For most people, aerodynamicist is an easily understood subject: round, smooth shapes glide through the air with less effort than exposed or sharp ones. For almost as long as motorcycles have been made, pains have been taken to reduce the turbulence caused by resisting air passing over the motorcycle and rider. The most basic fix involves making the package as narrow and slight as possible, while at the other more involved end of the spectrum, complex studies with computational fluid dynamics software and expensive wind tunnel experiments result in elaborate fairings and duct work.
In the fall of 2002, I was assigned to Yamaha Engineering Corporation (YEC) for a small project, to apply styling to the upcoming 2003 YZR-M1 MotoGP motorcycle. The year previous, Honda had unleashed the legendary RC211V and promptly won the championship on it with Valentino Rossi. The Honda, the first of the new 990cc four-stroke Grand Prix machines, had completely eschewed traditional aerodynamics and featured a purely cosmetic fairing that looked absolutely magnificent. Honda completed the trick by styling the street legal CBR600RR to match, thus winning the race for customer wallets as well. YEC and the whole of the Yamaha empire was stunned. Yamaha's street motorcycles at the time were winning design awards and being imitated by everyone, even the Italians. However, the look of the Yamaha YZR-M1 race motorcycle was, to put it mildly, not great. They had fairing entirely developed by the wind tunnel tests and lab results that had proven successful in the 500cc two-stroke Grand Prix period. Max Biaggi called the original 2001 Yamaha YZR-M1 'a whale' in the Italian press, something that didn't sound so good when the same people were calling the 2002 Yamaha YZF-R1 'the most beautiful Japanese motorcycle ever made.'
As a young industrial designer with no aerodynamic knowledge, being asked to apply R-series styling to the most expensive, high-profile product in the corporation was terrifying. My boss, Kuwata, a jovial man who was to become more surrogate father then mere mentor, sent me to Japan with simple instructions: 'listen to the engineers, do what you are told and work with the boundary.' I thought he meant boundaries, as in the rules governing division of labor. It turned out he meant something else.
In aerodynamics the critical element to control is called the boundary layer. It is the razor thin layer of air that touches the moving object on one side and brushes the undisturbed air on the other. The smoother this transition, the greater the reduction in aerodynamic drag. Unfortunately, motorcycles are among the most drag-inducing vehicles ever conceived, generating at best five times as much drag as a passenger car. Forcing air past a sitting person suspended between a mess of rotating and rolling shapes at high speed is akin to waking quickly in knee-deep water. The chief problem is that the boundary layer that so blissfully glides along those lovely fairing runs out of fairing at some point and collides into the mess of air circulating around the rider. This is called boundary layer separation. All that work done in the tunnel and in the lab concentrates on improvements of five percent around the front wheel or radiators, areas we actually can control. The rest is purely academic, particularly in light of where we are with power. Even in 2002, those Grand Prix motorcycle were putting out 240 horsepower in a package weighing 155 kilograms. What air we couldn't slip past, we could punch through with brute force.
That was the revelation Honda had made in the development of the 990cc Grand Prix machine, and so chose to apply design as a purely emotional element. They won decisively in 2002 and again in 2003, ending the era of aerodynamic purity in Grand Prix racing. The 2003 Yamaha YZR-M1 I worked on featured an upper fairing reminiscent of the YZF-R1, and a new fuel tank and tail that had no aerodynamic considerations what-soever. In Japan, I had learned that everything after the trailing edge of the front fairings was a mess of high-pressure, low-velocity turbulent air that did nothing but contribute to the motorcycle's inherently high parasitic drag. We might as well look good as we suck all those tiny uncontrolled vortices along for the ride.
All that nonsense you read about in the press releases and from amateurs who think they have invented some hitherto undiscovered wind-cheating technology is really just bunk. On the track, in the lab, and in the wind tunnel, the instinctive culture of aerodynamics gives way to an awful truth: no matter how much we cheat the wind with the motorcycle, it is the gangly creature astride it, moving constantly and covered in wrinkled leather, that is the chief problem. Of course, we could go back to the full 'dustbin' style fairings NSU and Moto Guzzi wore in the 1950s, but then what would Max Biaggi say? 'Whale' could start to sound complimentary.