A local group of guys decided to have a pinewood derby with no rules. The only stipulation was that we couldn’t cause harm to the track or spectators. We decided that this implied no combustibles. I knew the best way to win this would be some kind of CO2 powered vehicle. The bad news is that I was running out of time and didn’t know enough about CO2 valves to whip something up.
I decided to use the propeller, motor, and electronic speed controller from my Multiplex EasyStar RC Airplane. I also knew that only an autonomous vehicle would impress the crowd.
The track we were racing on held each car with a wooden rowel. The dowels dropped simultaneously to start the race. To make the car autonomous, I used a lever switch and the weight of the car to trigger an event to start the car.
The main controller of the car is an Arduino (yes, I know, I’m going against my own preaching). The Arduino held a simple state machine to control the motor. For safety reasons, I designed the state machine to only start the motor after the system had been intentionally armed.