The idea was to create a simple object that produces electricity. A swimming, mobile power station, consisting of as few, easy to get industrial manufactured components as possible.
Why do you use a tractor tire/tube?
The tractor tire is a familiar object from childhood, especially in combination with water.
It can be handled easily and has an extreme high load capacity. Furthermore, it is a perfect carrier object because the mechanics can be placed at its center. The tube is generally very robust, and even if it blows out, you can fix it quickly. Almost everyone on the world knows how.
We were faced with the basic problem of porous rubber because of the UV radiation. Considering the series production, we tested some things for UV stability. Rubber coating came out as the best solution. We also wrapped an elastic belt around the tube to protect it against flotsam.
Did you think about another floating body?
Yes, we added a second floating body with foam, which prevents the rotor from sinking in case the tire gets damaged. We experimented with PET bottles and water containers, but the simplest solution is foam.
We also built a second prototype with boat shape for better lift and flow, however, the additional weight and the production costs are disadvantageous.
What was your decision and why?
We wanted to use only materials that can be easily repaired or recycled all over the world, that’s the reason why we decided against a boat shape made of plastic.
There is another design with steel drums, it can handle the weight and is nearly indestructible because of its reinforcement. The drums can also cover the mechanics and are waterproof. The problem is the venting, cooling and condensation.
We also experimented with a combination form of tire and a boat shape in front of it. It works well until too much water spills over and the Rotor submerges itself.
The best solution is the tire; because you can fold it and simply inflate it on site it is also perfect for shipping. We tested different tires and decided in favor of the one with the best price-performance ratio.
What could be improved?
At the moment we are testing a light-stable belt stable, that gives the tire more stability, and offers protection from damage and UV radiation. Some kind of solid, light shell as cover around the tire would be ideal but is difficult to make.
Prototype with boat shape