Preparing for a battle of increments

Mercedes-AMG F1
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emailBy Edd Straw | March 10, 2021 7:26 AM

With Formula 1’s three days of pre-season testing about to begin, all eyes will be on the timesheets to see who has gained and lost out. But headline times are a notoriously fickle indicator of form, and you need to look more closely to get a more representative view of who is hot and who is not, which may well be blown out of the water come the first race anyway.

There are many measures of performance, but the most straightforward one is the least relevant. Outright lap time will allow us to compare the pace in testing to last November’s Bahrain Grand Prix weekend, albeit with the complication of varying fuel loads and programs, but that in itself will tell us very little.

In motorsport, what really matters is relative performance, and the 2021 season might be one of those unusual cases where going no faster than the previous year is a victory. Results will be dictated by how much faster or slower than the rest a team is, but this year is unique given the enforced carryover of much of the car.

This is complicated by the small, but significant, aerodynamic rule changes for 2021. The package of four tweaks has been implemented to prevent downforce levels from rising further given that the Pirelli tires have been carried over for a third successive season, aside from some modifications to the construction to improve their robustness.

Along with the reduction in width of the downforce-producing winglets on the lower part of the rear brake ducts and the shortening of vertical vanes in the diffuser, the key changes are to the floor: the triangular cut that means the floor tapers inwards towards the rear wheels, with the longitudinal slots eliminated. This creates an ‘exclusion volume’ around the rear wheels. Given the importance of the way the floor and rotating wheels interact in generating downforce, specifically in terms of the all-important sealing of the underfloor area, there’s a lot to be gained in terms of relative performance from effectively re-optimizing around the modifications.

“The combination of the floor area that people are trying to hide, the change in the brake duct shape and change to the diffuser fences, is a pretty substantial reduction in downforce,” says Alpine chassis technical director Pat Fry. “That area will be one of the main areas of development.

“We’ve certainly got a whole program lined up, and through a lot of the teams I’ve been at, that area is one of the things where you can never model the deflected car shape quite correctly in the windtunnel anyway. So I suspect you’ll see everyone with a myriad of test items turning up in Bahrain and the first few races.

“We haven’t just got one solution, we’ve got many things to test and get on top of. It’s certainly been a significant loss. We haven’t recovered all of it yet, but it’s still a work in progress. When we get to the first test, it will become really interesting, seeing how well things are relating to CFD and windtunnel, as well as the absolute numbers that we get out of the car.”
The shortening of two vertical vanes in the diffuser – helpfully illustrated here by Mercedes – is part of a 2021 package imposed upon the teams by F1 to reduce downforce. Image via Mercedes-AMG F1

So these changes are the confounding factor that create the opportunity for teams to get it right or wrong. Estimates are mixed on if, and when, teams will get to the same downforce levels as in 2020 – and the answer will vary, given the differing levels of downforce last year. But it’s likely to be one of the most powerful sources of performance swings.

There are others. Ferrari took a big hit ahead of last season thanks to the series of technical directives issued to tighten up the engine regulations. Ferrari worked with the governing body to create these after the FIA could not prove what it called “suspicions that the Scuderia Ferrari PU could be considered as not operating within the limits of the FIA regulations at all times” in 2019 – suspicions it said Ferrari “firmly opposed”. As engines were frozen during the season last year, upgrades couldn’t be introduced, and a significant step is expected this time around. While Ferrari concedes Mercedes is still likely to have the edge power-wise, team principal Mattia Binotto is confident that Ferrari will no longer have the weakest engine.

Overall, Ferrari is the team with the biggest potential for improvement. Not only does it have engine gains, but last year’s car was too draggy and suffered from rear-end instability.

“Last year the main issue was the speed on the straight lines, both power and drag,” says Binotto. “We’ve worked a lot, both on the power unit and the car aerodynamics to reduce the drag of the car, and based on our simulations today, based on what we can see in terms of power output from the dynos, and the drag of the car from the windtunnel, I think that we recovered quite a lot of speed on the straight lines.

“So, I’m expecting the speed not to be such an issue as it was. We believe that our car is certainly more efficient compared to the one we had last year, both from the aero point of view, and from the power unit point of view.”

As Ferrari was in the tightly-packed midfield group last year, it won’t take much to elevate it from sixth to third – especially if new signing Carlos Sainz makes a bigger points contribution than Sebastian Vettel managed last year. Ferrari was 71 points behind third-placed McLaren in 2020, which sounds substantial but only amounts to an average loss of 4.2 points per race. More significantly, it was only an average of 0.240% slower than third-fastest Racing Point. That equates to 0.2s of a second around a 90-second lap, which is well within what can be gained.

So while jumping three positions to third is relatively straightforward for a team with the resources of Ferrari and the many obvious upsides – provided, of course, it’s got things right – a far bigger step is needed to move up to second. It was 0.721% slower than second-fastest Red Bull, which is a lot to ask, doubly so when you consider how much stronger Red Bull was in the closing stages of the season.