Wind power is not only a renewable energy source that can be used to power buildings and homes, it is also an energy source that can be used to power an experimental model car. Balsa wood cars can be built to be powered by a number of things, from mousetraps to gravity. With the proper design, however, a wind-powered car can go further than any other design. In a few steps, you can make your own wind-powered, balsa-wood car for your science class.

Cut out two rectangular strips of balsa wood that will serve as the sides of the body of your vehicle. For the example, the strips will measure 5 cm (2 inches) wide by 20 cm (8 inches) long, giving the car an overall length of 20 cm. Use a compass and utility knife to measure and cut a hole with a diameter of 16 mm (5/8 inch) 40 mm (1.5 inches) away from the ends of each strip. The holes must be in the same location on both strips, so that when you place the strips together, the holes line up.

Cut out a square piece of balsa wood whose sides measure exactly half the length of your vehicle. For the example, the square piece's sides would measure 10 cm by 10 cm (4 inches by 4 inches). Use a compass and utility knife to measure and cut a hole in the centre of your wood square that is roughly 6 mm (1/4 inch) in diameter.

Measure one-quarter of the length of your car from the ends of each wood strip and mark the measurement. For the example, a mark would be made two inches from the ends of each strip. Connect the markings with a straight line and cut a 1.5 mm (1/16-inch) slit along this line. Make sure the slit is in the same location on each wood strip. If you measured correctly, the slit should be the same length as the wood square you made in Step 2.

Apply a small amount of wood glue to two parallel edges of the wood square. Insert each edge into one of the slits you made in Step 3. Let the glue dry for several minutes before continuing.

Cut two balsa-wood dowels to a length that is 1.5 times the width of the wood square you made in Step 2. For the example, the dowels would be 15 cm (6 inches) long. Insert the dowels through the holes you made in the strips in Step 1. These will be the axles for your vehicle.

Wrap masking tape around each end of the axles until the diameter of the wrapped tape measures nearly 16 mm (5/8 inch). These masking tape ends will serve as a plug for the centre of the CD wheels. One at a time, apply a small amount of cyanoacrylate glue to the outside of the masking tape plugs and insert the plugs into the centre of the CDs. Hold to the CDs in place for several seconds to allow the glue to dry before moving on to the next wheel.

Apply a thin layer of cyanoacrylate glue around the perimeter of one of the CD wheels and stretch a rubber band around the perimeter of the wheel. Hold the rubber band in place while the glue dries. Repeat for the other three wheels.

Cut two dowels to the length of your car. For the example, these dowels would be 20 cm (8 inches) long. Cut a third dowel to the length of your car, plus 5 cm (2 inches). For the example, this dowel would be 25 cm (10 inches). Make one notch in the longer dowel 5 cm (2 inches) from one end and another notch at the very tip of the opposite end. These notches should be 6 mm (1/4-inch) wide (the width of your dowels) but do not have to be any specific depth. Avoid making notches with a depth that is more than half of the width of your dowel (more than 3 mm (1/8 inch)).

Make similar notches in the exact middle of the two shorter dowels. For the example, each shorter dowel would be bisected by a notch that was 10 cm (4 inches) from each end. Apply a small amount of wood glue to the inside of each notch and insert the shorter dowels into the notches in the longer dowel so that the notches in the shorter dowels line up with the notches in the longer dowel. This is the frame for your sail.

Cut a rectangular piece of fabric with two sides that are equal to the length of your car and two sides that are equal to the length of your car, plus 2.5 cm (1 inch). Apply a small amount of wood glue along the length of the short dowels on the frame you built in Step 9 and glue the short sides of the fabric along the length of the short dowels. Let the glue dry for several minutes before continuing.

Apply a small amount of wood glue to the end of the long dowel. Insert the dowel into the hole you cut in the square piece you made in Step 2, with the sail facing the front of the vehicle. Hold the sail in place for several minutes or until the glue is dry enough to hold the sail in place.

#### Tip

Avoid making a car that is longer than 30 cm (12 inches).

#### Tips and warnings

- Avoid making a car that is longer than 30 cm (12 inches).

### Things you need

- Ruler
- Utility knife
- 1.5 mm (1/16-inch) thick balsa-wood sheets
- Compass
- Pencil
- Wood glue
- 6 mm (1/4-inch) diameter balsa-wood dowels
- 4 CDs
- Masking tape
- Cyanoacrylate glue
- Fabric
- Scissors

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