OEM Patents highlight the direction of travel

Big Brand Developments show increased emphasis on Motorcycle Aerodynamics

It wasn’t until 1976 that the first truly aerodynamics production motorcycle reached showrooms in the form of BMW’s wind tunnel-developed R100RS and the pace of development remained slow. But today, with efficiency ever more at the forefront of engineers’ thoughts whether in pursuit of a performance edge or reduced emissions, drag reduction is increasingly taking centre stage and that’s reflected in the secret R&D activities behind the scenes at virtually every major bike company on the planet.

Those activities are, by their very nature, generally kept hidden away, but it’s possible to keep tabs on innovations by watching the patent applications those companies make, as they’re often the side effect of larger, ongoing development projects. We’ve glanced through the records to pick out some of the most interesting recent patent applications that show how aerodynamics and efficiency are pushing into the mainstream in the form of the four Ds:

1. Drag reduction

2. Downforce

3. Ducted airflow

4. Downsizing

Drag Reduction

Making a motorcycle cut through the air cleanly might be simple on the face of it, use a shape like a Hayabusa, a race bike or even a land-speed machine and you’ll make a much smaller, cleaner hole in the air. But all that effort goes for nought the moment the rider adopts anything other than a full-race crouch so in the real-world manufacturers need to look for something a bit more subtle to get their aero gains.

Examples of this ‘real world’ drag reduction that can be found in recent patents from big-name brands include a clear focus on movable components: if you can’t rely on the rider to move into the most aero-efficient pose, instead you can ask the bike to clean up its aero in certain circumstances.

For example, both BMW and Yamaha have filed patents around the idea of closable shutters to reduce or eliminate airflow through radiators when maximum cooling isn’t needed: a concept that’s been around since the pre-WW2 era in both aviation and car design, but one that’s yet to make an appearance on a production bike. Yamaha’s patent application, published last year, puts the emphasis on closing the air outlets on the sides of the bike when maximum cooling isn’t required, cleaning up the airflow around the bodywork, it’s aimed more at high-performance, full-faired motorcycles. BMW’s version looks at naked and adventure bikes and proposes shutters in front of the radiator, pushing air around it instead of through it. In both instances, it’s a logical move: electromechanical actuators are increasingly cheap and reliable, and radiators need to be designed to provide cooling in the most extreme circumstances (full throttle runs at high ambient temperatures) so in day-to-day use they’re arguably much larger than required.

The affordability of actuators also emerges in patent applications from China’s CFMoto, proposing the idea of downforce-generating winglets that can fold away into the sides of the bike, either when top speed is required or at low speeds when the winglets would provide little worthwhile downforce but still create drag (as well as being vulnerable to damage). Fellow Chinese brand Benda has had similar ideas, reviving the idea of pop-up headlights that was once key to any self-respecting supercar, and applying it to motorcycles: a concept that has now reached production in its LFC700 Pro model, albeit only in markets outside Europe. Again, the theory is that if the lights are only needed part of the time, why have them blocking airflow full-time, although that’s probably a secondary consideration to the cool factor of simply having pop-ups in the first place. The same idea also emerged earlier on patent applications for the company’s yet-to-be launched VTR300 Turbo, a small-capacity sports bike concept we’ll be mentioning again later on.

Downforce

The idea of movable parts also features heavily in aerodynamic innovations in the quest for downforce on motorcycles, because adjustable surfaces offer the clearest route to generating worthwhile downforce at low speed or in corners without creating unacceptable high-speed drag.

So far, the adoption of such ideas in the real word have been limited. Bimota’s KB998 Rimini is the first to use variable winglets in a production bike, but CFMoto has already demonstrated a much more ambitious version of the idea on its forthcoming V4 SR-RR superbike, with huge aero surfaces that can move independently of each other to alter their angle of attack.

Patent documents show others are also in on the action. BMW has applied for patents on both front and rear winglets that alter their angles via linear actuators, with the potential to mount them either on the bodywork or on unsprung parts, like the fork lowers and swingarm to transmit their downforce directly to the tyre without compressing the suspension. The same company has also worked on wings that alter their lateral angle rather than pivoting to change pitch. The idea is to keep the aerodynamic surfaces parallel with the ground even when the bike leans into corners, creating much more predictable levels of downforce. Most recently, BMW has even investigated Flettner rotors instead of winglets; cylindrical rods spinning at up to 80,000rpm to create downforce via the Magnus effect, the same phenomenon that allows spinning balls to curve in flight. They have the benefit of variable downforce with a reduced reliance on forward speed and aren’t impacted by a bike’s pitch: even in a wheelie they’ll provide downforce when a conventional winglet might create lift.

Ducted Airflow

Ducting air though a motorcycle rather than concentrating purely on the external elements has clearly been a major focus for White Motorcycle Concepts, but others are also looking for gains from unseen airflow.

BMW is again among the leaders, at least in terms of patent applications, with a plethora of ideas related to ducting air behind their bikes’ bodywork. The company’s patents include ideas for fan-assisted ducts, vectoring airflow where it’s needed to improve cornering, and a variation of that idea that directs the exhaust from an internal combustion engine through valved pipework to exit where it’s favourable for the bike’s cornering attitude.

Another system, believed to have been used in the company’s WSBK bikes already, is the concept of crossflow ducting, scooping air from a high-pressure zone on lower side of the bike when it’s cornering and ejecting it from the other side.

Further patent applications on the same theme include documents from Suzuki showing winglets with air ducts inside them, ejecting air from slots in the lower surface to reduce drag when valves are opened, and in MotoGP we’ve seen virtually every manufacturer adopt downwash ducts on the front lower edge of their fairings in the pursuit of a diffusor-style effect from the belly bodywork in corners.

Downsizing

The fourth pillar of improved aerodynamics comes less from the aero ideas themselves and more from the simple fact that if you make the mechanical components (most notable the powertrain) more compact, you open the door to more aerodynamic options. Whether that’s reducing frontal area by making the whole bike slimmer or using the freed-up space for internal ducting, there’s an advantage to downsizing the power unit if it can be done without sacrificing power.

Forced induction is a clear leader in this area, and most major bike companies have been working on the idea in recent years. Honda’s V3R, with its electric compressor instead of a conventional turbo or supercharger, is heading for production next year and has been at the heart of patents from the company, but others taking that route include Yamaha (with its own e-turbo triple) and KTM, which has filed patents for a small, blown single-cylinder engine using an electric compressor.

We’ve already mentioned Benda’s proposed VTR300 Turbo, a bike that was promised some years ago but has yet to be launched, using a forced-induction, small-capacity V-twin. Since then, the same brand has shown its ‘P51’ concept, using a tiny 250cc boxer twin paired to an electric hybrid powertrain for the performance of a much larger bike. Meanwhile, Suzuki has spent more than a decade filing multiple patents around a turbocharged version of its 800cc parallel twin engine – which was shown in public in boosted form long before it reached production as a normally-aspirated engine. It hasn’t launched a production turbo motorcycle since the mid-80s XN85, but all that development work suggests that if a new boosted bike boom emerges, Suzuki will be ready to join in.