Paper airplanes demand precise placement of the creases, so don’t skip the introductory Symbols Key and folding tips presented in the next chapter, even if you have other paper folding experience. If the models you fold do not fly well, go back and master the simple, but critical folding techniques. In a short amount of time you will learn a lot about paper, develop fundamental folding skills, understand the symbols in an origami diagram, and learn what makes these paper airplane designs so neat.
Paper Selection
Paper selection for competition may be important, but for practice paper, just look in your recycle bin. You can find suitable paper for airplanes nearly everywhere. The designs presented in this book work well with the most widely available paper types: letter-size, 20-pound bond, and common sizes of square “origami paper.” Printer and copy paper is fine for any project in this book. If more types are available, use the heavier papers for simpler designs, and save the larger, lighter-weight papers for the more complex designs.
Paper is often supplied at a paper airplane competition (which simplifies the judging) but sometimes you will be given a choice. For competition, first select the best airplane design for the category (e.g., greatest distance, greatest time aloft, best aerobatic, best target accuracy, coolest design, etc.) and then select the paper for that design that works best for you. When you have a choice of papers, consider:
• Paper format
• Squareness
• Weight
• Thickness
• Foldability
• Rigidity
• Aesthetics (color, finish, graphics)
This photo shows an assortment of common paper rectangle types: square, 8 ½ by 11-inch US office paper and A4 letter paper.
Paper Formats
Most published origami paper airplanes have been designed to be folded from one of these three common, handy rectangles: square origami paper; 8½ by 11-inch office paper used in North America; or A4 letter paper used most everywhere else.
We have included designs for all three formats. We have also included instructions on how to produce these three rectangles from stock so that you may enjoy folding all of the designs, no matter what format of paper is handy. For practical purposes, rectangular papers can be expressed in terms of absolute measurements, aspect ratio and diagonal angle measurements. Understanding these expressions will allow you to scale rectangles into larger or smaller sizes as needed.
Avoid performance-affecting inconsistencies, such as the one shown in this illustration, by taking care to use only accurately, cut rectangles.
Rotate part of a stack of paper 180 degrees, square one end, and then check the other end for squareness.
You can also inspect squareness by folding a piece of paper in half to make sure that the loose corners line up on both sides.
Squareness
Many folders blame themselves if their folding seems off, without ever considering that the paper may not be cut properly. When you open a package of square origami paper, remove a few sheets from the center of the stack, rotate it 90 degrees, and align the ream with one edge of the stack on the table. If the sheets you turned stick out, either on top, or on a side, you know that paper was not square. Similarly, when you open a ream of office paper, turn a few sheets from the center around 180 degrees and align one end with a tap on the table. Look at the top edge to see if the rotated sheets are even along the top, or if they stick out at either side.
You can also try the following folding experiment. Take a sheet of letter paper and fold it in half, long edge to long edge. Are the edges and corners of the top layer matching those of the layer beneath?
Next, unfold the paper and form a simple “airplane point” at one end of the sheet by folding the two halves of a short edge to meet at the center crease. Do the two square corners meet?
Unfold the paper and try the same thing at the other end. It is not uncommon for a sheet to fail these tests for trueness. In most cases, trim discrepancies are slight and can be accommodated for folded paper airplanes. However, when the trim error is off by several millimeters you should consider re-trimming the paper to true it up. This will be especially important for performance-critical contest entries.
To learn if your store-bought origami paper is acceptably symmetrical simply fold the sheet in half diagonally, corner to corner. The edges and the free corner of the top layer should match those of the bottom layer.
Thickness
The planes in this book were designed to be folded from many common types and sizes of paper—either origami paper or 20-pound letter bond—but a general guide will be to use thinner papers on the complex models and thicker on the simplest ones.
There is also the issue of relative thickness, which can be expressed as a ratio of thickness to area. You can use a thicker paper if the area is increased, but thinner stock must be used if you decrease the area of the sheet.
If you were to graph the variables of the acceptable planes, you would determine the designs’ acceptable range of relative thickness. Each paper airplane design will have an optimum size for a given thickness. When designing new paper planes it is wise to keep the technical handling of the folds well within the doable limits of the paper with which you are experimenting. Some paper folding design plans may accumulate many layers in certain places, such as the nose or the leading edge of the wings. Choose paper thin enough to accommodate the folding in the thickest places of the model. If an airplane folded from thick paper does not perform well, perhaps that design should be folded from a larger sheet, in order to bring the design back into the “doable range” (or window of acceptability).
Weight
Most office and printing stocks fall into one of two types: “Bond,” and “Offset.” Each type has different weights, sold in packs, or reams, of 500 sheets. The ream is marked with a number indicating the weight, such as 20-pound (abbreviated 20 #, 20 lb, etc.). When you lift a 500-sheet ream of 20-pound bond, the first thing you notice is that it cannot possibly weigh 20 pounds. That is because all grades of bond are labeled with the weight, in pounds, of a much larger ream measuring 11 by 22 inches—which is called the basis size for bond papers.
It’s confusing, but reams of so-called “offset” paper stocks (including “book,” “text” and “coated” stock) used in professional printing presses are made by different machinery, so their weight is described by a different basic size sheet: 25 by 38 inches. You can’t compare the two types by only considering the area. The 50-pound offset stock is slightly lighter than 20-pound bond because the machinery that makes the offset paper uses a process that makes it thinner and denser.
The system is useful when comparing the weights of the same types of paper: 24-pound bond is 20% heavier than 20-pound bond