Draft model 03 - Round tube test & Resilience test

I prepared balsa wood for trial testing. It is lightweight and easy to shape.

I found a gel pen refill (with a stiff shape), which is relatively thin, and is suitable for the middle round tube test in combination with the hot melt glue gun back cover. At the same time, I also looked for a thicker straw comparison test. The bottom is equipped with spring and rubber materials for resilience test.

During the experiment, I found out that the gel core is about 4-5mm in diameter and 2.5-3mm in inner diameter is very slim. For raindrops, if the entrance is too slender, it will be difficult to gather into it. At this time, the air pressure in the tube is greater than the water pressure, and it is too light to produce sufficient pressure on the spring.

But for straws with a larger diameter, the hydraulic force is greater than the air pressure. Raindrops can easily gather inside the tube, and for soft rubber, it can be squeezed to the sinking position more easily.