Why “Ra”? Ra, in fact, was the ancient Egyptian god of the sun. Appropriately, Ra’s symbol was the falcon, representing not only Ra 9’s source of energy, but also speed, agility, and precision.
Ra 9 is a complete redesign, unlike any of our previous cars. Ra 9 was built because of a regulation change for the World Solar Challenge mandating a four-wheel car. Since we had to design and build an entirely new body, we also decided to redesign the electrical system, simplifying driver controls and implementing a new BMS.
The car’s electrical system can be broken down into three parts: the solar array, the battery pack, and the motor.
The Solar Array
Ra 9 features a 6m^2 Silicon Array.
The Battery Pack
The car battery pack uses Nomura Superior Lithium Polymer Batteries.
The car runs on a DC Brushless hub motor manufactured by Mitsuba.
The car’s mechanics can be broken down into four parts: the chassis, movable fairings, braking system, and steering.
The chassis is the frame of the car, made from chromoly steel for its strength to weight ratio. It houses the driver, batteries, and many of the car’s electronics. The chassis also holds the wheels and body of the car together.
The fairings are the parts of the body that cover the wheels. The two front fairings are connected so that the wheel pushes them out when the car is turning.
The car brakes using brake discs modeled after bicycle brake discs on the front two wheels. The back wheels (where the motors are) have regenerative braking, which are connected to the electronics of the car.
The steering wheel is connected to a steering column, which runs to the front of the car and connects to the two front wheels.
The body of the car is made from nomex honeycomb core sandwiched between carbon fiber. It is held together by epoxy. The shell of the car is made using two fiberglass molds – one for the upper body and the other for the lower body – to hold the shape the nomex and carbon fiber while they bond together and harden. The two halves are then shaved down slightly to fit together, since the initial shapes inevitably don’t match up perfectly.