Yamaha Patent Application Explains Downwash Ducts

Winglets have already become a mainstay of modern sportbikes in the handful of years since they were popularized in MotoGP. Now another piece of racebike tech might be finding its way to the street in the form of “downwash ducts” on the lower sides of a bike’s fairing.

So-called downwash ducts, or flow redirectors, first emerged on the MotoGP scene in 2021 when Ducati debuted distinctive, downturned air channels on each side of the Desmosedici GP21′s fairing at the preseason Qatar test. Since then, they’ve been duplicated by others, and Yamaha has joined the party in 2024 with its own take on the idea, but the ducts’ purpose has often been subject of speculation.

On the most basic level, these ducts look illogical. Sitting below the winglets that are clearly designed to create downforce in a straight line, they scoop in air from the sides of the bike and fire it out downward. You might have thought that would have the effect of trying to push the bike’s front end upward, but analysis of the design via independent studies (Aerodynamic Study of MotoGP Motorcycle Flow Redirectors) suggests that this isn’t the case. Instead, it appears that the ducts perform a dual purpose. In a straight line, they scoop up the “dirty” airflow in the wake of the front wheel and fork and direct it underneath the bike, helping to reduce drag and add some downforce. In corners, there’s higher air pressure at the front and inside of the corner, where the fairing comes close to the ground, encouraging high-velocity airflow underneath the bike to the lower pressure zone on the other side, creating downforce. The downwash ducts amplify that effect.

Yamaha’s new patent application adds another benefit from the downwash ducts, saying that they improve the bike’s cooling. The turbulent air coming from the front wheel and hitting the leading edges of the fairing is scooped away by the ducts and a low-pressure area is created on the fairing side just behind them—just where an outlet vent releasing hot air that’s gone through the radiator and oil cooler is positioned. That low-pressure zone helps draw air through the radiators, making them work more efficiently than they could without the downwash ducts. That means the radiators can be smaller and lighter, and the bike slimmer.

The current Yamaha M1 MotoGP bike appears to have adopted the idea, with exactly the downwash ducts and cooling outlets shown in the patent appearing on the latest version of the bike. Others may well have already been using the ducts for a similar purpose, as Ducati often positioned air outlets just behind the ducts in previous iterations of its design.

Yamaha’s patent application could be an indication that the company is considering adding similar ducts to future production motorcycles, as it’s relatively rare for race-only ideas to be the subject of patents. After all, the purpose of a patent is to provide protection for innovations in a commercial setting rather than in competition. Whether the idea is genuinely patentable, particularly given the seemingly similar designs used previously by Ducati and others on the track, will be one for the patent inspectors to decide.