The significance of sidepods in Formula 1

(Cover picture: Albert Fabrega)

The two collisions that occurred between Perez and Hamilton in the Sprint and between Sainz and Piastri in the race at the Belgian Grand Prix highlight the significance of the sidepods in today's Formula 1.

What is the role of the sidepods on nowadays single-seaters?

In both circumstances, following the contacts, one of the two cars (Perez on Saturday, Sainz on Sunday) suffered damage to the sidepods, with gashes measuring more than 20 cm in length.

Zak Mauger / Motorsport Images

For the record, these damages led both of them to retire their car: too much loss of aerodynamic downforce, to the point of making them easy prey for their opponents due to the performance lost in fast corners and braking zones... At that stage, as mentioned, retiring the car was the only viable option first for Checo, and the following day for Carlos.

We are used to thinking that the aerodynamic downforce in Formula 1 single-seaters is only generated by the two wings - front and rear - and by the floor, which in order to follow the same physical principle is shaped just like a large wing: for this very reason, in the 1970s people referred to the single-seaters as "wing cars"...

Giorgio Piola / Motorsport Images

The sidepods, on the other hand, have a very different geometry from that of a wing: without the presence of a pressure side and a suction side, how can they accelerate the air underneath them in order to generate downforce?

We can go even further, and ask ourselves if their descending trend doesn't actually cause an opposite effect, i.e. lift rather than downforce (which, absurdly, if predominant with respect to the downforce effect of the wings and the floor, would make the cars take off!)...

The answer lies in the fact that, today more than ever, sidepods don't generate downforce in itself, but help other components creating it! What are these components? Mainly the floor and the rear wing: let's analyze both the underlying aero mechanisms.

Interaction between sidepods and vehicle's floor

Thinking about what aerodynamic interactions there may be between sidepods and the floor, it's first of all necessary to understand how the latter works.

Without wanting to dwell on it and above all trying not to digress too much (in any case you can find here a technical focus on this topic), it's enough for us to know that a floor is able to accelerate the air underneath it provided that along its lateral edges there are no air infiltrations at ambient pressure...

Zak Mauger / Motorsport Images

To avoid this risk, a valuable sidepod must help in this task: if in its initial portion it has a large undercut (volume left free for the airflow that goes to the rear end), it's very likely that the vortex structures generated by the strakes at the floor inlet are fed by these airflows, helping to aerodynamically seal the entire floor assembly itself.

Andy Hone / Motorsport Images

In the middle portion of the sidepods, however, the need is exactly the opposite! In fact, when they adhere closely to the internal components of the Power Unit,  they don't guarantee adequate shielding of the floor edges from the aforementioned air infiltrations: this is the case of last year's Mercedes W13, in this regard very sensitive to the albeit minimal ride height variations.

This great sensitivity, also inherited from the initial version of the W14 this year, has been only mitigated when Mercedes abandoned the aerodynamic "zeropods" concept.

Interaction between sidepods and the rear wing

Different - and simpler, if you like - matter about the benefits that an appropriate geometry of the sidepods can guarantee in the exploitation of a rear wing.

Here the goal is to ensure that the rear wing + beam wing assembly is hit by an airflow with the lowest possible turbulence level: in this way the wing itself can draw on a greater energy content from the air, thus extracting more aerodynamic load.

Michael Potts / Motorsport Images

In this context, teams have found a development path in which the upper wall of the sidepods literally directs the airflow towards thesuction side of the rear wing (which is precisely the side where engineers prefer to have air at a higher speed): technical solutions as such are now well established on the grid, but credit goes to McLaren for having implemented it for the first time on their 2022 car, the MCL36.

And what about the fluid dynamics inside the sidepods?

Before concluding this article, we cannot fail to mention a fundamental aspect: that of internal fluid dynamics... Whereas the airflow outside the bodywork is based on geometries that seem drawn by the wind, inside the sidepods the situation is totally different!

Josè-Maria Rubio / Motorsport Images

The airflow entering the sidepods through the inlets must pass through the radiators, so that it cools the Power Unit components: as you know, the air mass flow to be used for cooling purposes - to the detriment of purely aerodynamic aims such as generation of downforce and drag reduction - is established in each session, depending on the track layout and on the environmental conditions.

Talking again about the accidents mentioned at the beginning of this article, one of the reasons that led Checo and Carlos to retire actually lies in the imbalance that has arisen between the air mass flow intended for cooling (internal flows) and the air mass flow intended for aero purposes (external flows).

In short, sidepods really have a key role in modern Formula 1: for this reason too, the technical efforts of the teams are often devoted to the development of these important components!

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