Formula 1 Insight

The Spread of Wheel Covers

You can't hold a good engineer down. In spite of the increasingly tight limits imposed by F1 technical regulations, the innovations continue to appear. Latest is McLaren's extension to the wheel covers that are spreading through the paddock this year.

McLaren MP4/23
McLaren MP4/23

I gave my opinion on the legality of the wheel covers in my post entitled Wheel Fairings and the FIA (and an interesting technical discussion resulted in the comments system), so I will not rehash the argument now. McLaren's development of the idea brings me back to the subject, however, and I am forced to ask, "Just what are they trying to achieve with this ugly addition?"

My first thought was a return to the brake cooling excuse employed by Ferrari to gain acceptance from the FIA scrutineers. That bit sticking forward from the cover could be a scoop intended to draw air in behind the insert and so cool the brakes. This function is already performed by scoops inside the wheel, however, and close inspection of the photographs available seems to indicate that it is too flat to contain a scoop.

Since the leading edge of the extension curves around to follow the shape of the tire at the front, the inevitable conclusion is that it is designed to conduct the airflow smoothly around the outside of the wheel. This would confirm that the primary intended function of the front inserts is aerodynamic; filling in the wheel well has the immediate effect of decreasing the vortices created by a wheel turning in the airstream and covering the tire in front of the well assists in this.

In fact, if one could extend the wheel insert so that it covers the outer sides of the tire completely, the reduction in drag through turbulence would be a big improvement in the overall aerodynamics of the car. Perhaps McLaren are working their way to this in small steps, hoping that the FIA will not ban it.

Whatever the reason given for the covers, they are a good example of how the spirit of the rules can be circumvented by stealth. Originally introduced by Ferrari on the rear wheels as assistance in brake cooling, the inserts have spread to the front and become static. Now they threaten to grow beyond any pretence at brake cooling.

Racecar Engineering had a novel explanation for the original introduction of the covers; this involved linking it with the "secret gas" so famously used by Ferrari to decrease graining in the tires. I found the reasoning dubious at best and irrelevant anyway once the innovation had spread to the front wheels.

Presumably, the FIA feel they cannot rule out the covers, having allowed them in the first place, but I would be surprised if they are not at least a little uneasy at the way in which they are being developed. It becomes clear that the front inserts needed to be static because their primary function is aerodynamic - if they moved, they could be banned immediately as movable aerodynamic devices. With the growth of the inserts to threaten covering the whole wheel, it might be necessary to go right back to the fifties and the ban on covered wheels to find an excuse to outlaw the things.

And they do need to be declared illegal. The expense and effort required for their development is illustrated by the fact that the poorer teams do not have them yet. How logical is it to allow such expensive modifications while claiming a desire to keep costs down? The inserts contravene the spirit, not only of the regulations, but also of F1 itself - hence the need to go as far back as the roots of the sport to find out why they look and feel so wrong. If the covered wheel is anathema to F1, then any new way found of covering them is still contrary to the original concept of the sport.

I say ban the horrible things before they can get any uglier.


Steven Roy
You sometimes get the impression that the FIA don't even grasp the basics of race car engineering.

F1 cars in common with every racing car I can think of do most of their braking at their front wheels. The thermal mass available to remove heat is much greater at the rear and the rear wing/diffuser must extract air from around the rear wheels. So why would anyone need special brake ducts for the rear wheels where less braking takes place and there is vastly more capacity to remove the heat. Had Ferrari first introduced these devices in their front wheels it would have made a lot more sense.

The gas is irrelevant as the front to rear balance is exactly the same whethet the gas/tyres run hotter or colder. You are still going to generate more heat at the front.

Clearly these devices are aerodynamic in nature. There can be no other reason for their existence. Max said they are not movable aero devices because they do not rotate but on the front wheels they are steered and they are mounted on the unsprung part of the car which means however limited they move with the suspension. I thought the original ban on high wings stated that aero devices had to be mounted on the sprung part of the car. However I doubt even Alianora could dig out that regulation.

To me the purpose of these devices on the front wheels is to smooth the airflow on turn in to a corner which has historically always been the most dificult phase aerodynamically. The rear 'ducts' simply smooth the airflow.

Are they illegal? Oh Yes.
Date Added: 15/02/2008

It does seem odd that the FIA are prepared to ban some things that appear to be in line with the regulations but ignore others that seem obvious breaches. To me, the wheel covers are clearly illegal and surely worth at least a discussion, therefore. But no, all we hear is a deafening silence from the FIA. Maybe they're too involved with wild experimentation of their own, night races for instance.
Date Added: 15/02/2008

Alianora La Canta
Nothing like laying down the gauntlet, Steven! I think I can meet your challenge, though.

After the high wing fiasco of Spain 1969, the CSI (F1's governing body of the time) introduced a rash of regulations to control them. These were described as "badly drafted". One of these was the rule now known as Article 3.15 of the Technical Regulations:

"With the exception of the cover [in the pit lane]... ...and the ducts... ...any specific part of the car influencing its aerodynamic performance:

- Must comply with the rules relating to bodywork

- Must be rigidly secured to the sprung part of the car

- Must remain immobile in relation to the sprung part of the car."

I would suggest that the front wheel fairings break all three of the sub-restrictions on Article 3.15.

Without the brake cooling justification, the fairings are illegal because brake ducts are the only form of bodywork permitted in the area around the wheels (Article 3.11.1).
Date Added: 15/02/2008

Alianora La Canta
Oh, and of course non-cooling wheel fairings are not attached to the sprung part of the car and do not remain immobile in relation to it. If Renault's mass damper can be banned according to that rule, surely the fairings can too?
Date Added: 15/02/2008

Steven Roy
I am amazed you found that.

I am also amazed at my memory.

As expected this proves that the 'brake ducts' are entirely illegal. At some point Max is going to be embarrassed into banning them. I wonder if they will be clarified in Melbourne?
Date Added: 16/02/2008

That will require someone to ask for clarification. McLaren dared to do that last year and look what happened to them. It will be a brave team owner that tries the same thing.
Date Added: 16/02/2008

Keith Collantine
I thought the additions McLaren had on their front wheel fairings in testing might have been a measuring device? Having said that, they've run a few different configurations.

Also, how are the fairings on the front wheels made to remain in the same position relative to the rest of the car, rather than rotating with the wheels? I can't get my head around that...
Date Added: 18/02/2008

That. as the saying goes, is the $64,000 question, Keith. I think Sam Michael was referring to that problem when he described how difficult and time-consuming it was for Williams to design their own version. They have to be attached to the wheel hub through the centre of the wheel, as far as I can see. Some very clever stuff going on, I think.

A measuring device? Hadn't thought of that - but what would they be measuring that couldn't be done in an easier way? I noticed in the videos that you put up today that McLaren were changing the position of the outlet on almost every run. That would indicate that they're still experimenting to find the ideal set-up. No sign of the extension in any of the videos, however.
Date Added: 19/02/2008

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