Mercedes AMG F1 W04

[BlackMercedes]

With ferraris exhaust exits seems to push the hot air around the tyre whereas merc and Rb want the airflow between the rear tyre and rear wing

[wesley123]

With ferraris exhaust exits seems to push the hot air around the tyre whereas merc and Rb want the airflow between the rear tyre and rear wing

Both solutions do the same thing; They try to get the exhaust airflow in between the diffuser and tire.

[turbof1]

With ferraris exhaust exits seems to push the hot air around the tyre whereas merc and Rb want the airflow between the rear tyre and rear wing

They are not. What benefit is there to push them around the tyre? Basicilly it is very simple to tell where they want the exhaust plume: between the tyre and the diffuser, sealing the latter for more rake. That is also why Red Bull can run such a big angle of rake: the ramp leaves no room for the plume to move even slightly out of position. The trade-off of course is less airflow towards the beam wing and start motor hole.

Actually, the amount of rake of a car runs, tells how well a team succeeds in pulling the exhaust gasses down.

[Nando]

In terms of Ferrari and Mercedes, Ferrari´s is probably more efficient but with the downside that it blows hot air right on to the rear tires, something Mercedes definitely do not need

[Artur Craft]

With ferraris exhaust exits seems to push the hot air around the tyre whereas merc and Rb want the airflow between the rear tyre and rear wing

They are not. What benefit is there to push them around the tyre? Basicilly it is very simple to tell where they want the exhaust plume: between the tyre and the diffuser, sealing the latter for more rake. That is also why Red Bull can run such a big angle of rake: the ramp leaves no room for the plume to move even slightly out of position. The trade-off of course is less airflow towards the beam wing and start motor hole.

Actually, the amount of rake of a car runs, tells how well a team succeeds in pulling the exhaust gasses down.

are you sure about this?

I know rake gives more downforce even if you are not sealing the diffuser with any exhaust gases whatsover. I was guessing what limits the rake they run is the front suspension and etc which will controll the splitter's height and avoid it to crack into the floor

Obviously the sealing of diffuser would enhance the rake effect even more as it would block some air, coming from the sides, to disrupt the underfloor flow, but I'm not sure if the sealing of diffuser is a limiting factor for rake necessarily

[Drewd11]

With ferraris exhaust exits seems to push the hot air around the tyre whereas merc and Rb want the airflow between the rear tyre and rear wing

They are not. What benefit is there to push them around the tyre? Basicilly it is very simple to tell where they want the exhaust plume: between the tyre and the diffuser, sealing the latter for more rake. That is also why Red Bull can run such a big angle of rake: the ramp leaves no room for the plume to move even slightly out of position. The trade-off of course is less airflow towards the beam wing and start motor hole.

Actually, the amount of rake of a car runs, tells how well a team succeeds in pulling the exhaust gasses down.

are you sure about this?

I know rake gives more downforce even if you are not sealing the diffuser with any exhaust gases whatsover. I was guessing what limits the rake they run is the front suspension and etc which will controll the splitter's height and avoid it to crack into the floor

Obviously the sealing of diffuser would enhance the rake effect even more as it would block some air, coming from the sides, to disrupt the underfloor flow, but I'm not sure if the sealing of diffuser is a limiting factor for rake necessarily

To my knowledge (which isnt much) the rake is correllated to how successfully the teams are sealing the diffuser by the simple fact that the more rake you run, the larger vertically the gap you need to seal between the diffuser and the tire. Hence, the more rake you can run while still effectively sealing the diffuser is to some extent an indication into how successful you have been with your exhaust solution.
This is because rake comes not only from how low your front end is but how high your rear is; if I remember correctly there were pictures on this forum showing what looked like a higher rear end of the floor on the W04 than some of the other teams.

[scarlet]

It's a question of balancing gains at the front with the rear. Ramping up the rake will almost always give gains in downforce at the front (lower front wing and splitter = better ground effects for these components). But this will only be beneficial if the downforce gained at the front can be balanced with gains at the rear. Raising the rear does increase diffuser volume, good in theory, but as explained beforehand the higher sides of the diffuser become much harder to seal, and if a team cannot do this the loss of diffuser performance, and rear downforce, will be massive.

If it was as simple as more rake = more downforce, with sealing an added extra, all teams would run the max allowed, and they don't.

[RicerDude]

The larger the exit of the diffuser the lower the pressure inside so you need a better seal created by the exhaust plume between the tire and diffuser edge to prevent the low pressure from sucking in the ambient air. Is this right?

[Nando]

I know rake gives more downforce even if you are not sealing the diffuser with any exhaust gases whatsover.

Almost. Let´s say you have no exhaust blowing anywhere near the diffuser, then you have a window where you have the optimal rake.
Below it and you are not utilizing all the potential, above it and you lose downforce.

[turbof1]

It's a question of balancing gains at the front with the rear. Ramping up the rake will almost always give gains in downforce at the front (lower front wing and splitter = better ground effects for these components). But this will only be beneficial if the downforce gained at the front can be balanced with gains at the rear. Raising the rear does increase diffuser volume, good in theory, but as explained beforehand the higher sides of the diffuser become much harder to seal, and if a team cannot do this the loss of diffuser performance, and rear downforce, will be massive.

If it was as simple as more rake = more downforce, with sealing an added extra, all teams would run the max allowed, and they don't.

That's because they can't fully seal it when it is max ramped. When it isn't fully sealed, air will spill and the diffuser will stall. That is why they are using since 2011 the exhausts to seal it so that they can increase the rake. They never could run such a rake if not for the exhaust plume. More sealing=more rake=more downforce. But teams are only limited in how much they can seal it; the only legal way is using the exhaust plume which has a minimum distance to the diffuser, and is angled away from it. So a little refrasing: the better teams are able to pull the plume down=the more sealing=the more rake=the more rear downforce. That was my original point: by the amount of rake you can tell how good a team is able to pull down the plume and to seal the diffuser.

The front is much less a concern. If it gives too much downforce they can always lower the AoA to balance it out. Removing downforce is by all means MUCH easier then adding it. More downforce by a lower front wing is actually a bonus: it allows you to convert the extra downforce into surface for flow conditioning to the back.

I know rake gives more downforce even if you are not sealing the diffuser with any exhaust gases whatsover.

Almost. Let´s say you have no exhaust blowing anywhere near the diffuser, then you have a window where you have the optimal rake.
Below it and you are not utilizing all the potential, above it and you lose downforce.

Yes, exactly. The exhaust gasses used to seal the diffuser, will allow you to go beyond that point without having the diffuser stalling at low speed. The more rake, the more surface you have to seal off to block air from spilling into the diffuser.

[k.ko100v]

IMO, even without blowing, the high rake gives more downforce. But this leads to very big CoG, and the downforce and the mechanical grip must compensate this, espesially in the mid and high speed corners.
High rake speaks for good mechanical grip and extremly good Rear DF (respectively blowing) which compensate the high CoG.

Turbo21: Here we don't have blowing but... we have DD which gives the amount of DF to compensate the high CoG

[turbof1]

The cars are designed with rake build in; they actually don't have to do anything with the suspension; they only rake the floor.

Look at the red bull As you see, only the floor has an angle; the rest of the car is more or less straight. The CoG penalty is easily been offset by the aero advantage.
The Brawn does indeed feature an interesting rake. Perhaps due the double diffuser it does not stall?

[beelsebob]

The cars are designed with rake build in; they actually don't have to do anything with the suspension; they only rake the floor.
As you see, only the floor has an angle; the rest of the car is more or less straight.

Nope. The floor exists on what is known as the "reference plane", and the "step plane". These two planes are parallel, and the rest of the car based around them. The front wing has a defined height that it must be, relative to extending the floor along the reference plane. The boxes you can put things in, or can't, are again, specified relative to the reference plane. The above photos all show a car built relative to the reference plane being level (the floor being level), and then having the car raked using the suspension.

[R_Redding]

The amount of rake seen on the car is an indication of how well the front wing is working and how well they have sealed the undersides of the floor.

The best example of a sealed underfloor would be the dragged skirt cars of the late 70,early80s.

The teams will try to run as much rake as they can , as the front wing will perform better the closer it is to the ground due to ground effect.(more df , less drag).

But they also use the front wing to create a vortex down the side of the car in an effort to create a air curtain.

Most top teams now run underwing VGs and front wings with complex end plates,which try to create vortices around either side of the tyre, just enough to get passed the tyre ,and then back to the underside

This CFD image from SFI shows the endplate and VG streams coming from the front wing to seal the floor sides.


So more rake in the W04 is prolly acievable because of a much better front wing http://www.formula1.com/wi/gi/597x478/f ... 4fe042.JPG

Rob

[Mika1]

Well, Rob that FW is outdated, they have a new one. I think you mean that one .