The black art of aerodynamics determines so much of Formula 1’s pecking order, and it goes hand-in-hand with the financial clout of the leaders and ‘Class B’ runners
“We’re not racing in Formula 1. It’s more like Formula 1.5. I don’t know how those cars are so much faster,” said Gene Haas about rivals Mercedes, Ferrari and Red Bull back in Austin in October. “But I talk to Ayao [Komatsu, Haas engineer] and he says you have got a couple of tenths on your tyres, a couple of tenths on your aero and your chassis is off a couple of tenths. That is your second or two.
“I know that we put a huge effort into trying to address all those parameters, but I don’t see how we are ever going to make up 1.5-2sec to these guys. They are just so much faster.”
Throughout the history of the sport the top teams have used money to go a lot faster than the smaller teams. But the mechanism by which the money translates into lap time changes. Money can find a way around whatever the barriers are, breaking down the obstacles that keep the smaller teams forever trailing.
McLaren had to run a much bigger rear wing than ideal – and its cars were consequently very draggy on the straights.
The critical path to that lap time is invariably formed as the accidental consequence of specific technical regulations. The regs throw up the randomly generated barriers, the money dissolves them – and eventually that knowledge spreads to the smaller teams. Then the regs change again and the process begins anew.
In place since 2017, the wide tyre/wide body regulations have determined the competitive picture to which Haas refers. In the first three years of the hybrid era, the competitive hierarchy was largely driven by differences in engine performance. Mercedes was dominant but even a Mercedes-powered independent like Williams could often out-perform Ferrari or Red Bull.
As the spread between the engines narrowed (and even disappeared in the case of Ferrari), so the second-order differences began driving the competitive balance. The big teams’ budgets were unleashed on those until they were no longer second-order. The 2017 introduction of the wide tyre/wide floor cars of today brought about a particularly demanding set of aerodynamic requirements that are challenging the modelling accuracy of the simulation tools.
Wider front tyres in combination with the pre-existing type of front wing – with its outer ends stopping half way across the width of the tyre, effectively imposing the extreme outwash endplates we now see – have made the critical flow down the side of the car potentially very unstable. The flow relies on spinning vortices of air to accelerate it down the sides after it has been out-washed around the front tyre; but if those vortices are in the wrong place or they burst, the downforce can suddenly reduce drastically.
“The flow around the wider front tyre, with an endplate sat in front of it, has got a higher pressure rise than before,” explains a former technical director, who shall remain nameless. “And that just disturbs what you’re trying to achieve. Similarly, with the rear corner – with the diffuser change and the wider rear tyre – you’ve got a similar thing going on there and you need to get the car to somewhere where it’s performing aerodynamically sensibly, then after that you can start working it.
“In the barge board area, where there is now a lot more real estate to work with, you have to start with something where, while you’re looking for load, you’re not throwing vast losses at the car. The danger is that you leap in too early on and try to crank load into it when you haven’t got the basics under control…”
This has been a contributory factor in McLaren’s tough 2018 season as performance director Andrea Stella explained. “With the current regs the capacity to keep delivering downforce in the corners is critical. This is the reason why there are cars that belong to another category, just because they can control the downforce through the corner in all the conditions of yaw, crosswind etc.”
The brittleness of that outwash flow, so difficult to model accurately, seems to be the biggest difference between the cars of the top three teams and even the very best of the rest. In McLaren’s case there have been additional barriers.
“We tried to expand and consolidate some concepts of the 2017 car into this one. In hindsight, after lots of methodical investigation, we had embedded some aero issues in the car, creating a bottleneck, making development of the car very difficult,” surmises Stella. “The fundamental capacity to keep delivering downforce through the corners had gone beyond our calculation.”
When the airflow down the sides cannot be accelerated in the desired manner, it seriously degrades the diffuser’s performance, which relies partly on the draw being made on it by the airflow that has travelled down the sides and then been squeezed between the rear tyre and diffuser. As the flow exits that gap it pulls on the flow coming through the diffuser, thereby making the underfloor work harder.
The consequence of not getting those vortices in the right places and losing the consistency of airflow down the sides of the body therefore usually mean a shortfall in rear downforce.
To get around the resultant lack of rear stability, McLaren had to run a much bigger rear wing than ideal – and its cars were consequently very draggy on the straights.
This knowledge has been painfully gained. But it will likely be of little value next season, when new aero regulations will define a wider front wing that runs to the full width of the tyres and a banning of the big outwash endplates.
This fundamentally alters the way the aerodynamics of the cars will work – and so those gains made by the smaller teams in catching up to the advances of the bigger ones will be wiped clean.
Since he began covering Grand Prix racing in 2000, Mark Hughes has forged a reputation as the finest Formula 1 analyst of his generation