Classroom: Sailing through Design
A flotilla of model sailboats chased by land-bound students with radio controllers took over Hanover’s Occom Pond at the end of spring term. This was no mere afternoon frolic. It was the ENGS 146 regatta, a demonstration of what students learned from a shop-based approach to computer-aided mechanical engineering design.
The premise of ENGS 146: “Computer-Aided Mechanical Engineering Design,” taught by Professor Laura Ray, is that the most important aspects of design aren’t found in a textbook. Students in this class head straight to the shop, where they work with software, handle tools and materials, and develop an intuitive feel for the process of designing and manufacturing a product.
“It gives them experience in things that are hard to learn except by doing,” Ray explains. “You can’t teach them the impact of the planning stage on the final fit of the pieces. They have to see it.”
Each boat had to meet the following requirements: a length of 1 meter or less; a hull manufactured either by Rapid Protoyping, thermoforming or composite layout; one vacuum-cast piece; and one injection-molded piece.
Software instructor Paula Berg, who taught design and modeling techniques, says she “pushed the students to think about their choice of materials, and about accommodating their designs to their chosen manufacturing and assembly processes.” Students discovered, for example, that large composite hulls are harder to manufacture than small ones and that structural protrusions don’t thermoform well. “They had to experiment,” Ray said, “They had to redo things. But I like experimentation, and I was really pleased with the quality of the parts they produced.”
Ray organized the regatta in lieu of formal project presentations. After all, she points out, the true test of a sailboat is how well it sails. Some boats struggled just to reach the starting gate, while others skimmed through with ease. A scaled-down 1901 America’s Cup craft, Shamrock II, finished the course three times before others were halfway through. Shamrock II co-builders Nathaniel Merrill Th’04, John McCall-Taylor ’03, and Nicholas Schaut ’05 think they know why: Their boat was the only one with an integrated keel, which required fewer parts, lightening the hull. “It was amazing to watch her heeling over in the wind, just like a real sailboat,” says Schaut.
Students made several other discoveries: Boats with larger rudders tacked more successfully than those with small ones. Boats with tightly bound rudders had difficulty coming about. Hull weight affected performance more than the number of hulls per boat.
Ray is eager to assign sailboats again. She’d like to improve the matching of parts to processes and have students spend more time designing the sails. Then it will be back to Occom Pond.comments powered by Disqus