Mercedes problem!

[//j17]

Leithen said:

The bodywork appears to be secondary to the primary issue which is the floor.

The floor that attached to the bodywork...

With a 'wide bottom' sidepod design the upper bodywork extends more to the outter edge of the floor, so supporting and stiffening it more to its edges. With the Mercedes 'narrow/zero bottom' sidepod design the floor extends further out past the bottom of the body, meaning a large area of floor that needs to support itself. The thinking is on the Mercedes this outer/edge area is flexing with the aero loads/vibrations/etc at high speed...and with a ground effect cars it's that outser area that 'seals' the fast air under the car giving the ground effect. If that seal isn't consistent the amount of fast air being kept under the car will change, which will change the ground effect pulling the car down. Again the thinking as none of this has been tested (or rather revealed publically by Merc.) is that the car hits X mph and generates Y ground effect, compressing the car into the ground by Z - but this causes the floor edge to flex (a tiny bit) changing the seal and letting air escape. That lost air reduces the generated ground effect to Y-1 so the compression on the car reduces to Z-1 and the car lifts up. That reduction in compressive load lets the floor edge 'unflex', giving the better seal again, so increasing ground effect to Y again, which compresses the car Z back in to the ground...which causes the floor edge to flex and we porpoise down the road.

[sparta6]

HustleRussell said:

I bet it'll be a front runner by the end of the season, and I bet it'll pay dividends from 2023-2025.

So a return to endless front row lockouts and cruising off into the distance ?

Just what the sport needs

[wpa1975]

//j17 said:

Leithen said:

The bodywork appears to be secondary to the primary issue which is the floor.

The floor that attached to the bodywork...

With a 'wide bottom' sidepod design the upper bodywork extends more to the outter edge of the floor, so supporting and stiffening it more to its edges. With the Mercedes 'narrow/zero bottom' sidepod design the floor extends further out past the bottom of the body, meaning a large area of floor that needs to support itself. The thinking is on the Mercedes this outer/edge area is flexing with the aero loads/vibrations/etc at high speed...and with a ground effect cars it's that outser area that 'seals' the fast air under the car giving the ground effect. If that seal isn't consistent the amount of fast air being kept under the car will change, which will change the ground effect pulling the car down. Again the thinking as none of this has been tested (or rather revealed publically by Merc.) is that the car hits X mph and generates Y ground effect, compressing the car into the ground by Z - but this causes the floor edge to flex (a tiny bit) changing the seal and letting air escape. That lost air reduces the generated ground effect to Y-1 so the compression on the car reduces to Z-1 and the car lifts up. That reduction in compressive load lets the floor edge 'unflex', giving the better seal again, so increasing ground effect to Y again, which compresses the car Z back in to the ground...which causes the floor edge to flex and we porpoise down the road.

Makes sense, doubt they can make it much stiffer without adding more weight.

[Byker28i]

wpa1975 said:

Makes sense, doubt they can make it much stiffer without adding more weight.

But if a little weight means the car is significantly more driveable and then faster?

[jimPH]

Byker28i said:

wpa1975 said:

Makes sense, doubt they can make it much stiffer without adding more weight.

But if a little weight means the car is significantly more driveable and then faster?

They could always take off a sandbag if weight is an issue.

[//j17]

Byker28i said:

wpa1975 said:

Makes sense, doubt they can make it much stiffer without adding more weight.

But if a little weight means the car is significantly more driveable and then faster?

And I be amazed if any F1 car actually tipped the scales at 798kg without the help of some (optimally positioned) ballast.

The issue's probably the fact the floor might only be flexing by a fraction of a mm, so hard to detect WHERE it's happening - espcially as this doesn't seem to be something that came up in the CFD or wind tunnel testing. That tiny flex could be the butterly's wing beat that amplifies with each oscillation till it becomes the serious porpousing that can be seen.

[LordGrover]

//j17 said:

The floor that attached to the bodywork...

With a 'wide bottom' sidepod design the upper bodywork extends more to the outter edge of the floor, so supporting and stiffening it more to its edges. With the Mercedes 'narrow/zero bottom' sidepod design the floor extends further out past the bottom of the body, meaning a large area of floor that needs to support itself. The thinking is on the Mercedes this outer/edge area is flexing with the aero loads/vibrations/etc at high speed...and with a ground effect cars it's that outser area that 'seals' the fast air under the car giving the ground effect. If that seal isn't consistent the amount of fast air being kept under the car will change, which will change the ground effect pulling the car down. Again the thinking as none of this has been tested (or rather revealed publically by Merc.) is that the car hits X mph and generates Y ground effect, compressing the car into the ground by Z - but this causes the floor edge to flex (a tiny bit) changing the seal and letting air escape. That lost air reduces the generated ground effect to Y-1 so the compression on the car reduces to Z-1 and the car lifts up. That reduction in compressive load lets the floor edge 'unflex', giving the better seal again, so increasing ground effect to Y again, which compresses the car Z back in to the ground...which causes the floor edge to flex and we porpoise down the road.

That's interesting. Ta.

Does the Ferrari porpoise for the same reason?
It doesn't seem as bad as Mercedes, but it deffo looks a bit bouncy-bouncy at times.

[Nova Gyna]

LordGrover said:

//j17 said:

The floor that attached to the bodywork...

With a 'wide bottom' sidepod design the upper bodywork extends more to the outter edge of the floor, so supporting and stiffening it more to its edges. With the Mercedes 'narrow/zero bottom' sidepod design the floor extends further out past the bottom of the body, meaning a large area of floor that needs to support itself. The thinking is on the Mercedes this outer/edge area is flexing with the aero loads/vibrations/etc at high speed...and with a ground effect cars it's that outser area that 'seals' the fast air under the car giving the ground effect. If that seal isn't consistent the amount of fast air being kept under the car will change, which will change the ground effect pulling the car down. Again the thinking as none of this has been tested (or rather revealed publically by Merc.) is that the car hits X mph and generates Y ground effect, compressing the car into the ground by Z - but this causes the floor edge to flex (a tiny bit) changing the seal and letting air escape. That lost air reduces the generated ground effect to Y-1 so the compression on the car reduces to Z-1 and the car lifts up. That reduction in compressive load lets the floor edge 'unflex', giving the better seal again, so increasing ground effect to Y again, which compresses the car Z back in to the ground...which causes the floor edge to flex and we porpoise down the road.

That's interesting. Ta.

Does the Ferrari porpoise for the same reason?
It doesn't seem as bad as Mercedes, but it deffo looks a bit bouncy-bouncy at times.

Yeah, really interesting. Thanks for the explanation.

Any ideas as to why the Merc’ looked relatively calm during one of the early sessions, Friday I think when GR set fastest time?

The next day/session it looked as if the porpoising was as bad as ever

[Dunit]

They have fitted support stays but these only support a small area , And the Ferrari does do the hokey pokey as well but in a different zone.
The only one who has got on top of this completely is Red Bull , But Adrian must have had knowledge of this from his past designs!
This is why they are so quick at the end of the straight, Ferrari has a equally powerful engine but is still comprisied by the porpoise drama.

[Sandpit Steve]

wpa1975 said:

Makes sense, doubt they can make it much stiffer without adding more weight.

They’ll be trying out dozens of different ways to lay up the carbon and other composites, in order to specifically stiffen the affected area in the direction it needs to be stiffer, while adding as little weight as possible to the design.

It’s not the work of a week or two, which is why we haven’t seen a new floor yet. Maybe in Barcelona?

[//j17]

Nova Gyna said:

Yeah, really interesting. Thanks for the explanation.

Hey, don't over-quote me, I wasn't explaining the issue, just explaining one of the possible theories that might, perhaps, be just one explanation of the issue Mercedes are having. It could turn out to be something completely different!

That's the real issue Mercedes have though, they have a number of theories but don't (or at least initially didn't) know exactly what the issue is as it wasn't something that came up in CFD/windtunnel testing. And with testing milage and in-season development spend limited it's not like they can just try bolting sensors/test parts on and have a test driver hammer up and down a runway to see what makes it better/what makes it worse.

[Frimley111R]

sparta6 said:

HustleRussell said:

I bet it'll be a front runner by the end of the season, and I bet it'll pay dividends from 2023-2025.

So a return to endless front row lockouts and cruising off into the distance ?

Just what the sport needs

That's pretty much happened every year in F1 with one team or another

[//j17]

Frimley111R said:

sparta6 said:

HustleRussell said:

I bet it'll be a front runner by the end of the season, and I bet it'll pay dividends from 2023-2025.

So a return to endless front row lockouts and cruising off into the distance ?

Just what the sport needs

That's pretty much happened every year in F1 with one team or another

It's what generally happens when they change the regulations, as someone will guess better than the rest and maintain that lead for a few seaons due to the leading taking a development step forward for every two steps the rest of the field make. They don't tend to stay ahead for too many seasons if the rules are stable though as it's a game of deminishing development returns - and for a lot of stuff the rest of the field can see what you've done and copy it.

But the FIA being the FIA they are always looking backwards, so you have three of four seasons where team X is dominant and they decide they need to spend two years coming up with regulation changes to 'fix' things...the two seasons where the pack has generally close in on the leaders and multiple teams are fighting for race victories and titles, just to get split up again by the new rules coming in.

[swampy442]

//j17 said:

t the car hits X mph and generates Y ground effect, compressing the car into the ground by Z - but this causes the floor edge to flex (a tiny bit) changing the seal and letting air escape. That lost air reduces the generated ground effect to Y-1 so the compression on the car reduces to Z-1 and the car lifts up. That reduction in compressive load lets the floor edge 'unflex', giving the better seal again, so increasing ground effect.

I thought it was the exact opposite, the floor edge flexes down, sealing it and chocking venturi, which suddenly loses downforce and pops the car up, once the ride height in increased the venturi unchokes, downforce is restored, car sits down

[//j17]

swampy442 said:

//j17 said:

t the car hits X mph and generates Y ground effect, compressing the car into the ground by Z - but this causes the floor edge to flex (a tiny bit) changing the seal and letting air escape. That lost air reduces the generated ground effect to Y-1 so the compression on the car reduces to Z-1 and the car lifts up. That reduction in compressive load lets the floor edge 'unflex', giving the better seal again, so increasing ground effect.

I thought it was the exact opposite, the floor edge flexes down, sealing it and chocking venturi, which suddenly loses downforce and pops the car up, once the ride height in increased the venturi unchokes, downforce is restored, car sits down

Could be - unless we have an Mercedes insider we're all guessing really

Making ground effect work is all about taking as much air as you can in at the front and getting it to go into a smaller and smaller space. To get the same volume of sir into a smaller space if needs to go faster, and the faster the airspeed the lower the air pressure. Critically though you want the amount of air going in one end and out the other to be stable. The edges of the floor control how much air can escape out the sides and so avoid the venturi. If the edges of the floor had an oscillating flex that would be constantly cycling the airflow through the venturi and so downforce. Equally though if the leading edge of the floor had an oscillating flex that would be changing the size of the entry hole, so the airflow getting into the venturi with similar results. Actually thinking about it that could potentially have even worse results as the leading edge flex could be causing an eddy/making the airflow into the ventrui turbulant rather than laminar, which would be very ugly from the aerodynamics POV!

Or it might not be a direct impact. From what I've read, without the option of movable side skirts as the last generation of ground effect cars this generation are using all sorts of aerodynamic witchcraft, deliberatly generating vortexes to run down the side of the floor and act as a barrier to air escaping the ventrui. This could be some other part of the floor flexing and interfearing with those vortices.

Glad I'm not an F1 aerodynamicist and having to try and work it out!

[SturdyHSV]

//j17 said:

To get the same volume of sir into a smaller space if needs to go faster

I've typically heard women say the opposite. Ba-dum tish.

[Hill92]

Who said F1 isn't relevant to road cars anymore?

https://youtube.com/shorts/TGSxD_8mmd0

[Hazmat1]

Recent article from
Toto said it was an easy fix, stiffen the floor to the point it stops flexing and then it’s all fixed.

However they were reluctant as there is so much Time gained if your floor can flex just the right amount and produce even more downforce, The teams that manage this will have a huge advantage Hence the persistence with the current floor

[HustleRussell]

Also stiffness is presumably weight. No point fixing the flex and then being 10kg+ over.

[TheDeuce]

Hazmat1 said:

Recent article from
Toto said it was an easy fix, stiffen the floor to the point it stops flexing and then it’s all fixed.

However they were reluctant as there is so much Time gained if your floor can flex just the right amount and produce even more downforce, The teams that manage this will have a huge advantage Hence the persistence with the current floor

The floor basically just needs to give up 'enough' to prevent the stop/start routine of negative pressure that leads to porpoising. Working in the flexible elements that make that possible without falling foul of the regs is the really tricky bit.

They're up against what is legal right now, not what is possible.