Students in the Manufacturing and Design class were racing cars inside Alumni Hall of Engineering this past semester.
Teams of three students each designed, built, and tested battery-powered mini-dragsters for the course, which is taken primarily by sophomore mechanical engineering students, as well as juniors who miss it while taking Lafayette’s study abroad program in Belgium. Class instructors are Scott Hummel, assistant professor of mechanical engineering, and Steven Nesbit, associate professor and head of mechanical engineering.
The winning car in the culminating double-elimination race tournament, held in the Farinon Center Marlo Room at the end of the semester, was designed by mechanical engineering majors Ethan Blose ’03 (Monroeville, Pa.), Jared Mast ’03 (Easton, Pa.), and John Ritter ’03 (West Chester, Pa.). It traveled the 28-foot distance in 2.688 seconds.
The students pick their own teams; 12 teams typically are in the class. Each has $200 available for purchase of parts such as the motor, batteries, and raw materials. The teams also have use of 16 hours of machine time at $60 per hour, making the total budget for each car $1,160.
All design work is done on computer. The rules and obstacles are changed slightly for each semester’s class. Students are provided a motor, motor mount bracket, ten batteries, and battery holders by the instructors to start them off. The cars must be no more than 9.8 inches wide, 18 inches long and five inches tall. “They are given a lot of design freedom,” Hummel explains. “It closely simulates industry because it’s so open-ended.”.
Speed is never the only objective, however. This semester, a pendulum awaited cars 36 inches past the finish line to measure the amount of energy transferred if the mini-dragsters struck it. Those that hit too hard were penalized. Many teams designed braking systems activated by a bar placed above the finish line to lock the front or back wheels and lessen or avoid contact. Some vehicles braked so precisely that the full length of the car did not cross the finish line. Unfortunate entries striking the pendulum at too high a speed continued past it and off the racing platform. Students had two minutes between rounds to repair damaged dragsters. Poorly braking cars built to be extremely light for speed faced elimination from their lack of durability.
“By the time students are sophomores in college, they’ve had a dozen years or more of math instruction,” notes Hummel. “This design and construction project brings together all of the mathematics they’ve learned. Using advanced calculus, for example, they can predict in the design phase how long it will take for their cars to get down the track within two percent – less than one tenth of a second. It’s a great project because it’s the first time students are using all of the skills they’ve acquired in math and engineering.”
Manufacturing and Design is required for mechanical engineering students, but is gaining in popularity among students in other engineering disciplines. Course topics include Computer Aided Design (CAD) and Computer Aided Manufacturing (CAM), as well as hands-on learning of conventional manufacturing techniques such as milling, turning, and injection molding.