Hobbies And Interests
Pinewood Derby Car
Building a derby car is a study in simplicity. Kits are available at any hobby store, and depending on the level of woodworking skill you possess, these cars allow a huge range of freedom in design. If you are intending to enter the car in a derby, stick to your contest's rules. Most have weight requirements as well as width and length guidelines. Beyond that the design is totally up to you.
The wheels are plastic and attach with included hobby nails into pre-drilled grooves. You may want to sand down the plastic molding ridge present on most wheels. Use a fine-grit sandpaper and sand little by little, making sure not to flatten the wheel in any places.
Solar Powered Cars
You can make a solar powered car in many ways, but hooking up a solar panel directly to an electric motor is the simplest. Connect the motor to an axle by way of interlocking cogs. You can buy a basic kit with an electric motor and wheels at any hobby shop, or you can source them from an older toy car to simplify this process. Otherwise you're going to have to mix and match parts and possibly build your own.
Once you have a motor that spins wheels, you can use anything for a body. Many people simply use an old plastic soda bottle because it's lightweight and doesn't require much in the way of an electric motor to move, so it goes faster. Keep in mind that you want it lightweight but also big and strong enough to hold your motor, wheels and solar panel.
Obviously, the bigger the panel, the more electricity it will generate, so make sure you have a motor that can handle it and won't be over-driven by excess power.
Balloon Power
Another popular toy racing car revolves around using a balloon for propulsion. If you intend to make your own rather than buy a kit, keep in mind the limitations of balloon propulsion. While gravity and solar power are rather constant sources of power, a balloon will provide a short burst of power and then run out. To get the most speed and distance out of this power delivery, you'll need a small, lightweight car body and a way to make sure the balloon doesn't come free.
A small piece of cardboard with wheels is actually a perfect setup. Source wheels from any sort of building toy kit like K'nex or LEGO. Once you make sure that everything rolls freely, attach the balloon. Because you can't pierce the balloon, you must either find or build a bracket to hold it in place by wrapping around the neck. Getting a heavy plastic drinking straw and cutting off a length long enough to tape down works wonderfully. Just thread the mouth of your balloon through it.