New Paradigm

New paradigm

TDC

Kevin Cameron

THE PUBLIC’S IDEA OF RACING IS ALWAYS colored by the imaginations of those who report it, who invariably emphasize the extreme, unmanageable power of the machinery, the quirky, vicious nature of its handling and the dreadful hazards looming on all sides. Racing drivers and riders may have “motored” in Britain, but here in the U.S. they “blasted down the straightaways” and “screamed” through the turns, “on the ragged edge of traction,” while staring ahead through oil-smeared goggles at fate, hurtling toward them at 300 clicks. What made them “dice with death” in this way? They were crazy, obviously. That’s entertainment.

It’s hard to ignore all of this nonsense, no matter how devoted one may be to the mundane truths of racing. Therefore, when in 1974 riders set out for their first rides on Yamaha’s 90-hp TZ750A, most of them thought of improvement in terms of more power. We worked hard to make those machines harder to ride, and we succeeded. Racing motorcycles were supposed to be hard to ride. Sliding and wobbling were symptoms of rider sincerity, and many were those who recited the old adage, “If you ain’t slidin’, you ain’t ridin’. ” As the TZ750 era faded, that of Superbikes and 500 GP two-strokes took over. The era of the exit high-side had arrived, when riders, accelerating out of turns, encountered a rude combination of chassis weave and incipient traction loss that produced violent and repeated opportunities to be thrown from the machine. Glorious.

Now, somehow, we have emerged onto the sunny uplands of a new era, in which engineers think differently. Yesterday’s paradigm was lap time through power. Today’s is control-to make smooth and predictable the machine’s responses to all controls, making it easier to ride. Speed now comes from controlled traction, from civilized handling, suppression of chatter and the tuning out of all upsetting phenomena. Why now? At last, computers, sensors and actuators make it possible to know what’s happening, tame the worst disturbances and devise long-term solutions.

There are two basic approaches to this: passive and active. Passive torque tailoring is the process of adjusting an engine’s powerband in detail to make it so smooth that a rider’s reflexes are fast enough to control it. This process works best when an engine’s torque is fairly smooth to begin with.

“It’s getting away from me just a bit on the exit of 5-the torque’s coming up pretty fast at 11,000,” says the rider. The team’s electronics specialist pulls down the maps for ignition timing and fueling, and reduces the torque slope in the troublesome region. In the next practice, the rider finds that having less but more easily controlled torque allows him to safely and predictably apply more throttle.

You may object that trimming torque in one area may hurt performance elsewhere. True, and for that reason, each rider and team has its own style of applying such remedies. Some apply it locally. Others seek overall smoothness.

The active way to match torque and grip is to automate it with an anti-spin system. Tire slip is measured and controlled directly, in real time. As the slip rate rises, indicating that a slide is imminent, the control computer retards ignition timing to soften the torque. If that’s not enough, fuel reductions are added. With the engine now making a bit less torque, the rear tire’s slip rate falls back into the safe zone. Some people say that current Ducati MotoGP bikes permit their riders to just pin the throttle out of turns and let the system manage torque control.

Some people assume that tire slip can only be detected by comparing front and rear wheel speeds. Not so. A microwave interferometer-on-a-chip can measure the motion of the pavement directly, or the rate of acceleration of the rear

tire can be held to a schedule of values. No matter what anti-technology rule a sanctioning body may make, there is always a counter-technology, which is why F-l elected to stop trying to police engine-control software.

So far, the reliability of the passive approach has won most of the races, but active torque-control technology is developing in parallel with it.

In the dark, uncivilized past, we put in all-nighters of welding and grinding to boost straight-up acceleration and top speed. More power! Our success was measured in unrideability. In truth, we were working on the wrong end of the straightaway. Power increases do nothing to increase acceleration in the crucial off-corner phase, when an extra mile per hour gained is added to your speed all the way down the next straight. Power smoothing allows the rider to accurately match torque to grip, without surprises that break traction and interrupt the drive. Anti-spin systems achieve the same goal by performing the torque-to-grip match without action from the rider.

The first technique has long been applied during development to the torque curves of powerful production bikes in the interest of control and safety. The second will surely appear in showrooms as soon as manufacturers are sure that: a) it has reached a point of real usefulness; and b) it can be made fully reliable.

In 2007, MotoGP cuts displacement from 990cc down to 800. Some pundits believe this will force manufacturers to tune their engines more sharply, thereby bringing back the theater of violent powerbands and the spectator-thrilling threat of high-sides. I disagree. Smooth power has proved so potent a tool in cutting lap times that no one will be willing to go back to the power paradigm. Remember that two-stroke 500 lap times became stagnant during the 1990s, indicating that progress in power and tires was achieving nothing. As soon as steep, hard-toride two-stroke torque was replaced by intentionally smoothed four-stroke torque, lap times again began to drop dramatically. As smoothing and/or control techniques improve, lap times continue to drop. Smooth power has proven too effective to be replaced by a step backward. Ways will be found to make the new 800s both smooth and powerful. □