November 20, 2012
Fall Quarter SSCP Progress Report
by Aravind Arun
It’s been a busy Fall Quarter here at the Stanford Solar Car Project. With just a little under a year left before the 2013 World Solar Challenge, our shop here at the Automotive Innovation Lab is bustling with activity as we work on the design for our brand-new WSC entry. What follows is a recap of our progress so far.
This past summer, we chose to participate in the competition’s “Challenger Class”. This means our new solar car will be designed to maximize efficiency, rather than practicality. The ultimate goal of a team in this class is to be the first to cross the finish line in Adelaide. The alternative to the Challenger Class is the Cruiser Class, in which cars are evaluated based on their power consumption, user-friendliness, comfort and extra features in addition to the speed and distance traveled. While many of us were attracted by the novelty and innovation represented in the Cruiser Class, we ultimately decided that the Challenger Class’s more singular design target would help the team improve systems integration and refine the car through testing. Reliability was one of our biggest areas for improvement in last year’s race; due to various factors, we were unable to thoroughly test Xenith to eliminate its bugs. We therefore intend to arrive at Darwin next year with a vehicle which, while more reliable than Xenith, will still boast cutting-edge technology from Stanford and the Silicon Valley – a combination which we believe will help us win the race.
With this decision made, our first task was to design the car’s aerobody. After many weeks of SolidWorks modeling and CFD analysis, Nathan Golshan and Ian Villa came up with a sleek and shiny new look for our car, with valuable help and input from Sean O’Donnell, Nathan Hall-Snyder, and various Xenith alumni. We sent the final CAD model to Christensen Fiberglass Tooling, a Michigan-based company. They are currently manufacturing our molds using an awesome 5-axis CNC mill, while we watch the whole process in ecstasy over a live feed!
In the meantime, our various sub-teams are hard at work designing the cutting-edge technology that will move the aerobody and the rest of the car from Darwin to Adelaide. Here’s what each team has been up to:
Mech Team: The Mech Team’s main project this quarter, spearheaded by Wyles Vance, is a jig for measuring the rolling resistance of the car’s tires. Minimizing rolling resistance is absolutely critical in Solar Car racing; it is the second-highest contributor to exterior loadings on the vehicle, just behind aerodynamic drag. We hauled out an old dynamometer from the depths of our shop, ripped out some old components, and converted it into a rolling-resistance jig using a new motor, some custom machined parts, and an amazing servo drive from Advanced Motion Controls, Inc.
Array Team: Xenith’s array worked flawlessly throughout WSC 2011 – in fact, it often threatened to overcharge the battery pack! Following this success, our Array Team, led by the intrepid Toby Sachs-Quintana, is making great progress on the solar array for our next car. They are currently testing the efficiency and power output provided by various encapsulation schemes, as well as figuring out how to stretch solar cells over the multi-axis curves that characterize our new topshell, without allowing them to either break or wrinkle.
Strategy/Telemetry Team: Led by Paul Chen this year, our strategy and telemetry team continues to pursue its goal of making sure our car maximizes its power production while encountering as little aerodynamic drag as possible. They have modeled our car and simulated the grueling 3000 km course that awaits us in Australia, calculating our ideal velocity at each stage while taking into account a series of variables, from the batteries’ predicted state of charge to the grade and altitude of the road at each point in the course. They are also figuring out new and exciting ways to plan our race strategy using portable weather stations, working around factors such as solar insolation and wind speed/direction to give us an edge over the competition!
Electrical Team: Our E-team, currently under the dynamic leadership of John Bolander, is working on a new Battery Management System (BMS), which will protect the car’s electrical system and batteries from damage while allowing the team to collect more data about the status of the car’s electronics. With new circuitry for current and voltage measurement, this system will enable much more accurate measurements of the batteries’ state of charge. Other E-team projects include sensors for monitoring tire pressure and suspension travel, and redesigning the power distribution architecture for better data collection. They are also collaborating with Nathan Hall-Snyder and Sam Lenius on the creation of our all-new electric motor.
Of course, not all positions at SSCP are technical. Our business team has been working to reel in enough funds for our tools and materials. Meanwhile, we’ve been attending numerous outreach events in order to promote the project and recruit more budding engineers seeking to employ their talent. One recent event we made an appearance at was the Stanford Activities Fair, in White Plaza on the Stanford campus:
There’s obviously much left to do, but the team is making great progress. We’re all excited for next year’s race, and hope to be among the top contenders for the checkered flag!