Origami with Fluid

In this section, I briefly explored what happens when origami and fluid are together.

Water and Origami Boat

Origami boat with flat bottom

These are three examples of flat bottom origami boats. Although their shapes are different, they all need to be turning inside out as the last step of folding. On the water, all three origami boats are very stable. The blue boat has an upturned bow due to shape.

From the wet area of the bottom of the boats, due to some errors in origami, these ships are not completely symmetrical. The hull will tilt slightly towards the heavier side, causing the hull on one side to become slightly wet.

Origami boat with edge as bottom

Here are two common origami boats that use the edge as bottom. On the water, the performance of the two boats is very different. The orange boat, which has double edges, is more stable on the water. While the red one’s hull is actually in contact with the water, instead of the bottom edge.

Air and Origami Aircraft

Paper plane

There are many different folding methods for paper planes, but the final shapes are all similar. Most importantly, they all have a heavier head, and they all need a forward force when they are thrown.

Origami hang gliding

The yellow origami gliding wing is heavier in the middle and lighter on the sides. It will rotate autonomously when landing. No initial power is required, letting go from high to glide.

The purple gliding wing mimics the shape of the space shuttle, but during testing it was found that it did not stay well in the air. It needs a forward momentum and then flips after a brief glide in the air.

The blue origami gliding wing has a heavier front and smaller wings. No initial power is needed, and after letting go from a high place, it will automatically glide forward for a long distance.

Origami with air blowing

In the Yoshizawa–Randlett System, there is a special symbol for inflating an origami.

For example, the paper lantern we folded before needs to be inflated as the last step. Many other origami that require air blowing are similar in shape.
Another type of origami is that it will have some movement with air blowing. For example, the Kresling pattern tube we had for Origami for a wind sensor will stretch during blowing.
The small rocket below can also be launched by blowing into the straw.

Enjoy this video from testings ︿( ̄︶ ̄)︿

Pop-up Book

Here is the first pop-up book I ever made:

There are total of 11 pages, I integrated some basic paper actions and used them in this book. As I am making this book, I understand the paper movement more clearly.

If we look at it mathematically, every paper movement follows some laws. For example, each movement involves changing the angle in three dimensions. The most common change is that the angle between the two faces increases, so that the part that pops up can be supported when the page is opened, which means that the support structure will be somehow symmetrical. If we can summarize such paper movements with mathematical models, we may be able to draw more possibilities through such these models in the future.

Origami for a wind sensor

For the MOOG HACKATHON 2020, our team would like to make an e-trombone, and I am trying to design an air flow sensor with paper. This is mainly because the current air flow sensor on the market is not sensitive enough to meet the needs of playing musical instruments. The initial idea was to use carbon coated paper to build the sensor.

I first created a CAD model of the trombone and 3D printed the mouthpiece. In order to observe the effect of the airflow on the paper during the blowing, I pasted some small pieces of paper on the end of the mouthpiece and recorded the slow motion video of different blowing.

The performance of paper is completely different under two different ways of blowing. When only blowing air, the paper sheet will be slightly inclined inwardly. When blowing with the lips vibrate, the paper will vibrate according to the frequency of the lips.

Through this experiment, I can conclude that using the carbon coating paper to build the sensor was not feasible. Which means we may have to add the light to make the sensor. The current idea is to keep the current paper and mouthpiece design and add light-related sensors to the blowpipe.

I also tried the Kresling pattern, which allows me to make a scalable feature. My original expectation was that it could retract itself when the blowing stopped, but during testing it was found that it would slowly unfold and only fold again when breathing in. This origami can be used to make a harmonica, which needs both inhale and exhale.

Yoshizawa–Randlett System

This week, I learned about the Yoshizawa–Randlett System. This system was created by Yoshizawa, then translated and organized by Randlett. This system is now considered as an international standard. These symbols can be found on Wikipedia: Yoshizawa–Randlett system

Based on these symbols, I recorded my process of folding paper lantern:

Through this process, I found that the Yoshizawa system still has some defects. For example, some symbols are not easy to understand; for the process of inserting after folding, it cannot be expressed in detail. I bought the book The Origami Bible in the hope that I can learn more about how to show the the origami process.

Yoshizawa also created the Wet-folding. This method will wet the paper then easily fold it.This method is more commonly used for folding non-geometric patterns, such as animals.

Another commonly used system is using black lines to show cut, red lines as mountain fold, and blue lines as valley fold. These usually whos in the crease patterns, a.k.a. CP diagram. This method is very helpful in analyzing the geometric pattern of origami, but it does not communicate the steps of origami well.

Origami with Non-square Paper

I observed some origami creases and came up with the assumption: round paper can do the same job, but with less paper, and there are even more possibilities.

I originally planned to fold out the paper cranes. But when I faced a round piece of paper, I completely forgot how to start. This is a very strange feeling. Then I noticed that for the same crease, square paper can have two different results, but round paper has only one result.

Square origami seems to be easier, because line-to-line alignment is used for folding, while round paper requires using dots as a reference. Along with my self-doubt, I finished the paper crane with the round paper.

From this origami, I think my initial assumption was wrong. But I want to prove it wrong from another angle, so I did some analysis on the origami cp (crease patterns) diagram. I add a circle to the cp diagram I found online.

After comparing this picture with my actual origami, I found that they are different. In the actual folding, I intentionally modified some crease patterns to create acute angles and straight edges. From the results, the round paper cannot show the angles when folding the paper crane. The convex part in the middle of the paper crane is similar in size, but the round origami lacks corners, so the result of the square origami is more slender.

What if we avoid origami that emphasizes corners? With this question, I completed the following two origami.

The first one is a paper bag, while rounded edges make this origami easier to close and open.

The second one is an umbrella. Round paper can also be used to make paper umbrellas directly, while square paper needs to be cut into polygons.

In addition to square paper, rectangular paper is also widely used. Take the Sui’s sewing organizer bag I made earlier as an example, rectangular paper with an aspect ratio of 1: 2 is used many times.

Trapezoid paper based on rectangular paper can make some origami that is layered and deformable. Below is an origami toy I made this week.