Why “Ra”? Ra, in fact, was the ancient Egyptian god of the sun. Appropriately, Ra’s symbol was the falcon, representing not only Ra 7s’ source of energy, but also speed, agility, and precision.
Ra 7s is a modified version of our previous car Ra 7. The main change is from a Gallium Arsenide Array to Silicon Array. When it came time to design Ra 7 we took inspiration from the Massachusetts Institute of Technology (MIT) 1995 Manta car. We chose this design because of its aerodynamic characteristics and the ability to put our driver in the needed seating position required by the WSC 2009 regulations. Our objective has always been to make the most compact, aerodynamic, and efficient car we could.
Electrical
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 7s features a 6m^2 Silicon Array.
The Battery Pack
The car battery pack uses Dow Kokam Superior Lithium Polymer Batteries.
The Motor
The car runs on the NuGen Mobility SCM150 motor.
Mechanical
The car’s mechanics can be broken down into four parts: the chassis, movable fairings, braking system, and steering.
The Chassis
The chassis is the frame of the car, made from aluminum 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.
Movable Fairings
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.
Braking System
The car brakes using standard bicycle brakes on the front two wheels. The back wheel (where the motor is) has regenerative braking, which is connected to the electronics of the car.
Steering
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 steering column also encloses the electronics connected to the driver display on the steering wheel.
Body
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.