The reduced pontoons from Mercedes are considered by all to be an aggressive but completely legal design.
The same cannot be said for the way Mercedes has implemented its concept of mirrors at the top of the side impact area, with rivals questioning whether or not they take advantage of a gray area in the regulations.
Ferrari team boss Mattia Binotto believes the mirror design is something that needs further clarification, and fears it is a piece that could open the door to a development war costing a lot of money and forcing teams to look for “spaceship” solutions.
So, what has most bothered Ferrari and the rest of its rivals in the mirrors of the Mercedes?
To clear up any confusion, this has nothing to do with the aerodynamic fairing around the upper side impact structure (referred to as the SIS). While it seemingly contradicts everyone else’s designs, that solution is no less effective from a security standpoint.
Those standardized impact structures were introduced in 2014 and can be built in-house to specification, or purchased from Red Bull Technologies .
Structure design had spiraled out of control in recent years, so a common setup was introduced that prevented teams from spending excessive amounts on complex structures that fit their aerodynamic demands and could pass crash tests.
This means that, as a standard element, it is no longer necessary to pass control. All the teams need to do is ensure that the structures fit within the limits of the legality boxes set out in the technical regulations.
It has been fashionable to place the top of the two SISs in a lower position since the 2017 rule change (see bottom right inset below with an example from the Mercedes W10) as it could be mounted separately from the main bodywork of the pontoon, providing protection against the wake of the front tire, while allowing the size of the entrance to be reduced as well.
Comparison of the pontoons of the Mercedes W13
However, the new rules have forced everyone to rethink that design, as they now need to be at least 50mm taller than before.
In Mercedes’ case, it has simply positioned its structure near the upper limit of the permitted frame, allowing it to once again use the bodywork as a flow conditioner and influence the pontoon and intake design.
Where Mercedes’ design has come under scrutiny from the other teams is in the design of its “mirror mounts” (blue arrows), as the outermost mount is divided into multiple surfaces within the permitted zone. They undoubtedly serve an aerodynamic purpose, rather than offer structural support.
And the key here is that the FIA in its rules requires that any aerodynamic benefits of the mirror components must be ‘incidental’, and not intended.
The rules are loose on that, as several teams have flow conditioning brackets that extend back over the sidepod’s shoulder, as with the mirror bracket used in the original W13 design (top right inset, above). .
Also, it’s not just Mercedes that has chosen to split their mirror mounts into smaller vortex-generating fins. AlphaTauri may have flown under the radar, but it too has a very similar design (top left in this photo below).
Comparison of the fins on the mirrors
The legality of rear view mirrors on the Mercedes and AlphaTauri designs is actually based on the following clause within that section of the rules:
iii. When cut by any ‘X-Plane’, it must form a single section measuring no more than 50mm in Z and no more than 10mm in Y.
That means that if a cut were to be made through the mirror mount section, there should be no more than one section of bodywork, which, as you can see from the dotted line in the main image of the article, in the X plane, there is no interaction between the sections.
However, if there was overlap, as shown in the example box, that would be considered illegal.
The mirrors of the Mercedes W13, legal
It will be interesting to see how this theme continues to develop over the course of the season, as there is clearly a return to be found in the different solutions, with some even sensing that the boundaries of the rules are being pushed.
