Returning to the Track with MSXII
By: Midnight Sun Solar Rayce Car Team
Tags: Solar Energy, Solar Power, University Of Waterloo, Race, Solar Car

Midnight Sun XII (MSXII) — 3rd place at the American Solar Challenge 2018

The Midnight Sun Solar Car Team has been designing and building solar-powered electric vehicles at the University of Waterloo since 1988. We proudly represent the University at the American Solar Challenge and the World Solar Challenge. While we have started designing our next vehicle, we will be returning to competition with MS-XII at the FSGP 2019.

The Formula Sun Grand Prix is an annual competition that brings together post-secondary students from around the world to race self-constructed solar-powered electric vehicles. With the next race only three weeks away, we are busier than ever preparing MSXII for its return to the roads for the first time since the 2018 American Solar Challenge.

After placing third last year at the ASC, we have set the bar higher and will be attending the FSGP 2019 with a fresh team of new leads and recruits. These last few weeks before departing for the competition are being used to make improvements to MSXII and vehicle testing at track days. Last week, we had our first track day of the term, where we conducted roll-down and brakes tests.

UW Midnight Sun Solar Car Team arriving bright and early for track day

By 9:45am on June 1st, the team was packed and ready to rollout. Guided by police escorts, we drove MSXII from our work bay to one of the University of Waterloo’s campus parking lots, the testing location for the day.

We started with roll-down testing first as the weather forecast predicted that the winds would be higher later in the day. The roll-down test is used to determine the aerodynamic losses and the rolling resistance of the car . It consists of accelerating the car to a desired speed, and once achieved, the driver removes their foot from the accelerator and waits until the car coasts to a stop. We then obtained a relationship for aerodynamics & rolling resistance by plotting telemetry data on a speed vs. time graph. Additionally, wind speed and direction were measured using an anemometer, which were then factored into our calculations.

During preparation for brakes test, we noticed that the vehicle was taking longer than expected to come to a stop. On one of our practice runs, we accelerated to ~36km/hr and it took 4.6s for the car to come to a complete stop after flooring the brake. We then found that brake fluid was leaking from the front wheels, which put our testing on hold. Over the next two hours, the mechanical team removed the wheels and took off one of the brake calipers. After replacing the caliper, the mechanical team re-assembled the wheels and bled the brakes. Finally, the car was ready to resume testing at 5:30pm.

Rolldown testing in progress

The brake test involves the vehicle reaching a certain speed, then braking when a flag is dropped. Using a stopwatch, the deceleration of the vehicle can be determined based on its initial speed and time to come to a complete stop. To qualify for the race, teams must pass an official brakes test where the car must decelerate to a stop within a tenth of the speed of the car in miles per hour (i.e. if the car is travelling 30mph, it must stop within 3 seconds). This year, our brakes have been remodelled with a new master cylinder and during our track day wet brake testing, MSXII managed to stop within the required time frame. However, the top speed MSXII hit was 26mph, and with the real test being run at 30mph we will need to test in proper conditions before concluding that MSXII will consistently pass.

Firmware and Hardware teams inspecting Solar Array System

Leading into next week’s track day, the team is looking to have the entire car put together and fully prepared to do simulated scrutineering and dynamics testing on the emergency services track nearby. The team will be pushing hard this week to make final adjustments and calibrations leading into the second round of testing to be ready for the FSGP.

See you at FSGP 2019!