what Merc don’t have a good handle on.

Underfloor aero and floor sealing edges will be huge contributors to its behaviour as contrary to airplane design where the lifting wings are designed to avoid twisting and creating more lift as they deflect, in F1 as the floor and edge translate down and deflect (the floor edge) the DF increases—this is an unstable situation prone to aeroelastic anomalies if the damping is inadequate. I believe some teams have a better handle on this modeling and the result is better control of the porpoising through appropriate floor design (and understanding of its performance mapping) and suspension behaviour and modeling.

And, who knows, perhaps Merc’s choice of having a quite horizontal rear push rod layout is not providing sufficient motion ratio so damping effectiveness is compromised.

Nice analysis.
I do wonder how much of their issue is related to the change to 18” wheels/tyres and the removal of TMD’s from the suspension system. This would complicate modelling and has a big knock-on effect on suspension rates & system control, couple that with the very acute pushrod position (and it’s effect on motion ratio), so they may have solved their modelling issues and created a kinematic issue?
Some will question this (because Aston Martin…), but from the outside it seems plausible.

[Espresso]

Porpoising is ultimately an aeroelastic phenomenon so interaction between aero, elastic (suspension) and inertia loads and where damping (structural, suspension, and aero) is critical.

+1 Well said. They might look and learn from the past how it has been done. Not taking lessons from the past is a missed opportunity. Also understanding the correlation (read working together) seems to me a missing piece of the puzzle. They are in deer need of someone (like ing. ) who has a bird´s eye view and grasp off the whole context.

[ing.]

Porpoising is ultimately an aeroelastic phenomenon so interaction between aero, elastic (suspension) and inertia loads and where damping (structural, suspension, and aero) is critical.

Since this can’t be tested or simulated prior to the roll out of the actual car and a scale model with representative weight, stiffness, suspension, etc.—similar to what is done for airplanes, sans suspension obviously—is a practical impossibility, the car needs to be properly modeled to predict its dynamic behaviour. I suspect that this is what Merc don’t have a good handle on.

Underfloor aero and floor sealing edges will be huge contributors to its behaviour as contrary to airplane design where the lifting wings are designed to avoid twisting and creating more lift as they deflect, in F1 as the floor and edge translate down and deflect (the floor edge) the DF increases—this is an unstable situation prone to aeroelastic anomalies if the damping is inadequate. I believe some teams have a better handle on this modeling and the result is better control of the porpoising through appropriate floor design (and understanding of its performance mapping) and suspension behaviour and modeling.

And, who knows, perhaps Merc’s choice of having a quite horizontal rear push rod layout is not providing sufficient motion ratio so damping effectiveness is compromised.

Nice analysis.
I do wonder how much of their issue is related to the change to 18” wheels/tyres and the removal of TMD’s from the suspension system. This would complicate modelling and has a big knock-on effect on suspension rates & system control, couple that with the very acute pushrod position (and it’s effect on motion ratio), so they may have solved their modelling issues and created a kinematic issue?
Some will question this (because Aston Martin…), but from the outside it seems plausible.

If I’m not mistaken, Fallows made some comments that implied he wasn’t fully convinced about the rear suspension he inherited from Merc though trying to figure what exactly was the issue would be pure speculation.

[ing.]

Porpoising is ultimately an aeroelastic phenomenon so interaction between aero, elastic (suspension) and inertia loads and where damping (structural, suspension, and aero) is critical.

+1 Well said. They might look and learn from the past how it has been done. Not taking lessons from the past is a missed opportunity. Also understanding the correlation (read working together) seems to me a missing piece of the puzzle. They are in deer need of someone (like ing. ) who has a bird´s eye view and grasp off the whole context.

I would imagine Merc have some pretty clever boffins working this but I also imagine it’s not a simple task. The science of aeroelasticity in aerospace is quite mature but adapting the principles to a ground (and ground effects) vehicle is not the work of a few days. Unlike in aerospace I don’t imagine there is much literature and exchange of knowledge on the subject.

[PlatinumZealot]

What's peculiar about Mercedes is that they have undergone a rather significant philosophy shift from the W13 and W14, and yet the high speed weakness + bouncing is still haunting them.

This hints towards a deeper fundamental issue that somehow Mercedes is missing the third year in a row. It just seems to me, that from a conceptual point of view, their aerodynamics is not flawed in itself since we've seen RedBull incorporate design elements of the W14 into their own car and see benefits from it. But there must be something about the Mercedes' platform which is not allowing them to exploit the full potential they see from their design in CFD / wind tunnel.

We've had Ferrari sticking to their own suspension configuration, with the technical team there claiming suspension design is overrated, words which I must admit, I thought would come to bite them in the ass. However they have kind of proven their point with how that car is performing.

That's why I don't think the suspension configuration is to blame for whatever is troubling Mercedes at the moment. It's bizarre how this car was losing ~0.6s to McLaren in S1 at Jeddah. That's an enormous amount of laptime which you can't attribute to wing/downforce levels alone.

Well W14 is the same philosophy actually. Nothing changed just a midseason sidepod "upgrade". The chassis and floor concept was the same as W13 but a bit "tamer" so they could get a better base-line.

The W15 is a clean concept change, but the underlying ways of work and the base creativity of the existing Mercedes engineering team has been lacking compared to RedBull and Ferrari.

There is something about the aerodynamics and suspensions interaction with it that they are not able to capture with their tools and techniques.

I don't blame Lewis for seeing his way out in this slump.

[PlatinumZealot]

What's peculiar about Mercedes is that they have undergone a rather significant philosophy shift from the W13 and W14, and yet the high speed weakness + bouncing is still haunting them.

This hints towards a deeper fundamental issue that somehow Mercedes is missing the third year in a row

My strong suspicion is the lack of proper procedures in establishing floor performance targets. Ferrari had to reinvent their post-TD39 floor targets and design verification procedures last year - which different conditions for CFD/WT are to be used, how they are weighed to determine which design direction to follow etc. I'm sure Mercedes also did this, but somehow they seem to have missed something. Think they will need to "sacrifice" a weekend and practice sessions to perform new and expanded correlation runs, like Ferrari did in Zandvoort 2023.

Agreed. Very poor, or low quality racing scanarios combined with the CFD mesh of the car from front to back as it goes through these scenarios it whats I think they behind in.

Imagine the car in roll and yaw through a high speed turn, with all the tyredeflections, tyre squirt, heat from the brakes etc... I bet their mesh is not capturing all that!

[Henk_v]

A mesh is the spatial translation of 3D data for a solver. It "does" nothing but define the lattice for the Navier/Stokes equations.