ASEE Prism On-line, February 2000
teaching toolbox
On Campus
Engineering Goes Downhill

By Linda L. Creighton

Illustration by Peter Horjus Students who want to strut their stuff on the ski slopes this winter might think about taking an engineering class. That's what undergraduates are finding at the Worcester Polytechnic Institute, where mechanical engineering professor Christopher Brown teaches the elective course, "Technology of Alpine Skiing."

Originally developed by Brown as part of a series taught at Dartmouth on the technology of everyday things, the course is very popular with the first-year students for whom it's designed. Instead of just math or science, students learn techniques and exercises that can be applied to real skiing or the design and manufacture of ski equipment.

Brown, who grew up in a Vermont skiing family and was an all-American skier in 1973, became fascinated by the parallels between skiing and machining while doing graduate work at the University of Vermont. Brown got a request from a friend at Berkeley to test out a new instrumented ski. He was intrigued to find that the basic process of machining, where chips curl off a material during cutting, was the same process at work when his skis slid through the snow or when he turned or stopped, carving up a shower of chips.

Fortunately for Brown and later his students, his discovery became a way for him to combine his dual passions of engineering and skiing. "It gets them thinking like real engineers,'' says Brown. "It lets them make that jump from theory to application."

Seniors at the Worchester, Mass, university take the class as well, and find that it's a good way to integrate many of the concepts they've learned during their undergraduate course work. As they quickly learn, the same principle that engineers use to make skyscrapers stand is used to design skis with a person standing on top. And tribology— the science of rubbing, friction, and lubrication—applies to the way skis interact with snow as they speed down the slopes.

Brown says that he uses alpine ski racing as the focus of his course because it confronts students with a clear technical problem: How does a skier maximize speed down a snow-and-ice-covered course? And Brown also notes that alpine skiing offers a great model for discussion because worldwide racing competitions encourage constant revisions and tinkering, whether it be techniques for turning and positions, mechanical changes to ski boots for control, or ski designs that enhance speed under variable conditions.

Students do in-class experiments and demonstrations, and dissect slow-motion videos of skiers and their equipment in action. They assess contributory causes to ski injuries—recreational setbacks that cost the nation up to $400 million annually in medical bills, lost work time, and rehabilitation expenses. As many of Brown's students will tell you, the most common injury on the slopes continues to be ruptured anterior cruciate ligaments (ACL), a knee injury that results from falls in stiffer, backward-leaning boots that enhance skier control.

Studying a Vermont ski safety video, his students learn that they may not be able to change the mechanics of skiing enough to prevent falls, but by changing their style of falling, the risk of ACL injury is dramatically reduced. "There are certain things you do that are style, and others that are mechanical," says Brown. "The students learn to separate the two."

Students are familiarized with dramatic ski design changes using reinforced polymers and composite beams. Shaped skis, which make it much easier to turn, are changing the industry, and Brown says that computer and numeric controls have opened the way to such changes in geometry.

Brown's students realize after learning about product liability suits against the multibillion-dollar ski industry that design changes require constant reality checks. As Brown sees it: "It's important for engineers to know the impact of their design and standards," adding "We look at whether the inherent, man-made risk can be mitigated."

But Brown says the real learning may take place on the slopes where students take to heart many of the classroom lessons. The dry subject matter of the "fastest path between two non-vertical points on an inclined plane" may not keep you awake in class. But out on the slopes you may want to know how that translates into "escaping from the path of an avalanche."

Brown says that since his class is at the undergraduate level, he doubts if his students have so far contributed to actual design changes adopted by manufacturers. Manufacturers have an eye on classrooms like his, however. Rossignol has donated some equipment for demonstrations and labs to Brown's courses. When he taught at Dartmouth four years ago, the American ski maker K2 participated in one of his labs. And a graduate student at Stanford did her Ph.D. dissertation on ski design.

Brown's course is dedicated to the memory of his late father-in-law, Mickey Cochran, who at age 50 coached the U.S. ski team and raised four children who all skied in the Olympics. He obviously knew something others didn't. Maybe because he was an engineer.

On Campus
Making Skiing Safer for the Disabled

Photograph courtesy of the Univ of Colorado at Boulder
Engineering students are at work on ways to improve equipment used by disabled skiers, such as the "sit-ski."

While the snow falls gently outside a flourescent-lit classroom on the University of Colorado campus at Boulder, 27 first-year engineering students are bent over black lab tables tinkering with an array of hardware, fabric, and plastic. The devices that they have designed and built from scratch will, they hope, change the quality of life for some disabled members of their community—letting wheelchair-bound men, women, and children fly down the ski slopes just a few miles away instead of watching the snow from their windows.

The name of the course is assistive technology engineering, but any of these students will tell you that this is an exciting introduction to the reality of engineering for people. The program was developed five years ago by Melinda Piket-May, assistant professor in CU-Boulder's College of Engineering and Applied Science. Connecting the needs of the disabled in the community with students who could solve problems was the beginning of a rewarding experience for everyone involved. "Engineering students can bring things to the disabled that even therapists wouldn't have thought of," says Piket-May.

When chemical engineering professor Beverly Louie began teaching the course three years ago, she brought new and challenging problems to her students from her involvement in the National Sports Center for the Disabled in Winter Park, Colorado—the largest facility of its kind in the world. Having volunteered for years as a ski instructor to paraplegics, quadraplegics, and those with cerebral palsy, Louie understood that small but critical things can make skiing accessible to those with limited body strength. Her students could design those things.

Working in groups of five, Louie's students come up with ideas themselves or choose from a list Louie has compiled from her work at NCSD. They brainstorm about the idea, surf the Internet for existing products, and prowl the aisles of McGuckin Hardware store in town to begin assembling their material. Using their own money, the teams make drawings and prototypes, investing up to 100 hours of work to come up with a final product that they present to the whole class at the end of the semester.

This year, two of the projects were designed to improve the sit-ski—the commonly used equipment for disabled skiers—by making it safer and more comfortable.

First-year student Geoffrey Lindquist and his team were dismayed to find that if a skier's hands were not strong enough—a common condition in spinal-injury cases—to hold the outrigger ski poles that stabilize a sit-ski on its run down a mountain, the only existing solution was to duct-tape the skier's hands to the poles. "We went through a lot of ideas," says Lindquist. "Zippers, velcro, buttons." Scouring military-supply stores, Lindquist and his team cut a rain jacket into mitten shapes, a team member took it home to sew on his mother's sewing machine, and they attached plastic backpack buckles.

The result is "quad cuffs" (from "quadraplegic") that can be put on over a skier's own gloves and buckled to the poles—a major improvement for the 10 to 15 percent of all disabled skiers who need it. "I'd like to go skiing sometime and look over and see somebody using these quad cuffs," says Lindquist. "That would be kind of cool."

Steve Tamburini, a student in Louie's class and a skier himself, said he had often seen disabled skiers on the slopes but never thought much about the special challenges they faced as athletes. When Professor Louie invited NSCD equipment manager Paul Saarela to her class to discuss possibilities for student projects, he outlined the danger that faces a disabled skier when the sit-ski flips over. He suggested that a roll bar would eliminate injuries, as well as provide a handle for pushing the rig.

Tamburini and his team decided to take the challenge. Working twice a week in the class lab, they cut and drilled an aluminum pipe, filled it with sand, heated it, and bent it to fit the small frame of the sit-ski. Making the detachable brackets was the hardest part, first designing them on the computer and then cutting the aluminum. The team traded leader positions each week, and Tamburini says the only arguments were about how much money to spend on materials. The project worked, and was one of the 60 Boulder campus student projects featured at a design expo in December. The weekend that his device was completed, Tamburini went skiing and saw some disabled athletes on their sit-skis. "I thought about them differently,'' he says. "I have a lot more respect for what they want to do and how they do it."

Professor Louie says Tamburini's reaction to the course is typical of the more than 400 students who take the course annually. "They've really grown up with their projects," she says. "It's the beginning of giving back some engineering knowledge to society."

The equipment director at NSCD, Paul Saarela, is looking forward to seeing the completed work of the students. "The disabled skiers we have, they've come so far," he says. "We want to get them to the top of the mountain."

 

Linda Creighton is a freelance writer in Arlington, Va.

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