Behind the scenes of F1's new 2021 rules; and why they could work

by Lawrence Butcher on 25th July 2019

After details of Formula 1's new 2021 rules were revealed, we explain why Liberty and the FIA have this time given themselves the best chance of improving the racing

F1 2021 car aero rules work

Aero forces on the proposed 2021 F1 car, with red showing areas of higher pressure Image: FIA

Over the British Grand Prix weekend, Liberty Media and the FIA released more details of the 2021 Formula 1 regulations, which are due to finally be signed off in October. It would be fair to say that, if fully realised, they represent the most radical overhaul the sport has ever seen, fundamentally changing the way the cars generate downforce and how the flow of air over their bodywork is managed, in the hope of improving the racing.  

Whether these alterations, coupled with cost caps, spec parts and other proposed changes, will truly equalise the field remains to be seen, but what is certain is that Liberty and the FIA cannot be accused of not doing their homework, for which they should be commended.

The key is to make sure someone can’t find a way to break the regulations and get a huge advantage

A high-calibre, in-house team – including Pat Symonds, formerly of Benetton, Renault and Williams, Nicholas Tombazis, formerly of Ferrari – has been assembled to make sure the new regulations are not just a stab in the dark, and the teams enlisted to make use of their engineering firepower.

Of course, teams being teams, they all have their own agenda in such matters, but the way the rule-making process has been managed, to a great extent, should have negated this.


Concept work

The initial concept for the car shown here was Formula 1’s own work. It is the fruition of an extensive aerodynamic research program, the first step of which was simply to understand why it is so hard for one car to follow another. This is a very important point, as without knowing the reason behind the problem, it would be impossible to construct a ruleset to fix it.

To do this, Liberty went out and bought its own F1 car, in the form of the 2017 wind tunnel model and CAD data from the Manor Formula 1 team, following that team’s demise.

This model gave Liberty’s team the perfect basis to run its own CFD [computational fluid dynamics] simulations of the wake generated by a car. It compared the results of these simulations with those gathered in a wind tunnel (Sauber’s) to make sure its results were as true to life as possible. One example of the CFD wake simulations is illustrated.

Illustration of a modern F1 car's CFD wake

An illustration of a modern F1 car's CFD wake Image: FIA

Once the group was happy with the validity of the wake model, it was then able to study how the wake interacted with a car following behind, working out how much downforce the following car would lose in various positions and, importantly, why that downforce was being lost. As this process was underway, work also began on an aerodynamic design concept to minimise these effects.


Tyre wake

One of the major issues, which was already known but better understood as a result of the research, was the disruption to a following car’s aero performance caused by the air forced out to the side of the car in front.

A modern F1 car is phenomenally complicated from an aerodynamic perspective, but the bulk of downforce is generated by a few key mechanisms: the front and rear wings, the front edge of the floor and the diffuser. In essence, aerodynamicists are trying to manage the airflow over the cars in such a way that air reaches these parts in as controlled a manner as possible.  

More: Five classic Formula 1 ground effect cars

One of the biggest challenges for an F1 aerodynamicist is managing the messy flow that comes off the cars’ open wheels, both from the top of the wheel and its underside where it meets the track. The aim being to stop this ‘wake’ from the wheels disrupting the carefully constructed flows around the centre of the car.

You may have heard the term Y250 vortex bandied around in this context. All this is (in very simple terms) is the airflow running down the centre of the car, which is greatly influenced by the vortices that spin off the stacked wing elements, which end abruptly at the point they meet the spec central section of the front wing, extending 250mm either side of the car’s centreline (hence the Y250 vortex, Y being the axis down the centre of the car).

All of the protrusions, winglets and other carbon flicks that festoon the nose and area along the front sides of a car are designed to fine-tune this flow, maximising its usefulness when it gets to the powerful front floor section and retain its energy as it heads towards the back of the car. Having the wakes from the wheels barging in on this flow would ruin all of this work, hence why teams do everything they can to push these far out to the sides of the car.

Liberty and FIA have released more details on F1's proposed 2021 regulations

Liberty and FIA have released more details on F1's proposed 2021 regulations Image: Motorsport Images

The problem being, this makes life difficult for a following car as it ploughs through this mass of jumbled air swirling around at track level.

Liberty’s concept, the first iteration of which was codenamed Hotel, looked to stop the wheel wakes being pushed outboard and at the same time, reduce the detrimental impact of running in ‘dirty’ air.

Instead of placing emphasis on the previously mentioned tools for creating downforce, greater use would be made of the underfloor, with the current flat floor-diffuser set-up replaced with a tunnel system, creating a ground effect set-up where the underside of the car becomes one big venturi.

Generally speaking, and as shown by IndyCar, such an approach is less prone to being upset by the effects of following another car. Of even greater importance is the work Liberty has done to lock down the way airflow off the front wheels is managed.

The flow paths on a 2021 concept F1 car

The airflow paths on a 2021 concept F1 car Image: FIA

Looking at the front of a 2019 car, much of the ‘furniture’ towards the outside end of the wing, as well as the brake duct design, is responsible for pushing the wakes outboard, even after changes to the rules for this year reduced freedom in this area (which stemmed from the early 2021 work). The 2021 proposals remove the means to push the air outboard and the wheel wake is instead sucked back inboard.

With the current cars, this approach would greatly reduce downforce, but with a shift of emphasis to underfloor aero, the impact will be lessened. It also means that the wheel wakes will be drawn along the car, then ejected high up behind the car in the ‘mushroom’ of airflow created by the underfloor and rear wing, pushing it above any following car. The new car design also features a reworked rear aero layout to push this mushroom higher than it currently reaches.  

The process by which Liberty refined this concept is also laudable. Once the initial Hotel model was completed, Liberty and the FIA enlisted the assistance of the teams to run detailed CFD studies on the model as both a leading and a following car. The teams were given permission to complete CFD work outside of the current restrictions that the rules enforce, provided strict guidelines were adhered to.

Front view of the proposed 2021 F1 car

The proposed 2021 F1 car from the front Image: Pan_Nullo​

The data the teams gathered was then fed back to Liberty’s team to help refine its model and to allow back-to-back comparison between the wake effects of a 2018 car and the Hotel model. Following this round of work, completed in early 2019, a new model codenamed India, incorporating some modifications, was devised. This is the basis for the illustrations shown here.

The results were certainly encouraging, with the following car only losing about 10 per cent of its downforce when 10 metres behind another car. The current cars lose around 45 per cent.

There then followed two other development periods where the teams looked at specific areas of the model at the bequest of Liberty and the FIA, which concluded at the end of May. The teams also provided input on practical elements of the new design. It is all well and good having a shiny CFD model, but it is no good if it doesn’t provide sufficient cooling provision, for example.

Development of the rules package is ongoing, with Liberty now focusing on trying to ‘break it’ from the perspective of a team, as will be the case when they go live. They want to minimise the chances of the good work undertaken so far being undone by a team finding a development route that goes counter to their aims.

More: Ground effect to make a comeback in 2021 F1 rules proposals

Speaking to the teams at Silverstone, it appeared that the main concepts of the regulation proposals were agreed upon and that the reasons for the delay until October were wrangling over the fine detail and ensuring what appeared was a workable set of rules, rather than a mere concept idea.

One technical director commented, “I think that by moving the date to the end of October, it gives the time to check whether the regulations are robust enough… the key is to make sure someone can’t find a way to break them and get a huge advantage over everybody else.”

We’ll have to wait until 2021 to get a true impression of what the new cars will look like, but it is safe to say, the final form of the rules on which they are based will be a result of thorough research, rather than just informed guesswork as has often been the case in the past.


September 2019
The World According to Max



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