How F1 wheel rim covers work, why they were banned and why they’re back

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Alongside the much-vaunted return of the ground effect concept is the revival of wheel rim covers. F1 hopes these will help smooth out the turbulence ordinarily created by the wheel and tyre, and thus help reduce the overall wake generated by the lead car when another is chasing.

The rim covers used in 2022 will be a far cry from the complexity of what we’ve seen in the past though, as teams will have little influence in their design – in order that they don’t use them to damage the overall intent of their inclusion.

However, that won’t stop us taking a trip down memory lane to see how and why wheel rim covers have been deployed by teams in the past…

Ferrari 641 rims detail

Ferrari 641 rims detail

Photo by: Giorgio Piola

As can be seen from Giorgio Piola’s illustration (above), the roots of the wheel rim cover can actually be traced much further back than you might expect. Ferrari experimented with them at Monza in 1990 to reduce drag at the ‘temple of speed’ during qualifying.

The team was unable to use them under race conditions, however, as the brakes would have overheated, given there was nowhere for the heat generated under braking to escape. To make life even more difficult, not only in terms of regulating temperatures but also when needing to change tyres, a retractable panel was installed over the wheel nut.

 

It would take over a decade for another solution to reappear but, unsurprisingly, it was at Ferrari again. This time it came with a slight twist, as the team introduced a design for the rear wheel of 248 F1 that featured a shallow rim fairing.

Like the covers reintroduced for 2022, the fairing rotated with the wheel – something that was expanded upon later in the season with a cover that took up all but the central section in order to grant access to the wheel nut at pit stops.

 

This idea didn’t go unnoticed though, as can be seen here, with Toyota and Toro Rosso deploying their own variants at Imola and Silverstone respectively. Having previously protested the design, Renault also went on to introduce its own version of the rear wheel rim fairing in 2007 but it was Ferrari who continued to see the merits of using these rim covers to assist its aerodynamic endeavours.

Ferrari introduced an altogether more complex wheel rim cover at the British Grand Prix, one that was static, rather than rotating with the wheel. The cover being static opened up many new opportunities for the team in terms of rerouting the airflow passing through the brake duct assembly, with an aperture created in the lower rear portion of the cover designed to direct the airflow and influence the turbulence created by the wheel and tyre.

 

This was by no means the simple rim fairing that the team had been using at the rear of the car and had been copied by others. This was a complex system that incorporated several components to help route the internal airflow, including a row of guide vanes, while the entire axle, wheel nut and wheel gun all had bespoke designs to accommodate the new system.

The cover was convex in shape, rather than flat, in order that the airflow passing around the outside of the wheel didn’t have an adverse effect on what the team was trying to do internally.

It didn’t make any dramatic changes to the arrangement going into 2008 but did add a small guide vane across the upper section of the cover to help direct the airflow in that region more effectively.

While Ferrari hadn’t felt the need to alter the design too dramatically, others had taken note and a slew of new designs arrived up and down the grid…

 

McLaren’s design featured an outlet in the front lower quarter of the wheel rim cover, not the rear. This was obviously a choice based on its different aerodynamic demands and also resulted in designers looking at a variant which also included a forward deflector fence to help direct the turbulence.

Honda’s version included the rearward outlet position, albeit a little larger but, interestingly, had a small overlapping deflector in the lower forward corner too.

 

Toyota turned things up from a design perspective at the rear of the TF108 when it introduced a fan-like cover at the Spanish Grand Prix.

How wheel rim covers escaped 2009 aero overhaul

The regulation changes introduced in 2009 didn’t overturn the teams’ ability to use wheel rim covers and, despite the overall aerodynamic overhaul that ensued, they opted to use them as a means of altering the wheel wake turbulence.

Those aerodynamic changes did result in the teams having to optimise their pre-existing designs, while others developed new, more complex versions… 

 

For Ferrari, that resulted in the outlet being adjusted to take a more dominant location at the front of the wheel cover, while a deflector was added in the top corner.

When thinking of wheel rim covers, perhaps the Brawn BGP001 is the car that first springs to mind – its fluorescent yellow rim covers truly stood out, whereas everyone else tended to leave theirs blank or simply replicate the wheel rim design beneath.

 

Force India’s front wheel rim cover was more of a wedge-shaped affair that had a forward projected deflector.

At the rear of the Force India, a fan-like wheel rim cover was deployed – similar to the one we’d already seen on the Toyota the previous year.

 

The end for wheel rim covers

F1 opted to ban wheel rim covers from 2010 onwards, as not only had they contributed towards the overall failure to improve overtaking that the 2009 regulations had set out to accomplish, they were also an extremely costly solution, which seemed far too lavish to ignore at a point when teams were looking to rein in spending.

Even without those misgivings, there had also been several failures and pit stop incidents that contributed to their demise on safety grounds.

 

Ferrari wasn’t entirely done with trying to improve flow around the front wheel assembly though, as even without the rim covers it found a way to adjust the airflow’s behaviour. It added a pair of hoops on to the wheel rim design for 2010 (above), which other teams were unable to copy as the wheels were a homologated component.

Seen below on the Mercedes W10 mule car, which was designed to accept the larger 18-inch rims that will feature on the 2022 cars, these are the wheel rim covers that teams will use going forward.

The dished design is a compromise that erodes some of the aerodynamic inefficiencies created by the wheel and tyre, while also making them as easy as possible for the mechanics to handle during pit stops.

George Russell, Mercedes W10 mule

George Russell, Mercedes W10 mule

Photo by: Mark Sutton / Motorsport Images



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