Are Z-shaped floors the way to go in F1 2021?

Formula 1 teams appear divided over the best floor solution for the 2021 rules, as a new set of regulations once again results in two opposing design trends appearing.

Are Z-shaped floors the way to go in F1 2021?

But, have we seen enough evidence from just the first race to judge who's on the right track and who'll have to think again?

On one side, we have the conventional thinkers who have taken the new rules at complete face value when it comes to dealing with the lost floor section.

Ferrari, Alfa Romeo, Haas, McLaren and Williams all have floors that taper at the rear as the regulations intended. They have largely steered away from having too much aerodynamic furniture on the floor's edge to redirect the airflow too.

Ferrari, Alfa Romeo, Haas, Mclaren, Williams floor comparison

Ferrari, Alfa Romeo, Haas, Mclaren, Williams floor comparison

Photo by: Uncredited

Meanwhile, Mercedes, Aston Martin, Red Bull and Alpha Tauri all have a very different solution that's been on their cars since testing, while Alpine joined their ranks at the first race of the season.

The five teams employing this floor design have created a Z-shaped edge to their floor, with a section cutout around 200mm back from where the floor starts to taper. This has resulted in them giving up some of the total floor space that's available, but affording them more flexibility in terms of floor's shape.

The yellow highlight shows where the floor would have previously extended to in 2020, whilst the dotted line represents where the edge of the floor would be, had the teams followed the intent of the regulations.

Red Bull and Mercedes floor comparison

Red Bull and Mercedes floor comparison

Photo by: Uncredited

The teams that have opted for this Z-shaped cutout have essentially returned to a floor edge that's parallel to the car's centreline, as it was in previous years. This suggests they were unhappy with how the tapered edge affected the flow to the rear of the car.

That's not to say they've all followed the same path though, with this image making it abundantly clear just how much individuality there can be with this design.

In particular, Red Bull has opted to design the edge of its floor to have a much longer section that's parallel to the car's centreline than Mercedes has, for example.

The Z-shaped edge created also helps these teams to create flow structures/vortices at a point on the floor where other flow structures might otherwise be breaking down or deviating from their intended path.

They're accentuating this further with contouring to the floor and the fins mounted alongside it, with Aston Martin perhaps the most aggressive in this regard.

The fins (two rows in Aston Martin's case - see main image) are placed at a point on the floor where they will surely have an impact on how the airflow moves around the sidepod too. However, their role in regards to the floor will be to realign the flow structures with the straight floor edge in mind.

This area of the car is surely going to be a hotbed of development this season, as each team finds incremental gains from the interacting flow structures and tunes them accordingly.

Alpine, for example, has already made a serious effort in this regard, as whilst it not only joined the four other teams already using the Z-shaped floor cutout in Bahrain, it also had a number of parts to try in combination with it.

Alpine A521 Floor comparison

Alpine A521 Floor comparison

Photo by: Uncredited

Alpine's test programme highlights where the team's interests lie at this early stage of the season too, with two key areas seemingly the most ripe for development - the area around where the floor begins to taper and the area ahead of the rear tyre.

In Alpine's case, the floor tested during pre-season didn't have the Z-shaped cutout or fins (V1 – Blue). But, having installed a floor with the cutout, the team tested two other solutions - V2 not only had the two silver coloured fins mounted side-by-side and offset from one another, it also had two shorter triangular shaped fins mounted further downstream (red arrows).

It decided to race a slightly less aggressive solution though, with just a single fin mounted on the edge of the floor cutout (V3).

A batch of solutions was also tested just ahead of the rear tyre too, with the single element strake used during the preseason test cast aside (V1), firstly in favour of the trio of strakes used during the back end of the preseason test (V2) and then in a combination test with two other solutions (V3 & V4).

V3 and V4 both have four sections to them, albeit in a slightly different way, with V3 only having slots a portion of the way down the surface, whilst V4 is made of four individual strakes.

Not a one dimensional problem

As we've seen from the restructuring of the pecking order in the opening races, it's not a one size fits all equation though, with each of the teams at a different stage in the development cycle, having expended their resources in different ways.

There's also a tug-of-war for resources too, as whilst the floor is by far the largest change to the regulations, there's other changes that could have an impact on them and on global car performance too.

Mercedes W12 and Mercedes W11 diffuser comparison
Red Bull RB16B Vs RB16 rear detail

The reduction in the height of the strakes, for example, could play a role in the difference between the low and high rake runners, as their proximity to the ground plane is extended further still.

In the case of the low rake runners, they've likely exploited the vorticity that's created by the strakes ground proximity in the past, which in-turn generally helped with flow through the diffuser.

The overall design of the Mercedes diffuser is almost identical to 2020, at this stage, bar the design of the strakes, which have been reduced in height by 50mm to comply with the new rules.

McLaren is the real outlier in this respect, so far, having used a clever interpretation of the regulations to maintain taller strakes in the mid section of the diffuser.

Connecting its strakes in the central 500mm of the car to the transition wall, has allowed the team to keep the taller strakes. But it does come at a cost, as it must maintain a single section in that region.

This means that if you were to take a slice through that section you'd have no breaks in the slice. This does compromise the overall shape of the boat tail, and means there can be no slots in the strakes to optimize the flow around them.

It'll therefore be interesting to see if there's any changes in this area throughout the course of the season, as the designers search for ways to optimize the aerodynamic hand off of flow structures from one area of the car to the other.

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