Let’s close at least momentarily the section of the three patents filed by Aprilia regarding the aerodynamics of the MotoGP (here the first, the second and the third). We now inform you of a small discovery in another area.
In fact, by digging for the patents themselves to read them, sometimes we come across more interesting things, extremely interesting indeed. As in the case of patent WO2024028318A1 published this year 2024 by the already well-known Marco De Luca, this time associated with Germano Bergamo on behalf of Piaggio.
You already know Marco De Luca: he is an engineer who has worked at Lamborghini, Mercedes AMG and McLaren. Since 2019 he has been in Aprilia as head of the department responsible for the design of the RS-GP chassis, its aerodynamic development, engine and brake cooling, the design of the snorkel, the air box, the exhaust system and the fuel tank. fuel. In short, a big shot!
The Aprilia chassis
But if 3 patents had been registered in the field of the aerodynamics of the beast, so far nothing had concerned the very original chassis of the RS-GP. The Aprilia frame (in aluminium, never seen the carbon version before…) in fact takes up the concept inaugurated by Suzuki, with bolted engine supports (today with 3 screws compared to the 5 of the defunct GSX-RR), from 2017 until to 2022, with a new version (we talked about it here).
But as we can see in the following photo, while Suzuki could modify the rigidity of its frame by changing the bolted elements, in Aprilia we opted for another more advanced solution: connecting said supports to the frame itself via tie rods also called struts. Or “intelligent” tie rods…
Let’s be honest, the topic is so delicate that some of our photos (not this one) were sent back to Noale. This followed phone calls to kindly ask us to remove them to avoid problems for careless mechanics, which of course we did. But at the start of the 2024 season, the patent in question makes the matter public and our photographers will not fail to have fun at the first opportunity…
The Aprilia patent sheds light on some technical subtleties of MotoGP
“The technique involves motorcycle frames made of aluminum or composite materials to meet the needs of lightness and rigidity. Motorcycle frames usually have a “U” or “O” shape to connect the steering column to the rear wheel swingarm. The frames also allow the anchoring of the propulsion engine. Typically, the engine is installed directly on the chassis.
In some chassis the engine is installed on the chassis via brackets for rigidity reasons. The supports are connected to the frame by connecting means and the engine is installed on the supports. Thus it is possible to adjust the rigidity of the frame and optimize longitudinal and lateral rigidity. In practice, the rigidity of the supports is lower, or in any case different, from that of the frame and allows the typical torsions and movements of the engine to be transferred only partially to the frame.
In this last type of frame, the supports are designed to have sufficient longitudinal rigidity to avoid the so-called “frame closure” phenomenon. That is, excessive advancement of the engine relative to the steering column during braking. This phenomenon is even more evident on racing bikes, in particular on MotoGP ones.”
How to solve them?
“On these motorbikes the frames are very much affected by the deformations caused by braking, which are much more powerful than those of normal motorbikes. To solve this problem of “chassis closing” during braking, the engine supports are usually oversized. However, this leads to greater weight and a loss of performance, in terms of rigidity, when cornering. In fact, the frame becomes more rigid in both longitudinal and lateral deformations.
The aforementioned drawbacks of the prior art are now solved by a motorcycle frame. It comprises a main body extending in the longitudinal direction and a pair of supports connected to the main body and configured to at least partially support an engine, wherein said frame includes a pair of spacers, or struts, configured to be rigid in compression and free in tension.
Each spacer is connected at the front to the main body and at the rear to one of the aforementioned supports. The frame designed in this way has greater rigidity. When braking, the mass of the engine tends to move forward, unloading its weight partly on the supports and partly on the strut. During acceleration, however, the strut is free to extend and the engine only unloads its mass on the supports.”
The variable stiffness frame
2
Images
‘
In this way the pair of struts contributes to absorbing the compression loads acting on the main frame, remaining unused and irrelevant when loads other than compression ones act. These compressive loads are mainly those that develop during sudden decelerations and braking of the motorcycle and tend to “close” the main body of the frame, i.e. to generate angular momentum in a clockwise direction, as in Figure 2. The function of the struts is that to increase the rigidity of the supports during braking and to dissipate the forces mainly on the part of the main body located near the management column. In this way the bike is more stable when braking, allowing the rider to enter corners more smoothly.
At the same time, the pair of struts is “transparent” in other operating conditions of the motorbike, for example when cornering or accelerating, allowing labile deformations of the frame and supports. This ensures greater chassis flexibility, which is especially necessary when accelerating or cornering. The flexibility of the chassis allows for more grip from the tires and therefore more traction when accelerating out of corners.
2
Images
‘
Simply put, the chassis is very stiff when braking, but flexible when cornering and accelerating. This is how Aprilia just invented the variable stiffness frame. Two types of struts were made by Aprilia in MotoGP.
