From the moment the regulation floor trim of 2021 was announced there were competing theories about how it would affect the low-rake and high-rake cars respectively. The fact that the two low-rake cars – Mercedes and its relative, the Aston Martin – appeared to have significantly lost competitiveness in the opening race at least suggests that the change has favoured the high-rake concept popularised over the years by Red Bull and subsequently followed by most of the others. As such, the small tweak designed to ease the strain on the rear Pirellis may have fundamentally changed the competitive order.
A diagonal line in the outer floor, beginning 1800mm back from the front axle line to a point ahead of the rear tyre, 100mm inboard, defines the cut. In addition, the various slots and holes which previously helped to aerodynamically seal the floor and release the ‘tyre squirt’ air ahead of the rear wheels were outlawed. The vanes hanging down from the rear diffuser (beyond 250mm outboard of the centre line) were cut by 50mm and those attached to the rear brake duct were also heavily trimmed.
The rake angle of the floor helps define how much negative pressure (and therefore downforce) it produces. It’s multiplied by the area of floor. The Mercedes (and related Racing Point/Aston) has always compensated for the lower rake by having greater floor area from a longer wheelbase. So would the floor cut and associated changes hurt the low-rake cars more because the total loss of floor area would be greater (because of their longer wheelbases)? Or would the reduced sealing as a result of the banned slots force the shorter wheelbase cars to lower their rake angles to prevent the airflow stalling and thereby lose out more than the low-rake cars? With all the teams obliged by regulation to retain their 2020 chassis as part of a cost-containment measure in the pandemic they could not design a car from scratch to suit the floor trim regulations.