No Jerking, Shuddering or Noise, Please
My drive in the Waterloo vehicle followed another week of testing, this time at GM’s Milford Proving Ground, outside Detroit. The tests were modeled on the same challenges that any new production vehicle must meet: smooth and consistent drivability under all circumstances, without jerking, shuddering, or power-train noise; brakes that last through repeated hard stops from high speed; the ability to tow a trailer weighing 500 kilograms or more; air-conditioning that works flawlessly; ultrareliable accessories like electric windows and navigation system; high-quality interior trim and appointments; and so on.
Unlike last year, this summer the winning vehicles were pretty close to showroom-ready. Mississippi State University, the surprise come-from-behind victor over last year’s second-place University of Wisconsin-Madison team produced a vehicle so professional that it could easily have appeared on a dealer’s floor—assuming the multicolor paint job and 30 or so sponsor logos were removed. A neat cover shrouded its direct-injection 1.9-liter turbo diesel engine, and the batteries for its hybrid electric drive fit beneath the floor of the load bay, eliminating any compromise in load space. (The battery pack occupied the former spare-tire well, as all 17 teams were equipped with identical run-flat tires.) In fact, Mississippi managed to increase rear load space; they cleverly fitted updated, less intrusive interior panels from a 2007 Equinox. Their vehicle performed on the road, too, achieving a 48 percent reduction in fuel usage over the baseline unmodified 2005 Equinox.
”Most of the teams finished most of the events, but that wasn’t enough--we found the level of competition unexpectedly high”--
Eric ”Hot Shot” Schacht, Ohio State University
But the competition was fierce, and the two top teams were separated by merely 7 points out of a possible 1000: Mississippi scored 895.5, Wisconsin 888.3. Last year’s winner, Virginia Tech got 809 points, only enough this year to take third. As Ohio State’s Eric ”Hot Shot” Schacht put it, ”Most of the teams finished most of the events, but that wasn’t enough—we found the level of competition unexpectedly high.”
Like any competition, this one had its share of mishaps. Virginia Tech broke a half-shaft during the trailer tow. A pipe ruptured in Michigan State’s unique hydraulic hybrid, making quite a mess on GM’s test track. And the Waterloo team persevered through a series of freak accidents that earned it other teams’ astounded sympathy. During the first day’s first inspection, a hydraulic lift malfunctioned and the vehicle slipped sideways, damaging an expensive custom-made carbon-fiber doorsill. Then, in on-road testing, the suction cup holding the tester’s accelerometer to the windshield failed—dropping the instrument directly onto the dash-top kill switch, cracking its housing and triggering a full shutdown of the batteries and fuel cell at speed.
Weight Loss and Plastic Surgery
But such events are a standard part of development. And it had been a busy year of modifications, with every team tweaking, replacing, improving, and refining dozens of components, major and minor. Michigan Technological University, for example, cut its estimated coefficient of drag from 0.42 to 0.36 by adding rear-wheel-well covers (or ”spats”) and modifying the front air dam, to cut fuel usage at high speed and reduce wind noise. Wisconsin reduced the number of cells in its battery from 44 to 40, letting it restore rear load volume to standard. Penn State cut 5 kg from each disc brake by creating titanium rotors mounted on aluminum hubs.
Waterloo shaved the weight of its very heavy—and heavily modified—fuel cell vehicle by using carbon fiber for the hood (dropping it from 23 to 8 kg), creating a new wiring harness with 22-gauge wire rather than 18-gauge (8 more kg), moving the voltage controller (eliminating 7 kg of heavy cable), and so on. The final vehicle weighed in at 2173 kg, merely 4 kg under the maximum 2177 kg.
And that year of refinement really brought results. In drive after drive, the mongrelized SUVs—most with new engines, hybrid-electric drive added, and a plethora of sophisticated new systems—ran almost like production vehicles. One giveaway was the six-speed manual transmission used by many: Few North American SUVs even offer manuals. Diesel clatter was another telltale, though some teams muffled it better than others, with Ohio State’s active-damping of engine vibrations winning it the lowest-noise prize.
For all the teams, said on-site organizer Steve Gurski of Argonne National Laboratory’s Transportation Technology R&D Center, which coordinates the event, the biggest engineering challenge proved to be ”mimicking GM’s high-speed LAN protocols” after replacing the engine and adding new components. He stressed the enormous time it took to ensure compatibility among the control modules for new, more complicated hardware (battery packs and one or more electric motors) whose components had to interact frequently to provide smooth operation under any conceivable driving pattern.