How to Make a Balloon Car

A balloon car is an innovative science fair idea. It allows children showcase their engineering skills by building the car and also enhances their knowledge by presenting an opportunity to apply laws of classical Physics.

Science Project Experiment on Balloon Powered Car

Materials

• Corrugated cardboard or foam core
• Regular cardboard
• Wooden barbeque skewers
• Tape
• Straws
• Wire Cutters
• Balloons
• Scissors

Instructions

1. Using a pair of scissors, cut out a 6X3″ piece from a foam core or a corrugated cardboard. This will make the chassis of your car.
2. Use the wire cutters to snip a couple of 4” pieces of wooden barbeque skewer. It will serve as the axles.
3. The axles need to be mounted on the chassis in such a way that they can rotate freely. For the mounts, you need to cut two 3” sections of straw. Tape them along the breadth to the frontal and rear portions of the chassis.
4. Place the axles on the mounts.
5. Insert the wooden skewers through the center of the straws.

6. Now for the wheels, cut four quarter-size pieces of plain cardboard. Trace out circles of similar sizes on them and cut them out.
7. Fix the cardboard circles onto the ends of the skewers. Wheel mounting is complete.

8. Cut off the mouth ring from the balloon to enhance its seal with the exhaust pipe. The mouth ring is nothing but the lip of the balloon that you blow air into.

9. For making the exhaust pipe, insert a straw by 1 inch into the balloon. With the help of a tape, securely fasten the junction.

10. Mount the exhaust pipe in such a way that the separation between the straw and balloon connection and the end of the chassis is 1”. It is better to tape this point to the frame. Ensure that the open end of the straw points straight out of the chassis.

11. Inflate the balloon and press the opening of the straw with your hand to preserve the air inside. Place your homemade balloon rocket car on the ground, remove your hand and let it run.

Balloon Rocket Car Video

Balloon Race Car Designs

You can give wings to your creativity by rendering some quirky designs to the chassis to make your balloon car look fresh and funky. Instead of using the same supplies mentioned above, consider making the frame with things such as ice cream sticks, thin plastic tubes, empty milk or juice carton with one side chopped off, etc.

Another style of balloon cars, for this one, first use your imagination to construct LEGO cars in various designs. Then, put a few blocks at the back of your cars to hold the balloon straw ensemble. Making a wide lightweight car makes the structure more stable and prevents it from falling over.

Variations in Balloon Car Wheels

Small plastic bottle caps or any round structure, like candy mints with a central hole or CDs, can also serve as car wheels. Take the help of dry sponge, marshmallows cut in half, clay, foam, chewing gum or hot glue to connect the wheels to the axles.

Ideas to Make it Faster

Decide on the best design of balloon race cars by trying on wheels of diverse sizes since that influences how far the car can go. You can also trim the exhaust straw to various lengths or use straws having different diameters to check which system supplies maximum thrust.

A small amount of friction is necessary for propulsion. Making the surface of the wheels a little less smooth, increases the resistive forces and eases the movement on a surface. Fastest cars with high momentum have their balloon straws parallel to the plane on which they race.

A Few More Useful Tips

• Reduce the weight of the car as much as possible so it can run easily.
• Lessen the drag of your car by giving curves and wedge shapes to your vehicle. Ensure the frontal portion does not have a large flat surface.
• Lubricate the axles and axle tubes generously to reduce friction among the internal parts during movement.

Physics Behind Self-Propelled Balloon Cars

According to Newton’s third law of motion, every action has an equal and opposite reaction. This means that if an object A pushes another object B with a certain amount of force in one direction (action),  object B will put the equal force on A, but in the opposite direction (reaction). When the air stored in the balloon rushes out through the narrow opening in the straw, it exerts a force on the car (action). The car, in its turn, exerts an equal and opposite reactive force and is propelled forward.

The results are also in accordance with the law of conservation of energy. The potential energy stored in the balloon, is converted into kinetic energy when the air rushes out of it, causing the car to move.

Kids will not only love this activity, but they will also be happy with their own versions of jet toy cars. It is not every day that they engage in studies and end up with an exciting object of play.

References:

http://www.stevespanglerscience.com/lab/experiments/balloon-powered-race-car

https://www.questacon.edu.au/outreach/programs/science-circus/videos/balloon-powered-car

http://www.sciencebuddies.org/science-fair-projects/phpBB3/viewtopic.php?f=2&t=1955

http://www.science-sparks.com/2014/08/18/balloon-powered-lego-car/