With the 2021 Formula 1 season underway, we have been witnessing a lot of talks about the effect that the aero regulation changes have had on the current batch of cars.
For this year, we have seen the removal of part of the floors which teams were using in order to increase the downforce generated around the rear, with different types of slots poking out of them. Not only they created a stronger suction effect underneath the cars, the floor used to be very effective in fine-tuning vortexes and improving ground effect. With the 2021 regulations implying that the floor must now be solid, these slots have disappeared, reducing the downforce-generating surface area on F1 cars.
Furthermore, we have also seen changes to the rear brake duct winglets with the diffuser fences also shortened.
With Mercedes and Red Bull at complete opposites in terms of their rake philosophy and with the German team believing that their car (using a low-rake concept) has been the most affected by the new regulations, let’s look into the differences between low and high-rake F1 cars.
First, what is rake angle?
The ‘rake’ of an F1 car describes the rear ride height of an F1 car, the angle at which the car’s nose is pointing down. The high-rake concept was pioneered by Red Bull in 2009, under the supervision of Adrian Newey, in an effort to bring more downforce to their cars by generating ground effect and it was later adopted by the entire grid for some degree. The idea is that a car that is designed with a higher rake angle is able to generate a lot more downforce from the floor area and the diffuser than a lower rake one, because of the added air volume created underneath the car.
So, what is the difference between low and high-rake F1 cars? We are going to take a look at the differences between the two teams that tackled the opposed concepts best, Mercedes and Red Bull.
A low-rake F1 car has a lower rear ride height, with the car’s nose pointing down at a less aggressive angle. In recent years, Mercedes stuck to their low-rake long-wheelbase philosophy, giving the car more floor space to create volume in the area preceding the diffuser.
A high-rake F1 car has a higher ride height, with the car’s nose pointing down more aggressively. Pioneering the concept in F1, Red Bull’s high rake and shorter wheelbase concept increases the volume of air that goes through the diffuser, due to increased ground clearance.
But how big is the impact of the 2021 regulations on the F1 cars, depending on their rake concept?
Despite people initially suspecting F1’s new floor rules would hurt high-rake cars, it turns out that decreasing low-rake cars’ ability to seal the floor edges has brought bigger performance losses. With a section of the floor ahead of the rear tire cut out, teams like Mercedes seemed to struggle with sealing the edges of the new floor, losing downforce and displaying some unexpected side effects, while high-rake cars like Red Bull appeared to be less affected.
Why don’t low rake cars just raise the rear? That would solve the problem, right?
Despite popular beliefs, raising the car would not solve the problem imposed by the new aero regulations. Actually, doing that would only lead to the car losing even more performance. Low-rake F1 cars are designed (considering aerodynamics and suspension) to run only at a low-rake angle. In order to adopt a high-rake philosophy, teams like Mercedes would have to redesign their entire car.
The evidence seems to show that high-rake cars have more of an advantage in 2021, with teams running low-rake looking to find new ways of shaping the floors to cut down the performance losses.