Explaining Rake and Why More Teams Are Making a Switch
High rake cars are turning into a thing of the past; but Red Bull still believe in it.
Rake : The angle of the floor relative to the horizontal
Basically, positive rake means the rear is higher than the front and negative rake is when the rear is lower than the front. All the F1 teams run positive rake; but the matter in question here is the level of rake. It might seem like a small thing, but it has huge influence over your car's overall aerodynamics.
At one end of the spectrum you have Red Bull, who run an extreme version, and at the other you have Mercedes, who instead have a more passive concept.
So what's the difference?
In simple terms higher rake cars are more aerodynamically effective, but also more unstable.
Like most things in Formula 1, the actual answer on the high rake debate isn't black and white. The rake angle at which you have the car set up is, simply, an aerodynamic factor. The more angle you can apply without the diffuser flow being disturbed, then the more downforce you can create due to the larger volume of air flowing at a faster rate.
But there's always a limit where you can't achieve anymore downforce because there is too much disturbance (turbulent flow) in the system, so the flow under the car isn't uniform and efficient - the bane of aerodynamicists existence.
This could be what is happening to Red Bull this year, where the theoretical downforce peaks it can achieve in the wind tunnel aren't matched by the reality of how its car performs on track. Disturbance can be triggered by various factors, including ride height sensitivity, turbulence created by the front and rear wheels, an inefficient aerodynamic design or side winds (atmosphere in general) interfering with the flow.
This gives you an unstable rear with inconsistent grip and, inevitably, oversteer or a spin. This is what we've seen plenty of this year with Red Bull, especially in the earlier stages. In Austria, Styria (same place, but still) and Hungary they had significant issues.
Now this worked really well for them in the V8 era, back when they were pumping air through the engine and blowing the exhaust gases into the diffuser so equally pumping the rake higher and higher was mitigated by the downforce created by the blown diffuser.
Along with their flexi-wings, which managed turbulence coming off the front wheels, the high rake concept proved to be gold during their era of dominance.
As we moved into the hybrid era, some of those tricks were stripped away because the overall design of the cars were simplified.
This opened the door for the emergence of an aerodynamic rival to the high rake solution used by Red Bull. Mercedes, with its lower rake philosophy, made up some of the aerodynamic deficit by increasing the wheelbase, therefore increasing the length of the floor and lessening the impact that the turbulence had on its floor and diffuser by allowing the turbulence to straighten out as much as possible before hitting the all-important rear end.
Mercedes had and still continues to go for a more consistent and usable amount of downforce over a wider range of operating conditions that comes with their philosophy, rather than the absolute peak that’s possible with a higher rake setup.
In the case of Mercedes, this has always been helped by a very compliant suspension setup too, firstly with FRIC and, when it got banned, with independent hydraulic suspension arrangements (article talking about that on Wednesday), all of which keep the platform of the car more stable.
It’s an extremely long and costly road to travel to change from one concept to another, with rake just one ingredient in a very finely balanced recipe.
High rake has essentially become Red Bull’s hallmark and means it is unlikely to switch from it. The other teams that followed suit, which is most of the field, also went through the pain and expense of trading one concept for another.
But with Mclaren also considering switching from one idea to the other, maybe it is time, in the current climate at least, to consider low-rake concepts becoming the norm in F1.
The end of an era (sort of) for Red Bull?