Video footage of Red Bull’s rear wing tipping back at high speed on Barcelona Street at the last Grand Prix attracted the wrath of Mercedes, and Lewis Hamilton quickly drew attention to the “twisty” wing of the RB16B.
And so the can of worms was opened; Ferrari and Alfa Romeo also admitted having introduced aeroelasticity into their rear wings, and it clearly seems possible that there are more teams out there who indulge in flexi-wing training.
The situation now is that the FIA wants to introduce stricter tests at the French Grand Prix to ensure that the wings do not bend under load – even though the current wings are already successful at the technical acceptance.
As always in F1, this decision does not suit anyone; Mercedes and McLaren want the revised flex tests ahead of the Azerbaijan Grand Prix in Baku, while Red Bull, Ferrari, Alfa Romeo and anyone else who owns a flexible wing argue that it will cost them more money to do their designs stiffen.
At Sky Sports F1, Red Bull team boss Christian Horner, who had suffered several fights over flexing wings during his tenure as head of the squad, pointed out the front wing of Mercedes, which also seemed to bend down towards the ground, and suggested The concerns of the Silver Arrows were rooted in hypocrisy.
When Hamilton’s dismissive comment on the “pliable rear wing” was made, he pulled a thread that unraveled a major subplot for the 2021 season. Oh what fun!
Carlos Sainz Jr., Ferrari SF21
Photo by: Andy Hone / Motorsport Images
What is a Flexi-Wing and why do F1 teams use it?
Flexi wings are … well, wings that flex. Strictly speaking, all the wings bend because it is impossible to achieve infinite stiffness, but some do so more than others.
In Formula 1, this usually manifests itself in a tipping action. At high speed, the front and rear wings create more drag as the speed of the vehicle increases. In mathematical terms, the square of speed determines drag force according to the following equation:
Drag force = (drag coefficient * front area * air density * speed squared) / 2.
As the speed increases, the force pulling the car back increases exponentially.
As a result, you cannot use all of the maximum drive of the drivetrain to improve speed on the straights. On tracks like Monza, teams use thin wings to reduce drag. However, on more conventional tracks, you will need the full size of the front and rear wings to create downforce on the turns.
By tilting back quickly, the entire frontal area of the wing and possibly its drag coefficient can be completely reduced. Using the formula above, the increasing square of speed is offset slightly by the reduced area and drag coefficient.
The truth is that all teams would love to have infinitely flexible wings on their F1 cars, as the front and rear wings could theoretically straighten and colossally reduce drag on the fastest stretches of the track. However, for security reasons, they simply cannot.
The FIA conducts tests to ensure that the wings do not bend during the technical inspection. The front wings are subjected to load tests and the rear wings are subjected to retraction tests as described in the technical regulations under Article 3.9.
Antonio Giovinazzi, Alfa Romeo Racing C41
Photo by: Zak Mauger / Motorsport Images
Why are Flexi-Wings not recommended for safety reasons?
The study of aerodynamics in F1 is often viewed as “aerospace but turned upside down”. Because many of the same principles exist between the two areas, they have many of the same problems.
Aircraft wings bend very easily because the structure must be a compromise between stiffness and weight. Materials with high torsional strength are often heavy, and so is an F1 car.
F1 wings are made from carbon fiber these days and often use a low density core (e.g. foam) for added rigidity. So they are still light and stiff. But the same is true: the more weight you add, e.g. B. with more layers of carbon fiber, the stiffer it will be. So the compromise still exists.
But if a wing is too light, it is likely to lose strength. Under load, this means that the wing can break – be it through contact with another car or through effects developed by aeroelasticity.
Aeroelasticity is a scientific field in its own right; Although resilience is desirable for some applications, it leaves a wing or structure that is subject to phenomena such as flutter.
When an F1 wing flutters, it means that it is producing very unpredictable downforce that can fluctuate between extreme values.
Lewis Hamilton, Mercedes W12
Photo by: Steve Etherington / Motorsport Images
When a driver controls a car with this unpredictability, there will undoubtedly be instances where they will have very little downforce when braking on a corner. Of course, this can lead to a particularly bad accident if the car cannot be stopped in time.
Flutter is a harmonious movement that, when exposed to frequencies by oncoming airflow approaching its natural frequencies, can, in extreme cases, tear the wing apart. This can be avoided by increasing the rigidity.
For these reasons, the FIA is conducting an engineering acceptance test to assess the structural integrity of the vehicle and to ensure that the drivers remain safe in the cockpit.
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What will happen next?
With more stringent testing going on for the French Grand Prix, this should reduce the wing flex used by the teams even further. This will no doubt create a cost that will upset teams working close to the cost cap, but it can be argued that security is invaluable.
This won’t stop teams from flexing their wings to the maximum allowable level, but it will reduce the performance resulting from using flexible wing geometry.
In the future, as materials science advances, the F1 could allow the wings to change shape more noticeably over the course of a race – but current rules do not allow them to do so.
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