There are a lot of moving parts at a race and a lot of planning that goes into traveling to Texas, but perhaps the most important variable is our race plan and the strategy that goes along with it. Logistics and travel plans are important to make sure the team arrives on time and are prepared for the race, but the race changing aspect of the strategy is ever so important and interesting.
The strategy encompasses a variety of variables that we can and can’t control. In our design and manufacturing phase, we start to look into where we can save weight, make the car more aerodynamically efficient, and other various steps to make the chassis as lightweight and efficient for the race as possible. Once the chassis is built we start to focus on the bodywork of the car to make it aerodynamic, once these sections of the car are complete, they are incredibly difficult to change so we make sure to put time and focus on the design portion of the car. We design and create our energy systems based on reliability and efficiency, every amp matters at the race. Solar panels are also a major component of the car as well, we also take time designing and perfecting the system the best we can to gain every advantage at the race. All these components make the slight difference between winning and losing, and we need every advantage to make sure our car can run as efficiently as possible.
The goal of the race plan is to understand all the variables the best we can and prepare for all scenarios. The most important part of our race strategy is data, the more data we have, the more informed decisions we can make to improve our car designs, and make pivotal race decisions. We get this data by testing our car around various tracks. We test our car on the track PACCAR to best mirror the Texas Motor Speedway’s oval circuit. We test for several different reasons, most obviously is to gather data, but we also test to make sure our car is reliable and doesn’t break down in the middle of the race.
The two key things we test and simulate in testing are energy consumption and energy regeneration. Our first goal in testing the car after reliability is finding the most efficient speed the car can travel out. Our electric motor has an exponential energy to speed relationship and our job is to find the most efficient range for the car to travel at, this takes a lot of time and runs at different speeds to make sure we have an accurate estimate. Usually, the most efficient speed is between 30-50 km/h, and this range is dependent on the design factors we implement like weight and aerodynamics. The second thing our team tests for is the amount of energy the solar panels can capture, a major obvious obstacle is our location, the race occurs in Texas while we test in Seattle. So we test for several main things, first how efficiently do our solar panels capture the energy and are they capturing the maximum amount of energy possible. We test this a portable solar panel array before it even goes on the car, and then while we do our energy runs we are also simultaneously collecting the energy recovered from the panels. We then collect data from NASA and other various weather organizations to best simulate the energy we would recover with Texas sunlight to the best of our ability. We then compile all the data to make our race plan, we estimate the amount of energy we will use while driving each day and add a conservative estimate of the energy we will capture from the sun while driving. Based on how much solar energy we capture, we then either speed up or slow down to make sure we have a full battery for the next day and enough to finish the race.
Here is our 2019 motor power to speed chart. On the left, you can see all our plot points and the general trend our car followed, as predicted 30-50 km/h was the most efficient speed for the car. On the right is a more selective group of data taken from testing that best shows the energy usage compared to speed while at a constant rate, making a more accurate graph to take data from.
Strategy is the most powerful tool in the race, we can predict the correct speed to maintain to maximize the distance we can go. Solar energy is also of massive importance in the race as well and can make a huge difference to the final number of laps all teams travel, however, this is a universal benefit to all the teams and is unpredictable. We as a team take a great deal of time and go to extensive lengths to know all the factors and maximize the performance of our car and the strengths of our design. Our 2021 plan will be modeled after our 2019 plan with some minor improvements, however, we will be dedicating more time and energy to test and gain any advantage we can from the car.