Bending the F1 rules? The story behind McLaren's flexible rear wing

F1
- Last updated: October 14th 2024

Controversy over McLaren's flexible rear wing has dominated the F1 conversation in recent days. Here's how it works, why its legality was questioned and the reason it has to be changed

2024 Azerbaijan GP

Piastri's flexi-wing kept the field at bay in Baku

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After a week of social media sleuthing, and accusations from F1 rivals, McLaren has said that it will modify its flexible rear wing, as seen in the Azerbaijan Grand Prix.

As Oscar Piastri celebrated a brilliant drive to victory in Baku, the first videos of his car’s curious trait were emerging, showing how the wing — which is supposed to be an almost rigid body part — flexed at high speed. Under high aerodynamic load, it deformed to become flatter, also opening a wider gap between the top and bottom elements, which would have reduced drag and increased the car’s top speed.

Since then, the issue snowballed, leading to an investigation by racing’s governing body, the FIA. After discussing the issue with officials, McLaren has now said that it will modify the wing, which is expected to reduce its bending at high speeds. This may not be required in Singapore where the straights are shorter than in Baku, and top speeds around 20mph slower, which will reduce the load on the wing.

The benefits of a flexible wing are clear: high levels of downforce increase grip when the car is turning, allowing higher cornering speeds — such as in the tighter sections of the Baku circuit. Low downforce and reduced drag is beneficial on straights.

In this way, teams can go some way to having the best of both worlds and many have pushed the boundaries in this area over the years — producing front and rear wings that reduce drag at higher speeds. As a result, this area is tightly controlled by regulations and tests; McLaren stood accused by some rivals of going too far.

Ahead of the Singapore Grand Prix, the FIA stated that it was “closely monitoring the flexibility of bodywork on all cars”. While the McLaren passed all required tests, it’s less clear whether it conformed to other areas of the rules and FIA guidance which bans bodywork structures that deform in one way during the tests and another way on track.

 

How did McLaren’s flexible rear wing work? 

McLaren flexible wing at the 2024 Azerbaijan Grand Prix

Piastri’s flexible wing mean it proved impossible for Charles Leclerc to catch the McLaren

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The flexible element of McLaren’s rear wing was the upper element; the DRS flap, which can be opened on certain stretches of the circuit when a driver is within a second of the car in front to assist overtaking.

But the rear camera on Piastri’s car clearly shows that when DRS was not activated, the wing was pushed back by the aerodynamic load on straights, opening up a larger gap between the top and bottom elements, which has the effect of reducing drag. When Piastri braked and the load decreased, the wing returned to its previous state.

In theory, these parts of the car are meant to remain completely static, but the rules do allow a certain degree of flex. An F1 car can generate more than 2000kg of downforce at high speeds, with a significant proportion of that load pushing down on the rear wing. If the wing didn’t flex to some degree, then it could crack with devastating effect.

Flexing is controlled by official tests in the pitlane, to ensure that the rear wing only deforms within permitted tolerances when weights that are added. The McLaren has passed these tests, but its current wing, first introduced at the 2024 Belgian GP, appears to flex to a much greater extent when on track.

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The effect in Baku looks to have helped Piastri hold on to victory. Charles Leclerc spoke of how difficult it was to challenge the McLaren driver after Piastri took the lead. “They were actually very fast in the straights,” said Leclerc after the race. “I never really had the opportunity again to overtake.”

Speaking in Singapore, after the footage emerged, Leclerc added his thoughts on the rear wing: “From what I’ve been told, it’s controversial to say the least.”

 

What do the official F1 rules say? 

FiA and F1 flags

Will the FIA step in to kerb McLaren’s straight-line advantage?

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The FIA’s 2024 Formula 1 Technical Regulations state, in section 3.2.2: “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.”

The only exceptions to this ruling include driver adjustable bodywork (such as DRS) and certain flexible seals.

But an acceptance of the forces in play when racing at speed is added further down the rulebook, where permitted tolerances are set out. They state that the rear wing flap may deflect no more than 7mm when a 500N force is applied and rear wing endplates may deflect no more than 10mm when a 50N point load is applied. As McLaren’s rear wing does not exceed either of these set measurements, it was deemed legal in previous races.

However, simply passing the tests doesn’t put any team in the clear: there’s more in the FIA’s armoury. As a result of various teams probing loopholes in this area, and the impossibility of replicating the exact loads that are found in races, the FIA has issued a series of technical directives to clarify its rules. One technical directive 34 (TD34), outlaws bodywork structures that 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.”

Officials may have pointed out to McLaren that its wing appeared to be deforming differently on track compared to when tested in the pitlane. As such, it could have been ruled illegal if it is seen to do the same in future races.

Another area of the rules that may have tripped up McLaren are the specified gaps between both rear wing elements. This must be between 10mm and 15mm; by opening this gap when the wing flexed, the car may have been in breach.

 

F1’s long history of flexible wings

Lando Norris and Oscar Piastri 1-2

McLaren’s rear wing is legal — for now

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The benefits of flexible aerodynamics are so great that teams are constantly looking for ways of legally reducing downforce on straights while maximising it in corners.

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Only days before the Azerbaijan Grand Prix, the FIA announced that all of this year’s front wings were legal after suspicions over the amount of flex seen on McLaren and Mercedes.

Last year, also ahead of the Singapore Grand Prix, technical directive 18 (TD18) was issued to clamp down on any incidences of bodywork moving around joints — such as front wing elements moving up or down a car’s nose — which could adjust downforce levels.

That particular directive had its roots in the intense 2021 F1 championship battle when Mercedes and Red Bull traded accusations over wing flexibility.

 

Is McLaren’s flexible wing good for F1? 

Lando Norris McLaren x 2024 Dutch GP Zandvoort

Should McLaren’s outside-the-box thinking be celebrated?

McLaren

While rivals of McLaren may think it unfair that Lando Norris and Oscar Piastri appear to have an advantage in a grey area of the regulations, others would argue that exploiting loopholes and bending the rules has long been a part of F1’s history and contributed to its success.

After all, where would F1 be if the likes of Adrian Newey, Gordon Murray and Colin Chapman were restricted from thinking outside the box?

“That is what Formula 1 is for,” said Norris in response to queries over his McLaren’s flexing rear wing. “Exploring everything within the rules, and we’ve cleared all the tests and the FIA is happy so I am proud what the team is doing.

“They’re pushing the limits and that’s what you’ve got to do if you want to fight at the top and fight against people who are also known for doing such things and exploring every possible area.

“I’m proud of the team for pushing every single area that we can, we’ve not been in situations where we could do that in the past, but now we are in that position, so I am happy and it is a good thing to see.”

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