Renegade: Electric Dragster Builds New Skills
In the dusty basement of the Towne Building on Penn's campus, a shiny black vehicle sits amid the tools, spares and work benches of a mechanic's shop. It's Renegade, an electric car designed not for the limited ranges and low speeds commonly associated with such vehicles, but for the full-on sport of drag racing. The low-slung, carbon-fiber-bodied vehicle is the creation of the Penn Electric Racing Team, a student group that spent five years building the vehicle.
The team built the car from scratch, using its members' skills to design, weld, and fabricate the chassis, body, and power train; machine its components; and install electrical systems that together are expected to propel the vehicle down a drag strip at between 85 and 110 miles per hour.
The team wanted to show that electric cars don't have to be boring, utilitarian vehicles like golf carts, but can have the explosive speed and power needed for drag racing. "We went for a drag racer because it would show the power that you could get from an electric vehicle," says team captain William Price, a Mechanical Engineering major.
Renegade, powered by 23 lead-acid batteries, is distinguished from other electric dragsters by having two 11-inch brushed DC electric motors that operate in tandem to supply acceleration and speed in the correct sequence. The motors operate initially in series, supplying full current but only half the voltage to produce the full torque needed for dramatic acceleration. At a flip of the driver's switch, the motors change to run in parallel, giving full voltage but half the current, and enabling the car to reach its top speed.
Most team members are engineering students but some come from other disciplines, and even students with no prior knowledge of electric cars are welcome to join, says Price.
Sabrina Robinson, an International Relations major from the School of Arts and Sciences, reports that the team has shown her how to use Matlab, a programming language for engineering disciplines, and SolidWorks, a computer-assisted drawing program used to design the body of the Renegade. Robinson also helped to fabricate the vehicle's body, a painstaking nine-month process involving building multiple layers of carbon fiber over a machined-foam template.
The active membership of the team has recently quadrupled to about 40, and provides engineering students with valuable, work-related experience not usually found in the classroom. Price, a native South African, credits his work with the team for his summer 2011 internship with Tesla Motors, an electric car maker in Palo Alto, California. The company was more interested in Price's team leadership and strong practical portfolio than in his GPA, he notes.
After five years' work on Renegade, the expertise accumulated by the Racing Team may be lost to future generations of students if it's not recorded. But that information is now being stored in an internal wiki. These resources will feed plans for the team's next project, a street-legal electric car with a self-built battery pack and, Price hopes, in-wheel motors. That information will be used by future racing teams in their own learning process. "The whole point is that you can teach anybody anything," he says. "By the end of the year, a lot of these people are going to be doing things that they couldn't have expected at the start."
View the full article in Penn Engineering magazine "Renegade: Electric Dragster Builds New Skills" by Jon Hurdle.