Wing flexibility has been a Formula 1 battleground since the late 1990s but its competitive significance was amplified last year due to the characteristics of this generation of ground effect cars as they were developed further.
McLaren’s mastery of the technology played a major part in the competitive shaping of the 2024 season, bringing about the end of Red Bull’s long domination.
The irony of that is in previous years it was traditionally Red Bull which led the way on wing flex, of meeting the static load tests but having the wing flex beyond the stipulated measurement when it’s out on track. The loads out on track beyond speeds of 120-130mph significantly exceed those which can safely be imposed statically in a garage area. That’s where the window of opportunity lies.
It became a much more important endeavour last year as teams succeeded in running the ground effect cars ever-lower before encountering porpoising or bouncing. This accentuated the front wing’s tendency to generate powerful ground effect at high speed as its underside ran super-close to the ground.
This tended to make the cars unstable at the rear upon fast corner entry – ie the front wing was working too powerfully relative to the rear. Typically, controlling the rear instability in these situations meant reducing the front wing’s power with a less aggressive flap angle. But this only accentuated an F1 car’s tendency to understeer at low speed and oversteer at high. The front wings were not powerful enough at low speeds and too powerful at high. More flex was the way around this.
So a front wing which was relatively powerful at low speeds but less powerful (relative to the rear) at high speeds was facilitated by having it flex so much beyond a certain threshold of speed that it became less powerful. In that way, you could still use an aggressive flap angle to give a good low-speed front end. That opened up the set-up window massively, allowing a car to retain good downforce and good balance rather than one at the expense of the other.
Getting the wing’s construction and the flaps within the construction to remain within the flex limits in the FIA’s standard test (which involves applying a 1000N load to three different points across the wing’s span and separate tests on the flaps and endplates and measuring the resultant flex) but to still flex at speed is a complicated science. It involves a complex lay-up of the carbon fibre elements which make up the wing.
Red Bull was repeatedly reined in on front wing flexibility in the 2010s and into the 2020s and much of the team’s mastery in this crucial aspect was attributed to its then-chief designer Rob Marshall. Marshall transferred for 2024 to McLaren. The team’s Miami upgrade last May included a front wing with greater aero flexibility and from that point onwards McLaren was invariably super-competitive, occasionally dominant.
A way had been found to increase the flex at loads beyond that applied in the static test even beyond what was already being achieved. The key was in maintaining stiffness at the inboard part of the wing but allowing greater flex at the outboard. Levering a small amount of flex at the inboard to a non-linear increase in flex at the outboard end at high speeds was key to the 2024 generation of aero-flex wings. The computation and simulation involved are considerable and costly.
McLaren was the first to devise this ‘Mohican’ wing but before too much longer Mercedes had conceived a similar wing and Alpine joined the flexi gang with its Austin upgrade in October. Aston Martin too believed it was fully competitive in aero flexibility terms. However, Red Bull and Ferrari were both reluctant to follow this path with the former campaigning for a clampdown and the latter pressing the FIA for a decision about whether there would be such a clampdown before committing to the costs involved.
The FIA technical delegate Nikolas Tombazis professed himself satisfied with the status quo during the balance of last season. The smaller teams were left behind in this resource-hungry development race and have been pushing for a clampdown.
The latest technical directive stipulates that the inboard flex allowance will reduce from 3mm to 2mm with the resultant outboard flex now reduced from a permitted 15mm to 10mm. Increasing by one-third the vertical stiffness at the inboard end (when measured statically) should make it much more difficult to make a non-linear increase in flex at the outboard end at higher speeds.
This change is the compromise between the various pressures applied by the teams according to their situation. Initially a more draconian limitation applied from the start of the season was planned. The Spain introduction will give the likes of McLaren and Mercedes – and anyone else who has subsequently gone this route with their 2025 cars - time to adapt their cars around the new technical directive.
McLaren has found, just as Red Bull has in the past, that ingenuity can be outlawed if it proves too effective. But the processes and skills within McLaren which found this innovation are still there, ready to be applied where the next area of advantage can be found.
