Menu
Share
Share this story
Close X
 
Switch to Desktop Site

Designing cars needn't be a drag

Fresch-faced, exuberant, neatly clad in coat and tie, Jay Mays is on his way. He has a spanking new college diploma in one hand and a fancy new job offer in the other -- and he will probably never be heard from again. His ideas, however , promise to have a great effect on the thing Americans seem to do most, unfortunately: drive automobiles.

Last January, Jay Mays graduated from the Art Center College of Design here with a degree in transportation design. Cars. Nine of the world's major auto makers and designers, including Ford and Chrysler (what with getting married two days after graduation, he couldn't find time to meet with GM) beat a path to his door.

About these ads

Audi, part of the German Volkswagen-Audi car conglomerate, snatched him up. The company has enrolled him in some crash language courses and will soon whisk him off to Germany to tuck him away in some design laboratory. That will be it for Jay as far as public recognition of his name goes. Recognition of his work should be very different.

None of this would be worth mentioning -- auto companies hire Art Center students as fast as the college graduates them -- if the car Jay designed for his final project didn't look far different from anything seen on the road today. Jay is among the first of a new wave of car designers. What this 25 -year-old has to offer, and what the car industry sees as central to future design, boils down to one word: aerodynamics.

The need to reduce drag on a moving automobile has already produced changes on a number of vehicles. The Dodge Omni 0-24 sport coupe, the Plymouth TC3, Porsches, mazda's 626 sedan, Ford's Mustang and Capri, and the new Subarus were all specially designed to be "slippery" in the wind. A current vogue in auto advertising likes to show cars sitting in a wind tunnel with little streamers pasted all over them to show the direction of the wind blowing over the vehicle. Never mind that the streamers sometimes blow in the wrong direction, the ads reflect the manufacturers' perceptions of what the consumers now want from a car.

All this, however, constitutes just the first few drops in the bucket. Jay's car design, his final "thesis" for graduation and the first such project at the Art Center, looks like a teardrop turned on its side, point first and with the rear flat instead of rounded.

The teardrop shape is as old as the 1920s and has been followed almost religiously by the Porsche people, among a few others, ever since they began making cars. Jay added some new, significant twists.

His assignment was to design a four-passenger car that was aesthetically pleasing, and aerodynamically efficient.

"The word aerodynamics gets tossed around quite a bit, these days; but we don't really know for sure what is aerodynamically sound and efficient," says Harry Bradley, a professor of automotive design at Art Center and a former designer with General Motors.

About these ads

"We do know, however, about the effects of aerodynamics. The drag on a car as it drives down the road accounts for 29.5 percent of the total energy consumed by an automobile. If you reduce drag by 50 percent, the result is a 15 percent savings of fuel economy."

For most car manufacturers, aerodynamics is an afterthought. Designers generally shape a car with styling in mind, then stick the thing in a wind tunnel and reshape bits and pieces accordingly. Such tests take lots of time and lots more money.

Jay possessed neither, so he started with charts and graphs and then built a 1/4 scale model out of clay. California Institute of Technology chipped in some of its considerable technical expertise, and the use of the wind tunnel in its nearby Jet Propulsion Laboratory, which recently monitored the Pioneer spaceship missions to Jupiter. Their combined efforts worked.

Resistance to wind is measured by what is called the coef(CD). Arriving at the CD involves a rather complicated formula, but the smaller the CD, the more aerodynamic the shape. In the 1920s, cars had a CD of about .8. By the '40s, the number had dropped to .6 CD and by the '60's to .5 CD. In the '70s, design engineering took a back seat to ornamental styling, and the figure edged back up in Detroit to about .55. European cars of the '70s achieved about .45 CD.

Wind tunnel tests put the Mays car CD at .194, about a 65 percent improvement over most of cars rolling out of Detroit during the the last decade.

One of the key elements in Jay's car is a small arch along the bottom of the vehicle, in front of each rear wheel. That arch forces the air which would normally pass over the hood to instead go underneath the car.

"I wanted as little air as possible going over the top of the car," he said. Air going over the top of a car generally comes off the back with some amount of turbulence, which actually acts as a drag on the car. Rather like towing a small parachute.

Those arches draw most of the air past the side doors and down under the car near the rear wheels and allow it to exit out the rear very smoothly. No turbulence off the rear at all. To help that air out the back exit, Jay built a shallow venturi like a tunnel, under the car. It starts between the rear wheels (the car is front wheel drive, no rear axle) and leads to the back. The lines and shape of the car actually aim the oncoming air towards the rear wheels, but those arches draw it under the car, and the venturi guides it out the back.

"Almost any good aerodynamic design will push air around the car instead of over it," says Jay. The shape of a car accounts for 55 percent of its drag. However, protuberances -- hood ornaments, door handles, radio antennas, square rear-view mirrors, side molding, etc., etc. -- hold a car up for another 17 percent. Jay simply eliminated those.

Surface friction -- alignment of the body panels and the outside condition of the car (a clean car is more aerodynamic than a dirty one) -- account for another 9 percent.

About 17 percent of that drag comes from the turbulence that follows the driver down the road. For example, when you pass a big tractor-trailer truck coming from the opposite direction, your car gets rocked a second time by the mass of air constantly swirling 30 to 40 feet behind the truck. If most of the oncoming air can be persuaded to exit from under the car, Jay found, "then it seems to just disappear after it exits, eliminating that turbulence. We don't know exactly what happens to it, but in the wind tunnel tests there was no trace of the air leaving the rear of the car."

The rest of the drag goes to the air that flows through the car, from open windows, the venting-cooling system, and air passing under the car and into the engine compartment.

Air traveling underneath the car gets all tangled up in the multitude of exhaust pipes, gas lines, axles, and nuts and bolts that reside under there. Anything that causes air to move in some way other than in a straight line creates drag. Modern car makers get around this problem, partially by hanging air dams (strips of metal the width of the car) beneath the front bumper. The dams keep much of the air from under the car. The Mays car pretty much solves the under-car turbulence problem by sealing the underside, making it completely smooth. In 1983, Audi tentatively plans to produce a more "organically" shaped car with the rear third, underneath, sealed.

"Whenever air is admitted into the car, it must be exhausted in an appropriate way," commented Mr. Bradley. "That means smoothly, so that it doesn't exit with any turbulence. This design has the ability to accept air and flush it out very quickly."

A major impact of the Mays car will be to change the way Art Center professors, such as MR. Bradley, teach their students transportation design. "There is no question that we are going to place a major emphasis on aerodynamics," he said. "Plain and simple, aerodynamic designs are the cars of the future."

One might ask, at this point, about just how much significance the curriculum of one college, secluded in the smog-laden hills of Pasadena (next door to Los Angeles, hometown of the Rose Parade and Bowl), could have on an economic heavy such as the auto industry. Plenty. This is no fruit loop, artsy-craftsy refuge for students looking for a degree in pottery making. Art Center is them major supplier of designers to the US, West European, and Japanese auto industries.

Chances are pretty good that whatever you're driving an Art Center graduate had a hand in designing it. Over 50 percent of the designers plugging away at the drawing boards in Detroit came from Art Center. Chief designers at Volvo, Porsche, Audi, Toyota, Datsun (the list goes on well into the borders of boredom) got their start in the same manner as Jay Mays.

All this is to note that when Mr. Bradley says his future students will learn most of what there is to know about aerodynamics, the results will show up on production lines not too far down the road.

Before they do, however, the old guard stylists, (many of them from Art Center) especially in Detroit, predicts one industry observer, will go down fighting, clinging hard to styling ideas that emphasize primarily aesthetics: crisp, straight lines, square corners, hood ornaments, blunt front ends, etc., etc.

"You're going to see European cars with more organic designs within the next five years, very probably sooner. From Detroit, the next generation of design should take a little longer, maybe ten years," predicts one industry analyst. "Certainly not much longer than that, because most of the executives who cut their teeth on big cars with big engines are at or near retirement age . . . cars like the [Cadillac)$ Eldorado with their nifty elevated roofs are going to be a thing of the past."

Detroit is just beginning to go after aerodynamics in a big way. GM recently completed its own wind tunnel. Company executives won't even toss out a ballpark figure when asked the cost, but one official commented that "you could say it cost somewhere between tens of millions of dollars and a hundred million dollars."

A test in the GM tunnel costs an estimated $30,000 to $40,000 just to set up. Time spent in it runs at such a premium that fully equipped tool boxes are sunk into and flush with the floor, so that technicians can scamper out between "winds" and correct design deficiencies on the clay model in jig time. Temperatures in the tunnel usually run a humid 100 degrees or so, the result of heat generated by air particle friction in the 160 mph winds.

Auto aerodynamics is a brand new science, still far from precise, and a car company will guard its calculations and designs for reducing wind drag with all the joviality of a grizzly bear with a hangnail. At Pininfarina's (a major, independent European design firm, responsible for, among other cars, the VWs Scirocco's shape) wind tunnel in ITaly -- which is rented out to anyone with a sufficient bank balance -- the technicians never see the car they are testing, only the instruments that read out the results. That way, they can't pirate information about one company's aerodynamic successes for its competitors.

Ford plans to build an in-house wind tunnel sometime within the next few years. American Motors and Chrysler rent time at tunnels located around the country. Publicly, these latter two have no plans to build their own.

Jay says he chose Audi over the other eight companies "because they have the most advanced aerodynamic unit in the industry. They will probably be producing better aerodynamic designs sooner than anyone else."

"I think Detroit recognizes the importance of aerodynamic design," said Mr. Bradley. "There is no question about that. But there is not a great deal of certainty about what to do with it. If Jay had accepted a job in Detroit, I don't think he would have languished so much as he would have faced a great deal of uncertainty of direction." Efficiency notwithstanding, there are some definite drawbacks to the Mays car. Most americans will need a shift in taste before the Mays car looks appealing. And, horror of horrors, the thing demands air conditioning because the windows won't roll down. (The design saves more on fuel consumption than the air conditioning would burn.) "There will be a small, sliding panel in the glass so that you can pay tolls and things like that," he said.

On the other hand, this car was put together to be aerodynamically sound, not necessarily as a production model.

Nonetheless, what if consumers just don't like such a car? "It's not going to be so much whether consumers accept this kind of design," says Mr. Bradley. "The energy prospects pretty much demand that they will have to.

"It's like big cars. They just won't be available to consumers. By the end of this decade, when people walk into showrooms, this, or something like this, is what they will see."


Follow Stories Like This
Get the Monitor stories you care about delivered to your inbox.