The current crop of MotoGP machines might be the fastest we’ve ever seen but they’re also among the ugliest – sprouting ever more elaborate wings and fins in the effort to tame the airflow.  

Among this odd-looking bunch Aprilia’s RS-GP stands out with an even more unusual set of proportions than its rivals. 

It’s clearly effective, with Aleix Espargaro taking Aprilia’s first victory in the modern era and lying second in the title chase. Now new patent applications give some hints to why the RS-GP looks the way it does and how it’s proving to be one of the class bikes of the field.

Downforce and drag reduction are the key elements to the design. While Aprilia’s moustache-like nose winglets and the Mugello rear wing mean it has some of the most eye-catching downforce-generators on the grid, the patents reveal that they’re just the tip of the design iceberg.  

The secret to improving the downforce-to-drag ratio is revealed to actually be the bike’s belly and in particular the bulb-shaped leading edge below the radiator intake.  

On a conventional bike the size of this intake matches the size of the radiators behind it, and the front edge of the fairing sides are arc-shaped to follow the curve of the front wheel, but Aprilia’s design is quite different. On the RS-GP the fairing is further back from the wheel than its rivals, with a very high-looking nose. That’s because it draws in most of its cooling air from above the front wheel, between the forks. The air is then deflected downwards by the slanted upper radiator, towards that all-important, bulbous belly. 

Seen in cross-section from the side, the bellypan covers around half of the lower radiator, reducing the overall opening by around 20%, and its upper edge is honed to a sharp blade to slice the airflow travelling down behind the wheel.  

Half the air is caught in the front of the bellypan, where it slows down, creating a high-pressure zone to help force air through the lower radiator. The remaining air is directed down and under the bike, where it’s accelerated by the shape of the lower fairing. The faster air travels, the lower its pressure, so there’s low pressure under the bike. High pressure above the belly fairing and low pressure beneath it means the belly itself creates downforce.  

Further back, the body rises away from the ground, like most of its rivals, to accelerate the air further. Most come to a point where the bellypan ends ahead of the rear wheel, but the Aprilia’s curves upwards, smoothly linking to a channel between the rear wheel and its mudguard – using a scoop-style deflector under the swingarm to encourage air in that direction for more rear downforce.

In wet or cold weather, an additional hugger can be fitted much closer to the rear tyre to keep heat in and water away from it as the air from under the bike runs up and over the wheel. 

Drawing in air: Air enters over the front wheel, between the forks and under the unusually high nose of the RS-GP, before being diverted downwards by the forward-slanted upper radiator. 

Split the flow: The bulb-like chin on the lower fairing splits the downward-flowing air, creating a high-pressure area in the chin ahead of the lower radiator. This improves cooling and allows a smaller radiator opening to reduce drag. 

High/low pressure: The high-pressure air in the chin also creates a differential with the fast-moving, low-pressure air that’s diverted under the bike, adding downforce. Better cooling, less drag and more downforce – a win-win-win situation. 

Smooth blend: At the back airflow remains attached to the lower fairing and is diverted up over the rear wheel in a tunnel formed where the bellypan essentially blends into the inside of the rear mudguard. 

Fine-tuning: The additional wet/cold hugger is made of two close-fitting parts that can slide into one another, allowing its size to be altered to tailor rear tyre temperature. 

© 1955-2022 Bauer Media Group

Bauer Media Group consists of: Bauer Consumer Media Ltd, Company number: 01176085, Bauer Radio Ltd, Company Number: 1394141 Registered Office: Media House, Peterborough Business Park, Lynch Wood, Peterborough, PE2 6EA H Bauer Publishing, Company Number: LP003328 Registered Office: Academic House, 24-28 Oval Road, London, NW1 7DT. All registered in England and Wales. VAT no 918 5617 01 H Bauer Publishing are authorised and regulated for credit broking by the FCA (Ref No. 845898)