Sometimes You Just Have To Feel It

SOMETIMES YOU JUST HAVE TO FEEL IT

IGNITION

TDC

MORE PROOF THAT ENGINEERING IS FAR FROM A LIFELESS SUBJECT

KEVIN CAMERON

In my mind are powerful images contradicting the popular idea that engineering is cold, Cartesian, and lifeless. One is of Gene Romero, approaching Daytona's old turn two on the brakes, on the factory Triumph Triple, in practice for the 1971 200. The front end is close to fully compressed, and the image is one of large forces in balance. It is dramatic because, in the next instant, he will roll the bike over to the right and turn it in, switching off one set of maximized balanced forces and substituting another.

Another is my mental video short of the space shuttle's three R-24 hydrogen rocket engines starting. As they come to main stage, each thrust chamber does a little hula, verifying that the steering equipment that gimbals each one is on the case. Terrifying machines, engineered to contain and direct a continuous explosion whose controlled force lifts the spacecraft. I can't look at this without an inward thrill and a feeling of tears coming into my eyes.

Also high on my list is the on-bike camera video of Marc Marquez turning. The world tips up, way up, as he moves toward the apex. And then, impossibly, it tips up even more, and you know this is when his elbow so famously touches the track, and he can turn the bike more easily on the flexy very edge of the rear tire. Forces, elegantly in balance.

And Wayne Rainey, who led the way to today, in his ability to decide to trust the front tire. The temptation is to waste time getting to lean angle by degrees, hoping thereby to feel any lack of grip before it has vanished. But winning lap times require trust-not timidity.

Aman in casual dress sits in an office, working the controls of a forging machine that is squeezing a glowing steel billet, weighing maybe 100 tons, into a ship's propeller shaft. Maybe the ship is one of the new generation of single-diesel bulk carriers, superefficient machines now central to world trade. In that case, the shaft will transmit 100,000 direct-drive horsepower to a propeller turning 6o rpm or so, and shaft torque could approach a million pound-feet. To look at him, the man in the office could be playing a video game, but he is manipulating controls that position the shaft between the forge jaws, rotating and translating it. He clearly knows his business, as the shaft slims down and grows steadily longer as we watch.

Have you seen testing on a Dynojet or other make of rear-wheel roller dyno? The bike is strapped down, but as its engine comes on the power, you can see the bike's rear end strain hard against the straps, trying to rise. This lift force comes mainly from the top run of the chain not being parallel to the swingarm. If you're comfortable with such jargon, you might call this a tangent force.

As I watch, I know that this lift force is what stops a bike, exiting a corner, from squatting down at the back as a result of acceleration. If this lift force were absent, acceleration would squat the back, taking weight off the front tire, making it lose grip. You can see all of this on the track if you look carefully, and riders can for sure feel when the two forces are out of balance. An adjustable swingarm pivot height allows the chassis specialist to correct this. But then a change of sprockets upsets it again, by changing the angle between chain and swingarm. Forces, ideas, balance. Get it right.

BY THE NUMBERS

Although we associate Gene Romero with number 3, his Triumph carried the number 1 plate at Daytona in 1971 because he was the 1970 AMA Grand National Champion.

Maximum take-off weight of a Boeing 747-400, in pounds.

Maximum landing weight of a Boeing 747-400, in pounds.

A giant machine in a Spanish factory is rotating a very large forging. As multiple cutting tools move in and begin to remove metal with fascinating smoothness, it becomes clear that they are taking away everything that is not a crankshaft for a large diesel engine. Particularly breathtaking is the cutting of the connecting-rod journals. In the past, such a crank would have had to be chucked multiple times to center each crankpin in turn, allowing it to be turned by a tool that moved only along the length of the shaft.

But this is today, and we humans have the means to move the tool very precisely to follow the off-center crankpin as the crank turns around its own center. The cutter force is very large—big chips are shooting

off the tool, and the forging is a tough alloy steel. But so sure and so smooth are the motions of the cutter that it can follow the orbiting pin, turning it into a true cylinder smoothly and absolutely without chatter. Wonderful. As I watch, I think, “What is there now that we cannot do?” But I know the list is still impossibly large.

A favorite of mine (and of film directors) is the shot of a Boeing 747’s 16 main-gear wheels, coming closer and closer to the runway. The first eight, dangling like the legs of a mud-dauber wasp, make first contact, with rubber smoke boiling off the tires as they spin up. The others compress their oleo struts next. Half a million pounds have just come off the wing, onto these tires.

To keep the runway from breaking up under such heavy blows, the touch-down area is a 3-foot depth of steel-reinforced concrete. Whenever I think of weight and stress, this is the image that pushes into my mind—my own little movie gallery of emotion-charged engineering moments. Building that main gear is just a job for those who do it, but there must be moments when they think of the terrible force of those tires coming to earth.

Many of us motorcyclists build things—wheels, suspensions, engines, you name it. Whether you will it or not, your mind will inventory everything you have done in the process. After all the fasteners are tight and the last safety wire twisted, come the oil, fuel, and start-up. You’re cool because you know it has to run. But when it does, you not only know it, but you feel it. ETU

I CANT LOOK AT A SPACE SHUTTLE LAUNCH WITHOUT AN INWARD THRILL ANDA FEELING OF TEARS COMING INTO MY EYES.