Team ZoomMass overcame blustery winds, severe thunderstorms, and overwhelming odds to finish with a gritty, Rocky-like performance, beaten up but upbeat, at the Society of Automotive Engineers (SAE) Supermileage Competition in Michigan. “When we got on the track the wind was howling,” says Jonathan Rothstein, the team’s faculty advisor. “It was so bad it blew the windshield off the car, which promptly got stuck in the front wheel, causing the car to spin around and the front wheel to shear off as it slid sideways. It took us half the day to put the car back together and persevere through a number of other problems, like flat tires and thunderstorms.”
Team ZoomMass finally got its car back on the track just as the course was closing and recorded almost 400 mpg, which in itself was a small miracle. Despite hours of feverish pit-crew work, the wheels were still out of alignment and not tracking true, the body was weakened and wobbling, and the rear tire was rubbing on the skin.
Faced with the nightmarish weather, the friction and wind resistance from all these mechanical damages, and other problems beyond their control, team members worked through it all to see their little vehicle complete the course, put up a decent score, and finish a credible 12th place in the competition, which annually attracts more than 30 teams.
Thus, the 10-month odyssey of Team ZoomMass from the starting line last September, with nothing more to work with than a collection of spare parts, brilliant ideas, and bright dreams, to the finish line in June turned into exactly what it was designed to be. A capstone learning experience.
The object of all this learning was an eight-and-a-half-foot-long, 100-pound, teardrop-shaped, neon-green vehicle that’s as simple as it is elegant. During two semesters of intensive work on the vehicle, the team designed and built an 85-pound chassis, the mechanical workings, three motors, two transmissions, all the usual bells and whistles, and a removable 15-pound, fiberglass shell with its clear-plastic bubble.
As with every beneficial learning experience, it’s the journey, not the destination, that counts. The journey began last September, when Team ZoomMass began designing and building the vehicle from the ground up, starting with the standard, three-horsepower, 115-cubic-centimeter Briggs and Stratton lawnmower “starter engine” supplied by the SAE to every team in its competition. Actually, Team ZoomMass began scaling down and modifying three starter engines to see which was the most efficient. They created a 50 cubic centimeter fuel-injection engine, a 50 cubic centimeter carbureted engine, and a 25 cubic centimeter carbureted engine and then used the best of the three.
The team also experimented with two different transmissions. One is called a NuVinci continuously variable transmission. The name pays homage to Leonardo da Vinci, the first person to create the concept of a continuously variable transmission, which allows the drive shaft to maintain its most efficient RPM setting indefinitely.
“The other transmission is a variable-ratio transmission like the derailleur and sprockets you have on a bike,” explains Rothstein. “The real question for the bike transmission is can it handle the power being outputted by the engine.”
The almost year-long process of designing, building, assembling, and testing the supermileage vehicle puts much of the UMass mechanical engineering curriculum to work. The students use computer modeling software to design the car, they do fluid mechanical modeling to optimize the aerodynamics, they create three-dimensional CAD drawings of all the parts, and they use a special software to design the fiberglass shell.
They’ve even written a special mathematical code that takes into account the drag coefficient of the car, the rolling resistance of the bearings, the weight of the vehicle, the efficiency of the engine, and other factors to predict the ultimate mpg they will achieve.
“It’s a great culminating experience for our seniors because they take a lot of the principles that they’ve been learning in the classroom and they apply them to a year-long project,” says Dr. Rothstein. “The project depends on a very big design component, fluid dynamics, making composite materials, teamwork, project management, time management, and much more.” (July 2011)