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Mercedes released a Q&A session with James Allison! The Mercedes Technical Director talks about the technical aspects of the new car and more.
Question: What would you say are the biggest challenges for the upcoming season?
James Allison: Without a doubt, the biggest difference is the introduction of the cost cap. This new rule requires us to manage our resources very judiciously through the year. We won’t be able to fly through the season introducing update after update any more, but instead will have to bring a more limited number through the year, making sure that we spend our cost cap dollar as wisely as possible on our upgrades. We also have some significant modifications to the aerodynamic regulations for this year, plus new tyres and changes to how much we’re permitted to use the wind tunnel. All these things stack up to be quite a big change, very far from the carryover year that it was expected to be.
Question: The cost cap is one of the biggest regulatory changes the sport has seen in some time. What impact does its introduction have on creating the new car, and how will it influence the team through the 2021 season?
James Allison: Back in the spring of 2020 it was already clear that COVID-19 would create a difficult environment to develop a completely new car. So, the decision was made for the 2021 cars to inherit a lot of the backbone of the 2020 cars and this has lessened the explosion of work and expenditure that normally happens over the winter. This decision has cushioned the birth of the new car a little from a financial point of view. However, as the year progresses, the cost cap constraints will be felt ever more keenly. We will try to ensure that we protect the rate at which we learn how to make the car go faster, but the cost cap will inevitably change the intervals between updates. We will have to wait longer, to combine the gains into bigger steps, before we spend the money to manufacture them, in order to ensure we don’t run out of development budget early in the season.
Question: What can you tell us about the new car? What has been the main focus of development for W12?
James Allison: By far and away the biggest area of technical development has been adapting to the new aerodynamic rules. 2021 brings a profound set of changes that affect the performance of the floor. If you’re looking to slow a car down, which is effectively what the regulation changes were intended to do, modifying the floor is by far the easiest and cheapest way of achieving your objective. The floor is such an important aerodynamic component that small geometrical changes bring large reductions in performance. Once the rules had been established, our task was to figure out how to recover the losses brought by the changes. The rest of the aerodynamic work has been the normal fare of seeking out aerodynamic opportunity across every square centimetre of the car with particular attention to finding places where we can invest extra weight into fancier aerodynamic geometry. 2021 permits the cars to be 6kg heavier, and we have an additional few kilos to spend as a result of DAS being banned. Beyond this, the carryover rules have confined us to figuring out how we can make some parts live longer, so we don’t have to replace or buy them so often. And of course, our colleagues over at Mercedes AMG High Performance Powertrains have been pushing hard to find gains to the Power Unit, delivering us a useful step forwards in a year where all the gains need to be packed into a single release of hardware.
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Question: There are four aerodynamic changes on the car for 2021, as part of the regulations, so let’s break them down one by one. What’s the first key aero change?
James Allison: I’ll explain the triangular cut-out on the edge of the floor first. This is located just in front of the rear wheels, reducing the area and shape of the floor. It may not look like a big change, but the way the floor and the rear wheels interact is critically important to the performance of the car. So, removing this part of the floor has a big impact on downforce.
Question: Where is the second aero change located and what’s different on the W12?
James Allison: It’s related to the rear bake ducts, which for several seasons have featured a proliferation of winglets that are mounted on the brake ducts and point inwards towards the centreline of the car. These winglets generate a little bit of downforce in their own right, but their far more important role is to guide the interaction between the rear tyres and the floor, helping the floor to produce far more downforce than the winglets could ever manage on their own. The span of these winglets has been reduced by a few centimetres so they don’t overlap as much with the floor as they used to, thereby reducing the performance of the car.
Question: What’s the third area of aerodynamic change?
James Allison: The third change is at the back of the car around the diffuser area. When we are designing the diffuser, we are trying to expand the air as much as we can while keeping the air attached to the surface of the diffuser. More expansion means lower pressures under your car, which means more suction pulling the car to the road, which means more downforce. However, if you get too greedy, expanding the air too rapidly, then the air will not follow the shape of the diffuser and instead of being swept upwards, it will separate from the car. This is called stalling, and it causes the downforce to decrease dramatically. One of the tricks to expand the air more aggressively without stalling is to separate the diffuser into distinct areas with carefully designed fences called “diffuser strakes”. For 2021, the inboard set of strakes, the ones nearest the centre line of the car, have had their bottom 50mm sawn off so that they don’t sit as close to the ground as before. By making the fences shorter, they are less effective at dividing the diffuser into separate regions and therefore less effective at controlling the rate of expansion of the air. All things being equal, this makes it harder to be greedy with the diffuser expansion, and so it reduces the downforce on the car.
Question: And what’s the fourth and final aero change?
James Allison: This is related to the edges of the floor, near the bargeboards and the radiator air intakes. In recent seasons all the cars have sported an array of slots on the floor in this section of the car, almost looking like a venetian blind. For 2021 the rule has changed, requiring us to seal those slots up. This reduces our ability to create downforce at the lateral periphery of the floor.
Question: There have been changes to the Aerodynamic Testing Restriction (ATR) rules, which determine the number of wind tunnel test runs and computational fluid dynamics (CFD) hours that teams can use to develop their cars. What do those entail?
James Allison: There have been two key changes to the ATR: the first is that everybody felt it would be better for us to be doing less work in the wind tunnel and on CFD, because this form of research is expensive. So, the general amount of time allocated for wind tunnel testing and the amount of computer access granted for CFD testing have been reduced. The second change is that superimposed on the general reduction is a form of handicapping, which grants teams less or more access to their aerodynamic tools based on where they finished in the 2020 championship. The team that finished at the top of the Championship gets the least access and the team that finished last is granted the most. The difference between the top and the bottom is 22% and in between is a sliding scale of gradually reducing access the closer you get to the top. We have always tried to get the most out of every wind tunnel and CFD session, but there’s nothing like having a new constraint imposed to renew the spur to become more productive and efficient. We are determined to find better ways of working so that we can mitigate the effect of this handicapping.
Question: The tyres are changing for 2021, can you tell us about them and their impact on the cars?
James Allison: Pirelli’s 2019 tyre development programme was aimed at improving the durability of the tyres. The teams tested some proposals in 2019, but eventually rejected what was offered. As a consequence, we went into 2020 with effectively a two-year-old tyre against a backdrop of everincreasing performance in the cars. Not surprisingly, last year saw the tyre at the limit of its capabilities. Pirelli has responded to this by producing a new racing tyre for 2021 – despite the fact they were heavily constrained by a lack of in-season testing in this COVID-affected year. The new tyre is a lot more durable than the 2020 tyre. We tested it during free practice sessions in the 2020 season, first in Portimão, then in Bahrain and finally in Abu Dhabi. It is a little slower, owing to the trade-off for more durability, but it is consistent and should give us trouble-free racing. However, it will be an interesting competitiveness factor during 2021. Any time a tyre changes, it is always a learning race between the teams to find its sweet spot – where the new rubber gives its best performance. All the teams have had a go with the tyre, but none of us have had a lot of exposure to it. With pre-season testing being just three days, we will only have a limited opportunity to learn about the new tyre before racing begins. So that’s quite an exciting prospect and we’re looking forward to getting out on track and trying to find out what makes the tyre sing.
Question: Will only three days of pre-season testing change our approach?
James Allison: If it were 2022, we’d be a bit more anxious over the prospect of just three days on track, but the fact that many of the systems under the bodywork remain the same will mean that if we’re in decent shape, we won’t need to spend as much of winter testing accruing mileage as we normally would. And that will buy us more time pursuing performance investigations and learning about the tyres. If we have made a reliable car, we will be fine with three days of testing. If we have dropped the ball on one or more the main car systems, then there is a risk that we will be playing catch-up all year.
Question: The regulations for 2021 have meant some parts are being carried over from 2020, could you explain how that has worked?
James Allison: What’s carried over will be different from team to team, because the rules didn’t require you to carry over the same things. The rules freeze a large chunk of the car, but then give each team two tokens to spend on changing their car. Along with the tokens comes a shopping list showing how many tokens are required for each change. How teams decided what to use their tokens on was entirely up to them – they could implement two smaller changes for one token each or use both tokens at once for one large change. So, the only thing we can say with certainty at this stage is that everybody’s cars will have significant areas that are the same as their 2020 car but those areas will vary from car to car, depending on how they chose to spend their tokens. In addition, there are some parts of the car that you can change token-free, for example the Power Unit, the cooling systems, the suspension and of course all of the aerodynamic surfaces. We have spent our tokens, but we won’t reveal how we used them just yet. That’ll become clear in good time. Finally, notwithstanding the different token decisions that each team has taken pre-season, once the racing gets underway, pretty much everything under the skin of the car must then be frozen for the entire year. With the specific permission of the FIA, you can make changes for reliability or cost saving, but if part of your car isn’t performing well, then you are stuck with it for the whole season. No pressure then!
Question: Next year will bring a revolution to F1, with the biggest rule change in the sport’s history. How does this impact our 2021 season?
James Allison: It’s a very large set of changes, so it’s not something you’d like to dive into at the last minute. The ideal situation would be to have a car that is so brilliantly fast, you can almost turn your back on it immediately and focus on the next one. But Formula One is never that simple. The siren call of the 2021 racing campaign will inevitably draw our attention from the seismic changes of the 2022 regulations. We will walk a tightrope all year between doing enough to be competitive in 2021 and putting as much as we dare into 2022. Managing the bird in the hand and the one in the bush is the eternal challenge of F1 and doing so in the face of both the cost cap and the completely new 2022 technical regulations will be a challenge like no other.
Source: Mercedes-AMG Petronas Formula One Team
