Motorcycles with Mat Oxley
MotoGP aero: ‘the game has just started’
For more than half a century, aerodynamics has been the most unexplored area of motorcycle racing technology. During the 1950s many Grand Prix constructors created all-enveloping bodywork, but these so-called dustbin fairings could be deadly in side-winds, so they were quickly banned. The regulations that were written following the 1957 Grand Prix season have remained largely unchanged to this day, preventing all but the most rudimentary aero development.
Until now. A few years ago Ducati found a way around the regulations by fitting aerodynamic strakes to its Desmosedici MotoGP bike. The strakes increased front-end downforce, thereby bypassing the electronic anti-wheelie device that works by cutting torque delivery, which can hurt acceleration.
Unsurprisingly, other riders were unhappy with these protuberances, which Honda’s Dani Pedrosa called “knives on the side of the bikes”. Others complained that the dirty air behind a winged Ducati made it dangerous to get too close, so last autumn winglets were banned.
However, the latest MotoGP bikes are probably just about as dangerous without any front-end downforce. The fastest bikes now exceed 220mph, their front wheels only skimming the road in sixth gear as riders go for the brakes. This explains this season’s flourish of new aero designs, most notably Ducati’s hammerhead-shaped upper fairing (top), which once again skirts around the latest regulations.
“Ducati’s new aero has changed the game overnight,” says aerodynamicist Alistair Rowland-Rouse, who works on Sauber Formula 1 and Le Mans Prototype projects during the week and races a Triumph 675. “It’s going to be interesting because motorcycles are infinitely more complex than F1 cars.
“A lot of calculations are based on the centre of gravity position, which stays in the same place on an F1 car, but not on a bike, where the CofG is always moving; plus there’s a lot more feel involved in riding bikes. It’s about getting the set-up right for each rider; it’s not all cold, hard physics. For example, if you fed Marc Marquez’s riding technique into a computer, the response would be: ‘Does not compute’. ”
Inevitably, manufacturers are also looking at potential aero advantages in the corners as well as on the straights. But this is a tricky game to play with so little mechanical grip available.
“If you make a downforce device that acts straight through the centre of the tyre contact patch when you’re upright, as soon you’re leant over you increase the lateral acceleration, which is what your tyres fight against, so you reduce tyre grip,” adds Rowland-Rouse.
Aprilia, Honda, Suzuki and Yamaha have also revealed new aero designs, but none is anything like as radical as Ducati’s. Although each is different they all face the same laws of physics: their advantages are reduced wheelies and improved stability, their negatives are heavier turning through corners. Like everything in racing, it’s a compromise.
Rowland-Rouse believes Ducati has made the most of the current rules. “The important thing is that they’ve got a good separation between the upper and lower surfaces,” he says. “You get high pressure above a wing and low pressure below, so you don’t want those forces interacting. If the surfaces are too close the low pressure under the upper surface affects the high pressure generated by the lower surface, which will reduce downforce.
“The design is quite draggy, so it will probably come and go at different tracks. We do a lot of this in F1: we simulate an entire lap with each aero design, which tells us how much we gain in each corner and how much we lose on each straight, then you add it all up to see what works best at each track.”
Long-time Ducati rider Andrea Dovizioso believes the hammerhead is a step in the right direction. “I’m happy, because without winglets it’s very difficult to create the downforce you need to get stability from the front end,” says the former 125cc world champion. “But there is always a negative, this time in the middle of the corner, so it’s always a balance.”
Yamaha’s solution is the most elegant: the factory’s YZR-M1 features a slightly widened lower-fairing body, with pairs of vanes inside the outer skin. Arguably the vanes are too close together, so the upper vanes interfere with the lower vane’s aero. Nonetheless Maverick Viñales likes the design, at least at some circuits.
“At somewhere like Sepang the new fairing is better because there are no really fast corners and not so many changes of directions,” he says. “But somewhere like Losail, where there are many fast corners and changes of direction, the fairing makes the bike heavy to turn, so I cannot attack corners. The fairing helps in acceleration by keeping the front down, so will be an advantage at tracks like Le Mans, with many slow corners where the bike is always doing wheelies.”
Aprilia chief engineer Romano Albesiano expects big changes over the next year or two. “The game has just started,” he says. “As soon as one manufacturer finds the best way to exploit the potential, the others will follow.”