Mercedes AMG F1 W09 EQ Power+

[Just_a_fan]

The large rake cars get to run softer rear ends which helps rear tyre life. Mercedes, having less rake, can't run as soft and are struggling accordingly. They have to run stiffer rear end because, with less rake to start with, they have less "spare" ground clearance.

Isnt it rather opposite? High rake is more susceptible to ride height change because its front end floor tip is closer to the ground and gets choked easily by bumps kerbs etc. Less rake provides more consistent aero characteristics and softer suspension.

The high take cars tend to squat their rears as speed increases which allows them to shed some drag at high speed on the straights. This also means the suspension can be soft enough to help traction. The low rake cars can't afford to squat much at speed because they don't have the same "spare" ride height. Thus they need to run firmer suspension to stop the rear bottoming out at high speed. This firmer rear end hampers traction.

[Big Tea]

The track is irrelevant for the rules. The plank is the reference. The hight/angle/whatever between plank and road are free, as long as you don't scrape to much off the plank during the race. In the rule making of the plank (during the '94 season) rakes weren't "invented" yet. Those days it was normal to have the whole bottom as low to the ground as you dared.

But are not other parts measured reference to the plank? If the plank has an incline of (say) 50mm, which part of the plank can they reference? Any part? this would not seem to make sense, so I must be considering it incorrectly.

The plank/reference plane is a straight line and the technical bottom of the car. if the FW has to be 100 mm above the reference plane, you can imagine getting the wheels off the car, standing it on the plank on a level floor and then the FW has to be 100mm from the floor.

Ah!, so its the suspension that tilts the car, not body design?
I feel stupid now.

[muramasa]

The high take cars tend to squat their rears as speed increases which allows them to shed some drag at high speed on the straights. This also means the suspension can be soft enough to help traction. The low rake cars can't afford to squat much at speed because they don't have the same "spare" ride height. Thus they need to run firmer suspension to stop the rear bottoming out at high speed. This firmer rear end hampers traction.

I get what you mean as basic principle, but what it actually is not that simple, more than just simply being soft or hard or having more or less space to go down. F1 cars, particularly Mercedes have such sophisticated suspension system and Merc always had very soft/flexible suspension that moves around a lot yet car is always on the same state, as if active suspension. In this past year or two trick suspension is banned but still its suspension is more advanced than most others and the car characteristics is always this same "very soft yet stable". High rake setup cars has to squat to negate its deficit of higher drag rather than can afford to. All cars except Merc is wide nose - high rake - shorter wheelbase concept but cars lower than the top 3 are all bouncing a lot, up til last year McLaren for instance had such stiff car that it was bouncing a lot on bumps. RBR and Ferrari were managing well, but last year's Ferrari of higher rake car was no match to Merc, RBR even this year's still tend to spark more than others. Also what modern suspension does is it does not squat on corners but only do so on straight, raked cars are designed to work and produce df in that setup hence you dont want to squat on corners, and the higher the rake the more so. Considering all these, lower rake setup may have more leeway/margin in terms of suspension.

[godlameroso]

Low rake long wheelbase is also more stable under braking. For the same given weight and if it's equally stiff, a longer car will have less weight transfer. High rake means the car is more prone to aero pitch sensitivity, especially under heavy braking loads.

[henry]

Low rake long wheelbase is also more stable under braking. For the same given weight and if it's equally stiff, a longer car will have less weight transfer. High rake means the car is more prone to aero pitch sensitivity, especially under heavy braking loads.

Stiffness does not in itself directly affect weight transfer. The parameters that matter are COG height ,above the road, and wheelbase. If the high rake cars lift their rear during braking then a secondary effect due to raised COG will come in to play, increasing weight transfer. I’d guess the high rake cars have mechanisms that delay this raise to help stability and MGU-K charging.

[roon]

What's called sensitivity here might not be so bad. If the driver can toss the car around a bit more in pitch and roll, would this help them manage tire temps? The less 'stable' car would be able to spike the pressure/friction applied to the contact patches of the tires.

[godlameroso]

It's not necessarily bad, under braking the floor and the front wing both move closer to the ground, increasing front axle downforce, but equally important isn't just how hard and when you brake but also the brake release point. However when you release the brakes the front end lifts up a little and you lose some downforce before the apex. A car designed with less rake and longer wheelbase is less affected by this. The proof is in the pudding though, the Mercedes car has gone with slightly more rake this year than last, and although it's tamed some of the 'diva' characteristics(accelerating and carrying speed through low downforce low grip corners and less peak downforce), it seems like the new setup comes with it's own challenges(slightly less stable under braking).

Last year Mercedes could get away with less rake because they still had a clear power unit advantage, this year Ferrari has closed the gap on that end.

[gambler]

I agree Merc have had their act together and it would appear a flatter sitting car reflects that. I do wonder what the wind tunnel results are about it...if rake makes the car suck down, then that may be better than linear traction?

[godlameroso]

I think more importantly for Mercedes, after trying both design styles they'll come to the conclusion that the rake between the front wing and barge board/t-tray is probably more important than the rake between the diffuser and the front wing.

[roon]

...under braking the floor and the front wing both move closer to the ground, increasing front axle downforce, but equally important isn't just how hard and when you brake but also the brake release point. However when you release the brakes the front end lifts up a little and you lose some downforce before the apex.

So you're saying that they use the whole car as some sort of... movable aerodynamic device? Dear oh dear. Someone call Charlie.

[godlameroso]

...under braking the floor and the front wing both move closer to the ground, increasing front axle downforce, but equally important isn't just how hard and when you brake but also the brake release point. However when you release the brakes the front end lifts up a little and you lose some downforce before the apex.

So you're saying that they use the whole car as some sort of... movable aerodynamic device? Dear oh dear. Someone call Charlie.

Haha, it does sound silly when you put it like that doesn't it.

[Sierra117]

...under braking the floor and the front wing both move closer to the ground, increasing front axle downforce, but equally important isn't just how hard and when you brake but also the brake release point. However when you release the brakes the front end lifts up a little and you lose some downforce before the apex.

So you're saying that they use the whole car as some sort of... movable aerodynamic device? Dear oh dear. Someone call Charlie.

Don't worry Charlie, I assure you the software treats the car as two separate bodies but it is still the same body

[Shakeman]

I think more importantly for Mercedes, after trying both design styles they'll come to the conclusion that the rake between the front wing and barge board/t-tray is probably more important than the rake between the diffuser and the front wing.

Genuinely interested why this would be the case?

Are you able to elaborate please?

[godlameroso]

Simply put the two work in tandem to seal the diffuser, when they work in synergy the effect is much more powerful.

[McMrocks]

I am sure you talk about ride height. The rake (angle of the car) should be the same as the regulations take all measurements from the reference plane.

Unless the whole car is flexing