Basically, splitting your class into groups, your students come up with designs for a CO2 car. A CO2 car is powered by a small CO2 canister inserted into a cavity in the rear of the car. Small eye hooks are attached to the underside of the cars and fishing line is drawn out along the length of the track to the end block. Cars need to be started simultaneously for races and so a starting block is required. You are going to need a good level surface for the race of around 20-30m to avoid cars smashing into the end wall.
So what can your students learn? Well it addresses issues around Newton’s laws of motion, mass, drag and friction. In general it is a question of lighter cars with greater force going faster but their is a cost in terms of stability. Additionally it is a project that requires all the stages of manufacturing in the sense that your pupils are given a design brief, they come up with some initial designs and then build the prototypes and test them.
Some tips are check the wheels are free to rotate and Make sure that the eye hooks on the underside are aligned properly as otherwise it will increase friction.
You will need:
- a 3D printer
- some suitable 3D modelling software to produce the required files
- some suitable CO2 canisters, they are commonly found in Bike shops
- enough 3D printer filament, either ABS or PLA
- Fishing line
- eye hooks
- a starting block, possibly a finishing block too
As to the structure of the project you should first create a design brief for the students to follow. The students then need to brain storm some designs on paper in order to bring it to the next stage of the manufacturing process. Once a final design is selected (you could allow prototyping if you feel that you have the time and resources) a final, accurate drawing needs to be made in order to lead into the production of the model files. You can use the .STL files from our site as a starting point for the model files. Once the files have been constructed for the final design the model can be printed. Don’t forget its possible to test out different materials as well, so for example you could try using ABS or PLA filament.
The starter block requires a bit of thought and you will have to experiment with this your self. We have drawn an illustration to give you some ideas but we do not guarantee its safety.
Take a look at this video to see how it can work:
You can find the designs on Thingiverse