[cycleworld.com] - BMW Working on Superbike Aero

[Ninjette Newsbot]

As aerodynamics continue to evolve on racing motorcycles, brands like BMW look for advantages to increase efficiency and reduce lap times.

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BMW has been working on advanced aerodynamics on its M 1000 RR for years, but the next goal is to help push the bike down into the corner via crossover air ducts. (BMW/)Motorcycle aerodynamics have entered a completely new era over the last few years as MotoGP teams develop increasingly complex and effective solutions to boost speed. But the latest innovation comes from a company that isn’t involved in the MotoGP arms race, BMW.

While most aero innovations in motorcycling aim at increasing downforce, or at least counteracting lift, to push the tires into the asphalt, BMW is taking a different route and trying to use airflow to counteract centrifugal forces, reducing the work that the tires have to do and increasing cornering speeds in the process.

The Bavarian company has filed a patent application for a system of ducts that take air from one side of a bike and route it through to the opposite side, where it’s expelled through jetlike outlets. The single image accompanying the patent shows a simplified view of the underside of a bike fitted with the system and demonstrating the route that the air takes. The bike in the illustration is moving from right to left, so the wider section of fairing is toward the front.


In order to be able to race with winglets and advanced aerodynamic features, motorcycles must be fitted with them on the stock bike that the racing bikes are derived from. (BMW/)You’re probably thinking that the two air ducts and their corresponding jets must surely counteract each other? The patent explains that when the bike is going in a straight line, that’s true: The air on each side of the bike moves at the same speed, so the two ducts cancel each other out. But all that changes when the bike leans over into a corner.


A patent illustration of the underside of a faired motorcycle, like the M 1000 RR, that shows how the air ducts cross over intaking air on the side closer to the road surface and exhausting it on the higher side to help push the bike down into the road. (BMW/)This is the clever bit. When you’re cornering (for example turning left) the airflow on the opposite side (the right) can separate from the fairing, reducing the pressure on that side. Meanwhile, the pressure on the side that’s closer to the ground (the left in our example) increases. Essentially, it’s like the road surface and the fairing’s side act together to become an extended, wider channel for the duct on that side, squeezing the air toward the intake. Because the ducts cross over, that means the “jet” outlet on the opposite side expels more air, at higher pressure, pushing the tire toward the ground and the bike into the corner.

BMW’s patent goes on to explain that by making the intake larger than the outlet, and giving the outlet a nozzle-like design, you can increase the velocity of the air exiting from the “jet.” The document gives the example of having a 5,000mm2 intake (7.75 square inches) and a 1,000–2,000mm2 outlet (1.55 to 3.1 square inches).

Since BMW doesn’t compete in MotoGP, where an idea like this could be applied on a purely prototype machine, it’s possible the company is considering using the technology on a road-going superbike. The M 1000 RR would be the logical machine to adopt it since it’s a track-oriented bike that competes in WSBK racing.