Mercedes W13

[gluon]

From the above video Peter Wright says porpoising also induce bodywork oscillating adding maybe to the car/ICE frecvency (resonance?) that can lead to break the structures...
Thus all 4 customer PU teams which also have porpoising had to run in lower ICE modes just to diminish the bodywork resonance effect. That's why W13 and these cars are clipping sooner on the straights just to compensate with more harvesting and deployment...

In addition, for raising the ride hight to diminish the porpoiseing they need to compensate the downforce loss with both bringing a barn door rear wing and also with higher levels of AoA. It'll be useful to demonstrate this theory by showing some comparison between the rear wing levels of these 5 customer teams and the rest of the grid...

This is a very interesting point and it agrees with something I've been thinking for a while now.

I didn't know about this possible resonance effect but when trying to understand how all Mercedes powered cars were seemingly more affected by porpoising I was thinking that the mass distribution of the power unit and its ancillaries (being similar among them all) could have an effect.

Maybe not the mass itself, but the geometry, materials and linkage between the PU and the chassis somehow contribute to a resonating frequency which is more aligned with the frequency created by this heave/pitch movement created by the downforce.

[Tzk]

Maybe not the mass itself, but the geometry, materials and linkage between the PU and the chassis somehow contribute to a resonating frequency which is more aligned with the frequency created by this heave/pitch movement created by the downforce.

Another thought comes to mind when reading this:
Maybe it's indeed the suspension (wishbone) layout and it may even come down to the basic layout, so for example how much anti-squat mercedes designed into the wishbone mounting points. So let's assume their anti-squat choice dictates to a certain degree the damping and spring setup on the rear end, then this should also result in a certain resonance range of the suspension. And that may (or may not) result in porpoising, which then in turn gets even stronger when the aero is affected on the straights.

So i believe it's not only aero related, but many factors are in play here which makes it quite hard to track the issue down.

[matteosc]

Maybe not the mass itself, but the geometry, materials and linkage between the PU and the chassis somehow contribute to a resonating frequency which is more aligned with the frequency created by this heave/pitch movement created by the downforce.

Another thought comes to mind when reading this:
Maybe it's indeed the suspension (wishbone) layout and it may even come down to the basic layout, so for example how much anti-squat mercedes designed into the wishbone mounting points. So let's assume their anti-squat choice dictates to a certain degree the damping and spring setup on the rear end, then this should also result in a certain resonance range of the suspension. And that may (or may not) result in porpoising, which then in turn gets even stronger when the aero is affected on the straights.

So i believe it's not only aero related, but many factors are in play here which makes it quite hard to track the issue down.

It definitely depends on both suspensions and aero and in particular on how they interact with each other. I do not think weight distribution or PU matters much, but anything is possible.
They way I see it is that is that contrary to the upper surface of the car, the bottom (floor) is heavily affected by the car height (aerodynamics related). Mercedes currently cannot properly damp the porpoising motion (suspension related) and has to reduce floor's downforce. As consequence they have to increase wing's downforce, which is way more draggy.

[murphy]

In my humble opinion it smells of correlation problems, if so then they are in trouble.

[Mchamilton]

In my humble opinion it smells of correlation problems, if so then they are in trouble.

How can it be correlation problems when porpoising cant be recreated in cfd or the wind tunnel?

[matteosc]

In my humble opinion it smells of correlation problems, if so then they are in trouble.

It is definitely related to the fact that they cannot simulate or replicate in the wind tunnel the phenomenon, but this is true for all teams. I think they just have a car which is more susceptible to poropising and they are having an hard time in figuring it out.

[Sevach]

I think it's highly likely that a lot of teams(not just Mercedes) aimed for maximum downforce between 150-270 and stall at 280+, because that has been the aim to have "everything" (downforce at most useful speeds and low drag on the straights) for years now.
Teams might've understimated what that would do in regulations where the floor is responsible for a much larger portion of the downforce than previously.

Now they have to re-do the homework on both floor and suspension.

[pursue_one's]

Updates on the way for the W13
Mercedes are expected to equip the W13 with an updated floor design for the Imola round, with an evolved aerodynamic package to include wing tweaks and a sidepod re-design at the Spanish Grand Prix.

Will these changes be enough to see Mercedes join in the fight with Ferrari and Red Bull at the front? Certainly, in the paddock, there were those betting against it – particularly if the budget cap is to be respected.

The Mercedes power unit had also come under scrutiny at this early point of the season, due to its apparent horsepower deficit to offerings from other manufacturers.

The rumours suggest it is affected by the position of the radiators, given they are partially covered by the sculpted sides of the chassis, which could affect the heat exchange for the power unit.

As aforesaid, it is just a rumour, but it appears strange that all the Mercedes-powered cars have failed to show competitively so far, despite varying chassis and aero designs.

Source: Gazzetta Newspaper

https://racingnews365.com/how-mercedes- ... porpoising

[matteosc]

I think it's highly likely that a lot of teams(not just Mercedes) aimed for maximum downforce between 150-270 and stall at 280+, because that has been the aim to have "everything" (downforce at most useful speeds and low drag on the straights) for years now.
Teams might've understimated what that would do in regulations where the floor is responsible for a much larger portion of the downforce than previously.

Now they have to re-do the homework on both floor and suspension.

I really do not think there is any planned stalling, especially not of the floor.

[Vanja #66]

How can it be correlation problems when porpoising cant be recreated in cfd or the wind tunnel?

I think teams might be able to recreate bouncing now, either in WT or CFD or both. In any case, multi-dynamics simulations can be made to capture all the suspension, aero and other effects.

When you can't replicate in simulation something happening in real life, that's correlation issue and Mercedes does have those issues. Doesn't have to be CFD alone. Driving simulator correlation is equally important as CFD correlation, if not more!

I really do not think there is any planned stalling, especially not of the floor.

There isn't, things are now very different from partial diffuser stall of yesteryear... If there is a separation somewhere in the tunnels, the whole car loses downforce and straightens mid-to-high-speed corners.

[Andi76]

Some updates from Andrew Shovlin about Mercedes trying to solve their problems. They obviously do not want to trade downforce for less porpoising :

https://www-autosport-com.cdn.ampprojec ... 08717/amp/

[LM10]

Some updates from Andrew Shovlin about Mercedes trying to solve their problems. They obviously do not want to trade downforce for less porpoising :

https://www-autosport-com.cdn.ampprojec ... 08717/amp/

I think that the cutaway floor didn't give them what they were hoping for or what it brought to other teams. If yes, they definitely would have sticked with it. So in both races they eventually went for the certain solution which at the moment is to simply increase the ride height.

The explanation of Mercedes sticking to their idea of wanting to solve the issue without losing performance sounds like they are the only team rejecting compromises. In fact every single team is working on solving it without losing downforce, not just Mercedes. With the difference being that other teams use modified floors helping them reduce the issue and bridge the time until they bring proper upgrades to completely solve the porpoising. For some reason Mercedes make it look like they by choice have given up on the part-time solution (being a modified floor) even though it would provide better performance. I don't know, it doesn't make sense at all.

[elMaestro]

So from ive read on this topic so far is that they are having issues first with suspension, then the floor and last but not least theres the engine, right?

[vorticism]

In any case, multi-dynamics simulations can be made to capture all the suspension, aero and other effects.

Indeed. The porpoise is to better understand flow across moving surfaces.

[dans79]

In any case, multi-dynamics simulations can be made to capture all the suspension, aero and other effects.

Indeed. The porpoise is to better understand flow across moving surfaces.

https://external-content.duckduckgo.com ... f=1&nofb=1

Stuff like thats is always easier to simulate, because it generally assumes the fluid is infinite in all directions. As soon as you start putting other objects in close proximity to the object you are trying to model it gets a lot more complicated!