Winglets: Why They Just Won't Fly (MotoGP)

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I'm not sure what "winglets" are, in reference to a motorcycle. Are they on the front of the H2R?

I've seen them on the tips of airliner wings, but never knew they had applications in motorcycle racing as well.

They are airfoils mounted on the front of a racing motorcycle to theoretically add downforce. The main reason for this initially was to delay the onset of traction/wheelie control to keep the power down and the bike on the ground. Later, some people got the idea they would be helpful for cornering and braking but it was clear that the teams, especially Ducati, were not working with experienced engineers and simply trying things to see what would or would not work. Since there was no real design history of using these on motorcycles this was understandable.

Unfortunately the real detrimental effects of these things was well-illustrated at Motegi, where both Yamahas crashed due to lowside events.

Videopass gives access to a lot of fairly detailed information; Massimo Merigalli, Movistar Yamaha MotoGP Team Director, explained that after analysis of the data, each lowside was different. Rossi was trailing the brakes, where Lorenzo had just picked up the throttle. In Rossi's case, the difference in lean angle was just two degrees more than the previous laps. Merigalli said it was "difficult to judge" why the crash happened.

There were several seconds of outstanding closeup, slow-motion video of the Yamaha winglets in action under braking, and they demonstrated a significant oscillation that looks like what we could call "flapping". Lorenzo mentioned something he called a "vibration" that he could feel in the tire, and he attributed the problems to a poor tire choice but, as with most pilots, he's obviously not an aerodynamic engineer and really does not know quite what the winglets are doing to the handling. But the "flapping" tells the story.

The winglets create a tip vortex, inducing a lot of turbulence and unpredictable handling behaviour; here's an excerpt from a study of tip oscillation and vortices. Notice the word "catastrophic":

When the wing was oscillated through the deep-stall regime, a dramatic decrease in tip vortex strength and concentration was observed at the end of the upstroke, as a result of the growth of the leading-edge vortex and subsequent catastrophic flow separation.

-David M. Birch, Ph. D., University of Surrey, Guildford, Mechanical Engineering, Aerospace Engineering, Aeronautical Engineering

Basically that spells bad news, and the slo-mo video of the Yamaha winglets (pictured) proves it.

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Thanks for the great write-up.

I won't be sad to see them go. I never liked them from an aesthetics standpoint.

If it looks wrong, it probably is wrong.