Why flexi-wing tests were not F1's "magic bullet"

Formula 1’s flexi-wing furore has been simmering for months, but came to a ragged and inconsequential termination during the Spanish Grand Prix weekend when new deflection tests were applied – and not much changed.

The tests clamped down on the amount of flex permitted on the front wings of F1’s machinery, and followed a similar tightening of the regulation around aero-elasticity in rear wings earlier this season.

Red Bull had been among the cheerleaders for the new tests, even pushing for them to be introduced earlier in the belief that McLaren’s dominance was rooted in exploiting aero-elasticity for performance gain. Reality then dealt expectation the smack of firm government.

But while the overall spread of performance between teams remained broadly similar, Lewis Hamilton (for one) was overstating the matter when he declared the change “a waste of money”.

The key change in the new test was the permitted deflection of the wing planes when a force of 1,000 Newtons was applied on each side – 10mm rather than the previous threshold of 15mm. This move was signalled well in advance, with the FIA announcing the new rules in January as the latest in a series of clampdowns on aero-elasticity.

Since no component can be infinitely stiff, a degree of flex is inevitable – but materials can be designed and constructed in a way that they deflect by a roughly prescribed amount in order to eke out various performance benefits. But while rear-wing flexibility primarily affects top speed, lower drag is very much a secondary-order benefit of inducing flex on the front wing.

McLaren front wing detail

Photo by: Franco Nugnes

The primary benefit of an aero-elastic front wing in the current ground-effect era is to smooth out the mid-corner balance changes to which these cars are prone. So the effect of the new testing regime was always going to be subtle – and in some cases circuit-dependent.

Also, the picture in Barcelona was muddied by some teams introducing development steps with new front-wing geometries. Since there is no longer any regular F1 testing here, there is no way to directly compare ‘before’ and ‘after’ performance on the 2025 cars.

“I was interested to actually see if things would have unfolded like we anticipated, and they did,” said McLaren team principal Andrea Stella.

While it’s clear that McLaren, among several teams, had been pushing the boundaries of aero-elasticity, it had already evaluated a front wing that complied with the new tests. Lando Norris ran it in practice at Imola and, the team claims, felt no difference at all.

“We always thought the impact would have been relatively negligible because when we saw the numbers associated to this change of aeroelastic effect, there were small numbers in terms of downforce and in terms of variation of the downforce with speed,” Stella added.

“So, when we tested this wing in Imola, if we hadn’t told Lando that it was a different wing, he wouldn’t have spotted it. And when we simulated in the simulator or in the offline simulation, numerically it was almost zero.

Oscar Piastri, McLaren, Andrea Stella, McLaren

Photo by: Peter Fox / Getty Images

“So, we were not expecting a change of the packing order as a function of the technical directive that was released for this race. In terms of wasting the money or not, this is not a point of view that we actually reflected upon because the TD has been there for a long time, so this was long planned.”

If the impact on drag has been “negligible”, there have been more subtle ramifications up and down the grid depending on individual car characteristics. Without the smoothing effect afforded by more flexible front wings, there’s a greater tendency towards oversteer in fast corners and understeer in slow corners.

Cars already suffering balance problems in those areas will, therefore, have found the change exacerbates them. But it was not something that amounted to great chunks of lap time.