As initially reported by AutoRacer.it, the FIA has issued a draft technical directive to the Formula 1 teams outlining how it will clamp down on flexible wings through alterations to the load tests.

The issue of flexibility in wings became a big topic of discussion over the 2024 season as it became apparent that McLaren and Mercedes had capitalised on this with their front wings, possibly from the early stages of the season – perhaps from Miami for McLaren and Monaco for Mercedes.

In fact, Mercedes had been open with the fact that they were seeking out flexibility, with technical director James Allison saying after the Monaco front wing upgrade provided a clear performance boost that “provided your wing is bending like a thing bends when it has load on it, then there’s no drama to be faced with the governing body”.

Even so, this prompted Red Bull and Ferrari to seek clarification over their legality from the FIA, and a delay in this answer frustrated Ferrari team principal Fred Vasseur, who post-season spoke to it being an area of “clear performance” that they had to wait to exploit themselves.

The FIA’s official stance at the end of the 2024 season was that no changes would be made to the front wing load tests ahead of the 2025 season, with Nikolas Tombazis, head of single seaters at the FIA, citing challenges in assessing the front wing flexibility as reason for not introducing new tests.

“We are pretty happy with what we’ve seen,” Tombazis told Autosport. “I hasten to say that it’s not a question always of being happy or not. It’s also a question of whether you feel that a meaningful test can be made.

“One of the challenges in the front wing is that, compared to other parts of the car, the front wing loading is much more varied between cars in a given location and so on.

“So most tests relate to the load of a certain direction, certain position of application, certain magnitude must not produce a [certain] deformation.

“The most successful such tests imitate as much as possible what happens in real life with loads and, on the earlier wing for example, it’s reasonably successful. On the front wing, the variety between cars would make that quite difficult.”

However, a report from AutoRacer.it has suggested that the FIA intend to implement a new technical directive in June of this year to refine the tests conducted for front wings in particular, with the scope of the rear wing tests also increasing but from the first race – representing a u-turn of sorts.

Let’s deep dive into what flexi wings are, why the FIA are clamping down, and what the potential effects might be…

Why have flexible wings & how do they work?

In the era of stiff, ground effect cars, any element of flexibility may not only offer a performance benefit but also benefit the balance of the cars which has been a struggle for the teams since 2022.

Front wings are critically important as they impact the way the air flows over every other component behind them while also generating a significant proportion of the car’s overall downforce. While this downforce level reduced under the 2022 regulations, it has increased as teams looked to overcome the porpoising issues the ground effect triggered by running their cars ever lower. This increased the tendency of the front wing to produce a strong ground effect, and therefore higher levels of downforce.

But with this came a disequilibrium between the downforce at the front versus rear of the cars – the front was too powerful for the rear – resulting in rear instability at high speed (oversteer) that could be addressed by altering the front wing’s flap angle during pitstops or in the garage.

This is a mechanical adjustment, one that’s static as the car goes around the lap, and though decreasing the front flap angle for the entirety of the lap can fight these inherent issues, it can accentuate the cars’ tendencies to understeer at lower speed – making it unpredictable and tricky to drive.

By altering these inherent aerodynamic properties of the car in a flexible way, that is one that changes at different load levels or speeds, this need to alter mechanical balance to compensate can be overcome and the car can feel more predictable and consistent.

Having a wing that is flexible enough to effectively reduce the flap angle at high speed and under load but maintain its more aggressive angle at low speed not only reduces the drag level of the wing at high speed, increasing straight line speed, but keeps a higher level of downforce at the front in corners/low speed, maintaining a good balance and equilibrium.

Teams are thought to have achieved this through flexibility that rotates the flap elements rearwards rather than deflects them – keeping the inboard area stiff, while allowing the outboard area to flex to a greater extent.

This effect can be summarised through two broad ways in which the flexi-wings act:

1. Reducing drag at high speed (straights)

Aerodynamic load at high speed causes the front wing elements to flex rearwards, reducing their angle of attack, reducing drag and reducing oversteer by moving the balance rearwards.

2. Increasing downforce at low speed (corners)

The wing returns to its original state at lower speeds and under braking, returning to its higher attack angle, resulting in higher downforce and more stability between front and rear (less understeer).

It’s also important to note that while these wings can be powerful in their effect, they do not act alone (as is the case with any part on an F1 car) – their effect on performance is brought about in conjunction with the underfloor, floor edges and rear wing, for example.

Policing the inevitable

The concept of harnessing flexibility in wings, and broader aero elasticity, is not new and dates “back donkeys years” in Ross Brawn’s words, who said it’s something “we can’t avoid in F1”.

And this is true – it’s the job of F1’s highly skilled engineers to maximise performance by pushing the regulations to their very limits, and this is an unavoidable fact of the sport. However it’s the FIA’s role to put the boundary in place that teams, and the engineers, cannot (theoretically) cross. 

This is not only done through the more proactive technical regulations, but also through often more reactive technical directives that address areas of concern (in the FIA’s opinion) and give the teams and the FIA a common understanding of where the line lies.

The implementation and following of these theoretical rules by each team is then checked by the FIA through practical measures.

Policing flexibility of aerodynamic bodywork like the front and rear wings has always been, and likely will always be, a challenge for the FIA as these parts have to flex to an extent to cope with the loads they’re under at speed. 

F1’s technical regulations outlaw any flexibility in bodywork that affects the aerodynamics of the car, stating in article 3.2.2 that “all aerodynamic components or bodywork influencing the car’s aerodynamic performance must be rigidly secured and immobile”. 

“Furthermore, these components must produce a uniform, solid, hard, continuous, impervious surface under all circumstances,” reads article 3.2.2.

Knowing that this is not technically possible, the FIA accounts for the movement that will occur under load by specifying a level of deflection or rotation that is permitted and they check this with static load tests that are laid out in the regulations.

For example, the front wing flap must not deflect more than 15mm when the load is applied symmetrically or 20mm to just one side. Further to this, the trailing edge of any front wing flap can’t deflect more than 5mm when a 60N load is applied.

For the rear wing, the flap may deflect no more than 7mm when a 500N load is applied, with the end plates not permitted to deflect more than 10mm when a 10N load is applied.

Technical Directives

While a team may be theoretically in the clear by passing these static load tests, further technical directives close down loopholes in the regulations that teams may exploit in search of performance over the course of a season. There are numerous TDs in operation at any one time and they can be removed or brought back by the FIA as they see fit. With them not being public, keeping track of which are in operation at any one time is made difficult, so the following is not an exhaustive history of TDs and flexi wings.

TD018-21 – Response to “bendy wings” in 2021

In 2021, the FIA introduced TD018-21 to address flexi wing controversy between the title contenders, Mercedes and Red Bull. Mercedes accused Red Bull of using a “bendy wing” on the rear of their RB16B at the Spanish Grand Prix with Lewis Hamilton claiming it gained them “at least three tenths in speed” down the straights.

The FIA subsequently wrote to teams expressing that it had “become aware” that some rear wings were passing the load tests yet had “excessive deflections while cars are in motion”.

Following this, more stringent load tests were brought in from the French Grand Prix, three races later, to allow teams time to adjust their designs. Alongside these more stringent tests that would double the load applied in the ‘pull-back’ and ‘push-down’ tests, the FIA implemented the use of markers on the wings to allow them to monitor for excessive movement with video.

The aim of these extra measures were to look out for any “anomalous behaviour of the deformation of the rear wing”, according to Tombazis at the time.

Red Bull’s rear wing had passed the previous load tests and passed the new ones too, and Christian Horner maintained that the “FIA are happy”.

But later in the year, the accusations went the other way, with Red Bull asking questions about Mercedes’ rear wing.

Red Bull used alleged ‘score marks’ on the rear wing endplates of the Mercedes W12 in the later stages of the year as evidence that their rear wing was flexing at higher speeds, increasing their straight line speed as a result.

This reached a climax at the Brazil race in November, where Max Verstappen earned a hefty €50,000 fine for examining and touching the Mercedes wing in parc ferme after qualifying, “looking at how much the rear wing was flexing at that point”, in Verstappen’s words. Unrelatedly in the stewards’ view, Lewis Hamilton was subsequently disqualified from that session as the DRS flap opened 0.2mm more than it should have due to a fault – but this wasn’t what Red Bull took issue with.

Their main issue was shown the next day when Lewis came through the field from last to win using what Christian Horner described as “not normal”, “mind-boggling” and “exponential” straight line speed.

The FIA introduced additional rear wing tests from the following race in Qatar in a fact finding mission of sorts to gather new technical data and inform future rule making.

An FIA spokesperson is reported as having said that the tests were “intended to gather information” and “do not form part of the regulatory requirements” under article 3.9 (at the time) or TD018.

While Horner claimed these tests had brought the speed down; “I think the load test is doing it’s job because the straight line speed is under control”, Mercedes maintained that the wing had not changed.

TD018 – Brought back in 2023

TD018 was initially brought in 2021, updated through 2022 but removed before the start of 2023 as the FIA felt it wasn’t needed following regulation changes.

But it was then reintroduced in mid-2023 as the FIA believed the teams had been pushing the boundaries on what was allowed in terms of flexi wings over the first half of the season.

This specifically is reported to have affected Aston Martin who began the season strongly but then dropped back after being informally asked, among other teams, to alter their front wing designs before the Azerbaijan Grand Prix.

To ensure no other teams were going down a similar route, the FIA also issued a formal technical directive from the Singapore Grand Prix that stated it believed outfits were exploiting “regions of purposely design localised compliance” and “relative motion between adjacent components” to boost aerodynamic performance. It also listed four designs that were not permitted.

As part of this, the FIA also asked every team to submit assembly drawings and cross sections showing how the front wing elements were fixed to the nose, and how the rear wing elements were fixed to the end plates, rear impact structures and pylons too.

This was done with the intention of allowing the FIA to gather data to understand how the teams were passing the load tests yet still possibly benefitting from flexible wings. 

And while no changes to the load tests were made as a result, the FIA maintained at the time that they have methods to test beyond the load tests themselves including video footage, assessing the designs submitted or inspecting physical parts.

TD34

TD34 remained current in 2024 and states that certain behaviours of wings will not be tolerated, even if they pass the legality tests when static in the garages. It’s reported to be a long-standing technical directive, setting out the FIA’s expectations for wing behaviour beyond simply passing load tests.

The directive is reported to say that the FIA does not consider legal “designs whose structural characteristics are altered by secondary parameters, so as to produce (whilst running at the track) a different deflection characteristic than when stationary during the FIA checks. Examples of secondary parameters could be temperature, aerodynamic load etc.”

Broadly therefore, it outlaws parts that behave differently in terms of deflection in the garage versus out on track.

TD034G – 2024 Belgian Grand Prix

Technical directives can also be implemented to allow the FIA to gather data on how teams may be finding loopholes, so they can close them up in future as was done at last season’s Belgian Grand Prix with TD034G.

Amidst controversy over flexible front wings and finger pointing between the teams in the first half of the season, the FIA installed cameras on the nose of all teams’ front wings to monitor and gather data on flexibility through the field.

In the note issued to teams ahead of the weekend, the FIA stated that the cameras would be “focused on the inboard nominally vertical surfaces…to track the translation and rotation of target dots”. These dot stickers could be seen on the inside of the front wing endplates and on the edge of the flaps, circled with green on the Ferrari SF-24 on the image below.

From these investigations, the FIA concluded that no team was in breach of the technical regulations but they continued the use of on-board cameras to acquire additional data up to the Singapore Grand Prix to cover all different track types and their corresponding wing types. Ultimately though, no short term action was taken, with the FIA statement saying they were “evaluating the situation with the medium and long-term in mind”. 

What has prompted this new TD?

Flexi wings gained attention again in 2024, with specific examples of their believed use and controversy around these prompting this latest action.

Mercedes’ front wing (2024)

While it’s thought Mercedes were not alone in maximising flexibility in their front wing designs, they were one of the first to do this last year and one team to find perhaps the largest performance swing as a result.

The team brought an upgrade to Monaco that included a new front wing with a “larger chord inboard flap and redistribution of main plane chord”. The team’s reasoning for increasing inboard flap chord was to increase “the balance range of the front wing” while redistributing the outboard element chord “altered tip velocity and improved tyre wake control”. 

It’s no secret that Mercedes had struggled with balance and driveability of their cars since the 2022 regulations came in, also suffering the most of any team with porpoising and bouncing in the early phase of the regulations.

James Allison commented that running the car lower to overcome this had meant the team had to fight an “inherent behaviour” of the car to get “more nervous as it goes faster”.

This was arising from the balance moving further towards the front axle as the front wing generated increased downforce at speed due to the ground effect – with this new wing said to be “helpful with that” by Allison.

While it wasn’t explicitly stated by Allison that this wing was operating flexibly, flexibility would “help fight the inherent behaviour” that Allison had commented on, with him also saying that “there’s no drama to be faced with the governing body” so long as “your wing is just bending like a thing that bends when it has load on it”.

Mercedes’ initial wing specification for the 2024 season was unlike any other on the grid, with a very thin inboard section to the top element that widened as it moved outward. This had been aimed at improving the airflow to the floor on either side of the nose, adding load further back in an effort to overcome the inherent rear instability that Mercedes had suffered with. But a consequence of this was that the front end lacked load in slower corners, with Hamilton saying “the slower you go the less the car wants to turn”. 

The Monaco wing changes were seemingly a different way of addressing the same problem, reducing the rear instability but keeping load on the front through corners. And Andrew Shovlin, Mercedes’ trackside engineering director, revealed that the upgrade was “delivering performance” and “a benefit in terms of how the car was feeling” – both signs that it was a better route to go down than the initial concept.

McLaren’s front wing (2024)

This need for development to address an imbalance between low and high speed performance was something also seen on McLaren’s side in the early phases of 2024. The team had suffered with a lack of top speed and poor performance in long, faster corners. This was exposed at the Saudi Arabian Grand Prix given the nature of the circuit, as commented on by Andrea Stella at the time, and hinted at their need to more efficiently balance downforce and drag.

In Miami the team introduced a raft of upgrades that clearly boosted performance, not only allowing them to close the gap to the front runners, but also giving Lando Norris a car he could use to fight for and claim his maiden grand prix victory.

One of these was a completely new front wing, and this is thought to have had a sizable impact on the car’s performance particularly at lower speeds. 

The upgrade was aimed at a “significant improvement in flow control” which in conjunction with updates around the front corner and suspension would result in “overall load gain”, according to the team’s Miami upgrade notes.

Having clearly benefitted from this upgrade suite, the team went further down this development direction in Austria with another front wing change.

While McLaren were even more cryptic about what this development direction entailed practically than it could be argued Allison was on Mercedes’ behalf, Andrea Stella (team principal) said, “We saw that this concept worked well, so we wanted to pursue this direction further.

“And this is another attempt to improve, I would say, in particular, the low-speed behaviour of the car.

“Hopefully the compromise we’re working on is capable of delivering some low-speed benefits, but without affecting the high speed or the straight line too negatively.”

Are we sensing a theme?

But front wings weren’t alone in coming under scruitiny, with McLaren’s rear wing spotted flexing in Baku.

McLaren’s rear wing (2024)

At the Azerbaijan Grand Prix in September it was noticed that McLaren’s rear wing appeared to flex at high speeds down the straights, creating an opening at the corners of the flap even when the DRS was closed (areas marked green on below image). This became known as a ‘mini-DRS’ effect.

While it was noticed in Baku, the low drag rear wing specification it arose from had been used by the team in Belgium and Monza previously. It’s thought that it was first introduced in Spa, where the team’s upgrade notes included a low drag rear wing specification: “in anticipation of high isochronal circuits, a less loaded rear wing assembly is introduced for this event, with the aim of reducing drag efficiently.” 

Rear wing flexibility offers similar gains to flexibility at the front wing – reducing drag at high speeds while maintaining downforce at low speeds, something that could be of particular help at circuits like Baku or Monza where long straights are combined with some slower corners and chicanes.

The FIA had not initially intended to require changes to this wing from McLaren, however this stance changed after complaints from their rivals. In a statement issued at the Singapore Grand Prix weekend, McLaren said: “While our Baku rear wing complies with the regulations and passes all FIA deflection tests, McLaren have proactively offered to make some minor adjustments to the wing following our conversations with the FIA.” 

Only one low drag track remained on the calendar (Las Vegas) once the agreement to make alterations was reached, and Ferrari were aware that the effect had been maximised by the time it was clamped down on. Fred Vasseur expressed frustration at this fact, saying the wing was “more than borderline” given the close competition at these races in particular.

“If you remember perfectly the situation in Monza, we had five cars in two hundredths of a second. You can move from P1, P2 to P5 or P6 for two hundredths of a seconds.”

To completely cover off further speculation or question, McLaren made changes to their full suite of rear wings ahead of the United States Grand Prix the following month. At this event, the FIA also looked to have conducted further data collection in regards to flexibility, but this time for rear wings – increasing the number of reference dots placed on the rear wings, and reportedly using higher resolution cameras to increase the level of detail they were monitoring at.

While the media coverage and narrative on these changes focused on McLaren, their statement pointed to an expectation that the FIA would “have similar conversations with other teams in relation to the compliance of their rear wings” indicating perhaps that others were also benefitting from similar effects. Reports over the US Grand Prix weekend suggested that the FIA had requested changes to other designs it was concerned about too, though the teams they belonged to were not mentioned.

So why change things now?

Changes to the regulations in regards to rear wings were made ahead of 2025, specifically to address the grey area McLaren are understood to have used in the creation of the ‘mini-DRS’.

Article 3.10.1 (c) was altered to specify a smaller minimum gap along the span of the rear wing – between 9.4mm and 13mm – that would apply when the DRS is not deployed, and a maximum gap for when DRS is open of 85mm.

The wording around DRS actuation was also altered to state that DRS must only ever be in one of two positions and that when DRS closes the rear wing must return exactly to how it initially was.

But the regulations around front wings are as they were for 2024 in the current drafts of the 2025 technical regulations, in line with what had been said by Nikolas Tombazis at the conclusion of last season. Though this may be the case, the FIA “reserves the right to introduce further load/deflection tests on any part of the bodywork which appears to be (or is suspected of), moving whilst the car is in motion”, as outlined in article 3.15.1 of the technical regulations.

Going down the aero elasticity route of development is costly in terms of time and financial resources. It’s therefore likely that smaller teams who had been left behind in this development race were not happy, and so pushed for a clamp down from the FIA.

This is purely speculation, but given the likely impacts flexible wings and a team’s ability to create them versus their rivals’ would have on the championship in the final year of these regulations, it is possible.

The new TD – TD018 Modified

In what could only be described as a ‘u-turn’, the FIA’s reported draft new technical directive (a modified version of TD018) will introduce new more stringent load tests.

According to reports (as the technical directives are not public) the inboard flex allowance will reduce from 3mm to 2mm with the permitted outboard flex reduced from 15mm to 10mm. 

The FIA’s stated rationale for these changes is to “ensure that bodywork flexibility is no longer a point of contention for the 2025 season” while also “further refining our ability to monitor and enforce bodywork flexibility regulations”, making “a level playing field for all competitors to promote fair and exciting racing”.

The FIA will increase the scope of the rear wing tests from the opening Australian Grand Prix in early March while the additional front wing tests will be implemented later at the Spanish Grand Prix in May/June.

This delay in implementation is justified by the FIA as time for the teams to modify their front wing designs but this approach differs to what’s been seen in previous years, with TD018-21 for example.

TD018-21 was introduced within a month of it being announced to the teams – a much more reactive approach than what we’ve seen from the FIA in 2024 up to now.

Again this month was to allow teams to revise their designs and produce new components and meant they could use their existing wings for two further races before the clamp down began. Whereas now, the teams will have 9 or 10 races.

Possible implications of this new TD

Though rumours may swirl saying that some teams are happy with this and others are furious, it’s important to remember that this solution was likely a compromise between all parties following months of discussions. 

Though Red Bull and Ferrari have now got the clarification they were looking for when the issue first arose, it comes after an initial approval of the concept from the FIA which may have triggered work to begin on flexi wings of their own.

Ferrari are thought to have already brought a flexi front wing later in the year, potentially in Austin where they claimed a 1-2 and saw a clear performance boost following a front wing upgrade. Though no official upgrades were submitted for Ferrari at that weekend, article 19.1(c) of the sporting regulations says that only “major aerodynamic components and assemblies that have not been run at a previous competition or TCC [test]” have to be declared.

While Ferrari didn’t confirm that they had brought a new front wing, it was reported that they had worked on the construction of the wings to exploit flexibility more following the FIA opening the door for this development route.

Going down this route doesn’t come cheaply though and now it’s been closed up again, Ferrari, and Red Bull who have likely also invested in this pathway over the winter, will be wondering why the FIA didn’t act like this in the first place.

But that’s the bigger, front running teams, the smaller, midfield and backmarker teams will also be suffering the same problem. They may also have invested in aero elasticity over the break to find an edge over their close competitors, only for their budget to have possibly gone to waste.

While the front runners will likely look to maximise the flexi wing benefits in the first 9 races before the TD is implemented and then make changes, the smaller teams may have to make a choice between prioritising performance in this first phase of the year or the longer, second phase. This may mean optimising the wing for the new 10mm deflection rather than creating a 15mm one and then a 10mm one for the rest of the year, which is possibly a reality for the teams who want to be in the title fight.

It could therefore be argued that the aim of this TD to ensure “a level playing field for all competitors to promote fair and exciting racing” could be actually the opposite of its effects in practice.

Having to make this choice will also impact 2026 development given that teams will have all but signed off on their 2025 cars at this stage of the pre-season, and will have already diverted their attention to the significant incoming rule change. With this decision from the FIA, they will have to reopen the books on 2025 and move money and time and people to devise new front wings (and the areas impacted rearwards) to suffice the new tests while delivering performance. 

These are concerns surrounding the timing of this TD. Had it been implemented immediately following the 2024 season with a first race start date (the rear wing tests will be implemented from Australia, front wings from Spain) then teams could have had the longer adaptation time the FIA were seeking while having fewer effects on the running order or championship than it likely will now.

Yes, there still would have been cost cap and development concerns, but perhaps the impact of these would have been lesser.

The other question to ask is whether this TD will work to close down the use of flexibility in aero bodywork fully. If the teams are exploiting the flexibility in the way it’s believed they are – through rotation of the elements rather than deflection necessarily – then will load tests designed to assess deflection levels actually close the issue down?

Previous TDs that have strengthened the load tests, in 2021 for example (TD018-21), shut down the issue for a while before it resurfaced later in the year. Whether there was truth to the concerns either Red Bull or Mercedes had over the other’s wing is unclear, though all wings passed the tests before and after changes, but the teams continued arguing over these issues even with action from the FIA.

These debates are a part of F1, especially as competition gets tighter and more fierce, and title rivals will always question each other’s cars – it’s almost a fact of the championship.

Whether this action will have the desired effects remains to be seen, but history says it’ll take more than a technical directive to prevent discussions like this.