Parts

When you have selected a part, additional dialog boxes appear allowing you to choose the material and dimensions of the part.

Your car is composed of the following parts:

• Outer layers: These are the left and right outer walls of the car body.
• Inner layers: These layers, stacked together, form the inner part of the car body, held together by the outer walls. The large round hole in each inner layer forms the chamber in which the spring resides.
• Wheel tread: This is the tread, such as a rubber band, that will be wrapped around the edge of the drive wheel to provide traction. It is assumed to have zero weight.
• Drive wheels: These are the wheels that propel the car. They should be connected rigidly to the drive axle. The drive wheels cannot be smaller than the outer diameter of the spring case, because then they would not reach the ground.
• Other wheels: These are the wheels that do not propel the car (they rotate freely). They should be rotatably attached to the Other Axle (see below). For example, in a rear-wheel drive car, the Other Wheels are the front wheels. A four-wheel-drive car does not have these wheels and they will not figure into any calculations.
• Spring: This is the wind-up, spiral spring that powers the car. This type of spring is also known as a power spring or clock spring. It is a rolled-up ribbon of plastic material cut from the walls of a common 2-liter or other size soda bottle, which is made of PETE (polyethylene terephthalate). One end is attached to the drive axle by thumbtacks or staples, and the other end is attached to the inner wall of the spring chamber (usually at its top) by a paper clip or other device.
• Drive axle: This is the axle that is connected to the spring and to the drive wheels. It helps propel the car.
• Other axle: This is the axle on which the Other Wheels rotate. For best results, the Other Wheels should rotate freely on this axle, and the axle should not rotate (should fit snugly) within in the car body.