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They are now working on the details of the details. Hundredths of a second. Inevitable when the difference between the best is a few tenths per lap. And since the power of MotoGP engines is able to 'push' fairings that are by now not the best from a Cx point of view, most of the work is aerodynamic research. But not to reach top speeds, as was the case in the past when fairings sought an optimal 'teardrop' shape, but to generate load, grip and traction.
We are entering the field of fluid dynamics, which is the study of the dynamics, of the movement of fluids in general. The motion of a body in a fluid, when it is slow enough, is "laminar", that is, the fluid moves as if it were made up of many thin plates that are capable of sliding one over the other. When the motion of the body in the fluid is too fast, turbulence is created, as small vortices form in a chaotic way. An appropriate shape of the object can favour laminar motion: the teardrop shape. It is nature from which we must learn everything. Laminar motion is in fact the one that guarantees the least resistance to forward motion to which the shape of a liquid that has to move inside a fluid vein adapts in nature.
Good, now that we understand what laminar motion is, let's forget it: no one is looking for the drop shape anymore. Nobody gives a damn about Cx anymore.
The Cx coefficient indicates the aerodynamic resistance encountered by a vehicle moving on the road cutting through the air. The lower the Cx, the more aerodynamically efficient the object. In F.1, for example, the Cx is very high (between 0.7 and 1.1) due to the wing elements that have to generate a high downforce, which is required to obtain the best possible performance.
Something that is happening now in motorcycling, where aerodynamics to obtain greater grip is much more difficult to study and interpret than in motor racing.
And the reason, indeed the reasons because there are at least two, are very simple: the first is that the bike moves like a pendulum on its axis to tackle curves, therefore the profiles used change incidence with motion; the second because unlike a single-seater, on the bike there is a mobile ballast of around 70 kg which significantly affects the aerodynamics: the rider.
All the manufacturers present in MotoGP today use the wind tunnel to test the best ideas of their aerodynamic engineers. After discarding the ideas that prove not to work in computer simulations, dynamic tests are made with all the others. In Cologne, for example, there is the Toyota tunnel which also uses a moving beltway to simulate progress.
With systems of this type it is possible to simulate the efficiency of an aerodynamic component of a motorcycle even in the leaning phases and it seems that the profiles of the current fairings - both the Ducati 'ears' and the Aprilia 'chest' - are starting to be efficient even in the phases preceding maximum lean.
Obviously we are not able to evaluate the real work of some of these devices, such as the Pokemon or Stegosaurus fins that Ducati has for example on the tail, but some suggest looking at them in the phase in which the bike is in maximum lean: in that position it is clear that we are dealing with a wing with multiple flaps. That is, a wing area capable of generating more downforce than its total surface area. What do you reckon?
We are in the field of guesswork, but aerodynamics is a complex science whose effects go beyond the imagination.
Let's think, for example, of the lowering device: its main function would seem to lower the centre of gravity, favouring better mechanical grip on the rear wheel. In reality there is also an important aerodynamic effect, because with the bike 'seated' the incidence of the winglets positioned in the front part of the fairing changes. In practice, the wings 'stall', they stop generating load, thus improving the penetration of the bike into the air due to the lower resistance to forward motion.
When the lowering device is disengaged, before braking, the wings return to their original incidence, generating front load which improves the braking phase and helps in cornering. The height of the suspension also plays its role in aerodynamics, and this is why Ducati had studied a front lowering unit, prohibited from this year.
2023 is going to be a really good season, because everyone is copying everyone. Even Ducati, which started all of this, is forced to do it. And very often one test is not enough, because as we said at the beginning, we are talking about hundredths. The reason why, probably, Aprilia has here reintroduced the zero incidence rear wing, which however becomes efficient in the braking phase, when the tail rises. Not everything is as it seems in aerodynamics. In addition to science, you have to use your imagination.
