Aerodynamics on Motorcycles

Aerodynamics on Motorcycles

Recently on Twitter I had a brief back and forth with Craig Scarborough (@ScarbsTech), he of much technical knowledge surrounding technology and engineering in motorsport. The subject matter was that of the new front aero designs on the Ducati superbike which includes a ‘wing’ in the fairing vane above the front wheel. The upper fairing which leads to the screen is also sculptured for creating aero load. This gives it one of the most radical looking aero packages in the field.

The Ducati fairing spotted at the first event, doctored image from Craig Scarborough

Previously, the aero fairing cropped up during pre-season testing in the form of a more basic design, which was ultimately dismissed due to it not having the desired effect the team were looking for. However, it looks like it gave the team something to build upon so it wasn’t a complete waste, and this new development looks to have taken a few of the teams in the paddock by surprise. 

The previous fairing during testing – note how the overall design of this is much simpler.

When I asked Craig how much aero can be applied to a sports bike, he replied explaining that you can apply enough to combat lift – pretty handy during hard acceleration to minimise the front wheel lifting – be he believes that adding anymore downforce would result in unnecessary drag, and that is certainly not something you need on a superbike.

Aerodynamics on motorcycles isn’t certainly something new. Take for instance the Bonneville speed trial and the famous Triumph Streamliners, which attained several land speed records, and recently tried to better that with help from Guy Martin. But their aim is to completely eliminate any drag, focusing just on speed. In MotoGP, as well as all forms of motorsport, you need speed in the corners too.

An example of a streamlined motorcycle taken to the extreme

At this point it’s worth mentioning that I don’t have a degree in engineering or aerodynamics, so I did what any budding armchair enthusiast would do and took to Google! I found this interesting article on Aerodynamic Motorcycles by a chap named Tony Foale. In it he describes the forces at work and the well known trend for a motorbike to lift at the front wheel, which is produced by a drag force acting on the rear wheel. That makes sense, powerful motorcycles have a tendency for the front wheel to climb which then has the added issue of air streaming underneath and exacerbating the effect.

Naturally, in a straight line the added aero devices employed by Ducati should serve well to keep that front wheel planted on the track, but what about in a corner? Tony goes onto explain that:

It is when we come to cornering that the situation is different. Assume that we get our extra down force by use of a wing … then as we lean into a corner this force acts in line with the bike and hence increases the horizontal force in direct proportion to the increase in the vertical force on the tyres. Therefore, any increase in the tyre’s ability to support greater corning forces is used up by the horizontal component of the aerodynamic force. In practice cornering speed may well be actually reduced, because the coefficient of friction of the tyres with likely be reduced with the extra load.

That’s pretty simple to follow, and Tony produced a nice image to go with that:

Image © Tony Foale, reproduced here for illustrative purposes only

He goes onto describe a rotating wing theory that would stay horizontal during cornering. Illustrated above, it can be seen that the downforce would then be exerted more vertically, and not lead to exceeding the contact patch of the tyre. While as clever as this sounds, I highly doubt this is something we’ll see in MotoGP anytime in the future, as it probably constitutes as a moving aerodynamic device, and we know that those – with the small exception of the Drag Reduction System in F1 – is a big no-no. 

Perhaps manufacturers will look elsewhere and try to incorporate underbody diffuser style aerodynamics on their bikes, although of course they are limited by the frames. Yamaha were the first to take flak on their controversial in-fairing winglets, external winglets being banned at the end of the 2016 season. It remains to be seen if this will be received well by the fans, and not get caught up in the aerodynamic-wizardry along the likes of F1.

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