#4 Reflect and Share


This is my final product. The picture and the video already appeared in the previous blog post, but they are presented again for convenience. This model is able to adequately convert elastic potential energy into kinetic energy to power a propeller. However, it does not work due to the high mass of the whole model. The kinetic energy generated from the rubber band releasing its elastic tension was not enough to power this model. Occasionally, with the right conditions, the propeller will move the car a few centimeters forward, but this process is not stable and makes this rubber band-powered car nowhere near its optimal functionality.

Of course, when building this model, some risks had to be taken, as the original design (idea taken from a YouTube video) was built out of a lightweight plastic bottle and a bottle cap to hold the propeller in place. Some creativity was required to find a way to hold the propeller in place, determine an optimal length and width to accommodate the wheel axles and rubber band length, etc. In this case, the risks did not resolve as they should have, making the design not work. However, I spent a good amount of effort into this project and I was still able to explain the conversion of energy by explaining the balance between mass and kinetic energy.

#3 Create and Improve

These are the materials that I gathered (from the first class). I will be using these materials to create my prototype. My original work plan was to use wood, but I believed that wood would be too heavy and time-consuming to work with, so I substituted cardboard for it instead.

As this is from the first work period, I do not have much to reflect on, but even if my design does not work, I hope that I can learn something from this project.

Using the materials that I cut and picked up from the first class, I started to build my prototype car. I met some problems, e.g. the propeller was situated too low to spin without hitting the ground, so I had to come up with creative solutions that changed my plan a little as I was not expecting these problems when I created the plan. Unfortunately, I do not have a test video of my final prototype, but the car worked – except that it was too heavy to be moved by the propeller.

Here is a photo of the finished prototype design. More rubber bands can be hooked onto the paper clip if necessary. I did not pay much attention to aesthetics, as this is a prototype and I had to see if my design worked.

The third and fourth classes were dedicated to building my final project. Because the propeller seemed to be too weak to push such a heavy object forward, I attempted to counter this problem by using a bigger propeller. I also used a smaller and more compact design to reduce weight. Some of the materials from the prototype were recycled for this design, some were given away to other people, and some were scrapped to be used again. I used white cardboard, as it looks brighter and complements the black wheels + propeller better.


This is a downloadable video of the final prototype in action (spoiler alert: it doesn’t work). The final prototype is quite unstable, but at least sometimes it moves a little. The last blog post will cover more of the reflection on this final design.