If the historic Scuderia Ferrari is far from the level of Red Bull, it is not because the Austrian team possesses hidden secrets. Its great performances do not come from magic tricks. No rabbits from the hat, in short. The strength lies in the mere understanding of the car and the mastery that the team currently possesses in using the tools at their disposal, such as simulation software, for example.
However, in technical terms, there is a mix of solutions that are setting the standard. Specifically, the Milton Keynes team has paid great attention to optimizing the flow in certain areas of the car, and from there, they have been able to gain a significant advantage in terms of aerodynamics. What are we talking about? We are referring, in particular, to two critical areas: the undercut zone and the area between the rear tire and the side “wall” of the diffuser.
Other teams are gradually catching up, but more slowly. This is evident in the mid-season changes made by Ferrari and Mercedes, two teams that have taken different paths but are aligning in certain concepts. Let’s try to understand why these two mentioned parts of the car are so important. The first one, which is the initial zone of the sidepods, plays a fundamental role in generating a large part of the outwash effect. The more they can raise the local static pressure, the more they create a pressure gradient from the inner to the outer zone of the car. The airflow will naturally be directed outward.
This transfer of airflow serves a specific purpose, which is to push away from the car all the turbulence (tyre wake) that the tire produces while rolling. Teams have tried many approaches in this regard. Ferrari had chosen to develop very large sidepods on the SF-23 single-seater, which resulted in a good level of outwash. However, the amount of clean air that managed to circumvent them and reach the rear was proportionally smaller compared to the solution of the RB19.
In Mercedes, they entered the 2023 Formula 1 racing campaign with the “zero pod” concept, an aerodynamic philosophy that, in fact, achieved an opposite setup compared to the red car: it did not create outwash but managed to direct a larger amount of clean fluid towards the rear of the car.
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Ferrari SF-23: Limitations of the 675 Project
The second crucial area on these cars is precisely the one between the rear tire and the diffuser. In this regard, Red Bull shows great expertise, as over the years, they have experimented with various ways to limit the effect of the rear tires. The mass of air is, in fact, dragged downward by the tire, and once it reaches the asphalt, the only thing it can do is escape laterally. This is what is called the ‘tyre squish area,’ where there is low-energy and highly disturbed fluid.
This fluid is generally sucked by the diffuser and affects the flow structure inside it, creating vortices that slide at the base of the tire. To counteract this phenomenon, teams usually used a vertical appendage at the base of the floor to generate a vortex with an opposite rotation, an action that is no longer allowed by the regulations. However, there are still a series of wing elements attached to the rear brake duct that should shield the floor and control the squish area.
This is where Red Bull is currently able to make a significant difference. We have analyzed the final section of their sidepods several times, noticing the presence of a cavity that increases the Y component of the flow. The goal is to feed that specific part of the car, which is so-called “lossy,” meaning it operates at low energy, with a flow of clean and energized air.
On this point, we mention Mercedes again, which still, after the aerodynamic modifications, continues to experience a certain degree of instability at the rear. At certain speeds and steering angles, the rear of the W14 loses downforce. It is possible that in some circumstances, the wheel’s turbulence penetrates the volume of the diffuser, instantly decreasing its efficiency. It is no coincidence that the team from Brackley has followed the Red Bull philosophy more closely and adopted a cavity in the final section of the sidepods.
On this front, the Maranello team has lagged behind a bit. The new sidepods introduced in Spain only partially solve the conceptual issue of the SF-23. The modifications do not address the specific zone in the same way, as the final section exhibits a trend that causes a certain inwash effect of the fluid. The intention of the Maranello engineers is to feed the area above the diffuser, which is not entirely wrong. However, to find rear downforce, something the red car lacks, they must address that area to minimize losses.
This part of the current cars is a crucial determinant in terms of performance. Although increasing the diameter of the wheels results in less tire deformation and, consequently, easier control of the tyre-squish, the regulatory abolition of the aforementioned “devices” complicates things. This factor has driven teams like Red Bull to devise solutions, reaching a broad understanding of this vital area.
Source: Alessandro Arcari and Niccoló Arnerich for FUnoanalisitecnica