McLaren MP4-28 Mercedes

[Pup]

http://www.f1technical.net/forum/viewto ... 50#p420650

[Tim.Wright]

Yea I still think everyone (except for one person on that page) have it backwards. It might have anti dive, but its a very low value. Tilting the arms back like that lowers the anti dive effect because it puts the side view instant centre down near the ground plane.

[trinidefender]

Yea I still think everyone (except for one person on that page) have it backwards. It might have anti dive, but its a very low value. Tilting the arms back like that lowers the anti dive effect because it puts the side view instant centre down near the ground plane.

Anti dive doesn't have much to do with that. The main way to produce anti-dive is produced by the use of heave springs and the like. They are bars, torsion bars, springs, dampers and struts that stop the front from pitching up and down to much. It is very similar in the way that an anti roll bar stops a vehicle from rolling left and right by connecting left and right wheels however works in a longditudanal plane rather than a horizontal one.

Mercedes solution to this is the much more complicated FRIC system where all of the dampers are passively connected together. The reason other teams probably don't use it is that it took Mercedes two seasons previous to this one just to get it to run properly.

[yener]

So far we've seen band aids on the car.
Mclaren are pretty good on aero development. They don't often miss. If they have been trying to fix the car for the past 4 races, expecting the problem to go away with each attempt, i'd be worried.
Truth is Mclaren know what their problem is, but the problem is so messed up, it's not just a simple wing change and voila! Redbull beater!
Putting a new nose on a dog of a car wont magically make everything work. The whole front wing affects "everything behind it" is true to some extent, but is very over exaggerated and overstated to the point things get out of hand.

Loking on last years car, which was very quick coming down to season's end, and this year's car you will have to look on what has changed.
It's more logical to point out the changes as the problem than something tried and proven like the front wing.

Now maybe, just maybe they do need a new multi element wing, to synchronize with the aerodynamic characteristics of what they have now. Maybe the Mp4-28 transient behavior warrants a 5 element wing. But the elephant in the room may be the less easier to blame things. Things that take more analysis to understand or things that simply cannot be changed, like the tub, and the team has to work around it.

Exactly that!
In my opinion they closed last season with the fastest car. What i find confusing is that McLaren changed their approach and suddenly got the duck nose (its covered) and changed alot compared to last years car. How is that logical while the rules remain the same? If you have a diamond you have to polish it, not cut pieces out of it.
i was quite confused and surprised seeing them with the "ducknose". Now they have a higher CoG and they ruined something worthfull they had.
They should go back to last years car and put all the aero updates they made this year especially the rear suspension bones. Honestly i think that would put them more to the front.

[Tim.Wright]

Yea I still think everyone (except for one person on that page) have it backwards. It might have anti dive, but its a very low value. Tilting the arms back like that lowers the anti dive effect because it puts the side view instant centre down near the ground plane.

Anti dive doesn't have much to do with that. The main way to produce anti-dive is produced by the use of heave springs and the like. They are bars, torsion bars, springs, dampers and struts that stop the front from pitching up and down to much. It is very similar in the way that an anti roll bar stops a vehicle from rolling left and right by connecting left and right wheels however works in a longditudanal plane rather than a horizontal one.

Then your understanding of anti dive is different to the definition used by everybody in the industry...

Anti dive is a geometric effect which comes from the kinematics of the control arms. It decides what ratio of braking force is tries to extend the suspension against the effects of forward load transfer. It (typically) has nothing to do with springs arbs etc, the effect comes almost purely from the links.

With regards to the McLaren, it looks to me, that the side view instant centre is near or below the ground. That means almost zero or a negative amount of the braking force is working to open the suspension.

Perhaps they are running low anti dive because they have hard springs at the front. Perhaps they have hard springs at the front because they have low anti dive.. who knows.

But basically, everybody need to stop saying this car has "extreme anti dive" because its actually quite the opposite. Any bit of reading on the subject will clear that up for you. Draw an FBD of the hub in side view during a braking event and you will see the same.

[trinidefender]

Yea I still think everyone (except for one person on that page) have it backwards. It might have anti dive, but its a very low value. Tilting the arms back like that lowers the anti dive effect because it puts the side view instant centre down near the ground plane.

Anti dive doesn't have much to do with that. The main way to produce anti-dive is produced by the use of heave springs and the like. They are bars, torsion bars, springs, dampers and struts that stop the front from pitching up and down to much. It is very similar in the way that an anti roll bar stops a vehicle from rolling left and right by connecting left and right wheels however works in a longditudanal plane rather than a horizontal one.

Then your understanding of anti dive is different to the definition used by everybody in the industry...

Anti dive is a geometric effect which comes from the kinematics of the control arms. It decides what ratio of braking force is tries to extend the suspension against the effects of forward load transfer. It (typically) has nothing to do with springs arbs etc, the effect comes almost purely from the links.

With regards to the McLaren, it looks to me, that the side view instant centre is near or below the ground. That means almost zero or a negative amount of the braking force is working to open the suspension.

Perhaps they are running low anti dive because they have hard springs at the front. Perhaps they have hard springs at the front because they have low anti dive.. who knows.

But basically, everybody need to stop saying this car has "extreme anti dive" because its actually quite the opposite. Any bit of reading on the subject will clear that up for you. Draw an FBD of the hub in side view during a braking event and you will see the same.

I stand corrected. One of the things with suspension set up is that you can only see part of the suspension and unlike aero where it is clear how you can see everything working. Nobody knows the compression and rebound settings on the suspension either. It does APPEAR that the front is set up very hard to run as low a ride height as possible.

[Tim.Wright]

It does APPEAR that the front is set up very hard to run as low a ride height as possible.

A stiff front combined with low anti dive makes senses. But like I said, I don't know which is the cause and which is the effect.

Maybe the stiff front influences the decision to use low anti dive...
Maybe the low anti dive forces them to use stiffer springs...

[Pup]

More likely I'd think that the stiffness is an attempt to control the porpoising they're experiencing. Rigid might be a more apt description, given the video that was posted a few weeks back. But then, Mclaren have been running rock hard suspensions since '09 I think, though they seem to be able to keep all the wheels on the ground these days.

[PlatinumZealot]

Rock hard since 2009 Singapore.. They managed to control it a little bit from 2011.

[trinidefender]

Seems their cars have been biased toward more of an aero grip setup that a pure mechanical grip set up. Hence the really high nose, stiff suspension and very aggressive aero bodywork which hasn't worked for them as intended

[Jackles-UK]

Couple of points i've considered over the last few days:

1. With regards to the McLaren trait of rock-hard suspension - if the suspension doesn't move then almost all of the damping is taken place through the tyres. With the changes to the rigidity/construction of the sidewalls (and the now infamous strange 60% tyre model that Pirelli gave to the teams for that matter) could it have hindered McLaren more because they rely more on the flex through the tyres which is either doing more or less bouncing than anticipated in 60% form?

2. The car seems to be far better in race-trim than in qualifying, but as the race goes on both drivers seem to have lost late places - could this be due to the added weight of the fuel dragging the car along the ground into its optimum operating window (in a similar way to the way it did in Jerez all that time ago)? Obviously it's not faster with the fuel in but maybe they lose comparatively less performance than others?

[Lycoming]

why does stiff suspension mean that the dampers aren't doing anything? If you play with the bellcrank motion ratios, even with the small amount of wheel movement that they have, you can still get enough damper movement for them to be working. The tire of course has its own damping properties but even under the best of circumstances thats rather difficult to measure/model.

[PlatinumZealot]

The cars only race at about 80% (?) of their maximum so the base performances of the cars come closer together.. but at peaks of performance needed in qualifying, there is a huge gap between the fast cars and the slow ones.

[Pup]

why does stiff suspension mean that the dampers aren't doing anything?

It doesn't, and surely they are. Just that any front suspension movement in the video posted earlier is imperceptible.

2. The car seems to be far better in race-trim than in qualifying, but as the race goes on both drivers seem to have lost late places - could this be due to the added weight of the fuel dragging the car along the ground into its optimum operating window (in a similar way to the way it did in Jerez all that time ago)? Obviously it's not faster with the fuel in but maybe they lose comparatively less performance than others?

Possibly. The Mercs certainly seem to prefer low fuel, if the last race is any guide - two different cars. The McLaren also seems to be a bit nicer to its tires on heavy fuel, but that advantage doesn't seem to cary through to the final stint.

[Tim.Wright]

1. With regards to the McLaren trait of rock-hard suspension - if the suspension doesn't move then almost all of the damping is taken place through the tyres. With the changes to the rigidity/construction of the sidewalls (and the now infamous strange 60% tyre model that Pirelli gave to the teams for that matter) could it have hindered McLaren more because they rely more on the flex through the tyres which is either doing more or less bouncing than anticipated in 60% form?

Not only the damping but most of the springing contribution in an F1 car is in the tyres. The tyres are typically a lot less damped than the suspension itself, so the more you rely on them the less damped the "complete" (springs + tyres) axle seems to be.

A note on the 60% tyres: As far as I know, they are only a "shape" for the wind tunnel. The teams wouldn't be extracting any other data from them like spring rate, damping etc. There isn't yet the technology to scale a tyres mechanical properties down to 60%.