After learning the unfortunate news that we would not participate in the Solar Car Challenge, Larsen Matthew Mendoza summed up our emotions: “It’s upsetting, it’s really upsetting, but it’s not about the destination but the journey.” So we persisted. Our focus shifted from the cross-country open-road challenge from Texas to California to an endurance challenge at home instead.
An endurance run tests the car’s capabilities and typically runs on a closed track to avoid interference with other vehicles, stop lights, and other hazards. Many of the top solar car teams in the world use short endurance runs to test their cars and the team’s capabilities. One common test is to drive as far as possible within 12 hours. The current world record holder is the Agoria Solar Team, with 1051 kilometers. We aspire! After the school year ended, we got to work to finish the car to take it to the PACCAR high-speed test track.
We are lucky to have PACCAR as one of our supporters. PACCAR is a global technology leader in the design, manufacture, and customer support of premium light-, medium- and heavy-duty trucks under the Kenworth, Peterbilt, and DAF nameplates; they operate a technical center and high-speed closed-loop test track location in Mt. Vernon, a short 90-minutes from our school. They have been very generous in letting us use the track on weekends to test our car and validate its systems. On 15 July, we had our first full test day.
We had four goals for the day:
- Validate Sockeye’s systems: Do the different components work as expected? Do the systems work together as expected?
- Get comfortable driving the car: What do drivers need to know and be able to do to manage the vehicle at slower or progressively higher speeds?
- Learn and refine communication protocols: Talking on the radio with multiple users (especially when one is driving a well-built but still experimental car!) is different than FaceTiming with your friends.
- Generate a power vs. speed curve: We know that increasing speed increases the power requirements by A LOT. To make an endurance run, we need to know how much.
Early in the morning, a team of four freshmen, three sophomores, two juniors, and one senior set off for what turned out to be a remarkable day. The day started at 0700 PDT with the two-hour drive to Mount Vernon (and a quick coffee break!)
After checking in and conducting the safety brief, we set up the tents, rolled the car out of the trailer, confirmed the radios were working, sent spotters to each corner of the 1.5-mile track, and set our first driver out for a couple of laps at relatively low speeds. As the driver cleared the corners, spotters waved and called out, sometimes taking interesting photos. Back at home base, the telemetry system collected speed, voltage, power remaining in the batteries, and two dozen additional parameters.
We repeated the process throughout the day with different drivers, enjoying the sun, each other’s company, and the flawless performance of the car. Our team’s mentor, Dr. Alain Semet, said we had “the best first run day at PACCAR ever thanks to [the team’s] hard work and dedication.”
Toward the end of the day, team captain Hagen Rankin insisted that Mr. McComb, the team advisor, take a turn driving the car on the track. He reports, “What a remarkable feeling to drive a student-built machine of this caliber! I acknowledge that I have high standards; the work students have done to create this car exceeds every other.”
By the end of the day, we had achieved each of our goals:
- The systems worked well individually and together. We have some minor issues to address, but it was nice to discover those issues in low-stakes situations, e.g., adding grip with more tack to the steering wheel.
- We understand the car MUCH better in its entirety. For example, we have regenerative braking. When we apply brakes, the motor becomes a generator replenishing the battery. And, as we predicted, it also causes the car to swerve a little to the right when braking.
- Our communication protocols are much tighter.
- We drove over 170 kilometers at various speeds and collected enough data to create a power vs. speed curve.
We look forward to using our newfound experience and data to plan our endurance run on Saturday, 22 July!