Even as CalSol is working hard for the upcoming American Solar Challenge, we continue to get sponsors for our projects. Bay Area Circuits graciously donated to us the service of fabricating our in-house designed circuit boards, which will make up our dashboard, pedals, motor interface, lights, and battery monitoring systems. Thank you for the boards, Bay Area Circuits! We’ll make good use of them.
We have finally completed Zephyr’s chassis, after a number of long months of design, testing, delays, and welding! Thank you to all of the different companies and people who have helped us throughout the design, verification, and fabrication process:
Garner Heat Treat – Test heat treatment for weld samples & actual chassis heat treatment
Dennis Lee & Michael Neufer – Tube bending, engineering advice, welding verification.
Maxal – Engineering advice and donation of 4943 Filler Rod
80/20Inc – Donation of 80/20 chassis jig materials
Terminal Manufacturing graciously took some time out of its schedule to teach 11 CalSol members how to do Tungsten-Inert-Gas (TIG) welding on aluminum. A big thanks to Jimmy for being a terrific teacher and allowing each and every one of us to actually get our hands on the machine and weld. His concern over safety really hit home with us and we will be taking every precaution when we weld too.
Since our design involves welding thin wall, aluminum tubing to form the structural chassis, this training could not have come at a better time. We will be using this knowledge to move forward with the construction of Zephyr.
Recently, the suspension/chassis team has been working hard on finalizing the designs for the structural components of Zephyr. Because of the hard work of our team members, we have been able to shave over 55 lbs overall from the suspension and chassis! Most of these weight savings have come from changes in material and optimization in designs.
Our previous car, Impulse, had a steel chassis which weighed 52 lbs, but Zephyr will have an aluminum chassis – the SolidWorks model currently weighs in at just under 30 lbs. The front suspension of Impulse was made primarily out of 6061 aluminum, while Zephyr will have one made primarily of 7075 aluminum. Though 6061 aluminum is quite strong, 7075 aluminum is stronger than some types of steel! This allowed us to drop the weight of the front suspension from 60 lbs to 30 lbs. As for the rear suspension, Impulse had a single rear wheel, and its rear suspension weighed 20 lbs. While Zephyr has two wheels in its rear, the combined weight of its rear suspension members is just 17 lbs. Through being conscious about weight savings, our car is slated to weigh under 400 lbs now!
Along with working towards finalizing designs, Brian Graf, Derek Chou, and Daniel Heywood have begun machining parts for the suspension in the past week. Several members of the suspension/chassis team are also in the process of getting machine shop training and aluminum welding experience such that we can increase our work rate, keeping us on track to a rolling suspension/chassis combo for Cal Day, April 20th, 2013!
Stage 5 of ASC: 150 miles from La Crosse, WI to St. Paul, MN. It seemed simple at first. Since we’d been driving 200+ mile stretches of road for most days before this, this seemed like it would be a relatively simple day. Except when it started raining.
Our strategy from the days before thankfully allowed us to start this day with a full battery pack, but since Stage 5 was a so-called “sprint” stage, we would be driving Impulse at highway speeds for good portions of the route.
We set our target speed at 59mph and blazed through the portion of the route that had us driving on the I-90, passing several surprised teams along the way. Partway through that segment, a surprise for us: The University of Michigan was pulled over on the side of the road! The radio chatter through our caravan was both confused and delighted: We had actually never seen their car on the road before – we would always see them at the start line, and then at the finish line, with nothing in between. Seeing them pulled over, making repairs to their car, really drove home the point that the rain affects everyone.
In the middle of the stage, we slowed down to reduce our power draw to save up for the large hill that was to come at mile 100. Long story short, the hill was no match for us, especially when the sun came out around that time. We increased our target speed to 62mph and set our sights on St. Paul.
Following our third place finish in Normal, IL, another stage loomed in front of us: Normal, IL, to Verona, WI, to La Crosse, WI. Our strategy from the days before seemed to be working quite well, so we decided to apply that same strategy to this stretch: drive sustainably, such that our batteries neither gain nor lose charge, such that we could net a gain over the evening and morning charging hours. This way, we would also be somewhat protected from bad weather conditions, since if the sky decided to be cloudy, we would have battery power left to use.
Indeed, the weather became cloudy halfway through the first day of Stage 4, and our strategy paid off. We made it comfortably to the checkpoint in Verona, WI around 4:30PM, and achieved a nice 1-hour break in the cool, cloudy weather. Some other teams weren’t as lucky, however, since the combination of the heat and clouds from the previous days had caused them to drain their batteries, making this stage tougher to weather.
Leaving the fully cloudy checkpoint, we made it just 10 miles out of the checkpoint before it became apparent that it would be uneconomical to continue on. We decided to try to find a large parking lot to set up for the night and for the coming morning.
Yesterday, we drove 161 miles from Rochester, New York, to Erie, Pennsylvania, cautiously setting our speeds since the forecast wasn’t very pretty — most of our sources said that there would be rain and thunderstorms. But as the day wore on, it became evident that there would be no storm at least for the time being. We still proceeded with care through the stage, monitoring the charge on our batteries through telemetry in case the evening and morning solar array charging times didn’t give us enough to sustain ourselves on the upcoming 214-mile journey.
The efforts paid off immensely. This morning, we woke up at 5:30AM to a giant thunderstorm, and though the rain had let up by our charging time at 7:00AM, there were clouds all around, and it was moderately raining by the time we started driving at 9:02AM. Despite a few pullovers for various issues, such as to check the weatherproofing that we hacked together the evening before, Impulse ran surprisingly smoothly through the thunderstorm in the morning, only picking up maybe a gallon of water, while a few teams were unfortunately pulled over due to spinouts.
We arrived bright and early at 7AM this morning so that we could undergo our scheduled tests: the electrical system, battery protection system, and driver body/sizing. With the memories of the testing we’d done before this first day of inspection, there was a mixed air of both excitement and anxiety, as we would finally get an idea of what our hard work has come to.
What we didn’t expect was that a thunderstorm would blow in right after noon, right after we’d gone through our electrical systems inspection and come back with a list of things to do. Work slowed as everyone was drenched in the rain and solar cars disappeared under tarps. That didn’t stop the inspection process, however. Through the intermittent showers, the testing schedule continued right on, forcing everyone to make do with the protection gear that they brought.