Lightweight Balloon Air Jet Powered Car

This is a car powered by the jet of air from a balloon. It was created to make science more fun for students in elementary school. The specific use was in a third grade class. I started reviewing designs on the internet but most of these were too heavy or fragile. I designed a lightweight and sturdy model that can be completely 3D printed and only weighs 24 grams. Experiments led to a nozzle size that lets the air exhaust slowly and provides relatively long-term thrust for the car. The plastic axel also reduces friction. The result is that the car goes fairly straight and can travel more than 40 feet on a smooth flat surface. 

All five videos listed below describing how this car was designed, and how it is printed, put together, and run are available at https://www.youtube.com/playlist?list=PLk3mG32Gj7lNOTcP79Jrg8bSVp16D5dEq

A video describing the design process is available at https://youtu.be/0ieO7YYvCm4?si=i7DYFe49AwidcGwx

A video showing the car going more than 40 feet is available at https://youtu.be/igYDiwf79-w?si=B6dM9p3ZMm35rD_9

This car can be used to explain action/reaction where the jet of air action leads to the car reacting by moving. It also demonstrates how the potential energy in the balloon leads to kinetic energy from the car. Finally it shows how the momentum from the air jet is opposite to the momentum on the car. The car goes faster the lighter it is due to conservation of momentum. Students can also practice graphing by measuring how far the car goes with different numbers of puffs of air used to inflate the balloon. I printed ten cars for use by the class and provide extra balloons and wheels.

As the parts on the print plate show, the wheels print in two parts. One part has the axel and the other is a wheel that snaps onto the axel. You might need to tap the wheel onto the axel gently. Also, as shown, I print the body with tree supports that snap off easily. It is curious that one of these supports goes through a hole in the flat front of the body.  When you put the balloon on, try to center the balloon on the upper support so it stands straight up when it is blown up. Blow the balloon up through the exhaust tube in the back.

A video showing how to remove the tree supports is available at https://youtu.be/RupuR3_qDAY?si=yXFxllsunyS-vmnQ

A video showing how to attach the wheels is available at https://youtu.be/PI45U7FezAE?si=efLgHERm2mWlbdKE

A video showing how to blow up the balloon and run the car is at https://youtu.be/5YOoDUdAnwk?si=UHT0PN7wQeOu-ENf