What F1 is clamping down on with flexi wings at the Spanish GP

From this weekend’s Spanish Grand Prix onwards, the testing regime governing the front wings of Formula 1 cars will be toughened to reduce the amount of permitted flex under load.
 
Under Article 3.15.4 of F1’s technical regulations, the flap areas of the front wings may deflect under load by no more than 15mm. This is now being reduced to 10mm.
 
Aero-elasticity has been an occasional focus of intrigue since the 1990s. It’s impossible for a wing or similar area of bodywork to be infinitely rigid under the loadings experienced at speed, so a degree of flex is inevitable.
 
Many teams have exploited – and continue to exploit – this by designing areas of bodywork to deform or flex under load in a relatively controlled manner, potentially cutting drag and enabling cars to achieve higher top speeds. Materials science has reached the stage where it is relatively straightforward to use finite element analysis to lay up the carbon fibre sheets in a composite component in such a way that they achieve optimum strength and weight, along with a predictable amount of flex.
 
As the current technical regulations mature and gains become harder to find, subtle tricks involving aero-elasticity have returned to the agenda and become the subject of frequent clampdowns by racing’s governing body. Last year there was a brouhaha surrounding McLaren’s rear wings, which rivals claimed were flexing in such a way that the gap between the two main planes increased slightly while at speed, cutting drag.
 
The FIA introduced new parameters and testing procedures to prevent this so-called ‘mini-DRS’, including high-definition on-board cameras to monitor the rear wings during practice. These were tightened up again before this year’s Chinese Grand Prix weekend; footage emerged of the McLaren rear wing appearing to flex during the season-opener in Australia, but FIA single-seater director Nikolas Tombazis had already decided on stricter rear wing measures during the pre-season test in Bahrain.
 
Changes to the front-wing testing regime were decided upon in January, though the introduction was delayed until this weekend’s Spanish Grand Prix to give teams more time to adapt their designs in what is a highly complex area with potentially long lead times from concept, through simulation to manufacture. It’s understood some teams – Red Bull being particularly vociferous – argued in favour of bringing in the new tests for the Emilia Romagna Grand Prix rather than Spain.

“This phased approach allows teams to adapt without the need to discard existing components unnecessarily,” explained the FIA.
 
“These adjustments are aimed at further refining our ability to monitor and enforce bodywork flexibility regulations, ensuring a level playing field for all competitors to promote fair and exciting racing.”
 
The key challenge with testing is that it’s impossible to measure wing flex while the car is moving. Instead a static load – in this case 1000 Newtons – is applied on both sides of the front wing simultaneously, and the areas under load must not deflect by more than 10mm. One Newton is the force required to make 1kg of mass accelerate in the direction of the applied force at a rate of one meter per second squared.
 
The smaller rear flaps are subjected to a 60-Newton load and may deflect by no more than 3mm at the outboard edge. This is to prevent too much flex being engineered into the so-called ‘fish plates’ which connect these wing elements to the main plane.
 
Naturally there has been much speculation and intrigue surrounding who might have been using such techniques, how much they have benefited and how much they may be affected by the change in testing regulations. Red Bull has frequently and publicly pointed the finger at McLaren concerning wing flexibility; since the MCL39 has passed all the existing tests, Red Bull’s only recourse has been to share video footage on social media to keep the issue alive.