Why McLaren joined F1 2021's Z-shaped floor trend

Rewind the clock to last year and the Woking-based team had actually been the first to test a 2021 specification floor, when it installed one on its MCL35 at the Belgian Grand Prix.

This allowed it to assess the aerodynamic havoc that the changes would wreak at the rear of the car, and which all of the teams had undoubtedly seen from their simulation work in CFD and the wind tunnel when the changes were announced.

For the most part, these tests were conducted with immature solutions, so as not to give away too much information to rivals ahead of time.

But the floor used by McLaren in that test formed the basis for the one it used in the opening three rounds this year, with the tapered floor edge following the intent of the new regulations.

Meanwhile, seven of its rivals had either started the season with the Z-shaped floor arrangement or moved to it during those first three races.

McLaren MCL35M floor comparison

Photo by: Giorgio Piola

And, while eight teams have now followed a general trend, each of their solutions carries some of their own DNA as they cater for the aerodynamic choices they've made up and downstream of the cutout.

McLaren, for example, has added two angled fins ahead of the cutout in order to intensify the effect it is looking for. It has made only a relatively short portion of their floor parallel with the car's centreline before it once again tapers back toward the rear tyre.

Having made changes to the fins and strakes ahead of the rear wheel during the first three races, it has not made further alterations here yet, although it is sure to optimise these in the coming weeks.

 

Red Bull began its campaign with a Z-shaped floor and, while the middle section of the floor has also been returned parallel to the car's centreline, this section is much larger than the McLaren arrangement.

A single strake dominates the floor ahead of the cutout to help create a flow structure in tandem with it, while two shorter, curved strakes have been added before the floor begins to taper toward the rear tyre.

The teams using a Z-shaped floor are essentially giving up some of the floor area that's available to them, as they consider the shape of the floor to be more important to how the airflow is treated.

Mercedes went to the effort of covering the edge of its floor during the car's launch in order that rival teams didn't get a head start on understanding what it had done.

And, while the W12 does feature the Z-shape cutout, it's more subtle than some of the other designs and isn't paired with fins or strakes to help set up a more aggressive aerodynamic structure.

 

The shorter straightened section of the floor leads to a much larger tapered section ahead of the rear tyre, which has also been lifted and has a downward facing Gurney tab on the trailing edge.

Mercedes has been much more aggressive with the design of the floor's edge ahead of the cutout too, with a wave-like contour used to influence the airflow that might have otherwise been affected by the slots that were allowed previously.

It would be expected for Aston Martin to have a very similar arrangement to Mercedes in many ways, given that both teams are using a low rake set-up. However, it has approached the challenge in a very different way.

While Mercedes has largely focused its recovery efforts on finding performance from the aerodynamic configuration it started the season with, Aston Martin has arrived with a succession of updated parts instead.

 

Aston Martin is already on its second generation Z-shaped floor design and has by far and away the most aggressive solution on the grid. It features a long parallel section in the middle of the two small tapered sections, which is made possible by a much larger cutout.

To reinforce its aggressive floor cut out, the team has also added two rows of fins near the front of the cutout, both of which are made up of multiple fins and arranged in a crescent shape.

It also has an aerodynamic structure as equally large as Mercedes on the tapered section of floor ahead of the rear tyre.

In an effort to improve the global performance of the car and potentially increase the effectiveness of the floor cut out, the team fast-tracked new parts to the Portuguese Grand Prix but only had enough for them to feature on Lance Stroll's car, with Vettel forced to wait until Spain for his car to be fitted with them.

 

The upgrades included a revised forward edge to the floor, with an additional crest added to the 'wavy section', while the scroll and Gurney-like extension above it were elongated and taper down to a point at the start of the floor cutout.

Meanwhile, at the rear of the floor, an additional 'r' shaped vane (red arrow, below) was added to the aerodynamic furniture mounted ahead of the rear tyre and the shape of the diffuser was also altered (circled).

Ferrari did not start the season with a Z-shaped cutout in its floor, as it favoured the tapered floor design that the rules had intended and it tested in 2020.

However, it quickly deployed a new design for the second race of the season, discarding the trio of fins midway along the floor as a by-product too.

 

As seen with most of the teams pursuing the Z-shaped cut out, Ferrari also paired it with an outwardly angled strake on the front corner to help set up the flow structure.

In an effort to improve performance further, Ferrari also began testing another new solution on the edge of the floor ahead of the rear tyre in Portugal, with their four-fin set-up making way for a seven-fin arrangement instead.

It only had one of these floors available in Portugal as it took the first steps in collecting real world data with the arrangement, with it or a similar solution expected to follow in the coming races.